technology/linux/audio_visual/ffmpeg.md
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@@ -20,3 +20,9 @@ ffmpeg -f alsa -ac 2 -i alsa -f x11grab -r 15 -i :0.0 -acodec libmp3lame -vcode
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```
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ffmpeg -i videofile.mp4 videofile.webm
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```
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+
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+### adjust crf
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+adjust constant rate factor to lower bit rate
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+```
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+ffmpeg -i input.mp4 -vcodec libx264 -crf 20 output.mp4
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+```