The m4a muxer doesn't support mjpeg as a regular video stream, causing
concatenation to fail when inputs contain album art. Extract art separately
and re-attach it with attached_pic disposition. Also strip leading track
numbers (e.g. "01 ") from chapter titles.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Shell script to recombine individual story m4a files back into
per-cassette files using ffmpeg concat demuxer (stream copy, no
re-encoding). Generates chapter markers from input filenames and
preserves album art.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
