[Mp4-tech] Query on Scalefactors in MPEG-4 AAC

[S. R. Quackenbush]

Dear Raj,
The theoretical maximum scale factor is derived from the maximum global gain
plus the maximum differential value as you reconstruct the set of scale
factors. The short answer is that it is huge, much larger that will be used
in practice. The precise answer is:
max sf = (2)^.25 * ((255-OFFSET)+49*60)
where 255 is max global gain, OFFSET is 100 (but check the standard), 49 is
# sfb in long block, and 60 is max DPCM SFB value.
Best Regards,
Schuyler
---
Dr. Schuyler Quackenbush, Audio Research Labs
336 Park Ave, Suite 200,  Scotch Plains, NJ 07076
office: 908 490 0700	  srq audioresearchlabs.com
mobile: 908 612 9423
fax:    908 842 9151	  www.audioresearchlabs.com
> -----Original Message-----
> From: mp4-tech-bounces lists.mpegif.org
> [mailto:mp4-tech-bounces lists.mpegif.org]On Behalf Of Raj Narayana
> Gadde
> Sent: Tuesday, November 04, 2023 11:18 PM
> To: mp4-tech lists.mpegif.org
> Subject: [Mp4-tech] Query on Scalefactors in MPEG-4 AAC
>
>
> Hi,
>       Can any one tell me the maximum value of scalefactor used in AAC .
> Hoping some answers in this regard.
> Thanks
> Raj
>
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