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In Reply to: Re: Beatles "Love" Audio Menu Mystery posted by Neil Wilkes on February 21, 2007 at 07:20:40:
Why is there such an artificial limit? If 3 streams can be squeezed in to the VTS, then why not?
Follow Ups:
In DVD-Video, you can have up to 8 Audio streams per VTS.
BUT - and this is the big one, the specifications for VTS in DVD-Audio are different.
A VTS for DVD-A can only have 2 Audio streams.
This is primarily because of a section of the specs that has been ignored by a lot of labels stating "All VTS Shall be pointed from the AMG (Audio ManaGer) of the ATS".
As this requires a "set system - Branch" command in authoring (When we link to a DD 5.1 or a DTS 5.1 stream in DVD-A we are actually jumping into the Video_TS from the Audio_TS) and as there can only be 2 Audio streams present in a single title in the Audio_TS, there are only 2 options for Set System. Audio=0 and Audio=1 (where Audio=0 is telling the player to access Stream #1 in the pointed VTS).
As most authors do not actually point or link to the VTS, this often gets overlooked. The correct way to do this where 3 (or more) streams are required in the VTS is to "Double-Author" and use 2 VTS, with 2 streams on each.
THe reasoning behind this is to give the end user more choice.
With linking done properly, if the content of a disc has
Advanced Resolution 5.1 (24/96 or 24/48)
Advanced Resolution 2.0
LPCM 2.0 (16/48 usually, sometimes 24/48)
DD 2.0
DD 5.1
DTS 5.1
Then it should be possible to access all 6 of these streams from the AMG. If you cannot do this, the disc is not correctly authored.
Is it the DVD-A authoring programs that create these out of spec discs or is it the authors?
Chances are high it's the authors. Most serious authors only use the Sonic DVD-Audio Creator, as nothing else actually gives you full access to the DVD-A specs.
It's a strange one and been the subject of often heated debates, because whilst most - and I stress most - players will easily handle these "out of spec" discs, it's not [i]technically[/i] DVD-Audio.
In the Beatles disc, you cannot access any of the lossy streams at all, so this is technically out of spec, although unlinked universals (or hybrids) are indeed common. It's all a matter of interpretation, and the spec states all VTS shall be linked.
My understanding (and many others) of the word "Shall" is that it must happen, has to be done, is not optional. Others disagree.
Nearly all the Warner titles are technically "off-spec".
Where it matters is at replication, and certain replication facilities will refuse to print a disc that fails verification for spec compliance. Here in the UK we have an insane situation - The company who used to be called Deluxe Media are one of only a couple who can replicate DVD-A, and they were bought out by Sony Media, who are now insisting on strict spec compliance.
Yet there are other replicators who will do the job & not be so fussy about things. What to do? It's probably better to stick with the specs, no matter how silly we feel the restrictions may be, because there are bound to be players out there that only conform to strict specs, and will therefore refuse to play certain discs at all. Hell, we know the Pioneer 563/565 has problems with discs that are to spec, never mind those that are not.
Thanks. Unlike CD-Audio which uses a different structure compared to the CD-ROM, AFAIK DVD-Audio is just a DVD-ROM meeting a certain spec. So why can't a DVD-A be replicated by anybody?
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