[vorbis-dev] clarifications on comments spec

[Segher Boessenkool]

Beni Cherniavsky wrote:
> http://www.xiph.org/ogg/vorbis/doc/v-comment.html is not entirely
> explicit on this.  It only says you must have one "framing bit" equal
> to 1 after the comments - what for?  The natural way to read it would
> be that if you do have the framing bit, everything after it should be
> ignored

That is how I read it, too.

 > -- but it doesn't take too much squinting at it to decide to
> do anything else (like complaining) when the packet doesn't end there.

Well, any packet is a multiple of 8 bits, so 87.5% of all packets
would get a complaint under that scheme.  It would be a good idea
to complain if that bit is zero, though (for a 1.0 decoder).

> If the intent is that such padding is legal, could this be written
> there explicitly?

Yes please.

> If you want to strain it, you could always keep lengthening following
> pages until you catch up with the page number of the original file, so
> that the rest can be trivially bit-copied.  This is not necessarily a
> good idea since long pages require bigger buffers (=> higher latency)
> at the decoder and reduce the fault-tolerance and seek effeciency(?).
> 
> Besides, all such tricks require deeper tying of the comment-handling
> to the Ogg framing implementation than if you just take the Ogg

To the Vorbis format, even, because of the unfortunate
granulepos situation...

<p>Segher

<p>--- >8 ----
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