[FFmpeg-devel] [PATCH] qcelp: silence handling

[Kenan Gillet]

Hi,

here is a set of patches that implements SILENCE
bitrate for qcelp.

I tested all the samples I have, and wav ouput are bits identical
since none has a SILENCE frame.
I am not sure if it should be commited without testing on any
real sample, but the changes look pretty harmless.
Kenan

FYI,
>From the specification (TIA/EIA/IS-733 2.4.8.7.2):

2.4.8.7.2 Blank Packets
For a blank packet, the scaled codebook vector
cd(n) is set equal to zero for the entire frame.
The pitch lag, L , is repeated from the last
pitch subframe of the previous frame.

The pitch gain, b, is also repeated from the
last pitch subframe of the previous frame with
the exception that if the pitch gain is greater
than 1, it is set equal to 1.

The previous frame's uninterpolated LSP
frequencies,  wi, are converted into LPC
coefficients.
The LPCs are bandwidth expanded to reproduce ai
and used for the entire frame of reconstructed
speech.
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