Issue:
Calling `mp4box -splits` doesn't distribute chapter marks onto the split files.

Example:
10min mp4 video with a chapter that starts at 9 minutes. After splitting, the first part contains the chapter mark even though that mark points to a section that is in another split file.

Command used:
`mp4box v.mp4 -splits 1024 -out v_$num%03d$.mp4`

Explanation:
While trying to split mp4 files by size (-splits option) I noticed, that chapter information is simply copied to ~~the first split while all other splits don't contain any chapter information at all~~ all splits without rebasing. This results in broken chapters, since chapters may point to times after the first split file.

Expected behaviour:
Chapter marks are distributed to the according split files (and rebased since every split video starts at 0 time again).

System info:
MP4Box - GPAC version 2.1-DEV-rev193-g7370ab0b-master
Windows 10 Pro 20H2



mp4box split option doesn't handle chapter data
This is a GitHub Issue
repo:gpac
owner:gpac
Title : mp4box split option doesn't handle chapter data
Issue date:

--- start body ---
Issue:
Calling `mp4box -splits` doesn't distribute chapter marks onto the split files.

Example:
10min mp4 video with a chapter that starts at 9 minutes. After splitting, the first part contains the chapter mark even though that mark points to a section that is in another split file.

Command used:
`mp4box v.mp4 -splits 1024 -out v_$num%03d$.mp4`

Explanation:
While trying to split mp4 files by size (-splits option) I noticed, that chapter information is simply copied to ~~the first split while all other splits don't contain any chapter information at all~~ all splits without rebasing. This results in broken chapters, since chapters may point to times after the first split file.

Expected behaviour:
Chapter marks are distributed to the according split files (and rebased since every split video starts at 0 time again).

System info:
MP4Box - GPAC version 2.1-DEV-rev193-g7370ab0b-master
Windows 10 Pro 20H2



--- end body ---
