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Trim mode for mpv — Turn mpv into Lossless Audio / Video Editor

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✂️ trim.lua

mpv script to create a "precise" clip of audio / video files without transcoding.

Overview

Differences from the other similar scripts

  • trim.lua is aimed only for extraction of clips with no-transcoding. Encodings will never be occured.
  • Without encoding, video trimming becomes tricky.
    • A point you can specify to trim is limited to keyframes.
    • Tested several softwares on macOS and as far as I know there is no software that can do it accurately. Well, there is, but none were perfect nor lightweight.
    • This script is to achieve accuracy as much as possible — Making a clip from a file within minimum keyframe distance, without transcoding.

In short, trim.lua turns mpv into a simple lossless audio / video editor.

Install

curl https://raw.githubusercontent.com/aerobounce/trim.lua/master/trim.lua >> ~/.config/mpv/scripts/trim.lua

Requirements

ffmpeg

  • If your shell has PATH to ffmpeg you're ready to use.
    • If not, rewrite ffmpeg_bin accordingly.
  • All Windows users likely have to specify full path to ffmpeg.
    • Or copy the standalone binary into the script directory (not tested).
-- trim.lua

-- macOS, *nix
ffmpeg_bin = "ffmpeg"

-- Windows
ffmpeg_bin = "ffmpeg.exe"

Usage

Enable trim mode

  • h or k

If initialized with h, default trim positions will be: Current time position to End of file.
If initialized with k, default trim positions will be: Head of file to Current time position.

Toggle strip metadata mode (After initializing trim mode)

Stripping metadata can fix certain corrupted files.

  • t

Save Trim Positions

To write out a clip, press either of the keys twice with the same start / end position.
To quit Trim Mode, close mpv instance.

  • h Save Trim Start Keyframe
  • k Save Trim End Position

Seeking

Seek to saved positions

  • shift + h Seek to the saved Trim start position
  • shift + k Seek to the saved Trim end position

With video file

  • LEFT Seek backward by keyframe (Minimum distance)
  • RIGHT Seek forward by keyframe (Minimum distance)
  • UP Seek forward by keyframe (Larger distance)
  • DOWN Seek backward by keyframe (Larger distance)
  • shift+LEFT Seek backward exactly by seconds (-0.1 seconds)
  • shift+RIGHT Seek forward exactly by seconds (0.1 seconds)
  • shift+UP Seek forward exactly by seconds (0.5 seconds)
  • shift+DOWN Seek backward exactly by seconds (-0.5 seconds)

With audio file

  • LEFT Seek backward by seconds (-1 seconds)
  • RIGHT Seek forward by seconds (1 seconds)
  • UP Seek forward by seconds (5 seconds)
  • DOWN Seek backward by seconds (-5 seconds)
  • shift+LEFT Seek backward by seconds (-10 seconds)
  • shift+RIGHT Seek forward by seconds (10 seconds)
  • shift+UP Seek forward by seconds (30 seconds)
  • shift+DOWN Seek backward by seconds (-30 seconds)

To create a valid video file

  • Beggining of the trim position must be a keyframe.
  • End position can be any point.

Concat with ffmpeg

After splitting, you can concat them with a script something like this.

CLIPS=("example_1.mp4" "example_2.mp4")
DESTINATION="concat_example.mp4"

ffmpeg \
    -hide_banner \
    -loglevel verbose \
    -f concat \
    -safe 0 \
    -auto_convert 0 \
    -err_detect ignore_err \
    -i <(
        while read -r; do
            echo "file '$REPLY'"
        done <<< "${CLIPS[*]}"
    ) \
    -copy_unknown \
    -map_chapters 0 \
    -c copy \
    "$DESTINATION"

Known Issue

  • Any embedded media other than video / audio will be lost, such as embedded subtitles. This will unlikely be fixed.