Windows media format 9 series что это

Codecs to work with WMA version 9

Works under:

Other programs to consider

AC’97 Audio Codec

A tool meant to be used with its namesake chip

dBpowerAMP

Convert to WMA and from WMA to other formats

LAME (Lame Ain’t an MP3 Encoder)

MP3 file downloader and encoder — closely secure your precious audio files

VLC media player

A powerful open source multimedia application that streams audio and video in several formats

Leaving without your download? Get alternatives to Windows Media Format 9 Runtime files

A tool meant to be used with its namesake chip

Convert to WMA and from WMA to other formats

LAME (Lame Ain’t an MP3 Encoder)

MP3 file downloader and encoder — closely secure your precious audio files

A powerful open source multimedia application that streams audio and video in several formats

4.28 /5 голосов — 135 Лицензия: Бесплатная Версия: | Сообщить о новой версии Обновлено: 01.03.2003 ОС: Windows XP, 2000, 2003 Интерфейс: Английский Разработчик: Microsoft Corporation Категории: Кодеки, декодеры — Кодеки, декодеры Загрузок (сегодня/всего): 0 / 56 494 | Статистика Размер: 1,35 Мб

Пакет всех самых необходимых кодеков, фильтров и плагинов для безпроблемного и.

Media Player Codec Pack — пакет кодеков для воспроизведения практически всех современных аудио и.

Windows 7 — набор самых необходимых кодеков для просмотра видео наиболее популярных форматов.

Codecs for Windows XP and Vista — огромный сборник всевозможных аудио/видео кодеков и фильтров для.

K-Lite Codec Pack Update — пакет обновлений кодеков, фильтров DirectShow и сопутствующих утилит из.

FFmpeg — нужный и важный набор библиотек для работы с видео и звуком. Позволяет записывать.

Отзывы о программе Windows Media 9 Series Codecs Package

Онега про Windows Media 9 Series Codecs Package [29-07-2009]

я скачала и установила,но проблема все та же.пишет ошибка загрузки кодеков.уже не знаю что делать.как это исправить?
2 | 3 | Ответить

John про Windows Media 9 Series Codecs Package [09-04-2007]

Все не учшего мнении надеюсь на 11й медиа пойдёт
2 | 2 | Ответить

миша про Windows Media 9 Series Codecs Package [03-11-2004]

Ламмер про Windows Media 9 Series Codecs Package [24-09-2004]

Надеюсь, что Ламмер — это не ругательство.
2 | 2 | Ответить

Ламмер про Windows Media 9 Series Codecs Package [24-09-2004]

Manage all of your Windows media files with this resource rich computer that is easy to use

MKV Codec 1.0

A lightweight MKV Codec for playing MKV files

AC’97 Audio Codec 20061201

Utility that adds the titular encoding to a multimedia player

AC3Filter 2.6b

Efficient Software to easily reproduce and reconfigure AC3 audio and video on your PC

LAME (Lame Ain’t an MP3 Encoder) 3.99

Free software download for Windows teaching tool to learn how to encode MP3

Vinyl Audio Codec 6.50

A useful driver for your multimedia outlets

Audio Convert Merge Free 10.1.2

Intuitive audio file converter that allows users to switch between many popular formats

Характеристики

Обновлено: 2019-05-13 13:56:42

Совместимость: Windows 98, Windows ME, Windows 2000, Windows XP

Язык: Другое, Русский, Английский

Описание

Windows Media Player 9 — программа, хорошо знакомая всем тем, кто когда-либо использовал Windows XP. С её помощью, вы сможете воспроизводить аудио и видео файлы в большинстве существующих форматов.

Описание

Используя эту программу, вы сможете в любой момент насладиться прослушиванием любимой музыки или просмотром видео в форматах MP3, MPG, MP2, AVI, WAV, WMA или многих других. При этом, Windows Media Player 9 обеспечивает высокое качество изображения и звука. В сравнении с предшественницей, программа получила более 120 функций, которые откроют перед вами новые возможности по взаимодействию с мультимедийным контентом на компьютере.

Программа может похвастаться встроенным инструментом для потоковой передачи мультимедиа, возможностью записи компакт-дисков, удобной мультимедийной библиотекой, радио-тюнером и рядом других приятных особенностей. Также, Windows Media Player 9 обладает набором функций, необходимых для современного проигрывателя, включая создание списков воспроизведения, настройка звука при помощи эквалайзера, отображение формы волны, а также изменение темы оформления. А обновленный интерфейс проигрывателя не оставит равнодушным никого.

Обратите внимание, что программа разработана специально для Windows XP и может не поддерживать более новые версии операционной системы.

Описание программы

Windows Media Player 9 — это распространенный проигрыватель аудио и видеофайлов, появившийся в Windows XP, и подходит для других операционных систем. Он обладает приятным, простым и интуитивно понятным интерфейсом.

Приложение позволяет синхронизировать музыку и видео, копировать и записывать их на различные диски, проигрывать файлы и сохранять плей-листы любимых исполнителей. В него встроены функции красивой визуализацией, что позволяет полностью окунуться в приятную музыку.

Кроме этого, виндовс медиа плеер автоматически обновляет библиотеки, находит картинки и совмещает в себе функции плеера и программы для просмотра изображений, что очень облегчает работу пользователя.

Советуем Windows Media Player 9 скачать бесплатно с официального сайта без регистрации, смс, вирусов и рекламы.

© Copyright 2018 МоиПрограммы — каталог программного обеспечения.

EssentialPIM Pro — программа-менеджер персональной информации для сбора и хранения различной информации в электронном виде

Разработчик: Astonsoft Ltd.

Загрузок: 7051

Условно-бесплатная

EssentialPIM — программа-менеджер персональной информации для сбора и хранения различной информации в электронном виде

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Свободный авиасимулятор для Linux, FreeBSD и macOS

Acronis True Image — пакет программ для полного резервного копирования и восстановления данных в Windows

Разработчик: Acronis

Загрузок: 185941

Условно-бесплатная

Бесплатная программа для конвертации видео, редактирования видео и записи на DVD и Blu-ray

Мультиплатформенное (Windows, Linux, macOS, Android) решение для удаленного доступа к компьютерам

IObit Malware Fighter — программа, специализирующаяся на выявлении, удалении или просто блокировке вредоносного или нежелательного программного обеспечения

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Госдума РФ приняла во втором чтении законопроект, который вводит запрет на использование общедоступных персональных данных без согласия владельца

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Курс биткоина вновь обновил исторический максимум. Рост стоимости самой популярной криптовалюты прокомментировал Илон Маск

Российские интернет-стартапы суммарно привлекли инвестиций на сумму около 500 миллионов долларов в 2011 году

Microsoft выпустила две новых тестовых сборки операционной системы Windows 10, которые относятся к веткам FE_RELEASE и RS_PRERELEASE

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О сайте и об авторе

Уважаемый читатель, приглашаю тебя в свой интернет-журнал!

Для начала, познакомимся. Меня зовут Иван Смирнов. Я являюсь основателем и автором ресурса. Здесь вы найдете интересную информацию на самую различную тематику. Расскажу обо всем ярко, оригинально и захватывающе, смогу вас заинтересовать.

Использую самые разнообразные источники информации. При этом, вы можете не волноваться о достоверности предоставленных сведений, я все внимательно проверяю и добросовестно отношусь к своему делу. Но если вы заметите ошибку или неточность, то, пожалуйста, расскажите об этом мне. Я заинтересован в улучшении своего контента и рад общению. Теперь, возьмите кофе и расположитесь поудобнее, пора начать знакомство с моим сайтом! Желаю вам отлично провести время и зарядиться положительными эмоциями!

Windows Media Audio 9

This codec samples audio at 44.1 or 48 kilohertz (kHz) using 16 bits, similar to the current CD standard, offering CD quality at data rates from 64 to 192 kilobits per second (Kbps). The resulting sound quality is 20 percent better than audio sampled with Windows Media Audio 8 at equivalent data rates.

The Windows Media Audio 9 codec (WMA 9) supports variable bit rate encoding (VBR), which enables even higher quality audio at smaller file sizes by automatically varying the encoding bit rate according to the complexity of the audio data. With VBR, the encoding bit rate increases to capture complex sections of data and then decreases to maximize the compression of the less complex sections, producing compact, high-quality compression.

