Mark Taylor wrote:
>
> The is one key difference: safe VBR mode chooses the total number of
> bits to use before *any* quantization occurs, based on a simple
> formula (also used by the CBR algorithm). The psycho acoustics are
> only used in allocating the bits among the frequency bands.
>
> The other VBR modes decide on the total number of bits to use based
> soley on how the quantization errors compare to the psycho acoustic
> masking. Ideally, this is a better way to do things, if your psycho
> acoustic model was perfect.
>
> But the psycho acoustic model in LAME far from perfect, and trusting
> it as much as VBR does can lead to mistakes: A good example of this is
> "vbrtest.wav", which was just added to
> www.sulaco.org/mp3/gpsycho/quality.html
>
Compared to CBR, VBR would have 2 purposes:
1) reduce file size, under the constraint of keeping the same quality
2) increase quality by slighly increasing file size
If I understand well from what is above and from other postings related to this
subject, the state-of-the-art VBR is reliable for purpose 2 only?
Pierre
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