[vorbis-dev] vorbis.com

Monty xiphmont at xiph.org
Fri Dec 29 22:23:25 PST 2000

On Sat, Dec 30, 2000 at 05:03:37AM +0100, Segher Boessenkool wrote:
> Form the vorbis.com homepage:
> "Ogg Vorbis does not compromise quality for freedom. Its stunning
> quality is coupled with aggressive features like fast bitrate scaling,
> surround channels, and fast sample-granularity seek and decode."
> This makes me wonder...
> -- What is "fast bitrate scaling"?

caling down to a lower bitrate without reencoding.  There aren't any
tools to do it yet.

> -- I've never seen anything in the source supporting surround channels.

Well, we can do 5.1 now, but I hope to make Ambisonics the official
surround post-1.0.  This is actually somewhat orthogonal to the rest.

> -- I don't think Vorbis can do sample-gran seeks (yeah, sure, we can
>    emulate it, but anyone can, and it's not implemented at this time).

Sure we can.  Vorbis streams include information (inferred from the
Ogg page granulepos) such that samples don't necessarily have to begin
or end on packet boundaries.  The whole packet is decoded, of course,
but n samples at the beginning or end can be marked to be discarded.
Thus the sample granularity seek/edit claim (well, seek is easy
regardless, but vorbisfile does provide it :-)


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