[vorbis-dev] lossless ogg encoding with good compression rate

[Christian Buchner]

The way I see it, the combination of ogg and diff file can never be encoded
as easily (or as compact) as the original wave file itself.

The reason is that the ogg encoding is in part based on a quantization process.
Quantization always creates a quantization error which by nature is noise.
This noise is present in the decoded ogg file - though inaudible, because the
noise is nicely hidden below the ear's masking threshold by the psychoacoustic
model.

When you form the diff between the decoded ogg and the original wave file,
this quantization noise will be imprimted on the diff file also. So what you
get is a diff with increased irrelevance (noise). Information theory (Claude
Shannon) teaches us that irrelevance is really hard to encode - basicall not
compressible.

Christian

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