fbpx
Wikipedia

Windows Media Audio

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

Windows Media Audio (WMA) is a series of audio codecs and their corresponding audio coding formats developed by Microsoft. 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. WMA Pro, a newer and more advanced codec, supports multichannel and high resolution audio. A lossless codec, WMA Lossless, compresses audio data without loss of audio fidelity (the regular WMA format is lossy). WMA Voice, targeted at voice content, applies compression using a range of low bit rates. Microsoft has also developed a digital container format called Advanced Systems Format to store audio encoded by WMA.

Contents

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. Malvar was a senior researcher and manager of the Signal Processing Group at Microsoft Research, whose team worked on the MSAudio project. The first finalized codec was initially referred to as MSAudio 4.0. It was later officially released as Windows Media Audio, 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; Microsoft also claimed that WMA delivered "near CD-quality" audio at 64 kbit/s. The former claim however was rejected by some audiophiles. RealNetworks also challenged Microsoft's claims regarding WMA's superior audio quality compared to RealAudio.

Newer versions of WMA became available: Windows Media Audio 2 in 1999, Windows Media Audio 7 in 2000, Windows Media Audio 8 in 2001, and Windows Media Audio 9 in 2003. Microsoft first announced its plans to license WMA technology to third parties in 1999. 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. Although earlier versions of Windows Media Player played WMA files, support for WMA file creation was not added until the seventh version. In 2003, Microsoft released new audio codecs that were not compatible with the original WMA codec. These codecs were Windows Media Audio 9 Professional, Windows Media Audio 9 Lossless, and Windows Media Audio 9 Voice.

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 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.

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. 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 bit rate 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.

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

Windows Media Audio (WMA) is the most common codec of the four WMA codecs. 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. Since then, newer versions of the codec have been released, but the decoding process remained the same, ensuring compatibility between codec versions. 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. WMA 9.1 also added support for low-delay audio, 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 a number of 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. 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.

Windows Media Audio Professional

Screenshot of Windows Media Encoder 9 Series, displaying new encoding options for Windows Media Audio 10 Professional.

Windows Media Audio Professional (WMA Pro) is an improved lossy codec closely related to WMA standard. 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). 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).

The codec's bit stream syntax was frozen at the first version, WMA 9 Pro. Later versions of WMA Pro introduced low-bit rate encoding, low-delay audio, frequency interpolation mode, 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. 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), Xbox 360, Windows Mobile-powered devices with Windows Media Player 10 Mobile, newer Toshiba Gigabeat and Motorola devices, and devices running recent versions of the Rockbox alternative firmware. In addition, WMA Pro is a requirement for the WMV HD certification program. On the software side, Verizon utilizes WMA 10 Pro for its V CAST Music Service, and Windows Media Player 11 has promoted the codec as an alternative to WMA for copying audio CD tracks. 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

Label for 5.1 surround sound, the maximum channel configuration for Windows Media Audio Lossless.

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, the last three have the advantage of being open source software and available for nearly any operating system.) Designed for archival purposes, 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.

Hardware support for the codec is available on the Cowon A3, Cowon S9, Bang & Olufsen Serenata 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, Windows Mobile-powered devices with Windows Media Player 10 Mobile, 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. 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

Windows Media Audio Voice (WMA Voice) is a lossy audio codec that competes with Speex (used in Microsoft's own Xbox Live online service), ACELP, and other codecs. Designed for low-bandwidth, voice playback applications, 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. WMA Voice supports up to 22.05 kHz for a single channel (mono) only. 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. In addition, BBC World Service has employed WMA Voice for its Internet radio streaming service.

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. 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).

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, 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 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

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. 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". 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".

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).

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

Apart from Windows Media Player, most of the WMA compression formats can be played using ALLPlayer, VLC media player, Media Player Classic, 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. On the Macintosh platform, Microsoft released a PowerPC version of Windows Media Player for Mac OS X in 2003, 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. Flip4Mac, however, does not currently support the Windows Media Audio Voice codec.

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.

Software that can export audio in WMA format include Windows Media Player, Windows Movie Maker, Microsoft Expression Encoder, Sony Sound Forge, GOM Player, RealPlayer, Adobe Premiere Pro, Adobe Audition, and Adobe Soundbooth. Microsoft Office OneNote supports encoding in all WMA codecs, 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.

Main article: Windows Media DRM

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.

