Mark Taylor wrote:
>
>
> To explain how this works, take a 128kbs CBR for example.
> In that case, LAME allocated a base amount of
> bits for each frame. This base amount is about 10% less than
> a 128kbs stream, so that the bit reservoir is slowly built up.
> LAME then allocates extra bits based on the "perceptual entropy",
> computed in psymodel.c. If the perceptual entropy is large,
> the frame can use the base amount + up to 60% of the reservoir.
> These ideas come straight from the ISO docs, but the implementation
> in LAME is new (the ISO dist10 code reservoir treatment is a disaster.)
>
> "Safe VBR" is even simpler: It computes the same base
> amount of bits for each frame, and then computes extra bits
> needed based on the perceptual entropy. But instead of
> relying on the bit reservoir (which might be empty)
> it just increase the frame size when extra bits are needed.
>
Hello,
Isn't this "Safe VBR" (let's say with 128kbs as a base bitrate) equivalent to a
classical VBR with a minimum bitrate: lame -v -b 128
??
Also, I ran lame3.83b and found that VBR mode produce *fully different* results
compared to 3.70, both in terms of average bitrate and in terms of histogram shape.
What happened ?
Pierre
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