WMA 9 is backward-compatible with previous Windows Media Audio-compatible decoders, which means that WMA 9 content can be played with previous versions of Windows Media Player or older consumer electronic devices that support Windows Media. As with all Windows Media 9 Series codecs, it supports the Windows Media digital rights management platform, which is used to securely package and distribute copy-protected digital media.

Windows Media Audio 10 Professional

Windows Media Audio 10 Professional (WMA 10 Pro) is the most flexible Windows Media audio codec available – supporting profiles that include everything from full-resolution 24-bit/96 kHz audio in stereo, 5.1 channel, or even 7.1 channel surround sound, to highly efficient mobile capabilities at 24 Kbps to 96 Kbps for stereo, and 128 Kbps to 256 Kbps for 5.1-channel sound. WMA 10 Pro offers incredible quality for consumers using high-fidelity hardware and 5.1 channel surround sound-equipped computers — and for consumers playing audio content on their mobile devices. WMA 10 Pro supports streaming, progressive download, or download-and-play delivery at 128 to 768 Kbps.

When using 5.1 surround sound audio compressed at 384 Kbps with WMA 10 Pro, most listeners cannot discern any differences between the compressed music and the original pulse code modulation (PCM) files. WMA Pro also offers dynamic range control using the maximum and average audio amplitudes that are calculated during the encoding process. Using the Quiet Mode feature in Windows Media Player 9 and later, users can hear either the full dynamic range, a medium difference range up to 12 decibels (dB) above the average, or a little difference range up to 6 dB above the average.

If a user tries to play back a file that was encoded using the 5.1 channel, 24-bit, 96 kHz sampling capabilities, but does not have a system or sound card that supports multi-channel or high-resolution sound, multiple channels are combined into stereo audio (for example, 16-bit, two channel audio), ensuring that users get the best playback experience their systems can provide.

The following table compares WMA Pro to competing compression technology.

Audio Data	Industry Compression*	Windows Media*	Compression Savings
2 ch x 48 kHz x 16 bits	Dolby Digital 2.0 at 220 Kbps	WMA 10 Pro at 128 Kbps	1.7:1
6 ch x 48 kHz x 20 bits	Dolby Digital 5.1 at 384 Kbps	WMA 10 Pro at 192–256 Kbps	1.5–2:1
6 ch x 48 kHz x 24 bits	DTS 5.1 at 1,536 Kbps	WMA 10 Pro at 768 Kbps	2:1

Windows Media Audio 9 Lossless

The audio quality of content that is compressed using this codec is the best of all Windows Media Audio codecs. It creates a bit-for-bit duplicate of the original audio file so that no data is lost, which makes it ideal for archiving content masters.

Depending on the complexity of the original, content will be compressed at a 2:1 or 3:1 ratio. Although this is lower than the ratio achieved with other Windows Media Audio 9 Series codecs, it provides the same benefits of compression while leaving the data intact.

Like Windows Media Audio 9 Professional, the Windows Media Audio 9 Lossless codec also offers dynamic range control using the maximum and average audio amplitudes that are calculated during the encoding process. Using the Quiet Mode feature in Windows Media Player 9 and later, users can hear the full dynamic range, a medium difference range up to 12 dB above the average, or a little difference range up to 6 dB above the average.

Windows Media Audio 9 Voice

This low-bit-rate codec is primarily targeted for speech content, but performs very well with mixed-mode content that includes both voice and music. In voice mode, the codec takes advantage of the relatively less complicated and narrower frequency range of the human voice to maximize compression. In music mode, the codec operates like the standard Windows Media Audio 9 codec. Encoded content can be configured to switch between voice and music modes automatically.

The Windows Media Audio 9 Voice codec offers superior quality for low-bit-rate streaming scenarios (less than 20 Kbps), such as radio broadcasts, advertising, e-books, podcasts, and voiceovers. The voice codec can also compress content to as low as 4 Kbps at 8 kHz.

Compatibility

The following table outlines what your audience will experience when playing Windows Media Audio 9 Series content on earlier Microsoft Windows operating systems than Windows XP or with earlier versions of Windows Media Player. This table also lists the compatibility for Apple Mac OS X and Windows CE–based platforms.

Codec	Feature	Player backward compatibility
Windows Media Audio 9	Constant-bit rate (CBR) encoding	Windows Media Player 6.4 or later on non-portable devices (using transcoding as needed) Windows Media Player 9 for Mac OS X Windows Media Player 9 Series and Windows Media Player 9.1 for Pocket PC* Windows Media Player 9 Series and Windows Media Player 9.1 for Smartphone*
Variable-bit-rate (VBR) encoding	Windows Media Player 7 or later on all devices that support the Player (using transcoding as needed)
Windows Media Audio 9 Professional	General	Windows Media Player 7 or later Windows Media Player 9 for Mac OS X
Discrete channel playback (for instance, 5.1)	Requires Windows Media Player 9 Series (or SDK) or later, Windows XP, and a multichannel audio card.
High-resolution audio (24-bit, 96 kHz)	Requires Windows Media Player 9 Series (or SDK) or later, Windows XP, and a high-resolution audio card.
Dynamic range control	Requires Windows Media Player 9 Series (or SDK) or later and Windows XP.
Windows Media Audio 9 Lossless	General	Windows Media Player 7 or later Windows Media Player 9 for Mac OS X
Discrete channel playback (for instance, 5.1)	Requires Windows Media Player 9 Series (or SDK) or later, Windows XP, and a multichannel audio card.
Windows Media Audio 9 Voice	General	Windows Media Player 6.4 or later Windows Media Player 9 for Mac OS X Windows Media Player 9 Series and Windows Media Player 9.1 for Pocket PC* Windows Media Player 9 Series and Windows Media Player 9.1 for Smartphone*

* All versions of Windows Media Player for Pocket PC and Smartphone are shipped as part of the Microsoft Windows Mobile operating system. Windows Media Player for Pocket PC and Windows Media Player for Smartphone are not available for download from Microsoft.

In 2006, the Society of Motion Picture and Television Engineers (SMPTE) formally published the Final Specification for SMPTE 421M, also known as VC-1. Formal standardization of VC-1 represents the culmination of years of technical scrutiny by over 75 companies, leading to a codec that is well-documented, extremely stable, easily licensable, and accepted by the industry. VC-1 supports three profiles: Simple, Main, and Advanced. The Simple and Main profiles have been complete for several years, and existing implementations such as WMV 9 have long supported the creation and playback of content using these profiles, as well as an early implementation of the Advanced profile. The completion of the Advanced profile and consequent standardization of all profiles in VC-1 represents the final step in a comprehensive specification that delivers high definition content—either interlaced or progressive—across any medium and to any capable device.

Windows Media Video 9

Windows Media Video 9 is the Microsoft implementation of the VC-1 SMPTE standard. It supports Simple, Main, and Advanced profiles.

Simple and Main Profiles

The Windows Media Video 9 Simple and Main profiles fully conform to the SMPTE VC-1 standard and provide high-quality video for streaming and downloading. These profiles support a wide range of bit rates, from high-definition content at one-half to one-third the bit rate of MPEG-2, to low-bit-rate Internet video delivered over a dial-up modem. This codec also supports professional-quality downloadable video with two-pass and variable bit rate (VBR) encoding. Windows Media Video 9 is already supported by a wide variety of players and devices.

Advanced Profile

The Windows Media Video 9 Advanced profile fully conforms to the SMPTE VC-1 standard, supports interlaced content, and is transport-independent. Content creators can use this profile to deliver either progressive or interlaced content at data rates as low as one-third that of the MPEG-2 codec—with the same quality as MPEG-2.

In the past, interlaced video content was always de-interlaced before encoding with the Windows Media Video codec. Now, encoding applications such as Windows Media 9 Series, and third-party encoding solutions can support compression of interlaced content without first converting it to progressive content. Maintaining interlacing in an encoded file is important if the content is ever rendered on an interlaced display, such as a television.

Transport independence also enables the delivery of Windows Media Video 9 Advanced Profile over systems that are not Windows Media-based, such as standards-based broadcast infrastructures (through native MPEG-2 transport streams), wireless infrastructures (using real-time transfer protocol [RTP]), or even DVDs.

The following table compares Windows Media Video 9 Advanced Profile to competing compression technology.

