These are the basics of the video processing tool “ffmpeg”.

Check FFmpeg documentation for all the info.

Table of Contents

Encode a video (using h264/libx264 codec) quickly

ffmpeg -i input.mp4 -c:v libx264 -preset veryfast -crf 22 output.mp4
  • -preset has several possible values (depends on codec used), faster encoding means less CPU load and less compression.
  • -crf stands for “Constant Rate Factor” and this is the recommended rate control mode for most uses. A lower value generally leads to higher quality, and a subjectively sane range is 17–28 (23 is the default).
  • You can add -f <format> to force a format for the output file (e.g.: -f mp4).
  • Ffmpeg cannot overwrite the input file, always use a different name for the output file.

Convert mkv to mp4

ffmpeg -i input.mkv -codec copy output.mp4
  • -codec copy makes ffmpeg omit the decoding and encoding step for the specified stream, so it does only demuxing and muxing. It’s the same as -c:v copy -c:a copy.

Encode several videos (Bash loop)

for i in *.mp4;do ffmpeg -i $i -preset ultrafast ${i/.mp4/_new.mp4};done

for i in *.mp4;do ffmpeg -i $i -preset ultrafast output/$i;done

Overwrite output file if exists

ffmpeg -y -i input.mp4 output.mp4

Extract audio from video

ffmpeg -i video.mp4 -vn sound.mp3

Remove audio

ffmpeg -i video.mp4 -an output.mp4

Cut a video

When cutting a video using -codec copy (add it after -i input.mp4), the video is not trimmed in the exact specified timeframe.

# from mm:ss to end
ffmpeg -i video.mp4 -preset superfast -ss mm:ss output.mp4

# from mm:ss to mm2:ss2
# e.g.: from 00:12 to 00:15 (3 seconds)
ffmpeg -ss mm:ss -to mm2:ss2 -i video.mp4 -preset superfast output.mp4

# from mm:ss, end when passes mm2:ss2
# e.g.: from 00:12, ends after 00:03 (3 seconds)
ffmpeg -ss mm:ss -i video.mp4 -to mm2:ss2 -preset superfast output.mp4

Speed up / slow down a video

# speed up to 2x
ffmpeg -i video.mp4 -vf setpts=0.5*PTS fast.mp4
  • Audio is not changed. To speed up the audio, add -af atempo=2 (for 2x video).
# slow down to 0.5x
ffmpeg -i video.mp4 -vf setpts=2*PTS slow.mp4
  • Audio is not changed. To slow down the audio, add af tempo=0.5 (for 0.5x video).

Change the resolution

ffmpeg -i video.mp4 -s 1280x720 output.mp4

Capture frames

Capture a video frame (at mm:ss) and change its resolution.

ffmpeg -ss mm:ss -i video.mp4 -frames 1 -s 1280x720 -f image2 image.png

Capture one frame per second of the video.

ffmpeg -i video.mp4 -r 1 -f image2 image%d.png

Capture a frame from a video device (webcam, etc.).

ffmpeg -i /dev/video0 -frames 1 -f image2 image.png

Join several videos (using a list file)

  1. Create a text file with the filenames.

        # list.txt
    file video1.mp4
    file video2.mp4

  2. Run ffmpeg:

    ffmpeg -f concat -safe 0 -i list.txt output.mp4
    • Using -codec copy will probably not work.

Change brightness, contrast or gamma (‘eq’ video filter)

ffmpeg -i video.mp4 -vf 'eq=contrast=1.5' output.mp4

ffmpeg -i video.mp4 -vf eq=gamma=1.2 output.mp4
  • Check FFmpeg documentation for more information.
  • Quotes around filter are optional, but recommended.

Adjust exposure

ffmpeg -i video.mp4 -vf exposure=0.8 output.mp4

Stack two videos horizontally

ffmpeg -i input1.mp4 -i input2.mp4 -filter_complex hstack output.mp4
  • The horizontal resolution is changed.

Flip a video horizontally

ffmpeg -i input.mp4 -vf 'transpose=0,transpose=1' output.mp4

More audio, video filters

  • Check FFmpeg filters.
  • When applying filters, use this schema: 
    -vf <filter1 name>=<prop1>=<value>:<prop2>=<value>,<filter2 name>=<prop1>=<value>
    • change -vf to -af for audio filters.
  • When using more than one inputs or outputs, use -filter_complex instead of -vf or -af.

Stabilize a video

See How to stabilize a video using ffmpeg.

Test with this online terminal:

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