  1. Smith, Tony (1999-03-12). "Microsoft readies MP3-killer digital music format". Archived from the original on 2008-03-21. Retrieved2007-08-16.
  2. "Analysis of the Microsoft Audio Codec". RealNetworks. Archived from the original on 2007-08-18. Retrieved2007-08-16.
  3. "Windows Media 9 Series Capabilities and Benefits Overview". International Narcotics Control Board. Archived from the original(DOC) on 2007-09-28. Retrieved2007-08-16.
  4. Hinchberger, Bill (2001-09-09). "Riding the Malvar Wave". Archived from the original on 2007-10-13. Retrieved2007-08-16.
  5. "Press Kit: Henrique Malvar". Microsoft Research. Archived from the original on 2007-08-25. Retrieved2007-08-16.
  6. "Communication, Collaboration, and Signal Processing". Microsoft Research. Archived from the original on 2007-07-17. Retrieved2007-08-16.
  7. "Microsoft Windows Media Technologies Gains Support for Downloadable Music from Top Music Sites, Independent Labels, Popular Bands And Innovative Developers". Microsoft PressPass. Archived from the original on 2007-10-24. Retrieved2007-08-16.
  8. Barry, Richard (1999-04-14). "MS Audio 4.0 will eat MP3..." Archived from the original on 2007-09-30. Retrieved2007-08-16.
  9. "Windows Media Technologies 4 Delivers Cutting-Edge CD-Quality Audio On the Internet". Microsoft PressPass. Archived from the original on 2007-10-24. Retrieved2007-08-16.
  10. "MS Windows Media Technologies Features". Microsoft TechNet. Archived from the original on 2007-10-24. Retrieved2007-08-16.
  11. "The Internet-audio (r)evolution". Archived from the original on 2007-10-10. Retrieved2007-08-16. some audiophiles challenge Microsoft's claims regarding WMA's quality
  12. "Broadcom Corporation: Audio Codecs". Archived from the original on 2007-06-08. Retrieved2007-05-30.
  13. "Microsoft Announces Windows Media Technologies 7". Microsoft. Archived from the original on 2007-10-24. Retrieved2007-08-16.
  14. "Microsoft Releases Windows Media Audio and Video 8". CDRInf. Archived from the original on 2007-09-26. Retrieved2007-08-16.
  15. "Microsoft Wins Major ISV Support for Windows Media Technologies 4.0". Microsoft PressPass. Archived from the original on 2007-09-12. Retrieved2007-08-16.
  16. Thurrott, Paul (2005-04-30). "SuperSite for Windows Media Player 7 Review". Archived from the original on 2007-08-18. Retrieved2007-08-16.
  17. "The Difference Between ASF and WMV/WMA Files". Microsoft. Archived from the original on 2007-08-19. Retrieved2007-08-16.
  18. "Windows Media Format 11 SDK Low-Delay Audio". Microsoft MSDN. Archived from the original on 2007-10-24. Retrieved2007-08-16.
  19. "Microsoft and Nokia Collaborate to Help Ensure Consumers Can Enjoy Digital Music Anywhere". Archived from the original on 2007-08-31. Retrieved2007-08-15.
  20. Carnoy, David (2005-03-23). "Sony PSP review". Archived from the original on 2007-08-10. Retrieved2007-08-16.
  21. "Windows Media Audio Codecs: Windows Media Audio 9 Professional". Microsoft. Archived from the original on 2007-09-01. Retrieved2007-08-16.
  22. "Paul Thurrott's SuperSite for Windows: Windows Media 9 Series reviewed". Archived from the original on 2007-05-28. Retrieved2007-06-24.
  23. "Windows Media Audio & Video 9 Series". Archived from the original on 2007-09-28. Retrieved2007-08-08.
  24. "Low-Delay Audio". msdn2.microsoft.com. Archived from the original on 17 April 2008. Retrieved30 April 2018.
  25. Smith, Tony (2007-02-21). "Best Practices for Windows Media Encoding". Archived from the original on 2007-08-31. Retrieved2007-08-16.
  26. "Voices: Microsoft's Amir Majidimehr: a window to the world of digital media - 11-23-2006 - EDN". Archived from the original on 2007-04-30. Retrieved2007-06-07.
  27. "Zune.net: How-To - Provide Content for Zune". Archived from the original on 2007-08-19.
  28. "Spring '07 Video Playback FAQ". Archived from the original on 2008-02-13. Retrieved2007-08-08.
  29. "Windows Media Player Mobile FAQ". Archived from the original on 2007-09-14.
  30. "Motorola and Microsoft Plan to Bring More Choice to Mobile Music Fans". Archived from the original on 2007-10-24. Retrieved2018-12-06.
