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SILK fixes following last codec WG meeting

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decoder:
- fixed incorrect scaling of filter states for the smallest quantization
  step sizes
- NLSF2A now limits the prediction gain of LPC filters

encoder:
- increased damping of LTP coefficients in LTP analysis
- increased white noise fraction in noise shaping LPC analysis
- introduced maximum total prediction gain.  Used by Burg's method to
  exit early if prediction gain is exceeded.  This improves packet
  loss robustness and numerical robustness in Burg's method
- Prefiltered signal is now in int32 Q10 domain, from int16 Q0
- Increased max number of iterations in CBR gain control loop from 5 to 6
- Removed useless code from LTP scaling control
- Optimization: smarter LPC loop unrolling
- Switched default win32 compile mode to be floating-point

resampler:
- made resampler have constant delay of 0.75 ms; removed delay
  compensation from silk code.
- removed obsolete table entries (~850 Bytes)
- increased downsampling filter order from 16 to 18/24/36 (depending on
  frequency ratio)
- reoptimized filter coefficients
This commit is contained in:
Koen Vos 2011-12-13 14:47:31 -05:00 • committed by Jean-Marc Valin
parent 6619a73637
commit bf75c8ec4d
71 changed files with 961 additions and 1005 deletions
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11
silk/float/LTP_scale_ctrl_FLP.c
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@ -39,19 +39,14 @@ void silk_LTP_scale_ctrl_FLP(
{
opus_int round_loss;
/* 1st order high-pass filter */
/*g_HP(n) = g(n) - 0.5 * g(n-1) + 0.5 * g_HP(n-1);*/
psEnc->HPLTPredCodGain = silk_max_float( psEncCtrl->LTPredCodGain - 0.5f * psEnc->prevLTPredCodGain, 0.0f )
+ 0.5f * psEnc->HPLTPredCodGain;
psEnc->prevLTPredCodGain = psEncCtrl->LTPredCodGain;
/* Only scale if first frame in packet */
if( condCoding == CODE_INDEPENDENTLY ) {
/* Only scale if first frame in packet */
round_loss = psEnc->sCmn.PacketLoss_perc + psEnc->sCmn.nFramesPerPacket;
psEnc->sCmn.indices.LTP_scaleIndex = (opus_int8)silk_LIMIT( round_loss * psEnc->HPLTPredCodGain * 0.1f, 0.0f, 2.0f );
psEnc->sCmn.indices.LTP_scaleIndex = (opus_int8)silk_LIMIT( round_loss * psEncCtrl->LTPredCodGain * 0.1f, 0.0f, 2.0f );
} else {
/* Default is minimum scaling */
psEnc->sCmn.indices.LTP_scaleIndex = 0;
}
psEncCtrl->LTP_scale = (silk_float)silk_LTPScales_table_Q14[ psEnc->sCmn.indices.LTP_scaleIndex ] / 16384.0f;
}