[M4IF Technotes] AAC: PNS scale factors

[John Cox]

Hi
Thanks for the pointer.  If those reference wav files are definitive
then the published standard is wrong and the reference software is
right.  The scale factor should read:
scale = 1/sqrt(size * MEAN_NRG);
Many thanks
John Cox
>Dear John,
>
>I don't have an answer to your first question.  But for the reference wav 
>files, you can fetch them from:
>ftp://mpaudconf:adif2mp4@ftp.iis.fhg.de/guests/mpeg4audio/incoming/testSequences/mpeg4audio-conformance/referencesWav/
>
>Regards,
>Eddie
>
>At 04:09 PM 6/18/2003 +0100, John Cox wrote:
>>Hi
>>
>>The standard says (ISO/IEC 14496-3:2001(E); 4.6.13.3 page 174) that the
>>initial scale factor for PNS values is:
>>
>>scale = 1/(size * sqrt(MEAN_NRG));
>>
>>however the reference software from the ISO site (both refSoft &
>>rewrite) seems to calculate it as:
>>
>>scale = 1/sqrt(size * MEAN_NRG));
>>
>>Which is "correct" and what have other people done?
>>
>>I've found the PNS reference streams AL18*.mp4 & AL19*.mp4 (though not
>>AL09,10,11) but no corresponding .wavs to check against - do they exist
>>anywhere?
>>
>>Many thanks
>>
>>John Cox
>>SJ Consulting