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06c2aa9f7b
WebRTC internal code should always use include paths that start from the root of the project and that clearly identify the header file. This allows 'gn check' to actually keep dependencies under control because 'gn check' cannot enforce anything if the include path is not fully qualified (starting from the root of the project). Bug: webrtc:8815 Change-Id: I36f01784fa5f5b77eefc02db479b1f7f6ee1a8c3 Reviewed-on: https://webrtc-review.googlesource.com/46263 Reviewed-by: Karl Wiberg <kwiberg@webrtc.org> Commit-Queue: Mirko Bonadei <mbonadei@webrtc.org> Cr-Commit-Position: refs/heads/master@{#21871}
103 lines
3.1 KiB
C
103 lines
3.1 KiB
C
/*
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* Copyright (c) 2011 The WebRTC project authors. All Rights Reserved.
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*
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* Use of this source code is governed by a BSD-style license
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* that can be found in the LICENSE file in the root of the source
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* tree. An additional intellectual property rights grant can be found
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* in the file PATENTS. All contributing project authors may
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* be found in the AUTHORS file in the root of the source tree.
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*/
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/******************************************************************
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iLBC Speech Coder ANSI-C Source Code
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WebRtcIlbcfix_GainQuant.c
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******************************************************************/
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#include "modules/audio_coding/codecs/ilbc/defines.h"
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#include "modules/audio_coding/codecs/ilbc/constants.h"
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/*----------------------------------------------------------------*
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* quantizer for the gain in the gain-shape coding of residual
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*---------------------------------------------------------------*/
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int16_t WebRtcIlbcfix_GainQuant( /* (o) quantized gain value */
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int16_t gain, /* (i) gain value Q14 */
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int16_t maxIn, /* (i) maximum of gain value Q14 */
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int16_t stage, /* (i) The stage of the search */
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int16_t *index /* (o) quantization index */
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) {
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int16_t scale, cblen;
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int32_t gainW32, measure1, measure2;
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const int16_t *cbPtr, *cb;
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int loc, noMoves, noChecks, i;
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/* ensure a lower bound (0.1) on the scaling factor */
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scale = WEBRTC_SPL_MAX(1638, maxIn);
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/* select the quantization table and calculate
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the length of the table and the number of
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steps in the binary search that are needed */
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cb = WebRtcIlbcfix_kGain[stage];
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cblen = 32>>stage;
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noChecks = 4-stage;
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/* Multiply the gain with 2^14 to make the comparison
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easier and with higher precision */
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gainW32 = gain << 14;
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/* Do a binary search, starting in the middle of the CB
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loc - defines the current position in the table
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noMoves - defines the number of steps to move in the CB in order
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to get next CB location
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*/
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loc = cblen>>1;
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noMoves = loc;
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cbPtr = cb + loc; /* Centre of CB */
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for (i=noChecks;i>0;i--) {
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noMoves>>=1;
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measure1 = scale * *cbPtr;
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/* Move up if gain is larger, otherwise move down in table */
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measure1 = measure1 - gainW32;
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if (0>measure1) {
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cbPtr+=noMoves;
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loc+=noMoves;
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} else {
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cbPtr-=noMoves;
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loc-=noMoves;
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}
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}
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/* Check which value is the closest one: loc-1, loc or loc+1 */
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measure1 = scale * *cbPtr;
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if (gainW32>measure1) {
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/* Check against value above loc */
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measure2 = scale * cbPtr[1];
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if ((measure2-gainW32)<(gainW32-measure1)) {
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loc+=1;
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}
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} else {
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/* Check against value below loc */
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measure2 = scale * cbPtr[-1];
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if ((gainW32-measure2)<=(measure1-gainW32)) {
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loc-=1;
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}
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}
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/* Guard against getting outside the table. The calculation above can give a location
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which is one above the maximum value (in very rare cases) */
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loc=WEBRTC_SPL_MIN(loc, (cblen-1));
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*index=loc;
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/* Calculate and return the quantized gain value (in Q14) */
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return (int16_t)((scale * cb[loc] + 8192) >> 14);
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}
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