140 lines
2.9 KiB
Markdown
140 lines
2.9 KiB
Markdown
---
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title: "ffmpeg"
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tags: [ "Documentation", "sound" ]
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---
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# Basics
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ffmpeg -i [input file] output_file.mkv
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The input file might be a device, such as a camera.
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Play video:
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> ffplay file.mp4
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#Record screen
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Take the format as 'grab the x11 screen'.
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> ffmpeg -f x11grab -s [screensize] -i :0.0 out.mkv
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Get screensize with
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> xrandr -q
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or maybe just...
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> ffmpeg -f x11grab -s "$(xdpyinfo | grep dimensions | awk '{print $2}')" -i :1.0 out.mkv
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#Add default pulse audio
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> ffmpeg -f x11grab -s [screensize] -i :0.0 -f alsa -i default out.mkv
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For problems, see pavucontrol.
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# Random online suggestion
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ffmpeg -video_size "$(xdpyinfo | grep dimensions | awk '{print $2}')" -f x11grab -i :0.0 -f pulse -ac 2 -i default ~/out.mkv
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# Rotate
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> ffmpeg -i in.mov -vf "transpose=1" out.mov
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0 = 90 Counterclockwise and verfical flip (default)
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1 = 90 Clockwise
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2 = 90 CounterClockwise
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3 = 90Clockwise and vertical flip
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# Lower Video Quality
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A crf quality of 18 is high, while 24 is low quality.
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ffmpeg -i input.mp4 -vcodec libx264 -crf 20 output.mp4
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# convert
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Check for supported formats:
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> ffmpeg -formats
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To convert from mkv to mp4 we can use a codec rather than proper conversion. Both are wrappers around other formats, so this conversion loses less quality than other conversion types.
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> ffmpeg -i LostInTranslation.mkv -codec copy LostInTranslation.mp4
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Opus to mp3
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> ffmpeg -i song.opus song.mp3
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> ffmpeg -i video.flv video.mpeg
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> ffmpeg -i input.webm -qscale 0 output.mp4
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# Video to Audio
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> ffmpeg -i input.mp4 -vn output.mp3
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# Convert all mkv files to mp4
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> for i in *.mkv; do
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> ffmpeg -i "$i" -codec copy "${i%.*}.mp4"
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> done
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# Change resolution
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> ffmpeg -i input.mp4 -filter:v scale=1280:720 -c:a copy output.mp4
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Or just crop:
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> ffmpeg -i input.mp4 -filter:v "crop=w:h:x:y" output.mp4
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Or aspect ratio:
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> ffmpeg -i input.mp4 -aspect 16:9 output.mp4
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Or trim to start and stop times:
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> ffmpeg -i input.mp4 -ss 00:00:50 -codec copy -t 50 output.mp4
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Indicate start times with -ss and time with -t in seconds.
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Or split a video into parts:
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> ffmpeg -i input.mp4 -t 00:00:30 -c copy part1.mp4 -ss 00:00:30 -codec copy part2.mp4
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# Compress Video
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> ffmpeg -i input.mp4 -vf scale=1280:-1 -c:v libx264 -preset veryslow -crf 24 output.mp4
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# Extract Images from Video
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-r sets the frame rate, and -f selects the format.
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> ffmpeg -i input.mp4 -r 1 -f image2 image-%2d.png
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# Add Images to Audio
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> $ ffmpeg -loop 1 -i inputimage.jpg -i inputaudio.mp3 -c:v libx264 -c:a aac -strict experimental -b:a 192k -shortest output.mp4
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# Create a Video from Multiple Parts
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First make a text file indicating all the parts, e.g.
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```
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file /home/sk/myvideos/part1.mp4
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file /home/sk/myvideos/part2.mp4
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file /home/sk/myvideos/part3.mp4
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file /home/sk/myvideos/part4.mp4
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```
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Then join with:
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> ffmpeg -f concat -i join.txt -c copy output.mp4
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# Add Subtitles
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> fmpeg -i input.mp4 -i subtitle.srt -map 0 -map 1 -c copy -c:v libx264 -crf 23 -preset veryfast output.mp4
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