[M4IF Technotes] MPEG-4 AAC LTP Question

[Ivan Dimkovic]

Dear M4IF people,
I've found a constant that is used in 14496-5 reference software:
NOK_MAX_LT_PRED_SFB, defining upper scalefactor band for long term
prediction for long blocks.
This value is set to 40 in both encoder and decoder
(nok_ltp_common_internal.h)
However, there is no such limit in the ISO 14496-5 standard. The question
is, is there a possibility to use scalefactor bands higher than 40 for LTP?
If that is the case, then ISO reference software decoder wouldn't be able to
decode such AAC bitstreams. We use this limit (40) in our encoder.
Best Regards,
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Ivan Dimkovic, Technical Manager
PsyTEL Research
Multimedia Coding Solutions
Belgrade Yugoslavia
phone:  +381 63 264 334
phone:  +381 64 11 40 600
fax:       +381 11 32 25 275
email:  dim   psytel-research.co.yu
www:  http://www.psytel-research.co.yu
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