800 lines
23 KiB
C++
800 lines
23 KiB
C++
/*
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* Copyright (c) 2012 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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#include "modules/audio_coding/codecs/opus/opus_interface.h"
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#include <cstdlib>
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#include "rtc_base/checks.h"
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#include "system_wrappers/include/field_trial.h"
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enum {
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#if WEBRTC_OPUS_SUPPORT_120MS_PTIME
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/* Maximum supported frame size in WebRTC is 120 ms. */
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kWebRtcOpusMaxEncodeFrameSizeMs = 120,
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#else
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/* Maximum supported frame size in WebRTC is 60 ms. */
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kWebRtcOpusMaxEncodeFrameSizeMs = 60,
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#endif
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/* The format allows up to 120 ms frames. Since we don't control the other
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* side, we must allow for packets of that size. NetEq is currently limited
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* to 60 ms on the receive side. */
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kWebRtcOpusMaxDecodeFrameSizeMs = 120,
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// Duration of audio that each call to packet loss concealment covers.
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kWebRtcOpusPlcFrameSizeMs = 10,
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};
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constexpr char kPlcUsePrevDecodedSamplesFieldTrial[] =
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"WebRTC-Audio-OpusPlcUsePrevDecodedSamples";
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static int FrameSizePerChannel(int frame_size_ms, int sample_rate_hz) {
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RTC_DCHECK_GT(frame_size_ms, 0);
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RTC_DCHECK_EQ(frame_size_ms % 10, 0);
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RTC_DCHECK_GT(sample_rate_hz, 0);
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RTC_DCHECK_EQ(sample_rate_hz % 1000, 0);
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return frame_size_ms * (sample_rate_hz / 1000);
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}
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// Maximum sample count per channel.
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static int MaxFrameSizePerChannel(int sample_rate_hz) {
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return FrameSizePerChannel(kWebRtcOpusMaxDecodeFrameSizeMs, sample_rate_hz);
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}
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// Default sample count per channel.
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static int DefaultFrameSizePerChannel(int sample_rate_hz) {
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return FrameSizePerChannel(20, sample_rate_hz);
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}
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int16_t WebRtcOpus_EncoderCreate(OpusEncInst** inst,
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size_t channels,
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int32_t application,
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int sample_rate_hz) {
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int opus_app;
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if (!inst)
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return -1;
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switch (application) {
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case 0:
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opus_app = OPUS_APPLICATION_VOIP;
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break;
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case 1:
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opus_app = OPUS_APPLICATION_AUDIO;
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break;
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default:
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return -1;
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}
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OpusEncInst* state =
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reinterpret_cast<OpusEncInst*>(calloc(1, sizeof(OpusEncInst)));
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RTC_DCHECK(state);
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int error;
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state->encoder = opus_encoder_create(
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sample_rate_hz, static_cast<int>(channels), opus_app, &error);
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if (error != OPUS_OK || (!state->encoder && !state->multistream_encoder)) {
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WebRtcOpus_EncoderFree(state);
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return -1;
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}
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state->in_dtx_mode = 0;
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state->channels = channels;
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*inst = state;
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return 0;
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}
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int16_t WebRtcOpus_MultistreamEncoderCreate(
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OpusEncInst** inst,
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size_t channels,
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int32_t application,
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size_t streams,
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size_t coupled_streams,
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const unsigned char* channel_mapping) {
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int opus_app;
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if (!inst)
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return -1;
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switch (application) {
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case 0:
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opus_app = OPUS_APPLICATION_VOIP;
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break;
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case 1:
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opus_app = OPUS_APPLICATION_AUDIO;
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break;
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default:
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return -1;
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}
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OpusEncInst* state =
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reinterpret_cast<OpusEncInst*>(calloc(1, sizeof(OpusEncInst)));
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RTC_DCHECK(state);
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int error;
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state->multistream_encoder =
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opus_multistream_encoder_create(48000, channels, streams, coupled_streams,
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channel_mapping, opus_app, &error);
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if (error != OPUS_OK || (!state->encoder && !state->multistream_encoder)) {
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WebRtcOpus_EncoderFree(state);
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return -1;
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}
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state->in_dtx_mode = 0;
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state->channels = channels;
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*inst = state;
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return 0;
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}
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int16_t WebRtcOpus_EncoderFree(OpusEncInst* inst) {
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if (inst) {
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if (inst->encoder) {
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opus_encoder_destroy(inst->encoder);
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} else {
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opus_multistream_encoder_destroy(inst->multistream_encoder);
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}
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free(inst);
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return 0;
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} else {
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return -1;
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}
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}
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int WebRtcOpus_Encode(OpusEncInst* inst,
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const int16_t* audio_in,
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size_t samples,
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size_t length_encoded_buffer,
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uint8_t* encoded) {
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int res;
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if (samples > 48 * kWebRtcOpusMaxEncodeFrameSizeMs) {
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return -1;
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}
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if (inst->encoder) {
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res = opus_encode(inst->encoder, (const opus_int16*)audio_in,
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static_cast<int>(samples), encoded,
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static_cast<opus_int32>(length_encoded_buffer));
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} else {
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res = opus_multistream_encode(
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inst->multistream_encoder, (const opus_int16*)audio_in,
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static_cast<int>(samples), encoded,
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static_cast<opus_int32>(length_encoded_buffer));
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}
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if (res <= 0) {
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return -1;
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}
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if (res <= 2) {
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// Indicates DTX since the packet has nothing but a header. In principle,
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// there is no need to send this packet. However, we do transmit the first
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// occurrence to let the decoder know that the encoder enters DTX mode.
