[Vorbis-dev] Short block encode computation time.

Doron Veltzer veltzerdoron at gmail.com
Thu Dec 21 06:35:54 PST 2006


Hello!

I've read this list pretty thoroughly before asking. Thanks in advance for
the help.

I'm interested in low-latency streaming of small packets of audio captured
from a sound card.
I want to focus on the compression computational time (not the transport). I
have several questions regarding Vorbis :

(1) Vorbis supports block sizes down to 64 samples according to the spec.
Can I encode, frame, and transport blocks of this size? Will the performance
of a standard vorbis encoder using short sample blocks differ significantly
from performance with the longer block lengths usually used?

(2) Are such short block lengths compatible with Managed Bitrate modes?

(3) What computation time can I expect  in encoding a 64-sample block?
128-sample? (Ordinary, modern P4 platform.)

(4) What are the main sources of computational time in encoding a short
block?

(5) How much of the overall compression is due to perceptual encoding? How
much due to entropy encoding (huffman)?

Thanks in advance.
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