Langbahn Team – Weltmeisterschaft

Libav

Libav
Developer(s)Libav team
Initial releaseMarch 13, 2011 (2011-03-13)[1]
Final release12.3 (February 12, 2018; 6 years ago (2018-02-12))
Written inC[2]
Operating systemLinux, BSD, macOS, Microsoft Windows, AmigaOS, MorphOS[3]
PlatformIA-32, x86-64, PowerPC, ARM, DEC Alpha, SPARC, and MIPS[3]
TypeMultimedia framework
LicenseLGPL-2.1-or-later
GPL-2.0-or-later[4]
Websitelibav.org

Libav is an abandoned[5] free software project, forked from FFmpeg in 2011, that contains libraries and programs for handling multimedia data.

History

Fork from FFmpeg

The Libav project was a fork of the FFmpeg project.[6] It was announced on March 13, 2011 by a group of FFmpeg developers.[7][8][9] The event was related to an issue in project management and different goals: FFmpeg supporters wanted to keep development velocity in favour of more features, while Libav supporters and developers wanted to improve the state of the code and take the time to design better APIs.[10][11]

The maintainer of the FFmpeg packages for Debian[12] and Ubuntu,[13] being one of the group of developers who forked FFmpeg, switched the packages to this fork in 2011. Hence, most software on these systems that depended on FFmpeg automatically switched to Libav. On July 8, 2015, Debian announced it would return to FFmpeg[14] for various, technical reasons.[15] Several arguments justified this step. Firstly, FFmpeg had a better record of responding to vulnerabilities than Libav. Secondly, Mateusz "j00ru" Jurczyk, a security-oriented developer at Google, argued that all issues he found in FFmpeg were fixed in a timely manner, while Libav was still affected by various bugs.[16] Finally, FFmpeg supported a far wider variety of codecs and containers than Libav.

As of 2022, Libav is an abandoned software project, with Libav developers either returning to FFmpeg, moving to other multimedia projects like the AV1 video codec,[17] or leaving the multimedia field entirely.

Confusion

At the beginning of this fork, Libav and FFmpeg separately developed their own versions of the ffmpeg command. Libav then renamed their ffmpeg to avconv to distance themselves from the FFmpeg project. During the transition period, when a Libav user typed ffmpeg, there was a message telling the user that the ffmpeg command was deprecated and avconv has to be used instead. This confused some users into thinking that FFmpeg (the project) was dead.[18]

This message was removed upstream when ffmpeg was finally removed from the Libav sources. In June 2012, on Ubuntu 12.04, the message was re-worded, but that new "deprecated" message caused even more user confusion. Starting with Ubuntu 15.04 "Vivid", FFmpeg's ffmpeg is back in the repositories again.

To further complicate matters, Libav chose a name that was used by FFmpeg to refer to its libraries (libavcodec, libavformat, etc.). For example, the libav-user mailing list, for questions and discussions about using the FFmpeg libraries, is unrelated to the Libav project.[19][20]

Software using Libav instead of FFmpeg

Debian followed Libav when it was announced, and announced it would return to FFmpeg for Debian Stretch (9.0).[21]

MPlayer2, a defunct fork of MPlayer, used Libav exclusively, but could be used with GStreamer with its public API. The MPV media player no longer supports Libav due to missing API changes.[22]

Codecs

Libav contains more than 100 codecs.[23] Many codecs that compress information have been claimed by patent holders.[24] Such claims may be enforceable in countries like the United States which have implemented software patents, but are considered unenforceable or void in countries that have not implemented software patents.

The Libav logo uses a zigzag pattern that references how MPEG video codecs handle entropy encoding.[25] It was previously the logo of the FFmpeg project until Libav was forked from it. Following the fork, in 2011 one of the Libav developers Måns Rullgård claimed copyright over the logo and requested FFmpeg cease and desist from using it.[26] FFmpeg subsequently altered their logo into a 3D version.[27]

Google Summer of Code participation

Libav participated in the Google Summer of Code program in 2011 and 2012.[28]

With participation in the Google Summer of Code, Libav has had many new features and improvements developed, including a WMVP/WVP2 decoder, hardware accelerated H.264 decoding on Android, and G.723.1 codec support.[28]

Technical details

Components

Libav primarily consists of libavcodec, which is an audio/video codec library used by several other projects, libavformat, which is an audio/video container muxing and demuxing library, and avconv, which is a multimedia manipulation tool similar to FFmpeg's ffmpeg or Gstreamer gst-launch-1.0 command.

