[Matroska-devel] Spec Change (chapter start time)

Steve Lhomme steve.lhomme at free.fr
Sat Jan 8 18:00:29 CET 2005


Steve Lhomme a écrit :
> So, is it OK to remove the mandatory flag for ChapterTimeStart ?
> 
> I'm modified DMX to keep most of the start timecodes. But I had to 
> remove the PTT level because it's just a seek point. I'm not sure if I 
> can remove it totally or I have to take it back with some more changes 
> in the code... Actually it's one element which StartTime is vital, but 
> I'm not sure it's needed. I'll check if there are DVD commands relating 
> to the PTT level, otherwise it will be totally dropped...
> 
> Also another thing we need is a better identification of segments. For 
> example the VMG segment (first used when you enter a DVD) usually have a 
> command JumpTT # (jump to title # x). That means jumping to another 
> segment. But so far we don't know how to map the title/domain to a 
> meaningfull element in Matroska. The Segment UID is an ID that should 
> unique over a lot (global) of Matroska files. It could work, but only if 
> you modify the value in the DVD command. IMO, that's not the way to go. 
> We should have a better way to map the domain to an ID in the Segment 
> Info. Hopefully something that would not be DVD specific, but more general.
> 
> Comments are welcomed !

PS: It has been decided that for infinite still frames we will use a 
"custom" command, using our own Chapter Codec. But we need to define it 
now, so that I can add it to DMX (for the moment it outputs something 
with a big TODO).

What kind of command should it be ?
- loop this ChapterAtom infinitely
- loop this ChapterAtom a given number of time (-1 = infinite)
- jump to a given timecode

I prefer option #2

Also how are we going to store our commands ? A statis struct-like 
format ? Or something EBML like ? With the command ID, the length of the 
command and the command data...




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