  31. "Motorola Dis Apple, Expect More Microsoft Music Phones: 3GSM". Archived from the original on 2007-09-27. Retrieved2007-08-08.
  32. "New WMA Audio Codecs". Archived from the original on 2011-01-06.
  33. "WMV HD DVD Encoding Profile Guidelines".
  34. "Verizon Wireless Chooses Microsoft Windows Media to Power Its New V CAST Music Service". Archived from the original on 2007-06-15. Retrieved2018-12-06.
  35. "Windows Vista Features Explained Windows Media Player 11". Archived from the original on 2007-09-13.
  36. "Welcome to the Apple Lossless Audio Codec Project". Apple Lossless Audio Codec. MacOS Forge. October 27, 2011. Archived from the original on June 15, 2016. RetrievedOctober 29, 2011.
  37. Foresman, Chris (October 28, 2011). "After seven years, Apple open sources its Apple Lossless Audio Codec". Ars Technica. Archived from the original on October 29, 2011. RetrievedOctober 29, 2011.
  38. von Eitzen, Chris (October 28, 2011). "Apple open sources its ALAC lossless audio codec". The H. Archived from the original on 15 May 2012. RetrievedOctober 29, 2011.
  39. "Windows Media Audio Codecs: Windows Media Audio 9 Lossless". Microsoft. Archived from the original on 2007-09-01. Retrieved2007-08-16.
  40. "ExtremeTech Audio Codec Quality Shootout". Archived from the original on 2011-06-07.
  41. "Archived copy". Archived from the original on 2010-11-25. Retrieved2010-11-25.CS1 maint: archived copy as title (link)
  42. Tushar (July 2019). "What is Windows Audio Endpoint Builder service And How To Start/Stop It". techcaption.com.
  43. http://www.serenatamobile.com Archived 2007-09-30 at the Wayback Machine
  44. "Is This Digital Music's Future". Archived from the original on 2007-07-15.
  45. "Online Stores in Windows Media Player". Archived from the original on 2007-07-27.
  46. Ralph Giles of Xiph.org explained that Xbox Live uses Speex for voice compression in the June 6, 2005 interview on LugRadio: "Archived copy". Archived from the original on 2007-10-14. Retrieved2007-10-10.CS1 maint: archived copy as title (link)
  47. "Windows Media Audio Codecs: Windows Media Audio 9 Voice". Microsoft. Archived from the original on 2007-09-01. Retrieved2007-08-16.
  48. "Roku - SoundBridge Internet Radio". Archived from the original on 2007-08-16. Retrieved2007-08-08.
  49. "Windows Media: Music". Archived from the original on 2006-04-15.
  50. Amorim, Roberto. "Results of Multiformat at 128 kbit/s public Listening Test". Archived from the original on 2009-01-23.
  51. "Lossy Audio Formats". MP3Developments. Archived from the original on 2007-08-15. Retrieved2007-08-16.
  52. "Codec Rivalry Spurs Development". streamingmedia.com Codec. Archived from the original on 2007-10-15. Retrieved2007-08-16.
  53. Microsoft's summary of the study Archived 2007-10-24 at the Wayback Machine. Full report from NSTL Archived 2007-11-28 at the Wayback Machine.
  54. VideoLAN team. "VLC playback Features". Archived from the original on 2010-01-03. Retrieved2010-01-03.
  55. "Media Player Classic - Player Features". Archived from the original on 2011-08-16. Retrieved2011-08-17.
  56. Shankland, Stephen (17 August 2006). "Real to plug Windows media support into Linux". CNET. CBS Interactive. Archived from the original on 24 April 2016. Retrieved5 April 2016.
  57. "Windows Media Player 9 for Mac OS X". Archived from the original on 2007-08-21.
  58. "Important information for Windows Media Player for Mac users". Archived from the original on 2007-08-22.
  59. "Flip4Mac forum post discussing WMA Voice support". Archived from the original on 2009-07-01. Retrieved2010-01-26.
  60. "RealPlayer Customer Support: What formats can I use to record tracks from a CD with RealPlayer?".[permanent dead link]
  61. Supported file formats in Adobe Premiere Pro 2.0 Archived 2007-10-13 at the Wayback Machine,
  62. "Supported file formats (Adobe Audition 2.0)". Archived from the original on 2007-10-15. Retrieved2007-08-08.
  63. "Soundbooth CS3 supported file formats". Archived from the original on 2007-10-15.
  64. "General information about the audio functionality in OneNote 2003". Archived from the original on 2007-10-24.

