Re: [VCDImager Bugs/Devel] SVCD sub header causing sound sync with Toshiba

[Herbert Valerio Riedel]

On Sun, 2003-03-23 at 12:08, William Hardy wrote:
> I get the same problem using Nero, and also with the Ulead DVD plug in.
> 
> After much research, I have pinned down the problem to the subcode
> header for the first sector in my test MPEG file, which was generated
> using TMPGEnc.  This sector contains a pack header, a system header and
> some padding to fill the sector.
> 
> The subcode header generated by VCDImager is the following:
> fn = 01   (file 01)
> cn = 01  (video)
> sm = 62 (Realtime + Form2 + Video)
> ci = 80   (MPEG2)
> 
> I downloaded a trial copy of VOB Instant CD 6.4, and generated a disc
> with that.  It played fine on both computer and DVD player.  It uses a
> subcode header as follows:
> fn = 01    (file 01)
> cn = 00   (empty)
> sm = 60  (Realtime + Form2)
> ci = 00    (empty)
> 
> All other subcode headers were identical.
> 
> On patching the subcode headers to the same value on the VCDImager disc,
> the disc played fine.

[..]

> The question is, is this a bug? I do not have access to the SVCD
> specifications, so I am not aware of what a compliant SVCD should be
> using.  I am therefore asking you, the experts as to the way forward.
> 
> If it is a bug, is this the correct way of fixing it?

yes, it is a bug... but not in vcdimager, it's either the svcd spec, or
your firmware... and in any way, a rather obscure one... :-)

the SVCD specs have a simplified subheader coding wrt to VCD2.x which
basically is:

  SVCD 1.0
  ~~~~~~~~
 
   empty sector:  fn=0 cn=0 sm=%00100000 ci=0
   data sector:   fn=0 cn=0 sm=%x0001000 ci=0
   mpeg sector:   fn=1 cn=1 sm=%x11x001x ci=0x80

(see libvcd/vcd_cd_sector.h for more...)

the mpeg sector applies to every sector that 'contain mpeg program
stream'... which is clearly the case even for just the sequence
header...

[..]
> If it is not a bug, then it would be nice to have some option of
> switching the subcode headers generated for system headers.  There are a
> lot of people using this player who have reported the same problem, and
> would be grateful for a fix (see the comments on Toshiba 220E in the DVD
> players list on http://www.dvdrhelp.com).
[..]

I'm willing to add this as an option; but I'd like to know how old this
toshiba model is, and whether it helps playback for vcd2.0 as well (or
whether it doesn't affect vcd2.0 playback at all...)

regards,
-- 
Herbert Valerio Riedel       /    Phone: (EUROPE) +43-1-58801-18840
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