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if (inst->in_dtx_mode) {
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return 0;
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} else {
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inst->in_dtx_mode = 1;
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return res;
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}
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}
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inst->in_dtx_mode = 0;
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return res;
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}
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#define ENCODER_CTL(inst, vargs) \
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(inst->encoder \
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? opus_encoder_ctl(inst->encoder, vargs) \
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: opus_multistream_encoder_ctl(inst->multistream_encoder, vargs))
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int16_t WebRtcOpus_SetBitRate(OpusEncInst* inst, int32_t rate) {
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if (inst) {
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return ENCODER_CTL(inst, OPUS_SET_BITRATE(rate));
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} else {
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return -1;
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}
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}
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int16_t WebRtcOpus_SetPacketLossRate(OpusEncInst* inst, int32_t loss_rate) {
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if (inst) {
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return ENCODER_CTL(inst, OPUS_SET_PACKET_LOSS_PERC(loss_rate));
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} else {
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return -1;
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}
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}
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int16_t WebRtcOpus_SetMaxPlaybackRate(OpusEncInst* inst, int32_t frequency_hz) {
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opus_int32 set_bandwidth;
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if (!inst)
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return -1;
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if (frequency_hz <= 8000) {
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set_bandwidth = OPUS_BANDWIDTH_NARROWBAND;
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} else if (frequency_hz <= 12000) {
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set_bandwidth = OPUS_BANDWIDTH_MEDIUMBAND;
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} else if (frequency_hz <= 16000) {
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set_bandwidth = OPUS_BANDWIDTH_WIDEBAND;
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} else if (frequency_hz <= 24000) {
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set_bandwidth = OPUS_BANDWIDTH_SUPERWIDEBAND;
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} else {
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set_bandwidth = OPUS_BANDWIDTH_FULLBAND;
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}
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return ENCODER_CTL(inst, OPUS_SET_MAX_BANDWIDTH(set_bandwidth));
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}
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int16_t WebRtcOpus_GetMaxPlaybackRate(OpusEncInst* const inst,
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int32_t* result_hz) {
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if (inst->encoder) {
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if (opus_encoder_ctl(inst->encoder, OPUS_GET_MAX_BANDWIDTH(result_hz)) ==
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OPUS_OK) {
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return 0;
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}
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return -1;
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}
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opus_int32 max_bandwidth;
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int s;
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int ret;
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max_bandwidth = 0;
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ret = OPUS_OK;
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s = 0;
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while (ret == OPUS_OK) {
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OpusEncoder* enc;
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opus_int32 bandwidth;
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ret = ENCODER_CTL(inst, OPUS_MULTISTREAM_GET_ENCODER_STATE(s, &enc));
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if (ret == OPUS_BAD_ARG)
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break;
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if (ret != OPUS_OK)
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return -1;
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if (opus_encoder_ctl(enc, OPUS_GET_MAX_BANDWIDTH(&bandwidth)) != OPUS_OK)
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return -1;
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if (max_bandwidth != 0 && max_bandwidth != bandwidth)
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return -1;
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max_bandwidth = bandwidth;
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s++;
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}
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*result_hz = max_bandwidth;
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return 0;
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}
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int16_t WebRtcOpus_EnableFec(OpusEncInst* inst) {
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if (inst) {
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return ENCODER_CTL(inst, OPUS_SET_INBAND_FEC(1));
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} else {
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return -1;
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}
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}
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int16_t WebRtcOpus_DisableFec(OpusEncInst* inst) {
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if (inst) {
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return ENCODER_CTL(inst, OPUS_SET_INBAND_FEC(0));
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} else {
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return -1;
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}
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}
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int16_t WebRtcOpus_EnableDtx(OpusEncInst* inst) {
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if (!inst) {
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return -1;
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}
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// To prevent Opus from entering CELT-only mode by forcing signal type to
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// voice to make sure that DTX behaves correctly. Currently, DTX does not
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// last long during a pure silence, if the signal type is not forced.
