[flac-dev] "keep qlp coeff precision such that only 32-bit math is required"

Martijn van Beurden mvanb1 at gmail.com
Mon Apr 20 10:14:34 PDT 2015

Op 20-04-15 om 18:45 schreef lvqcl:
> Well, the code in process_subframe_() calculates MAX value of 
> qlp_coeff_precision,
> while the code in evaluate_lpc_subframe_() adjusts CURRENT 
> qlp_coeff_precision.

Yes, but that MAX value is used to loop over the 
qlp_coeff_precision values between MIN and MAX. So, if the 
qlp_coeff_precision value is limited in the loop but MAX is not 
limited, the loop does the exact same thing multiple times: a 
waste of time. Therefore, only the MAX should be limited.

I don't think the logic is needed directly after
> min_qlp_coeff_precision = max_qlp_coeff_precision = encoder->protected_->qlp_coeff_precision;
because that value is either chosen by the encoder (it is a 
lookup value, and is always small enough not to trigger this, 
set in stream_encoder.c around line 700) or it is set through 
the encoder, in which case it should probably not be overriden 
without notice.

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