Video Data	Industry Compression*	Windows Media*	Compression Savings
480/24p 720×480 pixels/frame x 8 bits per channel x 24 fps	MPEG-2 at 4–6 Mbps	Windows Media Video 9 Advanced Profile at 1.3–2 Mbps	3:1
480/30i 720×480 pixels/frame x 8 bits per channel x 30 fps	MPEG-2 at 6–8 Mbps	Windows Media Video 9 Advanced Profile at 2–4 Mbps	2–3:1
720/24p 1280×720 pixels/frame x 8 bits per channel x 24 fps	MPEG-2 at 19 Mbps	Windows Media Video 9 Advanced Profile at 5–8 Mbps	2.4–3.8:1

Windows Media Video 9 Screen

The Windows Media Video 9 Screen codec is optimized for compressing sequential screen shots and highly static video that is captured from the computer display, which makes it ideal for delivering demos or demonstrating computer use for training. The codec takes advantage of the typical image simplicity and relative lack of motion to achieve a very high compression ratio.

During the encoding process, the codec automatically switches between lossy and lossless encoding modes, depending on the complexity of the video data. For complex data, the lossless mode preserves an exact copy of the data. For less complex data, the lossy mode discards some data to achieve a higher compression ratio. By automatically switching between these two modes, the codec maintains video quality while maximizing compression.

Overall, the Windows Media Video 9 Screen codec delivers better handling of bitmap images and screen motion, even on relatively modest CPUs. It is also up to 100 times more efficient than the commonly-used run length encoding.

Windows Media Video 9 Image Version 2

The Windows Media Video 9 Image Version 2 codec is different from the other video codecs. Instead of processing uncompressed video, it transforms still images into video by using pan, zoom, and cross-fade transitions between clips to create an unlimited number of effects.

The results can then be delivered at data rates as low as 20 kilobits per second (Kbps). These files are compressed using either constant bit rate (CBR) or one-pass variable bit rate (VBR) modes.

The Windows Media Video 9 Image Version 2 codec is not compatible with the Windows Media Video 9 Image codec.

Windows Media Video 9 VCM

The Video Compression Manager (VCM) version of the Windows Media Video 9 Series codec enables earlier versions of encoding and editing applications to support the Windows Media Video 9 Series codec in file containers such as Audio Video Interleaved (AVI). This codec package also allows Windows Media Video (WMV) files based on Windows Media Format 9 Series to be played in Windows Media Player 6.4, in both ASF and AVI file containers.

Compatibility

The following table outlines what your audience will experience when playing Windows Media Video 9 Series content on earlier Microsoft Windows operating systems or with earlier versions of Windows Media Player. This table also lists the compatibility for Apple Mac OS X and Windows CE–based platforms.

Codec	Feature	Player backward compatibility
Windows Media Video 9	General	Windows Media Player 6.4 or later Windows Media Player 9 for Mac OS X Windows Media Player 9 Series and Windows Media Player 9.1 for Pocket PC* Windows Media Player 9 Series and Windows Media Player 9.1 for Smartphone*
Frame Interpolation	Requires Windows Media Player 9 Series (or Software Development Kit) or later and Windows XP.
Windows Media Video 9 Advanced Profile	General	Windows Media Player 7 or later
Windows Media Video 9 Screen	General	Windows Media Player 7 or later
Windows Media Video 9 Image Version 2	General	Windows Media Player 7 or later

*All versions of Windows Media Player for Pocket PC and Smartphone are shipped as part of the Microsoft Windows Mobile operating system. Windows Media Player for Pocket PC and Windows Media Player for Smartphone are not available for download from Microsoft.

Источник

Расширение файлов: .wma

Аудио, сжатое в формат WMA поддерживается сегодня большим количеством аппаратных плееров.

Плюсы

• Полная поддержка со стороны Windows.

Минусы

• Низкое качество при низком битрейте.
• Полная закрытость.

Microsoft WMA V1

Этот формат кодирования аудиоинформации стал второй попыткой Microsoft штурмовать проблему сжатия звука. В 1995 году компания занималась активным продвижением и пропагандой формата сжатия Microsoft ADPCM, в котором на сэмпл вместо 16 приходилось всего 4 бита. Кроме того, радикально менялся смысл хранимой информации — если для обычного PCM формата значение сэмпла равно уровню сигнала в данный момент времени, то для ADPCM оно стало равно смещению уровня сигнала относительно предыдущего момента времени. В рекламных проспектах говорилось, что искажения, вносимые таким способом кодирования абсолютно незаметны на слух, однако в реальности частоты выше 15 кГц зарезались на корню, что делало этот способ сжатия неприменимым для хранения звуковых данных CD качества.

Windows Media Audio был создан сравнительно недавно, и, по всей видимости, основан на методе кодирования, похожем на МP3. На слух этот формат выдавал практически неотличимый от МP3 результат, что сделало WMA весьма сильным конкурентом.

Существенным недостатком WMA стало отсутствие поддержки битрейта выше 160 кбит/с.

По сути формат WMA отличается от МP3 кодеков, тем, что имеет одну единственную реализацию. Устанавливается он наравне с другими системными кодеками Windows 9x в качестве ещё одного формата сжатия звуков. После этого все MCI-основанные плееры начинают распознавать новый формат звуковых данных. Кроме того, для все тех же MCI-основанных программ появляется возможность конвертирования звуковых данных в WMA. Одной из таких программ является специальный plug-in к Winamp out_wma.dll.

Microsoft WMA V2

После успешной раскрутки первой версии своего формата WMA Microsoft решила выпустить его новую версию (V2), кодировщик которой закрыла от использования везде, кроме Microsoft Media Encoder 4.1. Декодер WMA V2 остался открытым, чтобы сторонние фирмы могли применять это формат в своих приложениях для хранения и воспроизведения звука. Тем не менее, Microsoft преследует и пресекает в судебном порядке все попытки создать декодер WMA-WAV.

Microsoft WMA V7

Эта версия формата вышла одновременно с Windows Millennium Edition, и была встроена в новую версию Windows Media Player. Важным отличием WMA V7 от V2 и V1 можно назвать поддержку битрейта 192. Само качество кодирования значительно ухудшилось по сравнению с первыми версиями формата. Кроме того, явно изменился алгоритм кодирования. Если первые две версии были основаны на алгоритме, похожем на МP3 — 2048 первых сэмпла в файле содержат «раскруточную» информацию, необходимую декодеру для корректного начала декодирования — то в V7 алгоритм радикально изменили, и сигнал начинается с 0 сэмпла. Однако в силу неизвестных причин 0 сэмплу декодированного сигнала соответствует ~40000 исходного — это означает, что теряется почти секунда в начале файла.

Microsoft WMA V9

Кодек претерпел большие изменения. Вернее это уже несколько кодеков в одном пакете. Каждый из них использует свою технологию сжатия, несовместимую между собой, например, битовые потоки Windows Media Audio 9 Professional не могут быть декодированы с помощью Windows Media Audio 9 декодера. Тем не менее, обратная совместимость все же существует. Разработка декодера была «заморожена» четыре года назад, и с тех пор улучшается только кодер. Новый WMA предлагает:

• Однопроходной CBR режим кодирования (единственный режим, который поддерживался в прошлых версиях), использующий улучшенный контроль частоты и маскирующие алгоритмы.
• Двухпроходной VBR режим кодирования, который позволяет добиться лучшего качества, чем однопроходной режим.

Итак, пакет состоит из следующих кодеков:

• Windows Media Audio 9 Professional
• Windows Media Audio 9 Lossless
• Windows Media Audio 9 Voice

Обзор Windows Media 9 Series

Windows Media Player is the standard multimedia player for Microsoft® Windows® systems.