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// TODO(minyue): Remove the signal type forcing when Opus DTX works properly
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// without it.
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int ret = ENCODER_CTL(inst, OPUS_SET_SIGNAL(OPUS_SIGNAL_VOICE));
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if (ret != OPUS_OK)
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return ret;
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return ENCODER_CTL(inst, OPUS_SET_DTX(1));
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}
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int16_t WebRtcOpus_DisableDtx(OpusEncInst* inst) {
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if (inst) {
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int ret = ENCODER_CTL(inst, OPUS_SET_SIGNAL(OPUS_AUTO));
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if (ret != OPUS_OK)
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return ret;
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return ENCODER_CTL(inst, OPUS_SET_DTX(0));
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} else {
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return -1;
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}
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}
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int16_t WebRtcOpus_EnableCbr(OpusEncInst* inst) {
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if (inst) {
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return ENCODER_CTL(inst, OPUS_SET_VBR(0));
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} else {
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return -1;
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}
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}
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int16_t WebRtcOpus_DisableCbr(OpusEncInst* inst) {
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if (inst) {
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return ENCODER_CTL(inst, OPUS_SET_VBR(1));
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} else {
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return -1;
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}
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}
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int16_t WebRtcOpus_SetComplexity(OpusEncInst* inst, int32_t complexity) {
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if (inst) {
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return ENCODER_CTL(inst, OPUS_SET_COMPLEXITY(complexity));
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} else {
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return -1;
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}
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}
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int32_t WebRtcOpus_GetBandwidth(OpusEncInst* inst) {
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if (!inst) {
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return -1;
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}
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int32_t bandwidth;
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if (ENCODER_CTL(inst, OPUS_GET_BANDWIDTH(&bandwidth)) == 0) {
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return bandwidth;
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} else {
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return -1;
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}
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}
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int16_t WebRtcOpus_SetBandwidth(OpusEncInst* inst, int32_t bandwidth) {
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if (inst) {
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return ENCODER_CTL(inst, OPUS_SET_BANDWIDTH(bandwidth));
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} else {
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return -1;
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}
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}
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int16_t WebRtcOpus_SetForceChannels(OpusEncInst* inst, size_t num_channels) {
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if (!inst)
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return -1;
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if (num_channels == 0) {
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return ENCODER_CTL(inst, OPUS_SET_FORCE_CHANNELS(OPUS_AUTO));
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} else if (num_channels == 1 || num_channels == 2) {
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return ENCODER_CTL(inst, OPUS_SET_FORCE_CHANNELS(num_channels));
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} else {
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return -1;
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}
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}
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int32_t WebRtcOpus_GetInDtx(OpusEncInst* inst) {
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if (!inst) {
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return -1;
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}
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#ifdef OPUS_GET_IN_DTX
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int32_t in_dtx;
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if (ENCODER_CTL(inst, OPUS_GET_IN_DTX(&in_dtx)) == 0) {
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return in_dtx;
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}
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#endif
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return -1;
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}
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int16_t WebRtcOpus_DecoderCreate(OpusDecInst** inst,
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size_t channels,
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int sample_rate_hz) {
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int error;
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OpusDecInst* state;
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if (inst != NULL) {
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// Create Opus decoder state.
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state = reinterpret_cast<OpusDecInst*>(calloc(1, sizeof(OpusDecInst)));
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if (state == NULL) {
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return -1;
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}
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state->decoder =
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opus_decoder_create(sample_rate_hz, static_cast<int>(channels), &error);
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if (error == OPUS_OK && state->decoder) {
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// Creation of memory all ok.
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state->channels = channels;
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state->sample_rate_hz = sample_rate_hz;
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state->plc_use_prev_decoded_samples =
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webrtc::field_trial::IsEnabled(kPlcUsePrevDecodedSamplesFieldTrial);
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if (state->plc_use_prev_decoded_samples) {
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state->prev_decoded_samples =
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DefaultFrameSizePerChannel(state->sample_rate_hz);
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}
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state->in_dtx_mode = 0;
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*inst = state;
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return 0;
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}
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// If memory allocation was unsuccessful, free the entire state.
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if (state->decoder) {
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opus_decoder_destroy(state->decoder);
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}
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free(state);
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}
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return -1;
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}
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int16_t WebRtcOpus_MultistreamDecoderCreate(
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OpusDecInst** inst,
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size_t channels,
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size_t streams,
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size_t coupled_streams,
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const unsigned char* channel_mapping) {
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int error;
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OpusDecInst* state;
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if (inst != NULL) {
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// Create Opus decoder state.
