bcec8b0b21
This is from the upstream library commit id 3326535126e435f1ba647885ce43a8f0f3d317eb, corresponding to Chromium 88.0.4290.1.
57 lines
1.8 KiB
C
57 lines
1.8 KiB
C
/*
|
|
* Copyright (c) 2011 The WebRTC project authors. All Rights Reserved.
|
|
*
|
|
* Use of this source code is governed by a BSD-style license
|
|
* that can be found in the LICENSE file in the root of the source
|
|
* tree. An additional intellectual property rights grant can be found
|
|
* in the file PATENTS. All contributing project authors may
|
|
* be found in the AUTHORS file in the root of the source tree.
|
|
*/
|
|
|
|
|
|
/*
|
|
* This file contains the function WebRtcSpl_LpcToReflCoef().
|
|
* The description header can be found in signal_processing_library.h
|
|
*
|
|
*/
|
|
|
|
#include "common_audio/signal_processing/include/signal_processing_library.h"
|
|
|
|
#define SPL_LPC_TO_REFL_COEF_MAX_AR_MODEL_ORDER 50
|
|
|
|
void WebRtcSpl_LpcToReflCoef(int16_t* a16, int use_order, int16_t* k16)
|
|
{
|
|
int m, k;
|
|
int32_t tmp32[SPL_LPC_TO_REFL_COEF_MAX_AR_MODEL_ORDER];
|
|
int32_t tmp_inv_denom32;
|
|
int16_t tmp_inv_denom16;
|
|
|
|
k16[use_order - 1] = a16[use_order] << 3; // Q12<<3 => Q15
|
|
for (m = use_order - 1; m > 0; m--)
|
|
{
|
|
// (1 - k^2) in Q30
|
|
tmp_inv_denom32 = 1073741823 - k16[m] * k16[m];
|
|
// (1 - k^2) in Q15
|
|
tmp_inv_denom16 = (int16_t)(tmp_inv_denom32 >> 15);
|
|
|
|
for (k = 1; k <= m; k++)
|
|
{
|
|
// tmp[k] = (a[k] - RC[m] * a[m-k+1]) / (1.0 - RC[m]*RC[m]);
|
|
|
|
// [Q12<<16 - (Q15*Q12)<<1] = [Q28 - Q28] = Q28
|
|
tmp32[k] = (a16[k] << 16) - (k16[m] * a16[m - k + 1] << 1);
|
|
|
|
tmp32[k] = WebRtcSpl_DivW32W16(tmp32[k], tmp_inv_denom16); //Q28/Q15 = Q13
|
|
}
|
|
|
|
for (k = 1; k < m; k++)
|
|
{
|
|
a16[k] = (int16_t)(tmp32[k] >> 1); // Q13>>1 => Q12
|
|
}
|
|
|
|
tmp32[m] = WEBRTC_SPL_SAT(8191, tmp32[m], -8191);
|
|
k16[m - 1] = (int16_t)WEBRTC_SPL_LSHIFT_W32(tmp32[m], 2); //Q13<<2 => Q15
|
|
}
|
|
return;
|
|
}
|