Supported formats

According to Microsoft® Knowledge Base Article 316992, Windows Media Player supports the following formats «out of the box»:

Type	Supported formats
Microsoft® media formats	Advanced Systems Format (.asf) Audio Visual Interleave (.avi) Audio for Windows (.wav) Microsoft® Digital Video Recording (.dvr-ms) Windows Media Audio (.wma) Windows Media Video (.wmv, .wm)
Microsoft® media metafiles	Advanced Stream Redirector (.asx) Windows Media Audio Redirector (.wax) Windows Media Download Package (.wmd) Windows Media Player Playlist (.wpl) Windows Media Redirector (.wmx) Windows Media Video Redirector (.wvx)
ISO/IEC (MPEG)	MPEG-1 (.mpeg, .mpg, .m1v) MPEG Audio Layer III (.mp3) MPEG Audio Layer II (.mp2, .mpa) Metafile Playlist (.m3u)
Industry standard	Audio Interchange File Format ( .aif, .aifc, .aiff) CD Audio Track (.cda) Musical Instrument Digital Interface (.mid, .midi, .rmi) Sun Microsystems and NeXT (.au, .snd)

Common Issues

MPEG-2 and MPEG-4 playback

Microsoft® does not bundle codecs for MPEG-2 or MPEG-4 with Windows and recommends purchasing them as part of a «DVD decoder pack» from a third-party vendor.

The symptom associated with a missing codec is Windows Media Player displaying the cryptic «C00D11CD» error code immediately after opening an MPEG-2 or MPEG-4 coded file or stream. At that point, you must purchase the appropriate codec, perhaps from Microsoft’s® list of approved vendors.

Streaming from VLC

To date, the only option for streaming from VLC to Windows Media Player is to:

• Transcode the file or feed into WMV format
• Encapsulate the transcoded stream in the ASF container format
• Use MMS or MMSH for the stream transport

This has also been discussed in the forum.

Otherwise, Windows Media Player does not appear to support streaming for anything other than its proprietary formats.

«Windows Media Player 9 Series can play files in a wide variety of digital media file formats, but Windows Media Services 9 Series cannot stream all of those files. In certain cases, you may need to convert digital media files into a compatible format before you can stream them.» [1]

Streaming to Windows Media Player over HTTP is supported, but the multimedia stream must be converted to a Microsoft-proprietary format with Windows Media Encoder beforehand.

Streaming is known to work with Windows Media Player 9 or higher. In particular, Windows Media Player 8 does not interoperate with VLC. This has also been discussed in the forum

Compatibility

If you discover problems with your Windows Media Player please download the latest version:

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This article is about audio encoding and decoding software. For the container file format, see .wma.

Windows Media Audio

Filename extension	.wma
Internet media type	audio/x-ms-wma
Developed by	Microsoft
Initial release	August 17, 1999; 23 years ago[1]
Type of format	Audio
Open format?	No
Free format?	No

Windows Media Audio (WMA) is a series of audio codecs and their corresponding audio coding formats developed by Microsoft.WMA is a lossless file format,This means that WMA media doesn’t lose as many sonic details during compression. It is a proprietary technology that forms part of the Windows Media framework. WMA consists of four distinct codecs. The original WMA codec, known simply as WMA, was conceived as a competitor to the popular MP3 and RealAudio codecs.^[2][3] WMA Pro, a newer and more advanced codec, supports multichannel and high resolution audio.^[4] A lossless codec, WMA Lossless, compresses audio data without loss of audio fidelity (the regular WMA format is lossy).^[4] WMA Voice, targeted at voice content, applies compression using a range of low bit rates.^[4] Microsoft has also developed a digital container format called Advanced Systems Format to store audio encoded by WMA.

Development history[edit]

The first WMA codec was based on earlier work by Henrique Malvar and his team which was transferred to the Windows Media team at Microsoft.^[5] Malvar was a senior researcher and manager of the Signal Processing Group at Microsoft Research,^[6] whose team worked on the MSAudio project.^[7] The first finalized codec was initially referred to as MSAudio 4.0.^[8][9] It was later officially released as Windows Media Audio,^[1] as part of Windows Media Technologies 4.0. Microsoft claimed that WMA could produce files that were half the size of equivalent-quality MP3 files;^[10] Microsoft also claimed that WMA delivered «near CD-quality» audio at 64 kbit/s.^[10] The former claim however was rejected by some audiophiles^[11] and both claims have been refuted through publicly-available codec listening tests. RealNetworks also challenged Microsoft’s claims regarding WMA’s superior audio quality compared to RealAudio.^[3]

Newer versions of WMA became available: Windows Media Audio 2 in 1999,^[12] Windows Media Audio 7 in 2000,^[13] Windows Media Audio 8 in 2001,^[14] and Windows Media Audio 9 in 2003.^[4] Microsoft first announced its plans to license WMA technology to third parties in 1999.^[15] Prior to Windows XP , WMA files were primarily streamed using the Windows Media Source Filter (DirectShow codec), later being removed in Windows Vista with the addition of Media Foundation.^[16] Although earlier versions of Windows Media Player played WMA files, support for WMA file creation was not added until the seventh version.^[17] In 2003, Microsoft released new audio codecs that were not compatible with the original WMA codec. These codecs were Windows Media Audio 9 Professional,^[4] Windows Media Audio 9 Lossless,^[4] and Windows Media Audio 9 Voice.^[4]

All versions of WMA released since version 9.0 – namely 9.1, 9.2, and 10 – have been backwards compatible with the original v9 decoder and are therefore not considered separate codecs. The sole exception to this is the WMA 10 Professional codec whose Low Bit Rate (LBR) mode is only backwards compatible with the older WMA Professional decoders at a half sampling rate (similar to how HE-AAC is backwards compatible with AAC-LC). Full fidelity decoding of WMA 10 Professional LBR bitstreams requires a WMA version 10 or newer decoder.

Container format[edit]

A WMA file is in most circumstances contained in the Advanced Systems Format (ASF), a proprietary Microsoft container format for digital audio or digital video.^[18] The ASF container format specifies how metadata about the file is to be encoded, similar to the ID3 tags used by MP3 files. Metadata may include song name, track number, artist name, and also audio normalization values. This container can optionally support digital rights management (DRM) using a combination of elliptic curve cryptography key exchange, DES block cipher, a custom block cipher, RC4 stream cipher and the SHA-1 hashing function. See Windows Media DRM for further information.

Since 2008 Microsoft has also been using WMA Professional in its Protected Interoperable File Format (PIFF) based on the ISO Base Media File Format and most commonly used for Smooth Streaming, a form of adaptive bitrate streaming over HTTP. Related industry standards such as DECE UltraViolet and MPEG-DASH have not standardized WMA as a supported audio codec, deciding in favor of the more industry-prevalent MPEG and Dolby audio codecs.

Codecs[edit]

Each WMA file features a single audio track in one of the four sub-formats: WMA, WMA Pro, WMA Lossless, or WMA Voice. These formats are implemented differently from one another, such that they are technically distinct and mutually incompatible; that is to say, a device or software compatible with one sub-format does not therefore automatically support any of the other codecs. Each codec is further explained below.

Windows Media Audio[edit]

Windows Media Audio (WMA) is the most common codec of the four WMA codecs. The colloquial usage of the term WMA, especially in marketing materials and device specifications, usually refers to this codec only. The first version of the codec released in 1999 is regarded as WMA 1. In the same year, the bit stream syntax, or compression algorithm, was altered in minor ways and became WMA 2.^[12] Since then, newer versions of the codec have been released, but the decoding process remained the same, ensuring compatibility between codec versions.^[12] WMA is a lossy audio codec based on the study of psychoacoustics. Audio signals that are deemed to be imperceptible to the human ear are encoded with reduced resolution during the compression process.

WMA can encode audio signals sampled at up to 48 kHz with up to two discrete channels (stereo). WMA 9 introduced variable bit rate (VBR) and average bit rate (ABR) coding techniques into the MS encoder although both were technically supported by the original format.^[12] WMA 9.1 also added support for low-delay audio,^[19] which reduces latency for encoding and decoding.

Fundamentally, WMA is a transform coder based on modified discrete cosine transform (MDCT), somewhat similar to AAC, Cook and Vorbis. The bit stream of WMA is composed of superframes, each containing 1 or more frames of 2048 samples. If the bit reservoir is not used, a frame is equal to a superframe. Each frame contains several blocks, which are 128, 256, 512, 1024, or 2048 samples long after being transformed into the frequency domain via the MDCT. In the frequency domain, masking for the transformed samples is determined, and then used to requantize the samples. Finally, the floating point samples are decomposed into coefficient and exponent parts and independently huffman coded. Stereo information is typically mid/side coded. At low bit rates, line spectral pairs (typically less than 17 kbit/s) and a form of noise coding (typically less than 33 kbit/s) can also be used to improve quality.

