From c8249b1fdcd23012f8756b6223657e284c534434 Mon Sep 17 00:00:00 2001 From: vincent Date: Sun, 25 Apr 2021 08:40:08 +0200 Subject: [PATCH] add ffmpeg.md --- IT/ffmpeg.md | 224 +++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 224 insertions(+) create mode 100644 IT/ffmpeg.md diff --git a/IT/ffmpeg.md b/IT/ffmpeg.md new file mode 100644 index 0000000..ccc942a --- /dev/null +++ b/IT/ffmpeg.md @@ -0,0 +1,224 @@ +# FFmpeg cheat sheet + +A list of useful commands for the ffmpeg command line tool. + +Download FFmpeg: + +Full documentation: + +## Basic conversion + +```bash +ffmpeg -i in.mp4 out.avi +``` + +### Remux an MKV file into MP4 + +```bash +ffmpeg -i in.mkv -c:v copy -c:a copy out.mp4 +``` + +### High-quality encoding + +Use the `crf` (Constant Rate Factor) parameter to control the output quality. +The lower crf, the higher the quality (range: 0-51). The default value is 23, +and visually lossless compression corresponds to `-crf 18`. Use the `preset` +parameter to control the speed of the compression process. +Additional info: + +```bash +ffmpeg -i in.mp4 -preset slower -crf 18 out.mp4 +``` + +## Trimming + +Without re-encoding: + +```bash +ffmpeg -ss [start] -i in.mp4 -t [duration] -c copy out.mp4 +``` + +- [`-ss`](http://ffmpeg.org/ffmpeg-all.html#Main-options) specifies + the start time, e.g. `00:01:23.000` or `83` (in seconds) +- [`-t`](http://ffmpeg.org/ffmpeg-all.html#Main-options) specifies the duration + of the clip (same format). +- Recent `ffmpeg` also has a flag to supply the end time with `-to`. +- [`-c`](http://ffmpeg.org/ffmpeg-all.html#Main-options) copy copies the first + video, audio, and subtitle bitstream from the input to the output file without + re-encoding them. This won't harm the quality and make the command run within seconds. + +With re-encoding: + +If you leave out the `-c copy` option, `ffmpeg` will automatically re-encode +the output video and audio according to the format you chose. For high quality +video and audio, read the [x264 Encoding Guide](https://ffmpeg.org/trac/ffmpeg/wiki/x264EncodingGuide) +and the [AAC Encoding Guide](http://ffmpeg.org/trac/ffmpeg/wiki/AACEncodingGuide) +, respectively. + +For example: + +```bash +ffmpeg -ss [start] -i in.mp4 -t [duration] -c:v libx264 -c:a aac -strict +experimental -b:a 128k out.mp4 +``` + +## Mux video and audio from another video + +To copy the video from in0.mp4 and audio from in1.mp4: + +```bash +ffmpeg -i in0.mp4 -i in1.mp4 -c copy -map 0:0 -map 1:1 -shortest out.mp4 +``` + +- With [-c copy](http://ffmpeg.org/ffmpeg.html#Stream-copy) the streams will be + `stream copied`, not re-encoded, so there will be no quality loss. If you want + to re-encode, see [FFmpeg Wiki: H.264 Encoding Guide](https://trac.ffmpeg.org/wiki/Encode/H.264). +- The `-shortest` option will cause the output duration to match the duration + of the shortest input stream. +- See the + [`-map` option documentation](http://ffmpeg.org/ffmpeg.html#Advanced-options) + for more info. + +## Concat demuxer + +First, make a text file. + +```bash +file 'in1.mp4' +file 'in2.mp4' +file 'in3.mp4' +file 'in4.mp4' +``` + +Then, run `ffmpeg`: + +```bash +ffmpeg -f concat -i list.txt -c copy out.mp4 +``` + +## Delay audio/video + +Delay video by 3.84 seconds: + +```bash +ffmpeg -i in.mp4 -itsoffset 3.84 -i in.mp4 -map 1:v -map 0:a -vcodec copy +-acodec copy out.mp4 +``` + +Delay audio by 3.84 seconds: + +```bash +ffmpeg -i in.mp4 -itsoffset 3.84 -i in.mp4 -map 0:v -map 1:a -vcodec copy +-acodec copy out.mp4 +``` + +## Burn subtitles + +Use the [libass](http://ffmpeg.org/ffmpeg.html#ass) library (make sure your +ffmpeg install has the library in the configuration `--enable-libass`). + +First convert the subtitles to .ass format: + +```bash +ffmpeg -i sub.srt sub.ass +``` + +Then add them using a video filter: + +```bash +ffmpeg -i in.mp4 -vf ass=sub.ass out.mp4 +``` + +## Extract the frames from a video + +To extract all frames from between 1 and 5 seconds, and also between 11 and 15 seconds: + +```bash +ffmpeg -i in.mp4 -vf select='between(t,1,5)+between(t,11,15)' -vsync 0 out%d.png +``` + +To extract one frame per second only: + +```bash +ffmpeg -i in.mp4 -fps=1 -vsync 0 out%d.png +``` + +## Rotate a video + +Rotate 90 clockwise: + +```bash +ffmpeg -i in.mov -vf "transpose=1" out.mov +``` + +For the transpose parameter you can pass: + +```bash +0 = 90CounterCLockwise and Vertical Flip (default) +1 = 90Clockwise +2 = 90CounterClockwise +3 = 90Clockwise and Vertical Flip +``` + +Use `-vf "transpose=2,transpose=2"` for 180 degrees. + +## Download "Transport Stream" video streams + +1. Loate the playlist file, e.g. using Chrome > F12 > Network > Filter: m3u8 +2. Download and concatenate the video fragments: + +```bash +ffmpeg -i "path_to_playlist.m3u8" -c copy -bsf:a aac_adtstoasc out.mp4 +``` + +If you get a "Protocol 'https not on whitelist 'file,crypto'!" error +, add the `protocol_whitelist` option: + +```bash +ffmpeg -protocol_whitelist "file,http,https,tcp,tls" -i "path_to_playlist.m3u8" +-c copy -bsf:a aac_adtstoasc out.mp4 +``` + +## Mute some of the audio + +To replace the first 90 seconds of audio with silence: + +```bash +ffmpeg -i in.mp4 -vcodec copy -af "volume=enable='lte(t,90)':volume=0" out.mp4 +``` + +To replace all audio between 1'20" and 1'30" with silence: + +```bash +ffmpeg -i in.mp4 -vcodec copy -af "volume=enable='between(t,80,90)':volume=0" out.mp4 +``` + +## Deinterlace + +Deinterlacing using "yet another deinterlacing filter". + +```bash +ffmpeg -i in.mp4 -vf yadif out.mp4 +``` + +## Create a video slideshow from images + +Parameters: `-r` marks the image framerate (inverse time of each image); +`-vf fps=25` marks the true framerate of the output. + +```bash +ffmpeg -r 1/5 -i img%03d.png -c:v libx264 -vf fps=25 -pix_fmt yuv420p out.mp4 +``` + +## Extract images from a video + +- Extract all frames: `ffmpeg -i input.mp4 thumb%04d.jpg -hide_banner` +- Extract a frame each second: `ffmpeg -i input.mp4 -vf fps=1 thumb%04d.jpg -hide_banner` +- Extract only one frame: `ffmpeg -i input.mp4 -ss 00:00:10.000 -vframes 1 thumb.jpg` + +## Metadata: Change the title + +```bash +ffmpeg -i in.mp4 -map_metadata -1 -metadata title="My Title" -c:v copy -c:a +copy out.mp4 +```