This document contains some of the ffmpeg snippets I use most commonly, and typically in the context of converting research-related image data to video. It is not meant to be exhaustive.
- Documentation: https://ffmpeg.org/ffmpeg.html
- Superuser community: https://superuser.com/questions/tagged/ffmpeg
- More on concatenation / named pipes: https://trac.ffmpeg.org/wiki/Concatenate
- A tutorial: Learn FFmpeg libav the Hard Way
- Add input:
-i <file(s)>, example:-i color-%01d.png - Add input alphabetically:
-pattern_type glob -i '*.png' - Set start frame (before -i):
-start_number <number> - Limit frames:
-vframes <number> - Overwrite without asking:
-y(contraty to-n) - Set ouput codec video/audio:
-c:v==-codec:v==-vcodec/-a:v==-codec:a==-acodec - Set bitrate video/audio:
-b:v <rate>/-b:a <rate>, examples:-b:v 1400K,-b:v 1M - Set offset between keyframes:
-g <offset> - Use video/audio filter:
-vf==-filter:v/-af==-filter:a - Set framerate (before input / output to pick target):
-r <number> - Format (input/output):
-f <fmt>, (use-f lavfito use filter as input) - Constant Rate Factor (h264,h265):
-crf(range: 0–51, 0=lossless, 23=default(h264), 28=default(h265), 51=worst)
- D->RGB:
[in]format=pix_fmts=rgb24[out]: convert greyscale to rgb (required for stacking) - Crop:
[in]crop=<w>:<h>:<x>:<y>[out] - Scale:
[in]scale=<w>:<h>[out] - Stack:
[left][right]hstack[out],[top][bottom]vstack[out] - Vary speed:
[in]setpts=0.5*PTS[out]: (remember to half the value of 'vframes', if set), (2x speed, here) - Textbox:
drawtext=fontfile=<ttf>: text='<text>': fontcolor=<color>: fontsize=<size>: box=1: boxcolor=<color>: boxborderw=<w>: x=<x>: y=<y> - Concat:
ffmpeg -i 1.mp4 2.mp4 3.mp4 4.mp4 -filter_complex "concat=n=4:v=1:a=0" - Width and height divisible by 2:
pad=ceil(iw/2)*2:ceil(ih/2)*2
- For web (more compatible):
ffmpeg -i <in>.mp4 -c:v libx264 -crf 23 -profile:v baseline -level 3.0 -pix_fmt yuv420p -movflags faststart <out>.mp4 - For web (less compatible):
ffmpeg -i <in>.mp4 -c:a libvorbis -c:v libvpx-vp9 -b:v 1400K -g 120 out.webm - For PC:
ffmpeg -i in.mp4 -c:a libvorbis -c:v libx264 -crf 32 <out>.mp4 - Better decoder support with:
-profile:v high -pix_fmt yuv420p -movflags faststart
Use additional input -f lavfi -i color=c=white:s=<w>x<h> and overlay with it [bg][fg]overlay=shortest=1.
You might want to keep the scale of a specific input instead of setting <w> and <h> for the background: [bg][fg]scale2ref[bg][fg]
Use trim filter [0:v]trim=duration=8[a] get video until second 8,
[0:v]trim=start=16,setpts=PTS-STARTPTS[b] get video from second 16 to end (otherwise use end=..),
finally, concat results "[a][b]concat"
See: https://superuser.com/questions/681885/how-can-i-remove-multiple-segments-from-a-video-using-ffmpeg
ffmpeg \
-i a.mp4 \
-i b.mp4 \
-filter_complex " \
color=white:1280x960,fade=out:st=4:d=1[alpha_a]; \
[0:v][alpha_a]alphamerge[overlay_a]; \
[1:v][overlay_a]overlay=0:0" out.mp4
ffmpeg \
-i a%01d.png \
-i b%01d.png \
-filter_complex "hstack=inputs=2, \
drawtext=fontfile=/usr/share/fonts/truetype/ubuntu-font-family/Ubuntu-R.ttf: text='3D labeled': fontcolor=white: fontsize=32: box=1: boxcolor=black@0.6: boxborderw=5: x=100: y=5, \
drawtext=fontfile=/usr/share/fonts/truetype/ubuntu-font-family/Ubuntu-R.ttf: text='3D colored': fontcolor=white: fontsize=32: box=1: boxcolor=black@0.6: boxborderw=5: x=1060: y=5" \
-vcodec libx264 out.mp4
# highest quality:
ffmpeg -i <video>.mp4 -qmin 1 -qmax 1 -q:v 1 %06d.jpg
# q normally ranges from 2-31, and it is more typical to use:
ffmpeg -i <video>.mp4 -q:v 2 %06d.jpg
ffmpeg -f lavfi -i testsrc -f matroska - | ffplay -