The command line-programs:

avconv
A video and audio converter that can also grab from a live audio/video source.
avserver
A streaming server for both audio and video.
avplay
A very simple and portable media player using the Libav libraries and the SDL library.
avprobe
Gathers information from multimedia streams and prints it in human- and machine-readable fashion.

The libraries:

libavcodec
A library containing all the Libav audio/video encoders and decoders.
libavfilter
The substitute for vhook which allows the video/audio to be modified or examined between the decoder and the encoder.
libavformat
A library containing demuxers and muxers for audio and video container formats.
libavresample
A library containing audio resampling routines.
libavutil
A helper library containing routines common to different parts of Libav.

This library includes Adler-32, CRC, MD5, SHA-1, LZO decompressor, Base64 encoder/decoder, DES encrypter/decrypter, RC4 encrypter/decrypter and AES encrypter/decrypter.

libswscale
A library containing video image scaling and colorspace/pixelformat conversion routines.

Contained codecs

Numerous free and open-source implementations of existing algorithms for the (usually lossy) compression and decompression of audio or video data, called codecs, are available. Please note that an algorithm can be subject to patent law in some jurisdictions. Here are lists of the ones contained in the libav library:

Video codecs

Libav includes video decoders and/or encoders for the following formats:[29]

Audio codecs

Libav includes decoders and encoders for the following formats:[34]

Supported file formats

Additionally to the aforementioned codecs, Libav also supports several file formats (file formats designed to contain audio and/or video data and subtitles, are called "containers", but that is just a special denomination.):

Supported protocols

Support for several communications protocols is also contained in Libav. Here is a list:

  • IETF standards: TCP, UDP, Gopher, HTTP, RTP, RTSP and SDP
  • Apple related protocols: HTTP Live Streaming
  • RealMedia related protocols: RealMedia RTSP/RDT
  • Adobe related protocols: RTMP, RTMPT (via librtmp), RTMPE (via librtmp), RTMPTE (via librtmp) and RTMPS (via librtmp)
  • Microsoft related protocols: MMS over TCP and MMS over HTTP

