[vorbis] YA-2496

[Giuliano Pochini]

On 06-Jan-2003 Michel Donais wrote:
>> The higher sample rate, the higher compression rate you get with a
>> lossless compressor. Did you tried ? 
> 
> [IMHO]Technically, this is true only when the sound quality is not good
> enough to allow for minute changes that are possible with the increased
> resolution.

If resolution means bits-per-sample, yes, more resolution results in
higher "noise" and lower chances to compress the sound. And background
noise (the real one) that usually stays in a few bits in a CD, at 24bpS
adds a lot of randomness to the sound which makes compression much
harder. If you mean higher sample rate, well... if you filter out high
frequency noise (above 24KHz?) that nobody can ear anyway, you get a
sound that's better than CD and can be compressed quite well.

> But in my case, the source will have more informations, and most sources
> will be live, thus containing a little bit of garbage.

Live records contain a lot of noise and lossless compressors don't
like it. But don't think that a lossy compressor handles this with
magic. Since that noise is well audible it will use a lot of bits
to encode the noise, draining bits from the music. Noise is always
a bad thing.

> That said, I haven't tried. The goal by talking to you immediately is to
> start seeing if there are any chances to get my favorite compression
> system in shape for 24/96 in a timely fashion.

Vorbis encoder doesn't support sample rates != 44.1KHz, and since very
few people needs a different sample rate and who needs an higher quality
is unlikely to choose a lossy codes, don't expect Xiph will add it soon.

Bye.

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