Like AAC and Ogg Vorbis, WMA was intended to address perceived deficiencies in the MP3 standard. Given their common design goals, the three formats ended up making similar design choices. All three are pure transform codecs. Furthermore, the MDCT implementation used in WMA is essentially a superset of those used in Ogg and AAC such that WMA iMDCT and windowing routines can be used to decode AAC and Ogg Vorbis almost unmodified. However, quantization and stereo coding is handled differently in each codec. The primary distinguishing trait of the WMA Standard format is its unique use of 5 different block sizes, compared to MP3, AAC, and Ogg Vorbis which each restrict files to just two sizes. WMA Pro extends this by adding a 6th block size used at 88.2/96 kHz sampling rate.

Certified PlaysForSure devices, as well as a large number of uncertified devices, ranging from portable hand-held music players to set-top DVD players, support the playback of WMA files. Most PlaysForSure-certified online stores distribute content using this codec only. In 2005, Nokia announced its plans to support WMA playback in future Nokia handsets.^[20] In the same year, an update was made available for the PlayStation Portable (version 2.60) which allowed WMA files to be played on the device for the first time.^[21]

Windows Media Audio Professional[edit]

Windows Media Audio Professional (WMA Pro) is an improved lossy codec closely related to WMA standards. It retains most of the same general coding features, but also features improved entropy coding and quantization strategies as well as more efficient stereo coding. Notably, many of the WMA standard’s low bitrate features have been removed, as the core codec is designed for efficient coding at most bitrates. Its main competitors include AAC, HE-AAC, Vorbis, Dolby Digital, and DTS. It supports 16-bit and 24-bit sample bit depth, sampling rates up to 96 kHz, and up to eight discrete channels (7.1 channel surround).^[22] WMA Pro also supports dynamic range compression, which reduces the volume difference between the loudest and quietest sounds in the audio track. According to Microsoft’s Amir Majidimehr, WMA Pro could theoretically go beyond 7.1 surround sound and support «an unlimited number of channels»; however, Microsoft chose to limit its current capability to eight (7.1 discrete channels).^[23]

The codec’s bit stream syntax was frozen at the first version, WMA 9 Pro.^[24] Later versions of WMA Pro introduced low-bit rate encoding, low-delay audio,^[25] frequency interpolation mode,^[26] and an expanded range of sampling rate and bit-depth encoding options. A WMA 10 Pro file compressed with frequency interpolation mode comprises a WMA 9 Pro track encoded at half the original sampling rate, which is then restored using a new compression algorithm.^[27] In this situation, WMA 9 Pro players which have not been updated to the WMA 10 Pro codec can only decode the lower quality WMA 9 Pro stream. Starting with WMA 10 Pro, eight channel encoding starts at 128 kbit/s, and tracks can be encoded at the native audio CD resolution (44.1 kHz, 16-bit), previously the domain of WMA Standard.

Despite a growing number of supported devices and its superiority over WMA, WMA Pro still has little hardware and software support. Some notable exceptions to this are the Microsoft Zune (limited to stereo),^[28] Xbox 360,^[29] Windows Mobile-powered devices with Windows Media Player 10 Mobile,^[30] newer Toshiba Gigabeat and Motorola devices,^[31][32] and devices running recent versions of the Rockbox alternative firmware.^[33] In addition, WMA Pro is a requirement for the WMV HD certification program.^[34] On the software side, Verizon utilizes WMA 10 Pro for its V CAST Music Service,^[35] and Windows Media Player 11 has promoted the codec as an alternative to WMA for copying audio CD tracks.^[36] WMA Pro is supported in Silverlight as of version 2 (though only in stereo mode). In the absence of the appropriate audio hardware, WMA Pro can automatically downmix multichannel audio to stereo or mono, and 24-bit resolution to 16-bit during playback.

A notable example of WMA Pro being used instead of WMA Standard is the NBC Olympics website which uses WMA 10 Pro in its low-bitrate mode at 48 kbit/s.^{[citation needed]}

Windows Media Audio Lossless[edit]

Windows Media Audio 9 Lossless is a lossless incarnation of Windows Media Audio, an audio codec by Microsoft, released in early 2003. It compresses an audio CD to a range of 206 to 411 MB, at bit rates of 470 to 940 kbit/s. The result is a bit-for-bit duplicate of the original audio file; in other words, the audio quality on the CD will be the same as the file when played back. WMA Lossless uses the same .WMA file extension as other Windows Media Audio formats. It supports 6 discrete channels and up to 24-bit/96 kHz lossless audio. The format has never been publicly documented, although an open-source decoder has been reverse-engineered for non-Microsoft platforms by the libav and ffmpeg projects.

Windows Media Audio Lossless (WMA Lossless) is a lossless audio codec that competes with ATRAC Advanced Lossless, Dolby TrueHD, DTS-HD Master Audio, Shorten, Monkey’s Audio, FLAC, Apple Lossless, and WavPack (Since late 2011,^[37][38][39] the last three have the advantage of being open source software and available for nearly any operating system.) Designed for archival purposes,^[40] it compresses audio signals without loss of quality from the original using VBR. When decompressed, the audio signal is an exact replica of the original. The first version of the codec, WMA 9 Lossless, and its revisions support up to 96 kHz, 24-bit audio for up to 6 discrete channels (5.1 channel surround) with dynamic range compression control. The typical compression ratio for music varies between 1.7:1 and 3:1.^[40][41][42]

Hardware support for the codec is available on the Cowon A3,^[43] Cowon S9, Bang & Olufsen Serenata^[44] Sony Walkman NWZ-A and NWZ-S series, Zune 4, 8, 80 30, Zune 120 (with firmware version 2.2 or later) and the Zune HD, Xbox 360,^[29] Windows Mobile-powered devices with Windows Media Player 10 Mobile,^[30] Windows Phone (version 8 and above), Toshiba Gigabeat S and V models, Toshiba T-400, the Meizu M3, and Best Buy’s Insignia NS-DV, Pilot, and Sport music players. The Logitech Squeezebox Touch now supports the format natively despite previously only supporting it via transcoding. Like WMA Standard, WMA Lossless is being used by a few online stores to distribute music online.^[45][46] Similar to WMA Pro, the WMA Lossless decoder can perform downmixing when capable audio hardware is not present.^{[citation needed]} As of 2012, the ffmpeg and libav projects have open source WMA Lossless decoders based on reverse engineering of the official decoder. Only 16-bit WMA files can be successfully decoded by ffmpeg as of June 20, 2012.

Windows Media Audio Voice[edit]

Windows Media Audio Voice (WMA Voice) is a lossy audio codec that competes with Speex (used in Microsoft’s own Xbox Live online service^[47]), ACELP, and other codecs. Designed for low-bandwidth, voice playback applications,^[48] it employs low-pass and high-pass filtering of sound outside the human speech frequency range to achieve higher compression efficiency than WMA. It can automatically detect sections of an audio track containing both voice and music and use the standard WMA compression algorithm instead.^[24] WMA Voice supports up to 22.05 kHz for a single channel (mono) only.^[48] Encoding is limited to constant bit rate (CBR) and up to 20 kbit/s. The first and only version of the codec is WMA 9 Voice.

Windows Mobile-powered devices with Windows Media Player 10 Mobile have native support for WMA 9 Voice playback.^[30] In addition, BBC World Service has employed WMA Voice for its Internet radio streaming service.^[49]

Sound quality[edit]

See codec listening test for a table of double-blind listening test results.

