121 lines
3.1 KiB
C
121 lines
3.1 KiB
C
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/*
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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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* This file contains some help functions that did not fit elsewhere.
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*/
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#include "dsp_helpfunctions.h"
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WebRtc_Word16 WebRtcNetEQ_CalcFsMult(WebRtc_UWord16 fsHz)
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{
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switch (fsHz)
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{
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case 8000:
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{
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return 1;
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}
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case 16000:
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{
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return 2;
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}
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case 32000:
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{
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return 4;
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}
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case 48000:
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{
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return 6;
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}
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default:
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{
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return 1;
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}
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}
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}
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int WebRtcNetEQ_DownSampleTo4kHz(const WebRtc_Word16 *in, int inLen, WebRtc_UWord16 inFsHz,
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WebRtc_Word16 *out, int outLen, int compensateDelay)
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{
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WebRtc_Word16 *B; /* filter coefficients */
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WebRtc_Word16 Blen; /* number of coefficients */
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WebRtc_Word16 filterDelay; /* phase delay in samples */
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WebRtc_Word16 factor; /* conversion rate (inFsHz/8000) */
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int ok;
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/* Set constants depending on frequency used */
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/* NOTE: The phase delay values are wrong compared to the true phase delay
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of the filters. However, the error is preserved (through the +1 term)
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for consistency. */
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switch (inFsHz)
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{
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case 8000:
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{
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Blen = 3;
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factor = 2;
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B = (WebRtc_Word16*) WebRtcNetEQ_kDownsample8kHzTbl;
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filterDelay = 1 + 1;
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break;
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}
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#ifdef NETEQ_WIDEBAND
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case 16000:
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{
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Blen = 5;
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factor = 4;
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B = (WebRtc_Word16*) WebRtcNetEQ_kDownsample16kHzTbl;
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filterDelay = 2 + 1;
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break;
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}
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#endif
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#ifdef NETEQ_32KHZ_WIDEBAND
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case 32000:
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{
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Blen = 7;
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factor = 8;
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B = (WebRtc_Word16*) WebRtcNetEQ_kDownsample32kHzTbl;
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filterDelay = 3 + 1;
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break;
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}
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#endif
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#ifdef NETEQ_48KHZ_WIDEBAND
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case 48000:
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{
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Blen = 7;
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factor = 12;
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B = (WebRtc_Word16*) WebRtcNetEQ_kDownsample48kHzTbl;
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filterDelay = 3 + 1;
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break;
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}
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#endif
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default:
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{
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/* unsupported or wrong sample rate */
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return -1;
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}
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}
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if (!compensateDelay)
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{
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/* disregard delay compensation */
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filterDelay = 0;
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}
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ok = WebRtcSpl_DownsampleFast((WebRtc_Word16*) &in[Blen - 1],
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(WebRtc_Word16) (inLen - (Blen - 1)), /* number of input samples */
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out, (WebRtc_Word16) outLen, /* number of output samples to produce */
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B, Blen, factor, filterDelay); /* filter parameters */
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return ok; /* return value is -1 if input signal is too short */
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}
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