Windows Media Audio
Windows Media Audio Language Watch Edit 160 160 Redirected from XMA audio format This article is about audio encoding and decoding software For the container file format see wma Windows Media Audio WMA is a series of audio codecs and their corresponding audio coding formats developed by Microsoft 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 1 2 WMA Pro a newer and more advanced codec supports multichannel and high resolution audio 3 A lossless codec WMA Lossless compresses audio data without loss of audio fidelity the regular WMA format is lossy 3 WMA Voice targeted at voice content applies compression using a range of low bit rates 3 Microsoft has also developed a digital container format called Advanced Systems Format to store audio encoded by WMA Contents 1 Development history 2 Container format 3 Codecs 3 1 Windows Media Audio 3 2 Windows Media Audio Professional 3 3 Windows Media Audio Lossless 3 4 Windows Media Audio Voice 4 Sound quality 4 1 Criticism of claimed quality 5 Players 6 Encoders 7 Digital rights management 8 See also 9 References 10 External linksDevelopment history EditThe first WMA codec was based on earlier work by Henrique Malvar and his team which was transferred to the Windows Media team at Microsoft 4 Malvar was a senior researcher and manager of the Signal Processing Group at Microsoft Research 5 whose team worked on the MSAudio project 6 The first finalized codec was initially referred to as MSAudio 4 0 7 8 It was later officially released as Windows Media Audio 9 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 RealNetworks also challenged Microsoft s claims regarding WMA s superior audio quality compared to RealAudio 2 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 3 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 Although earlier versions of Windows Media Player played WMA files support for WMA file creation was not added until the seventh version 16 In 2003 Microsoft released new audio codecs that were not compatible with the original WMA codec These codecs were Windows Media Audio 9 Professional 3 Windows Media Audio 9 Lossless 3 and Windows Media Audio 9 Voice 3 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 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 EditMain article Advanced Systems Format 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 17 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 bit rate 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 EditEach 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 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 18 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 a number of 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 19 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 20 Windows Media Audio Professional Edit Screenshot of Windows Media Encoder 9 Series displaying new encoding options for Windows Media Audio 10 Professional Windows Media Audio Professional WMA Pro is an improved lossy codec closely related to WMA standard 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 21 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 22 The codec s bit stream syntax was frozen at the first version WMA 9 Pro 23 Later versions of WMA Pro introduced low bit rate encoding low delay audio 24 frequency interpolation mode 25 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 26 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 27 Xbox 360 28 Windows Mobile powered devices with Windows Media Player 10 Mobile 29 newer Toshiba Gigabeat and Motorola devices 30 31 and devices running recent versions of the Rockbox alternative firmware 32 In addition WMA Pro is a requirement for the WMV HD certification program 33 On the software side Verizon utilizes WMA 10 Pro for its V CAST Music Service 34 and Windows Media Player 11 has promoted the codec as an alternative to WMA for copying audio CD tracks 35 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 Label for 5 1 surround sound the maximum channel configuration for Windows Media Audio Lossless 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 36 37 38 the last three have the advantage of being open source software and available for nearly any operating system Designed for archival purposes 39 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 39 40 41 Hardware support for the codec is available on the Cowon A3 42 Cowon S9 Bang amp Olufsen Serenata 43 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 28 Windows Mobile powered devices with Windows Media Player 10 Mobile 29 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 44 45 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 46 ACELP and other codecs Designed for low bandwidth voice playback applications 47 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 23 WMA Voice supports up to 22 05 kHz for a single channel mono only 47 