Microsoft claims that audio encoded with WMA sounds better than MP3 at the same bit rate; Microsoft also claims that audio encoded with WMA at lower bit rates sound better than MP3 at higher bit rates.^[50] Double blind listening tests with other lossy audio codecs have shown varying results, from failure to support Microsoft’s claims about its superior quality to supremacy over other codecs. One independent test conducted in May 2004 at 128 kbit/s showed that WMA was roughly equivalent to LAME MP3; inferior to AAC and Vorbis; and superior to ATRAC3 (software version).^[51]

Some studies concluded:

• At 32 kbit/s,^{[permanent dead link]} WMA Standard was noticeably better than LAME MP3, but not better than other modern codecs in a collective, independent test in July 2004.
• At 48 kbit/s Archived 2014-07-08 at the Wayback Machine, WMA 10 Pro was ranked second after Nero HE-AAC and better than WMA 9.2 in an independent listening test organized and supported by Sebastian Mares and Hydrogenaudio Forums in December 2006. This test, however, used CBR for WMA 10 Pro and VBR for the other codecs.
• At 64 kbit/s, WMA Pro outperformed Nero HE-AAC in a listening test commissioned by Microsoft but independently performed by the National Software Testing Labs in 1999. Out of 300 participants, «71% of all listeners indicated that WMA Pro was equal to or better than HE AAC.»^{[citation needed]} However, a September 2003 public listening test conducted by Roberto Amorim found that listeners preferred 128 kbit/s MP3 to 64 kbit/s WMA audio with greater than 99% confidence.
• At 80 kbit/s Archived 2014-07-08 at the Wayback Machine and 96 kbit/s, WMA had lower quality than HE-AAC, AAC-LC, and Vorbis; near-equivalent quality to MP3, and better quality than MPC in individual tests done in 2005.
• At 128 kbit/s, there was a four-way tie between aoTuV Vorbis, LAME MP3, WMA 9 Pro and AAC in a large scale test in January 2006, with each codec sounding close to the uncompressed music file for most listeners.
• At 768 kbit/s, WMA 9 Pro delivered full-spectrum response at half the bit rate required for DTS in a comparative test done by EDN in October 2003. The test sample was a 48 kHz, 5.1 channel surround audio track.

Criticism of claimed quality[edit]

Microsoft’s claims of WMA sound quality have frequently drawn complaints. «Some audiophiles challenge Microsoft’s claims regarding WMA’s quality», according to a published article from EDN.^[11] Another article from MP3 Developments wrote that Microsoft’s claim about CD-quality audio at 64 kbit/s with WMA was «very far from the truth».^[52] At the early stages of WMA’s development, a representative from RealNetworks claimed that WMA was a «clear and futile effort by Microsoft to catch up with RealAudio 8».^[53]

Microsoft has sometimes claimed that the sound quality of WMA at 64 kbit/s equals or exceeds that of MP3 at 128 kbit/s (both WMA and MP3 are considered near-transparent at 192 kbit/s by most listeners). In a 1999 study funded by Microsoft, National Software Testing Laboratories (NSTL) found that listeners preferred WMA at 64 kbit/s to MP3 at 128 kbit/s (as encoded by MusicMatch Jukebox).^[54]

Both MP3 and WMA encoders have undergone active development and improvement for many years, so their relative quality may change over time.

Players[edit]

Apart from Windows Media Player, most of the WMA compression formats can be played using ALLPlayer, VLC media player,^[55] Media Player Classic,^[56] MPlayer, RealPlayer, Winamp, Zune Software (with certain limitations—DSP plugin support and DirectSound output is disabled using the default WMA plugin),^{[citation needed]} and many other software media players. The Microsoft Zune media management software supports most WMA codecs, but uses a variation of Windows Media DRM which is used by PlaysForSure.

The FFmpeg project has reverse-engineered and re-implemented the WMA codecs to allow their use on POSIX-compliant operating systems such as Linux. The Rockbox project further extended this codec to be suitable for embedded cores, allowing playback on portable MP3 players and cell phones running open source software. RealNetworks has announced plans to support playback of DRM-free WMA files in RealPlayer for Linux.^[57] On the Macintosh platform, Microsoft released a PowerPC version of Windows Media Player for Mac OS X in 2003,^[58] but further development of the software has ceased. Microsoft currently endorses the third-party Flip4Mac WMA, a QuickTime component that allows Macintosh users to play WMA files in any player that uses the QuickTime framework.^[59] Flip4Mac, however, does not currently support the Windows Media Audio Voice codec.^[60]

Not all Android devices have native support for WMA files because the core Android platform doesn’t support this format, but third-party software that supports it also exists.

WMA format can be played in almost all Windows Mobile and later Windows Phone devices.

Encoders[edit]

Software that can export audio in WMA format include Windows Media Player, Windows Movie Maker, Microsoft Expression Encoder, Sony Sound Forge, GOM Player, RealPlayer,^[61] Adobe Premiere Pro,^[62] Adobe Audition,^[63] and Adobe Soundbooth.^[64] Microsoft Office OneNote supports encoding in all WMA codecs,^[65] and Windows Media Encoder supports all available bit rate and resolution options as well. Open source players like VLC media player can also do some encoding.

Digital rights management[edit]

The WMA codecs are most often used with the ASF container format, which has an optional DRM facility. Windows Media DRM, which can be used in conjunction with WMA, supports time-limited music subscription services such as those offered by unlimited download services, including MTV’s URGE, Napster, Rhapsody, Yahoo! Music Unlimited, and Virgin Digital. Windows Media DRM, a component of PlaysForSure and Windows Media Connect, is supported on many modern portable audio devices and streaming media clients such as Roku, SoundBridge, Xbox 360, and Wii. Players that support the WMA format but not Windows Media DRM cannot play DRM-protected files.

See also[edit]

• Windows Media Video – a video file format and codec developed by Microsoft
• WAV
• JPEG XR / HD Photo – an image file format and codec developed by Microsoft
• Surround sound
• Timeline of audio formats
• Comparison of audio coding formats

References[edit]

External links[edit]

• Windows Media homepage at Microsoft

This article is about audio encoding and decoding software. For the container file format, see .wma.

Windows Media Audio

Filename extension	.wma
Internet media type	audio/x-ms-wma
Developed by	Microsoft
Initial release	August 17, 1999; 23 years ago[1]
Type of format	Audio
Open format?	No
Free format?	No

Windows Media Audio (WMA) is a series of audio codecs and their corresponding audio coding formats developed by Microsoft.WMA is a lossless file format,This means that WMA media doesn’t lose as many sonic details during compression. It is a proprietary technology that forms part of the Windows Media framework. WMA consists of four distinct codecs. The original WMA codec, known simply as WMA, was conceived as a competitor to the popular MP3 and RealAudio codecs.^[2][3] WMA Pro, a newer and more advanced codec, supports multichannel and high resolution audio.^[4] A lossless codec, WMA Lossless, compresses audio data without loss of audio fidelity (the regular WMA format is lossy).^[4] WMA Voice, targeted at voice content, applies compression using a range of low bit rates.^[4] Microsoft has also developed a digital container format called Advanced Systems Format to store audio encoded by WMA.

Development history[edit]

The first WMA codec was based on earlier work by Henrique Malvar and his team which was transferred to the Windows Media team at Microsoft.^[5] Malvar was a senior researcher and manager of the Signal Processing Group at Microsoft Research,^[6] whose team worked on the MSAudio project.^[7] The first finalized codec was initially referred to as MSAudio 4.0.^[8][9] It was later officially released as Windows Media Audio,^[1] as part of Windows Media Technologies 4.0. Microsoft claimed that WMA could produce files that were half the size of equivalent-quality MP3 files;^[10] Microsoft also claimed that WMA delivered «near CD-quality» audio at 64 kbit/s.^[10] The former claim however was rejected by some audiophiles^[11] and both claims have been refuted through publicly-available codec listening tests. RealNetworks also challenged Microsoft’s claims regarding WMA’s superior audio quality compared to RealAudio.^[3]

Newer versions of WMA became available: Windows Media Audio 2 in 1999,^[12] Windows Media Audio 7 in 2000,^[13] Windows Media Audio 8 in 2001,^[14] and Windows Media Audio 9 in 2003.^[4] Microsoft first announced its plans to license WMA technology to third parties in 1999.^[15] Prior to Windows XP , WMA files were primarily streamed using the Windows Media Source Filter (DirectShow codec), later being removed in Windows Vista with the addition of Media Foundation.^[16] Although earlier versions of Windows Media Player played WMA files, support for WMA file creation was not added until the seventh version.^[17] In 2003, Microsoft released new audio codecs that were not compatible with the original WMA codec. These codecs were Windows Media Audio 9 Professional,^[4] Windows Media Audio 9 Lossless,^[4] and Windows Media Audio 9 Voice.^[4]

All versions of WMA released since version 9.0 – namely 9.1, 9.2, and 10 – have been backwards compatible with the original v9 decoder and are therefore not considered separate codecs. The sole exception to this is the WMA 10 Professional codec whose Low Bit Rate (LBR) mode is only backwards compatible with the older WMA Professional decoders at a half sampling rate (similar to how HE-AAC is backwards compatible with AAC-LC). Full fidelity decoding of WMA 10 Professional LBR bitstreams requires a WMA version 10 or newer decoder.

