Re: Chapter marks not where specified.

> On Thu, 5 Apr 2012 09:57:00 +1200, I wrote:
> 
> > On Wed, 4 Apr 2012 07:55:54 -0700, Scott Smith wrote:
> > 
> >> On Wed, Apr 4, 2012 at 4:01 AM, Lawrence D'Oliveiro
> >> <ldo-kC51rjc0cqs1dNLGKZg6taU/[email protected]> wrote:
> >>
> >>> Interesting. There is already code in mpeg2desc to show info about
> >>> GOPs and related stuff, but unfortunately it’s looking in the wrong
> >>> place, so it will never display anything...
> >> 
> >> mpeg2desc can show you information about the mpeg2 program stream
> >> (vobu's, etc), or the mpeg2 video stream (frames, etc) depending on
> >> whether its given a program stream or a video stream as input.
> > 
> > Yeah, of course: if those GOP etc headers are inside a PES packet
> > (program stream), they won’t be seen.
> > 
> > I’ll try to find a way to have them show both ways.
> 
> Done! Tom, would you like to give the latest source tree from GitHub a
> try, and see if the new mpeg2desc gives you the info you’re looking for?

O.K.  The day job intervened, but eventually, I built it, and I've run it on 
the offending file.  Here are the first few lines:

00000000: mpeg2 pack hdr, 0.460 sec
0000000e: system header; length=18
00000026: pes private2, PCI; length=980
00000400: pes private2, DSI; length=1018
00000800: mpeg2 pack hdr, 0.461 sec
0000080e: pes video 0; length=2028; hdr=17; pts 1.000 sec; dts 0.960 sec; 
(pext); pstd=234496 (scale=1024)
00000814: sequence hdr: 720x576, a/f:33, bitrate=20000
00000820: sequence extension hdr
0000082a: GOP: 0:00:00.00, open
00000832: picture hdr, frametype=I, temporal=0
0000083a: picture coding extension hdr, top
00001000: mpeg2 pack hdr, 0.463 sec

What is not obvious is what, if anything, marks a VOBU start.  So far as I can 
tell, Every GOP: line, in particular around the forced key frames, is preceded 
by the same three lines as above (with different times, of course).  What's 
also a bit curious is that times on the 'pes video 0; line are always about a 
second ahead of the GOP time.

Tom.





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