On Tue, May 23, 2000 at 10:03:01PM +0200, Roel VdB ([EMAIL PROTECTED]) wrote
> Hello Mark,
>
> Tuesday, May 23, 2000, 8:14:18 PM, you wrote:
>
> MT> Actually, there really are 22 "critical bands" or "scale factor bands"
> MT> used by MP3. I guess we should stick to the C convention, and call the
> MT> last band the 21'st band. Here are the frequency ranges,
> MT> along with the ATH:
>
> aha... I thought the downside of mp3 was that the heritage of L1 and L2
> was that there was a linear distribution in freq ranges, but this
> doen't look linear to me ... So instead of 32 linear just 22 log.
> thanks, I'll do some reading-up...
My understanding is: For encoding purposes, the audio is indeed
divided up into 32 bands by the polyphase filter -- just like MP1 and
MP2. However, MP3 makes this a bit better by super-imposing the
scalefactor bands on top of these. This is an advantage because the
SFB more closly correspond to the critical bands. These 22 SFBs may
apply to less than 1 (for the lower ranges), or more than 1 (for the
upper ranges) of the 32 linear bands created by the polyphase filter.
John
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