Container format[edit]

A WMA file is in most circumstances contained in the Advanced Systems Format (ASF), a proprietary Microsoft container format for digital audio or digital video.^[18] The ASF container format specifies how metadata about the file is to be encoded, similar to the ID3 tags used by MP3 files. Metadata may include song name, track number, artist name, and also audio normalization values. This container can optionally support digital rights management (DRM) using a combination of elliptic curve cryptography key exchange, DES block cipher, a custom block cipher, RC4 stream cipher and the SHA-1 hashing function. See Windows Media DRM for further information.

Since 2008 Microsoft has also been using WMA Professional in its Protected Interoperable File Format (PIFF) based on the ISO Base Media File Format and most commonly used for Smooth Streaming, a form of adaptive bitrate streaming over HTTP. Related industry standards such as DECE UltraViolet and MPEG-DASH have not standardized WMA as a supported audio codec, deciding in favor of the more industry-prevalent MPEG and Dolby audio codecs.

Codecs[edit]

Each WMA file features a single audio track in one of the four sub-formats: WMA, WMA Pro, WMA Lossless, or WMA Voice. These formats are implemented differently from one another, such that they are technically distinct and mutually incompatible; that is to say, a device or software compatible with one sub-format does not therefore automatically support any of the other codecs. Each codec is further explained below.

Windows Media Audio[edit]

Windows Media Audio (WMA) is the most common codec of the four WMA codecs. The colloquial usage of the term WMA, especially in marketing materials and device specifications, usually refers to this codec only. The first version of the codec released in 1999 is regarded as WMA 1. In the same year, the bit stream syntax, or compression algorithm, was altered in minor ways and became WMA 2.^[12] Since then, newer versions of the codec have been released, but the decoding process remained the same, ensuring compatibility between codec versions.^[12] WMA is a lossy audio codec based on the study of psychoacoustics. Audio signals that are deemed to be imperceptible to the human ear are encoded with reduced resolution during the compression process.

WMA can encode audio signals sampled at up to 48 kHz with up to two discrete channels (stereo). WMA 9 introduced variable bit rate (VBR) and average bit rate (ABR) coding techniques into the MS encoder although both were technically supported by the original format.^[12] WMA 9.1 also added support for low-delay audio,^[19] which reduces latency for encoding and decoding.

Fundamentally, WMA is a transform coder based on modified discrete cosine transform (MDCT), somewhat similar to AAC, Cook and Vorbis. The bit stream of WMA is composed of superframes, each containing 1 or more frames of 2048 samples. If the bit reservoir is not used, a frame is equal to a superframe. Each frame contains several blocks, which are 128, 256, 512, 1024, or 2048 samples long after being transformed into the frequency domain via the MDCT. In the frequency domain, masking for the transformed samples is determined, and then used to requantize the samples. Finally, the floating point samples are decomposed into coefficient and exponent parts and independently huffman coded. Stereo information is typically mid/side coded. At low bit rates, line spectral pairs (typically less than 17 kbit/s) and a form of noise coding (typically less than 33 kbit/s) can also be used to improve quality.

Like AAC and Ogg Vorbis, WMA was intended to address perceived deficiencies in the MP3 standard. Given their common design goals, the three formats ended up making similar design choices. All three are pure transform codecs. Furthermore, the MDCT implementation used in WMA is essentially a superset of those used in Ogg and AAC such that WMA iMDCT and windowing routines can be used to decode AAC and Ogg Vorbis almost unmodified. However, quantization and stereo coding is handled differently in each codec. The primary distinguishing trait of the WMA Standard format is its unique use of 5 different block sizes, compared to MP3, AAC, and Ogg Vorbis which each restrict files to just two sizes. WMA Pro extends this by adding a 6th block size used at 88.2/96 kHz sampling rate.

Certified PlaysForSure devices, as well as a large number of uncertified devices, ranging from portable hand-held music players to set-top DVD players, support the playback of WMA files. Most PlaysForSure-certified online stores distribute content using this codec only. In 2005, Nokia announced its plans to support WMA playback in future Nokia handsets.^[20] In the same year, an update was made available for the PlayStation Portable (version 2.60) which allowed WMA files to be played on the device for the first time.^[21]

Windows Media Audio Professional[edit]

Windows Media Audio Professional (WMA Pro) is an improved lossy codec closely related to WMA standards. It retains most of the same general coding features, but also features improved entropy coding and quantization strategies as well as more efficient stereo coding. Notably, many of the WMA standard’s low bitrate features have been removed, as the core codec is designed for efficient coding at most bitrates. Its main competitors include AAC, HE-AAC, Vorbis, Dolby Digital, and DTS. It supports 16-bit and 24-bit sample bit depth, sampling rates up to 96 kHz, and up to eight discrete channels (7.1 channel surround).^[22] WMA Pro also supports dynamic range compression, which reduces the volume difference between the loudest and quietest sounds in the audio track. According to Microsoft’s Amir Majidimehr, WMA Pro could theoretically go beyond 7.1 surround sound and support «an unlimited number of channels»; however, Microsoft chose to limit its current capability to eight (7.1 discrete channels).^[23]

The codec’s bit stream syntax was frozen at the first version, WMA 9 Pro.^[24] Later versions of WMA Pro introduced low-bit rate encoding, low-delay audio,^[25] frequency interpolation mode,^[26] and an expanded range of sampling rate and bit-depth encoding options. A WMA 10 Pro file compressed with frequency interpolation mode comprises a WMA 9 Pro track encoded at half the original sampling rate, which is then restored using a new compression algorithm.^[27] In this situation, WMA 9 Pro players which have not been updated to the WMA 10 Pro codec can only decode the lower quality WMA 9 Pro stream. Starting with WMA 10 Pro, eight channel encoding starts at 128 kbit/s, and tracks can be encoded at the native audio CD resolution (44.1 kHz, 16-bit), previously the domain of WMA Standard.

Despite a growing number of supported devices and its superiority over WMA, WMA Pro still has little hardware and software support. Some notable exceptions to this are the Microsoft Zune (limited to stereo),^[28] Xbox 360,^[29] Windows Mobile-powered devices with Windows Media Player 10 Mobile,^[30] newer Toshiba Gigabeat and Motorola devices,^[31][32] and devices running recent versions of the Rockbox alternative firmware.^[33] In addition, WMA Pro is a requirement for the WMV HD certification program.^[34] On the software side, Verizon utilizes WMA 10 Pro for its V CAST Music Service,^[35] and Windows Media Player 11 has promoted the codec as an alternative to WMA for copying audio CD tracks.^[36] WMA Pro is supported in Silverlight as of version 2 (though only in stereo mode). In the absence of the appropriate audio hardware, WMA Pro can automatically downmix multichannel audio to stereo or mono, and 24-bit resolution to 16-bit during playback.

A notable example of WMA Pro being used instead of WMA Standard is the NBC Olympics website which uses WMA 10 Pro in its low-bitrate mode at 48 kbit/s.^{[citation needed]}

Windows Media Audio Lossless[edit]

Windows Media Audio 9 Lossless is a lossless incarnation of Windows Media Audio, an audio codec by Microsoft, released in early 2003. It compresses an audio CD to a range of 206 to 411 MB, at bit rates of 470 to 940 kbit/s. The result is a bit-for-bit duplicate of the original audio file; in other words, the audio quality on the CD will be the same as the file when played back. WMA Lossless uses the same .WMA file extension as other Windows Media Audio formats. It supports 6 discrete channels and up to 24-bit/96 kHz lossless audio. The format has never been publicly documented, although an open-source decoder has been reverse-engineered for non-Microsoft platforms by the libav and ffmpeg projects.

