AW: AW: [vorbis-dev] PlusV algorithm -> CBR
hannes.guddat at igd.fhg.de
Sun Feb 2 07:44:12 PST 2003
<p>> -----UrsprÃ¼ngliche Nachricht-----
> Von: owner-vorbis-dev at xiph.org [mailto:owner-vorbis-dev at xiph.org]Im
> Auftrag von Michael Smith
> Gesendet: Sonntag, 2. Februar 2003 06:56
> An: vorbis-dev at xiph.org
> Betreff: Re: AW: [vorbis-dev] PlusV algorithm -> CBR
> On Thursday 30 January 2003 03:16, Dan Miller wrote:
> > fwiw, there are definitely applications that would use
> Vorbis but can't
> > until there is a _strict_ CBR mode. Meaning,
> architecturally the datarate
> > simply cannot exceed X no matter what happens to the
> quality. Send silence
> > if you have to, but limit the datarate.
> In situations like this, how is bitrate measured? When you
> say "cannot exceed
> X no matter what", what time-period is this over? Since vorbis is a
> block-based codec (as are many others, including mp3), it's
> essential to
> specify some time window - even if that's just a single block
> (but note that
> since there's more than one block size, even that can be problematic).
good conclusion, exactly to the point. I think, everyone here can live with a VBR codec, if at least you can make sure that within a certain window Y (be it seconds, or bytes of coded output) my desired datarate X is not exceeded. Which brings my to the next point..
> Nobody seems to want to say what they actually MEAN by "CBR".
Jup, I apologize on my part, as I titled my initial question "CBR". As stated above, I am just looking for a codec interface that can guarantee a maximum datarate X every (smallest possible) interval Y. Smallest possible, because datarate control adds up on the codec latency (in multiples, presumably). CBR, for me, is a rather hard restriction on a codec, which do not intend to force on vorbis, once I have a reliable upper boundary for bitrate. If I'd really like to fill my channel to a given datarate (why would I, for streaming?) I can still fill the packets with zeros, or whatever. For my part is says: "the less, the better, I just need consistency in time"
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