libavcodec is an integral part of many open-source multimedia applications and frameworks. The popular MPV, xine and VLC media players use it as their main, built-in decoding engine that enables playback of many audio and video formats on all supported platforms. It is also used by the ffdshow tryouts decoder as its primary decoding library. libavcodec is also used in video editing and transcoding applications like Avidemux, MEncoderorKdenlive for both decoding and encoding.
libavcodec contains decoder and sometimes encoder implementations of several proprietary formats, including ones for which no public specification has been released. As such, a significant reverse engineering effort is part of libavcodec development. Having such codecs available within the standard libavcodec framework gives a number of benefits over using the original codecs, most notably increased portability, and in some cases also better performance, since libavcodec contains a standard library of highly optimized implementations of common building blocks, such as DCT and color space conversion. However, while libavcodec does strive to achieve decoding that is bit-exact to their official format implementations, occasional bugs and missing features in such re-implementations can sometimes introduce playback compatibility problems for certain files.
Libavcodec contains more than 100 codecs,[8] most of which do not just store uncompressed data. Most codecs that compress information could be claimed by patent holders.[9] 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.
Furthermore, many of these codecs are only released under terms that forbid reverse engineering, even for purposes of interoperability. These terms of use are forbidden in certain countries. For example, some European Union nations have not implemented software patents and have laws expressly allowing reverse engineering for purposes of interoperability.[10]
ffdshow (wraps libavcodec as a DirectShow filter and adds postprocessing to improve image quality; once installed, it is automatically used by all Windows DirectShow video players, such as Windows Media Player, Media Player Classic, Winamp etc. It also wraps libavcodec as a Video for Windows filter; the framework used by most video editing software.)
^"Download". ffmpeg.org. FFmpeg. Archived from the original on 2013-09-27. Retrieved 2012-01-04.
^libavcodec can be configured to make it a proprietary and non-redistributable library since some optional external libraries are proprietary software and cannot be distributed under the terms of the GPL (e.g. Decklink).
^Wieckowski, Adam; Lehmann, Christian; Bross, Benjamin; Marpe, Detlev; Biatek, Thibaud; Raulet, Mickael; Jean Le Feuvre (2021). "A Complete End to End Open Source Toolchain for the Versatile Video Coding (VVC) Standard". Proceedings of the 29th ACM International Conference on Multimedia. pp. 3795–3798. arXiv:2107.13385. doi:10.1145/3474085.3478320. ISBN9781450386517. S2CID236469263.
