rlaphoenix/chapsnap

Resync Chapters by snapping them to Scene Changes

ChapSnap

Resync Chapters by snapping them to Scene Changes.

Usage

Usage: chapsnap [OPTIONS] VIDEO [CHAPTERS]

  Snap Chapters to Scene Changes.

  VIDEO       The video file to snap chapters to scene changes. All video formats are
              supported. You may alternatively provide a directory path to process
              video files in batch.
  [CHAPTERS]  Optional chapters file if you want to use chapters from a file
              rather than ones already muxed with the video.

Options:
  -t, --threshold FLOAT  Threshold on Scene Change probability scores. The
                         lower the value, the more unlikely the frame is to be
                         a Scene Change. Range: 0.0 (Impossible) - 1.0
                         (Definite).
  -o, --offset FLOAT     Offset to apply to each Chapter. A negative offset
                         may result in fewer Chapters.
  --trim INTEGER         Remove n Chapters from the start of the Video. A
                         negative value will remove n Chapters from the end of
                         the Video. Timestamps will be offset respectively.
  -nf, --no-forward      Do not try to resync Chapters forward in time.
  -nb, --no-backward     Do not try to resync Chapters backward in time.
  -k, --keyframes        Only sync to Scene Changes on Keyframes (I-frames).
  -0, --zero             Force the first chapter to be at `00:00:00.000`, even
                         after offsets and trims.
  -c, --chain            Chain sync adjustments from one Chapter to the next.
                         E.g., Chapter 1 had -2, so Chapter 2 will begin with
                         an offset of -2. Chapter 2 with -2 has a change of
                         -1, so Chapter 3 will begin with an offset of -3 and
                         so on.
  --overwrite            Apply new Chapters to the input video file in-place,
                         without making a duplicate.
  --help                 Show this message and exit.

Contributors

License

© 2023 rlaphoenix — GNU General Public License, Version 3.0

chapsnap's Issues

Fade-out then Fade-in is not detected as a Scene Change

The algorithm used is just a simple threshold on the scene change score calculated by FFmpeg.

Since a Fade-out doesn't wildly differ from its previous frame, the entire transition occurs without detection. Similarly, the Fade-in works out the same.

This is only a problem when a Fade-out is met with a Fade-in directly after. A Fade-out to then a jump-cut works fine. A jump-cut to a Fade-in also works fine.

The only fix I can think of is to remove the frames after the start of the transition, and before or on the end of the transition. This results in what looks to be a jump cut instead of a fade transition and the algorithm by FFmpeg with the threshold will pick it up as a Scene Change. However, doing so in an automated way is not such an easy task to pull off.

Add support for adding the new Chapters to .mp4 files

Currently, support for this feature is only possible with MKV files using mkvpropedit. Perhaps use FFmpeg for adding chapters on other formats.

Analyzing takes quite long on UHD HEVC videos

Some way to speed up analyzing UHD HEVC videos would be nice. It's likely long simply due to the amount of time needed to decode and run scene detection on every frame.

On my end, it's taking 5-6 minutes per 22 minutes of content. That doesn't seem too bad but when you need to run this on 100s of files, that adds up quickly.