libavcodec

libavcodec是一款LGPL 自由软件编解码库，用于视频和音频数据的编解码工作。带有这个名字的库有FFmpeg项目和Libav项目，但是它们却彼此不兼容。

libavcodec是个集成了许多开源多媒体应用和框架。常见的MPlayer、xine和VLC媒体播放器都使用它作为它们的主要内置解码引擎，用于许多音频视频格式在所有支持的平台上的重放。它也被ffdshow试用解码器用作主要的解码库。libavcodec也被用于视频编辑和转换应用，例如Avidemux、MEncoder（英语：MEncoder）或者Kdenlive既用它解码也用其编码。

libavcodec包含了解码器和为实现若干专有格式而存在的编码器。其本身在逆向工程方面的工作就是libavcodec发展成长的一部分。在标准的libavcodec框架下，有着这些有效的编解码器为使用原始的编解码器带来很大的益处，最明显的就是提升了移植性。另一些方面也增加了它的表现力，因为libavcodec包含了一份标准库，它高度优化了常见建立块的实现，比如DCT和色彩空间转换。但是，即便libavcodec致力于将字节提取级别的解码来实现最终结果，这样的重现中出现的错误和丢失的特征有时候能导致回放固定文件的兼容性问题。

已實作的影像編解碼器

libavcodec 包含如下的編解碼:^[1]

Asus v1 and v2
AVS (decoding only)
CamStudio (decoding only)
Cinepak (decoding only)
Creative YUV (CYUV, decoding only)
Dirac (decoding only, encoding through libdirac and libschroedinger)
DNxHD
Duck TrueMotion v1 and v2 (decoding only)
Flash Screen Video
FFV1
(animated) GIF
H.261
H.263
H.264/MPEG-4 AVC (native decoder, encoding through x264)
Huffyuv
id Software RoQ Video
Intel Indeo (decoding only)
Lagarith (decoding only)
LOCO (decoding only)
Mimic (decoding only)
MJPEG
MPEG-1
MPEG-2/H.262
MPEG-4 Part 2 (the format used for example by the popular DivX and Xvid codecs)

On2 VP3 (decoding only)
On2 VP5 (decoding only)
On2 VP6 (decoding only)
On2 VP8 (native decoder, encoding through libvpx)
Apple ProRes
Apple Computer QuickDraw (decoding only)
QuickTime: Graphics (decoding only), Video (decoding only) and Animation (RLE)
RealVideo RV10 and RV20
RealVideo RV30 and RV40 (decoding only)
Smacker video (decoding only)
Snow
Sorenson SVQ1
Sorenson SVQ3 (decoding only)
Theora (native decoder, encoding through libtheora)
Sierra VMD Video (decoding only)
VMware VMnc (decoding only)
Westwood Studios VQA (decoding only)
WMV — version 7 and 8
WMV — version 9 / VC-1 (decoding only)
Windows Media Video Image (decoding only)
Windows Media Video Screen 1 and 2 (decoding only)
Wing Commander/Xan Video (decoding only)

已實作的音頻編解碼器

libavcodec includes decoders and encoders for the following formats:^[2]

8SVX (decoding only)
AAC
AC-3
AMR (decoding only)
AMR-WB (decoding only)
Apple Lossless
ATRAC3 (decoding only)
Cook Codec (decoding only)
DTS (encoder is highly experimental)
EA ADPCM (decoding only)
E-AC-3
EVRC (decoding only)
FLAC
GSM 06.10 (native decoder, encoding through libgsm)
Intel Music Coder and Indeo Audio Coder (decoding only)
Meridian Lossless Packing / Dolby TrueHD (decoding only)
Monkey's Audio (decoding only)
MP1 (decoding only)
MP2
MP3 (native decoder, encoding through LAME)

Nellymoser Asao Codec in Flash
Opus via external library libopus
QCELP (decoding only)
QDM2 (decoding only)
RealAudio 1.0
RealAudio 2.0 (decoding only)
Shorten (decoding only)
Truespeech (decoding only)
TTA (decoding only)
TwinVQ (decoding only)
Vorbis
WavPack (decoding only)
Windows Media Audio 1 and 2
Windows Media Audio 9 Lossless (decoding only)
Windows Media Audio 9 Professional (decoding only)
Windows Media Audio Voice (decoding only)

引用libavcodec的庫

libavformat (FFmpeg之部份)
libgegl (GEGL可選之部份)
- libgimp (GIMP之部份)
libmpcodecs (MPlayer之部份)
- libmpdemux (MPlayer之部份)

使用 libavcodec的應用程式

影像播放器

音頻播放器

Audacious (Uses in audacious-plugins's ffaudio)
Rockbox (Includes only FLAC code)
XMMS2

多媒體播放器

視訊編輯

Visual Effects

CineFX

音頻編輯

Audacity (自 1.3.6版以後)
SoX (可選)

影像轉換

視訊庫

Optical disc authoring

K3b

圖庫

3D graphics editors

Blender^[4]

VoIP

多媒體流伺服器

多媒體架構

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.)
GStreamer via the GStreamer FFmpeg plugin
Perian
Bellagio OpenMAX Integration Layer – opensource OpenMAX IL API implementation

電腦視訊庫

OpenCV^[5]

瀏覽器

Google Chrome ^[6]

媒體中心

擷取螢幕

xvidcap^[7]

Device utilities

BitPim – utilities for CDMA phones

CCTV

ZoneMinder – video camera security suite
Motion – video camera security/monitoring program

遊戲

Performous – 音樂遊戲包含美聲, 樂團, 以及舞蹈.
StepMania

其他

Chameleo
CorePlayer
FreeJ
Ingex Studio – used by BBC
PulseAudio – includes only resamplers code^[8]

参考资料

^ General Documentation, Ffmpeg.org, [2012-01-17]
^ General Documentation, Ffmpeg.org, [2012-01-17]
^ Listed in FFmpeg Hall of Shame
^ Blender for Dummies, Books.google.com: 320, [2012-01-17]
^ Learning OpenCV: computer vision with the OpenCV library, Books.google.com: 9, 2008-09-24 [2012-01-17]
^ whatwg MPEG-1 subset proposal for HTML5 video codec, Lists.whatwg.org, [2012-01-17]
^ Open Source Development, Communities and Quality: IFIP 20th World Computer, Books.google.com: 167, [2012-01-17]
^ pulseaudio.git/tree – src/pulsecore/ffmpeg/, Git.0pointer.de, [2012-01-17]

[1] General Documentation, Ffmpeg.org, [2012-01-17]

[2] General Documentation, Ffmpeg.org, [2012-01-17]

[3] Listed in FFmpeg Hall of Shame

[4] Blender for Dummies, Books.google.com: 320, [2012-01-17]

[5] Learning OpenCV: computer vision with the OpenCV library, Books.google.com: 9, 2008-09-24 [2012-01-17]

[6] whatwg MPEG-1 subset proposal for HTML5 video codec, Lists.whatwg.org, [2012-01-17]

[ifip-20th-p167-7] Open Source Development, Communities and Quality: IFIP 20th World Computer, Books.google.com: 167, [2012-01-17]

[8] ulseaudio.git/tree – src/pulsecore/ffmpeg/, Git.0pointer.de, [2012-01-17]

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