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 29 In addition BBC World Service has employed WMA Voice for its Internet radio streaming service 48 Sound quality EditSee 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 49 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 50 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 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 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 51 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 52 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 53 Both MP3 and WMA encoders have undergone active development and improvement for many years so their relative quality may change over time Players EditApart from Windows Media Player most of the WMA compression formats can be played using ALLPlayer VLC media player 54 Media Player Classic 55 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 56 On the Macintosh platform Microsoft released a PowerPC version of Windows Media Player for Mac OS X in 2003 57 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 58 Flip4Mac however does not currently support the Windows Media Audio Voice codec 59 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 EditSoftware that can export audio in WMA format include Windows Media Player Windows Movie Maker Microsoft Expression Encoder Sony Sound Forge GOM Player RealPlayer 60 Adobe Premiere Pro 61 Adobe Audition 62 and Adobe Soundbooth 63 Microsoft Office OneNote supports encoding in all WMA codecs 64 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 EditMain article Windows Media DRM 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 EditWindows Media Video a video file format and codec developed by Microsoft JPEG XR HD Photo an image file format and codec developed by Microsoft Surround sound Timeline of audio formats Comparison of audio coding formatsReferences Edit Smith Tony 1999 03 12 Microsoft readies MP3 killer digital music format Archived from the original on 2008 03 21 Retrieved 2007 08 16 a b Analysis of the Microsoft Audio Codec RealNetworks Archived from the original on 2007 08 18 Retrieved 2007 08 16 a b c d e f g Windows Media 9 Series Capabilities and Benefits Overview International Narcotics Control Board Archived from the original DOC on 2007 09 28 Retrieved 2007 08 16 Hinchberger Bill 2001 09 09 Riding the Malvar Wave Archived from the original on 2007 10 13 Retrieved 2007 08 16 Press Kit Henrique Malvar Microsoft Research Archived from the original on 2007 08 25 Retrieved 2007 08 16 Communication Collaboration and Signal Processing Microsoft Research Archived from the original on 2007 07 17 Retrieved 2007 08 16 Microsoft Windows Media Technologies Gains Support for Downloadable Music from Top Music Sites Independent Labels Popular Bands And Innovative Developers Microsoft PressPass Archived from the original on 2007 10 24 Retrieved 2007 08 16 Barry Richard 1999 04 14 MS Audio 4 0 will eat MP3 Archived from the original on 2007 09 30 Retrieved 2007 08 16 Windows Media Technologies 4 Delivers Cutting Edge CD Quality Audio On the Internet Microsoft PressPass Archived from the original on 2007 10 24 Retrieved 2007 08 16 a b MS Windows Media Technologies Features Microsoft TechNet Archived from the original on 2007 10 24 Retrieved 2007 08 16 a b The Internet audio r evolution Archived from the original on 2007 10 10 Retrieved 2007 08 16 some audiophiles challenge Microsoft s claims regarding WMA s quality a b c d Broadcom Corporation Audio Codecs Archived from the original on 2007 06 08 Retrieved 2007 05 30 Microsoft Announces Windows Media Technologies 7 Microsoft Archived from the original on 2007 10 24 Retrieved 2007 08 16 Microsoft Releases Windows Media Audio and Video 8 CDRInf Archived from the original on 2007 09 26 Retrieved 2007 08 16 Microsoft Wins Major ISV Support for Windows Media Technologies 4 0 Microsoft PressPass Archived from the original on 2007 09 12 Retrieved 2007 08 16 Thurrott Paul 2005 04 30 SuperSite for Windows Media Player 7 Review Archived from the original on 2007 08 18 Retrieved 2007 08 16 The Difference Between ASF and WMV WMA Files Microsoft Archived from the original on 2007 08 19 Retrieved 2007 08 16 Windows Media Format 11 SDK Low Delay Audio Microsoft MSDN Archived from the original on 2007 10 24 Retrieved 2007 08 16 Microsoft and Nokia Collaborate to Help Ensure Consumers Can Enjoy Digital Music Anywhere Archived from the original on 2007 08 31 Retrieved 2007 08 15 Carnoy David 2005 03 23 Sony PSP review Archived from the original on 2007 08 10 Retrieved 2007 08 16 Windows Media Audio Codecs Windows Media Audio 9 Professional Microsoft Archived from the original on 2007 09 01 Retrieved 2007 08 16 Paul Thurrott s SuperSite for Windows Windows Media 9 Series reviewed Archived from the original on 2007 05 28 Retrieved 2007 06 24 a b Windows Media Audio amp Video 9 Series Archived from the original