[FFmpeg-devel] AMR-NB decoder

Robert Swain robert.swain
Wed Aug 12 23:55:36 CEST 2009


2009/8/12 Colin McQuillan <m.niloc at googlemail.com>:
> 2009/8/12 Robert Swain <robert.swain at gmail.com>:
>> 2009/8/10 Colin McQuillan <m.niloc at googlemail.com>:
>> [...]
>>> I have tried to address every other comment made in the thread. The
>>> main changes are cosmetics, using fixed point tables to save space,
>>> and keeping the algebraic codebook vector sparse until
>>> anti_sparseness.
>>> amrnb-decoder-r2.patch uses high-pass-filterf.patch, agc-3.patch, and
>>> circ-addf.patch.
>> circ-addf committed after editing the comments a little and discussing
>> them with Colin on IRC. I think maybe the high-pass filter should be
>> made at least somewhat generic as the missing QCELP postfilter uses a
>> filter that is the same order but with different coefficients. I think
>> using the stuff from iirfilter.{c,h} would be overkill for this
>> purpose. I'm discussing this with Colin too.
> Here's a more general ff_acelp_high_pass_filterf.

It seems the QCELP postfilter is in the encoder and not the decoder so
this wouldn't be used in our current QCELP code.

Michael - is the generalisation desirable or should we use the simpler
version with hardcoded coefficients and keep it in amrnbdec.c for now?


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