[vorbis-dev] two questions re vorbisfile API

[Ralph Giles]

On Monday, October 28, 2002, at 07:46 PM, Alejandro G. Belluscio wrote:

> But may be he means the there can only be one comments page/packet
> (I alwas confuse the term) in ogg vorbis. Actually the second one
> always has to be a comment. But I haven't read the specification so I
> don't know if you can have more.

Sorry, I was confused by your terminology. 'Tag' means a particular 
comment entry in a comment header. A comment header is a packet. Pages 
are irrelevant for this. The terminology is definitely confusing.

Anyway, you're correct. The only way to insert a new set of comment 
tags is to break the stream, inserting a chaining boundary with a new 
copy of the other headers as well.

On disk, the additional overhead is negligible, and being able to find 
the new comment packet by doing a binary search for the chain boundary 
is a huge win. There's been some discussion about this in a streaming 
context, where the tradeoff is less clean if e.g. you want to insert a 
bunch of 15-second commercials. However, the codebook headers have 
shrunk quite a bit since then, and I think it was decided not to make 
any change.

  -r

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