on 2007 09 28 Retrieved 2007 08 08 Low Delay Audio msdn2 microsoft com Archived from the original on 17 April 2008 Retrieved 30 April 2018 Smith Tony 2007 02 21 Best Practices for Windows Media Encoding Archived from the original on 2007 08 31 Retrieved 2007 08 16 Voices Microsoft s Amir Majidimehr a window to the world of digital media 11 23 2006 EDN Archived from the original on 2007 04 30 Retrieved 2007 06 07 Zune net How To Provide Content for Zune Archived from the original on 2007 08 19 a b Spring 07 Video Playback FAQ Archived from the original on 2008 02 13 Retrieved 2007 08 08 a b c Windows Media Player Mobile FAQ Archived from the original on 2007 09 14 Motorola and Microsoft Plan to Bring More Choice to Mobile Music Fans Archived from the original on 2007 10 24 Retrieved 2018 12 06 Motorola Dis Apple Expect More Microsoft Music Phones 3GSM Archived from the original on 2007 09 27 Retrieved 2007 08 08 New WMA Audio Codecs Archived from the original on 2011 01 06 WMV HD DVD Encoding Profile Guidelines Verizon Wireless Chooses Microsoft Windows Media to Power Its New V CAST Music Service Archived from the original on 2007 06 15 Retrieved 2018 12 06 Windows Vista Features Explained Windows Media Player 11 Archived from the original on 2007 09 13 Welcome to the Apple Lossless Audio Codec Project Apple Lossless Audio Codec MacOS Forge October 27 2011 Archived from the original on June 15 2016 Retrieved October 29 2011 Foresman Chris October 28 2011 After seven years Apple open sources its Apple Lossless Audio Codec Ars Technica Archived from the original on October 29 2011 Retrieved October 29 2011 von Eitzen Chris October 28 2011 Apple open sources its ALAC lossless audio codec The H Archived from the original on 15 May 2012 Retrieved October 29 2011 a b Windows Media Audio Codecs Windows Media Audio 9 Lossless Microsoft Archived from the original on 2007 09 01 Retrieved 2007 08 16 ExtremeTech Audio Codec Quality Shootout Archived from the original on 2011 06 07 Archived copy Archived from the original on 2010 11 25 Retrieved 2010 11 25 CS1 maint archived copy as title link Tushar July 2019 What is Windows Audio Endpoint Builder service And How To Start Stop It techcaption com http www serenatamobile com Archived 2007 09 30 at the Wayback Machine Is This Digital Music s Future Archived from the original on 2007 07 15 Online Stores in Windows Media Player Archived from the original on 2007 07 27 Ralph Giles of Xiph org explained that Xbox Live uses Speex for voice compression in the June 6 2005 interview on LugRadio Archived copy Archived from the original on 2007 10 14 Retrieved 2007 10 10 CS1 maint archived copy as title link a b Windows Media Audio Codecs Windows Media Audio 9 Voice Microsoft Archived from the original on 2007 09 01 Retrieved 2007 08 16 Roku SoundBridge Internet Radio Archived from the original on 2007 08 16 Retrieved 2007 08 08 Windows Media Music Archived from the original on 2006 04 15 Amorim Roberto Results of Multiformat at 128 kbit s public Listening Test Archived from the original on 2009 01 23 Lossy Audio Formats MP3Developments Archived from the original on 2007 08 15 Retrieved 2007 08 16 Codec Rivalry Spurs Development streamingmedia com Codec Archived from the original on 2007 10 15 Retrieved 2007 08 16 Microsoft s summary of the study Archived 2007 10 24 at the Wayback Machine Full report from NSTL Archived 2007 11 28 at the Wayback Machine VideoLAN team VLC playback Features Archived from the original on 2010 01 03 Retrieved 2010 01 03 Media Player Classic Player Features Archived from the original on 2011 08 16 Retrieved 2011 08 17 Shankland Stephen 17 August 2006 Real to plug Windows media support into Linux CNET CBS Interactive Archived from the original on 24 April 2016 Retrieved 5 April 2016 Windows Media Player 9 for Mac OS X Archived from the original on 2007 08 21 Important information for Windows Media Player for Mac users Archived from the original on 2007 08 22 Flip4Mac forum post discussing WMA Voice support Archived from the original on 2009 07 01 Retrieved 2010 01 26 RealPlayer Customer Support What formats can I use to record tracks from a CD with RealPlayer permanent dead link Supported file formats in Adobe Premiere Pro 2 0 Archived 2007 10 13 at the Wayback Machine Supported file formats Adobe Audition 2 0 Archived from the original on 2007 10 15 Retrieved 2007 08 08 Soundbooth CS3 supported file formats Archived from the original on 2007 10 15 General information about the audio functionality in OneNote 2003 Archived from the original on 2007 10 24 External links EditWindows Media homepage at Microsoft Retrieved from https en wikipedia org w index php title Windows Media Audio amp oldid 1049722313, wikipedia, wiki, book,

books

, library,

article

, read, download, free, free download, mp3, video, mp4, 3gp, jpg, jpeg, gif, png, picture, music, song, movie, book, game, games.