See also

References

  1. ^ "Libav Home/News Page". libav.org. 2012-05-09. Archived from the original on 2022-06-22. Retrieved 2018-09-01.
  2. ^ "Developer Documentation". libav.org. 2011-12-08. Archived from the original on 2012-04-22. Retrieved 2012-05-17.
  3. ^ a b "FATE". libav.org. Archived from the original on 2018-09-02. Retrieved 2012-05-17.
  4. ^ Kunhya, Kieran (2020-04-16). "[libav-devel] What is the status of this project?". Archived from the original on 2020-08-12. Retrieved 2020-12-20.
  5. ^ "About Libav". libav.org. Archived from the original on 2014-12-05. Retrieved 2014-11-30. ... which convinced us to fork "properly" under the name Libav with its own website, mailing lists, IRC channel and repositories, thus completely separating from the old FFmpeg project{{cite web}}: CS1 maint: bot: original URL status unknown (link)
  6. ^ "Libav project site". libav.org. Archived from the original on 2022-06-22. Retrieved 2012-01-04.
  7. ^ Ronald S. Bultje (2011-03-14). "Project renamed to Libav". gmane.org. Archived from the original on 2016-11-07. Retrieved 2012-01-04.
  8. ^ "A group of FFmpeg developers just forked as Libav". phoronix.com. Phoronix. 2011-03-14. Retrieved 2012-01-04.
  9. ^ "What happened to FFmpeg". multimedia.cx. 2011-03-30. Archived from the original on 2012-03-07. Retrieved 2012-05-19.{{cite web}}: CS1 maint: bot: original URL status unknown (link)
  10. ^ "FFMpeg turmoil". lwn.net. 2011-01-19. Retrieved 2012-01-04.
  11. ^ "transition: Libav 0.7". debian.org. 2011-05-01. Archived from the original on 2015-02-11. Retrieved 2012-01-04.{{cite web}}: CS1 maint: bot: original URL status unknown (link)
  12. ^ "Ubuntu Release Management: Transition: "Libav"". canonical.com. Archived from the original on 2012-01-07. Retrieved 2012-01-04.
  13. ^ "libav and FFmpeg: switch over". debian.org. 2015-08-02. Retrieved 2015-08-02.
  14. ^ "Debate/libav-provider/ffmpeg - Debian Wiki". debian.org. 2015-08-02. Retrieved 2015-08-02.
  15. ^ "FFmpeg and a thousand fixes". 10 January 2014. Archived from the original on 2021-09-15. Retrieved 2021-09-15.{{cite web}}: CS1 maint: bot: original URL status unknown (link)
  16. ^ "Luca Barbato's (Libav developer) blog". 9 April 2019.
  17. ^ "Bug #939863 "Warning message from ffmpeg program needs update" : Bugs : libav package : Ubuntu". Launchpad. 2012-02-23. Retrieved 2024-07-02.
  18. ^ "What are the differences and similarities between ffmpeg, libav, and avconv?". February 28, 2012. Retrieved 14 August 2015.
  19. ^ "The FFmpeg/Libav situation". 30 June 2012. Archived from the original on 1 July 2012. Retrieved 14 August 2015.
  20. ^ "Debian to switch back to ffmpeg". July 8, 2015. Archived from the original on 2015-07-26. Retrieved 14 August 2015.{{cite web}}: CS1 maint: bot: original URL status unknown (link)
  21. ^ "mpv - README - FFmpeg vs. Libav". GitHub. April 20, 2018. Archived from the original on September 15, 2021. Retrieved June 5, 2018.{{cite web}}: CS1 maint: bot: original URL status unknown (link)
  22. ^ "Supported File Formats and Codecs". libav.org. Archived from the original on 2014-05-04. Retrieved 2014-05-04.
  23. ^ "Libav License and Legal Considerations". libav.org. Archived from the original on 2014-04-14. Retrieved 2014-05-04.
  24. ^ FFmpeg logo Archived 2017-04-28 at the Wayback Machine - FFMpeg mailing list, 20 Feb 2007
  25. ^ Legal Threat - ffmpeg.org 28 May 2011
  26. ^ "FFmpeg License and Legal Considerations". ffmpeg.org. 2011-05-31. Archived from the original on 2012-01-03.
  27. ^ a b "FFmpeg/Libav Summer of Code". multimedia.cx. Archived from the original on 2011-11-17. Retrieved 2012-05-19.
  28. ^ "General Documentation". libav.org. Archived from the original on 2012-05-27. Retrieved 2012-05-19.{{cite web}}: CS1 maint: bot: original URL status unknown (link)
  29. ^ a b c d e f g banan (17 April 2007). "Changelog". mplayerhq.hu. Retrieved 26 April 2007.[permanent dead link‍]
  30. ^ "Add libx265 encoder". Github.com. Retrieved 19 January 2023.
  31. ^ "OpenHEVC/Libav · GitHub". GitHub. Archived from the original on 25 August 2013.
  32. ^ a b ivo (7 May 2007). "FFmpeg development mailing list". mplayerhq.hu. Archived from the original on 11 August 2007. Retrieved 24 December 2010.
  33. ^ "General Documentation". libav.org. Archived from the original on 2012-05-27. Retrieved 2012-05-19.
  34. ^ "#210 (24bit flac encoding) - FFmpeg". Ffmpeg.org. Retrieved 2012-02-03.
  35. ^ vitor (13 April 2008). "FFmpeg development mailing list". mplayerhq.hu. Retrieved 14 April 2008.[permanent dead link‍]
  36. ^ vitor (30 March 2008). "FFmpeg development mailing list". mplayerhq.hu. Retrieved 30 March 2008.[permanent dead link‍]
  37. ^ faust3 (21 March 2008). "FFmpeg development mailing list". mplayerhq.hu. Archived from the original on 25 April 2008. Retrieved 21 March 2008.{{cite web}}: CS1 maint: numeric names: authors list (link)
  38. ^ benoit (14 April 2008). "FFmpeg development mailing list". mplayerhq.hu. Retrieved 14 April 2008.[permanent dead link‍]
  39. ^ ramiro (18 March 2008). "FFmpeg development mailing list". mplayerhq.hu. Archived from the original on 17 August 2008. Retrieved 18 March 2008.
  40. ^ banan (8 June 2008). "FFmpeg development mailing list". mplayerhq.hu. Archived from the original on 14 January 2009. Retrieved 8 June 2008.
  41. ^ "Page showing Libav and FFmpeg snapshots VLC uses (people can compile VLC with either FFmpeg or Libav)". videolan.org. Archived from the original on 2018-04-07. Retrieved 2018-04-06.
Quelle: https://en.wikipedia.org/wiki/Libav