1）常用命令
1、最简单转换命令
ffmpeg -i input.mp4 output.mkv
2、更加精准的控制转换命令
ffmpeg -i input.mp4 -c:v vp9 -c:a libvorbis output.mkv
（-c:v 控制视频格式， -c:a 控制音频格式）
3、调节比特率
ffmpeg -i GVG-981.mp4 -c:v libx264 -b:v 2M -maxrate 2M -bufsize 1M GVG-981-out.mp4
ffmpeg -i input.webm -c:a copy -c:v vp9 -b:v 1M output.mkv
（-b:v 1M 代表着视频的比特率变成1Mb
This will copy the audio (-c:a copy) from input.webm and convert the video to a VP9 codec (-c:v vp9) with a bit rate of 1M/s (-b:v), all bundled up in a Matroska container (output.mkv).）
4、调节帧率
ffmpeg -i 002.mp4 -filter:v fps=fps=29.97 002-out.mp4
ffmpeg -i input.webm -c:a copy -c:v vp9 -r 30 output.mkv
（This creates a new Matroska with the audio stream copied over and the video stream's frame rate forced to 30 frames per second, instead of using the frame rate from the input (-r 30).）
5、调节视频尺寸（分辨率）
ffmpeg -i FC2PPV-402422-1.mp4 -c:a copy -s 854x480 FC2PPV-402422-1-out.mp4
ffmpeg -i input.mkv -c:a copy -s 1280x720 output.mkv
（声音原封不动拷贝过去，视频编码格式不变，只是尺寸调整到1280x720）
6、截取部分视频(时长)
ffmpeg -i input.mkv -c:a copy -c:v copy -ss 00:01:00 -t 10 output.mkv
（音视频格式不变， 从00:01:00开始拷贝10s过去）
7、 提取关键帧
ffmpeg -skip_frame nokey -i 480P_2000K_204282351.mp4 -vsync 0 -r 30 -f image2 480P_2000K_204282351%02d.png
8,使用 ffmpeg 命令将 raw.mp4 的音频替换为 out.wav 的音频
ffmpeg -i raw.mp4 -i out.wav -map 0:v -map 1:a -c:v copy -c:a copy replaced_audio.mp4
8、对视频进行帧提取
您可以使用以下命令将视频分解成图片序列：
ffmpeg -i input.mp4 -vf fps=1 frame_%04d.png
这条命令将 input.mp4 视频分解成图片序列，每秒保存一帧。输出的文件名为 frame_0001.png、frame_0002.png 等。您可以根据需要更改输入文件名、帧率和输出文件名模式。
ffmpeg -i .\input.mp4 -vf 'select=gte(n,1),setpts=PTS-STARTPTS' 'input/%05d.png'
ffmpeg -i .\input.mp4 -vf 'select=gte(n,1),setpts=0.5*PTS' 'input/%05d.png'
ffmpeg -i .\input.mp4 -vf 'select=between(n,{START_FRAME},{END_FRAME}),setpts=0.5*PTS' 'input/%05d.png'
setpts的具体参数含义如下：
Start counting PTS from zero
setpts=PTS-STARTPTS
Apply fast motion effect:
setpts=0.5*PTS
Apply slow motion effect:
setpts=2.0*PTS
Set fixed rate of 25 frames per second:
setpts=N/(25*TB)
Set fixed rate 25 fps with some jitter:
setpts='1/(25*TB) * (N + 0.05 * sin(N*2*PI/25))'
Apply an offset of 10 seconds to the input PTS:
setpts=PTS+10/TB
Generate timestamps from a "live source" and rebase onto the current timebase:
setpts='(RTCTIME - RTCSTART) / (TB * 1000000)'
Generate timestamps by counting samples:
asetpts=N/SR/TB
9、从png序列生成视频文件
ffmpeg -y -r {TARGET_FPS} -f image2 -pattern_type glob -i '*.png' '/content/gdrive/My Drive/{OUTPUT_FILE_PATH}'
2）命令基本语法
注意：这里面的非方括号部分（蓝字）都是必须得有的。
全局选项：
Global options (affect whole program instead of just one file:
-loglevel loglevel set libav* logging level
-v loglevel set libav* logging level
-report generate a report
-max_alloc bytes set maximum size of a single allocated block
-y overwrite output files
-n do not overwrite output files
-stats print progress report during encoding
-bits_per_raw_sample number set the number of bits per raw sample
-vol volume change audio volume (256=normal)
输入输出选项：
Per-file main options:
-f fmt force format
-c codec codec name
-codec codec codec name
-pre preset preset name
-map_metadata outfile[,metadata]:infile[,metadata] set metadata information of outfile from infile
-t duration record or transcode "duration" seconds of audio/video
-to time_stop record or transcode stop time
-fs limit_size set the limit file size in bytes
-ss time_off set the start time offset
-timestamp time set the recording timestamp ('now' to set the current time)
-metadata string=string add metadata
-target type specify target file type ("vcd", "svcd", "dvd", "dv", "dv50", "pal-vcd", "ntsc-svcd", ...)
-frames number set the number of frames to record
-filter filter_graph set stream filtergraph
-reinit_filter reinit filtergraph on input parameter changes
Video options:
-vframes number set the number of video frames to record
-r rate set frame rate (Hz value, fraction or abbreviation)
-s size set frame size (WxH or abbreviation)
-aspect aspect set aspect ratio (4:3, 16:9 or 1.3333, 1.7777)
-bits_per_raw_sample number set the number of bits per raw sample
-vn disable video
-vcodec codec force video codec ('copy' to copy stream)
-timecode hh:mm:ss[:;.]ff set initial TimeCode value.
-pass n select the pass number (1 to 3)
-vf filter_graph set video filters
-b bitrate video bitrate (please use -b:v)
-dn disable data
Audio options:
-aframes number set the number of audio frames to record
-aq quality set audio quality (codec-specific)
-ar rate set audio sampling rate (in Hz)
-ac channels set number of audio channels
-an disable audio
-acodec codec force audio codec ('copy' to copy stream)
-vol volume change audio volume (256=normal)
-af filter_graph set audio filters
Subtitle options:
-s size set frame size (WxH or abbreviation)
-sn disable subtitle
-scodec codec force subtitle codec ('copy' to copy stream)
-stag fourcc/tag force subtitle tag/fourcc
-fix_sub_duration fix subtitles duration
-canvas_size size set canvas size (WxH or abbreviation)
-spre preset set the subtitle options to the indicated preset