When you have sync'ed chapters coming from another source to a video file, you may wish, as a final step, to slightly shift the timecodes to the nearest I-frame. This script automates that final step, although it will be sometimes better to do it manually, as a human being will take the best decisions. The script takes a Matroska chapter file (either xml or txt) and a video file as inputs and generates a new chapter file with timecodes appropriately shifted.
This script needs a working installation of VapourSynth with the ffms2 indexer.
usage: syncChapter.vpy [-h] [-p PFRAME] [-o OUTPUT] chapter video
This script changes timecodes in a xml/txt chapter file to match the nearest I-frame of a video file (or a P-frame if the nearest I-frame is too far)
positional arguments:
chapter Absolute or relative path to xml/txt chapter file
video Absolute or relative path to mkv/hevc/265/avc/264 video file
options:
-h, --help show this help message and exit
-p, --pframe PFRAME Maximal admissible distance to nearest I-frame
-o, --output OUTPUT Output filename
If the -p option is not provided, then the script will always search for the nearest I-frame, no matter how far it is. If this option is given with an integer argument, the script will first search for an I-frame within the admissible range and fall back to the nearest P-frame if no I-frame is found within the admissible range.
The script generates a new xml/txt chapter file with all the timecodes updated. It prints on stdout the number of frames by which each chapter has been shifted and whether the corresponding new frame is a I-frame or a P-frame.