Vorbis dev - May 2005 - How to specify sample sizes?

Hi,
quoting the vorbis doc
"Vorbis frames may be one of two PCM sample sizes specified during codec 
setup. In Vorbis I, legal frame sizes are powers of two from 64 to 8192 
samples. Aside from coupling, Vorbis handles channels as independent 
vectors and these frame sizes are in samples per channel."

I want to explicitly specify the sample size, so, how can I do it?
Can I set min_size == max_size?
If so, is there any disadvantage? which ?

Thanks,

    Nico

On Fri, May 20, 2005 at 08:22:10PM +0200, Nico Sabbi wrote:
> I want to explicitly specify the sample size, so, how can I do it?
These are generally referred to as "block sizes". They're in the
vorbis
info header if you're curious what your files are using.

They can't be easily changed; doing so involves developing new modes for 
the encoder.
> Can I set min_size == max_size?
> If so, is there any disadvantage? which ?
The idea is to use short blocks for impulsive sounds (percussion, 
instrument 'attack's and so on) and longer blocks for tonal sounds.
Longer blocks are more efficient, but cause artefacts with sharp sounds, 
so the best thing is to mix the two depending on the input audio. One 
can of course produce valid vorbis streams where both block sizes are 
the same, or where only one block size is actually used, but such 
streams will generally be lower quality per bitrate.

HTH,
 -r