ffmpeg

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2014-11-10 更新

2014-11-16 更新:字幕提取相关

2014-11-22 更新: 更多有用链接

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What is ffmpeg, avcodec, x264?

FFmpeg is a software project with lots of people involved, a Wiki, a bug tracker, some funding, etc.
ffmpeg is one of the tools they offer (others are ffplay and qt-faststart, for example).
Libav is a fork of the FFmpeg project, which supplies the avconv binary. They both develop independently, but FFmpeg usually merges commits from Libav—not the other way 'round. (Some might say Libav suffers from NIH).

The ffmpeg tool is, like you said, a command line wrapper for a number of libraries designed for handling multimedia content. These include:

libavcodec, for encoding and decoding of audio, video and subtitle bitstreams
libavformat, for muxing and demuxing containers
libavfilter, for applying a variety of filters on audio, video and subtitles
libswscale, which scales images and video or resamples audio
libavresample, which was originally pushed to Libav and later integrated into FFmpeg. See this thread for more about the history.

Common external encoders include:

libx264
libvpx (for VP8 and VP9 video)
libfaac, libfdk-aac, libvo-aacenc for AAC audio
libmp3lame
libvorbis
libxvid

FFmpeg and AAC Encoding Guide

What's the difference between FFmpeg's “-vcodec copy” and “-sameq”?

sameq does not mean "same quality"

=========== 2014-11-10 ============

FF FFMPEG and H.264 Encoding Guide

FFmpeg command to convert to DivX

Up-to-date syntax:

ffmpeg -i input.file -c:v mpeg4 -q:v 5 -tag:v DIVX -s 640x480 -c:a libmp3lame -q:a 5 -ac 2 -ar 44100 output.avi

Old syntax:

ffmpeg -i input.file -vcodec mpeg4 -qscale 5 -vtag DIVX -s 640x480 -acodec libmp3lame -aq 5 -ac 2 -ar 44100 output.avi

Two-pass encoding

Note that Windows users need to use NUL rather than /dev/null. Use this if you want to target a specific size, otherwise just use the VBR quality-targeting -qscale option. These examples will fit a 90-minute movie onto a 700 MB CD-ROM.

Up-to-date syntax:

ffmpeg -y -i input.file -c:v mpeg4 -b:v 868k -tag:v DIVX -s 640x480 -an -pass 1 -f rawvideo /dev/null
ffmpeg -i input.file -c:v mpeg4 -b:v 868k -tag:v DIVX -s 640x480 -c:a libmp3lame -b:a 192k -ac 2 -ar 44100 -pass 2 output.avi

Old syntax:

ffmpeg -y -i input.file -vcodec mpeg4 -b 868k -vtag DIVX -s 640x480 -an -pass 1 -f rawvideo /dev/null
ffmpeg -i input.file -vcodec mpeg4 -b 868k -vtag DIVX -s 640x480 -acodec libmp3lame -ab 192k -ac 2 -ar 44100 -pass 2 output.avi

Note that you don't strictly need -ac 2, since MP3 only supports two channels, so any surround-sound audio will automatically get mixed down.

H.264 Profile、Level、Encoder三张简图

H.264 Profile、Level、Encoder三张简图