Windows Media Audio Lossless (WMA Lossless) is a lossless audio codec that competes with ATRAC Advanced Lossless, Dolby TrueHD, DTS-HD Master Audio, Shorten, Monkey’s Audio, FLAC, Apple Lossless, and WavPack (Since late 2011,^[37][38][39] the last three have the advantage of being open source software and available for nearly any operating system.) Designed for archival purposes,^[40] it compresses audio signals without loss of quality from the original using VBR. When decompressed, the audio signal is an exact replica of the original. The first version of the codec, WMA 9 Lossless, and its revisions support up to 96 kHz, 24-bit audio for up to 6 discrete channels (5.1 channel surround) with dynamic range compression control. The typical compression ratio for music varies between 1.7:1 and 3:1.^[40][41][42]

Hardware support for the codec is available on the Cowon A3,^[43] Cowon S9, Bang & Olufsen Serenata^[44] Sony Walkman NWZ-A and NWZ-S series, Zune 4, 8, 80 30, Zune 120 (with firmware version 2.2 or later) and the Zune HD, Xbox 360,^[29] Windows Mobile-powered devices with Windows Media Player 10 Mobile,^[30] Windows Phone (version 8 and above), Toshiba Gigabeat S and V models, Toshiba T-400, the Meizu M3, and Best Buy’s Insignia NS-DV, Pilot, and Sport music players. The Logitech Squeezebox Touch now supports the format natively despite previously only supporting it via transcoding. Like WMA Standard, WMA Lossless is being used by a few online stores to distribute music online.^[45][46] Similar to WMA Pro, the WMA Lossless decoder can perform downmixing when capable audio hardware is not present.^{[citation needed]} As of 2012, the ffmpeg and libav projects have open source WMA Lossless decoders based on reverse engineering of the official decoder. Only 16-bit WMA files can be successfully decoded by ffmpeg as of June 20, 2012.

Windows Media Audio Voice[edit]

Windows Media Audio Voice (WMA Voice) is a lossy audio codec that competes with Speex (used in Microsoft’s own Xbox Live online service^[47]), ACELP, and other codecs. Designed for low-bandwidth, voice playback applications,^[48] it employs low-pass and high-pass filtering of sound outside the human speech frequency range to achieve higher compression efficiency than WMA. It can automatically detect sections of an audio track containing both voice and music and use the standard WMA compression algorithm instead.^[24] WMA Voice supports up to 22.05 kHz for a single channel (mono) only.^[48] Encoding is limited to constant bit rate (CBR) and up to 20 kbit/s. The first and only version of the codec is WMA 9 Voice.

Windows Mobile-powered devices with Windows Media Player 10 Mobile have native support for WMA 9 Voice playback.^[30] In addition, BBC World Service has employed WMA Voice for its Internet radio streaming service.^[49]

Sound quality[edit]

See codec listening test for a table of double-blind listening test results.

Microsoft claims that audio encoded with WMA sounds better than MP3 at the same bit rate; Microsoft also claims that audio encoded with WMA at lower bit rates sound better than MP3 at higher bit rates.^[50] Double blind listening tests with other lossy audio codecs have shown varying results, from failure to support Microsoft’s claims about its superior quality to supremacy over other codecs. One independent test conducted in May 2004 at 128 kbit/s showed that WMA was roughly equivalent to LAME MP3; inferior to AAC and Vorbis; and superior to ATRAC3 (software version).^[51]

Some studies concluded:

• At 32 kbit/s,^{[permanent dead link]} WMA Standard was noticeably better than LAME MP3, but not better than other modern codecs in a collective, independent test in July 2004.
• At 48 kbit/s Archived 2014-07-08 at the Wayback Machine, WMA 10 Pro was ranked second after Nero HE-AAC and better than WMA 9.2 in an independent listening test organized and supported by Sebastian Mares and Hydrogenaudio Forums in December 2006. This test, however, used CBR for WMA 10 Pro and VBR for the other codecs.
• At 64 kbit/s, WMA Pro outperformed Nero HE-AAC in a listening test commissioned by Microsoft but independently performed by the National Software Testing Labs in 1999. Out of 300 participants, «71% of all listeners indicated that WMA Pro was equal to or better than HE AAC.»^{[citation needed]} However, a September 2003 public listening test conducted by Roberto Amorim found that listeners preferred 128 kbit/s MP3 to 64 kbit/s WMA audio with greater than 99% confidence.
• At 80 kbit/s Archived 2014-07-08 at the Wayback Machine and 96 kbit/s, WMA had lower quality than HE-AAC, AAC-LC, and Vorbis; near-equivalent quality to MP3, and better quality than MPC in individual tests done in 2005.
• At 128 kbit/s, there was a four-way tie between aoTuV Vorbis, LAME MP3, WMA 9 Pro and AAC in a large scale test in January 2006, with each codec sounding close to the uncompressed music file for most listeners.
• At 768 kbit/s, WMA 9 Pro delivered full-spectrum response at half the bit rate required for DTS in a comparative test done by EDN in October 2003. The test sample was a 48 kHz, 5.1 channel surround audio track.

Criticism of claimed quality[edit]

Microsoft’s claims of WMA sound quality have frequently drawn complaints. «Some audiophiles challenge Microsoft’s claims regarding WMA’s quality», according to a published article from EDN.^[11] Another article from MP3 Developments wrote that Microsoft’s claim about CD-quality audio at 64 kbit/s with WMA was «very far from the truth».^[52] At the early stages of WMA’s development, a representative from RealNetworks claimed that WMA was a «clear and futile effort by Microsoft to catch up with RealAudio 8».^[53]

Microsoft has sometimes claimed that the sound quality of WMA at 64 kbit/s equals or exceeds that of MP3 at 128 kbit/s (both WMA and MP3 are considered near-transparent at 192 kbit/s by most listeners). In a 1999 study funded by Microsoft, National Software Testing Laboratories (NSTL) found that listeners preferred WMA at 64 kbit/s to MP3 at 128 kbit/s (as encoded by MusicMatch Jukebox).^[54]

Both MP3 and WMA encoders have undergone active development and improvement for many years, so their relative quality may change over time.

Players[edit]

Apart from Windows Media Player, most of the WMA compression formats can be played using ALLPlayer, VLC media player,^[55] Media Player Classic,^[56] MPlayer, RealPlayer, Winamp, Zune Software (with certain limitations—DSP plugin support and DirectSound output is disabled using the default WMA plugin),^{[citation needed]} and many other software media players. The Microsoft Zune media management software supports most WMA codecs, but uses a variation of Windows Media DRM which is used by PlaysForSure.

The FFmpeg project has reverse-engineered and re-implemented the WMA codecs to allow their use on POSIX-compliant operating systems such as Linux. The Rockbox project further extended this codec to be suitable for embedded cores, allowing playback on portable MP3 players and cell phones running open source software. RealNetworks has announced plans to support playback of DRM-free WMA files in RealPlayer for Linux.^[57] On the Macintosh platform, Microsoft released a PowerPC version of Windows Media Player for Mac OS X in 2003,^[58] but further development of the software has ceased. Microsoft currently endorses the third-party Flip4Mac WMA, a QuickTime component that allows Macintosh users to play WMA files in any player that uses the QuickTime framework.^[59] Flip4Mac, however, does not currently support the Windows Media Audio Voice codec.^[60]

Not all Android devices have native support for WMA files because the core Android platform doesn’t support this format, but third-party software that supports it also exists.

WMA format can be played in almost all Windows Mobile and later Windows Phone devices.

Encoders[edit]

Software that can export audio in WMA format include Windows Media Player, Windows Movie Maker, Microsoft Expression Encoder, Sony Sound Forge, GOM Player, RealPlayer,^[61] Adobe Premiere Pro,^[62] Adobe Audition,^[63] and Adobe Soundbooth.^[64] Microsoft Office OneNote supports encoding in all WMA codecs,^[65] and Windows Media Encoder supports all available bit rate and resolution options as well. Open source players like VLC media player can also do some encoding.

Digital rights management[edit]

The WMA codecs are most often used with the ASF container format, which has an optional DRM facility. Windows Media DRM, which can be used in conjunction with WMA, supports time-limited music subscription services such as those offered by unlimited download services, including MTV’s URGE, Napster, Rhapsody, Yahoo! Music Unlimited, and Virgin Digital. Windows Media DRM, a component of PlaysForSure and Windows Media Connect, is supported on many modern portable audio devices and streaming media clients such as Roku, SoundBridge, Xbox 360, and Wii. Players that support the WMA format but not Windows Media DRM cannot play DRM-protected files.

See also[edit]

• Windows Media Video – a video file format and codec developed by Microsoft
• WAV
• JPEG XR / HD Photo – an image file format and codec developed by Microsoft
• Surround sound
• Timeline of audio formats
• Comparison of audio coding formats

References[edit]

External links[edit]

• Windows Media homepage at Microsoft