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state = reinterpret_cast<OpusDecInst*>(calloc(1, sizeof(OpusDecInst)));
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if (state == NULL) {
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return -1;
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}
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// Create new memory, always at 48000 Hz.
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state->multistream_decoder = opus_multistream_decoder_create(
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48000, channels, streams, coupled_streams, channel_mapping, &error);
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if (error == OPUS_OK && state->multistream_decoder) {
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// Creation of memory all ok.
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state->channels = channels;
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state->sample_rate_hz = 48000;
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state->plc_use_prev_decoded_samples =
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webrtc::field_trial::IsEnabled(kPlcUsePrevDecodedSamplesFieldTrial);
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if (state->plc_use_prev_decoded_samples) {
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state->prev_decoded_samples =
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DefaultFrameSizePerChannel(state->sample_rate_hz);
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}
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state->in_dtx_mode = 0;
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*inst = state;
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return 0;
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}
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// If memory allocation was unsuccessful, free the entire state.
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opus_multistream_decoder_destroy(state->multistream_decoder);
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free(state);
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}
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return -1;
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}
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int16_t WebRtcOpus_DecoderFree(OpusDecInst* inst) {
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if (inst) {
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if (inst->decoder) {
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opus_decoder_destroy(inst->decoder);
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} else if (inst->multistream_decoder) {
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opus_multistream_decoder_destroy(inst->multistream_decoder);
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}
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free(inst);
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return 0;
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} else {
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return -1;
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}
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}
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size_t WebRtcOpus_DecoderChannels(OpusDecInst* inst) {
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return inst->channels;
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}
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void WebRtcOpus_DecoderInit(OpusDecInst* inst) {
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if (inst->decoder) {
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opus_decoder_ctl(inst->decoder, OPUS_RESET_STATE);
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} else {
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opus_multistream_decoder_ctl(inst->multistream_decoder, OPUS_RESET_STATE);
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}
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inst->in_dtx_mode = 0;
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}
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/* For decoder to determine if it is to output speech or comfort noise. */
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static int16_t DetermineAudioType(OpusDecInst* inst, size_t encoded_bytes) {
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// Audio type becomes comfort noise if |encoded_byte| is 1 and keeps
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// to be so if the following |encoded_byte| are 0 or 1.
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if (encoded_bytes == 0 && inst->in_dtx_mode) {
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return 2; // Comfort noise.
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} else if (encoded_bytes == 1 || encoded_bytes == 2) {
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// TODO(henrik.lundin): There is a slight risk that a 2-byte payload is in
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// fact a 1-byte TOC with a 1-byte payload. That will be erroneously
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// interpreted as comfort noise output, but such a payload is probably
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// faulty anyway.
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// TODO(webrtc:10218): This is wrong for multistream opus. Then are several
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// single-stream packets glued together with some packet size bytes in
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// between. See https://tools.ietf.org/html/rfc6716#appendix-B
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inst->in_dtx_mode = 1;
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return 2; // Comfort noise.
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} else {
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inst->in_dtx_mode = 0;
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return 0; // Speech.
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}
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}
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/* |frame_size| is set to maximum Opus frame size in the normal case, and
|
|
* is set to the number of samples needed for PLC in case of losses.
|
|
* It is up to the caller to make sure the value is correct. */
|
|
static int DecodeNative(OpusDecInst* inst,
|
|
const uint8_t* encoded,
|
|
size_t encoded_bytes,
|
|
int frame_size,
|
|
int16_t* decoded,
|
|
int16_t* audio_type,
|
|
int decode_fec) {
|
|
int res = -1;
|
|
if (inst->decoder) {
|
|
res = opus_decode(
|
|
inst->decoder, encoded, static_cast<opus_int32>(encoded_bytes),
|
|
reinterpret_cast<opus_int16*>(decoded), frame_size, decode_fec);
|
|
} else {
|
|
res = opus_multistream_decode(inst->multistream_decoder, encoded,
|
|
static_cast<opus_int32>(encoded_bytes),
|
|
reinterpret_cast<opus_int16*>(decoded),
|
|
frame_size, decode_fec);
|
|
}
|
|
|
|
if (res <= 0)
|
|
return -1;
|
|
|
|
*audio_type = DetermineAudioType(inst, encoded_bytes);
|
|
|
|
return res;
|
|
}
|
|
|
|
static int DecodePlc(OpusDecInst* inst, int16_t* decoded) {
|
|
int16_t audio_type = 0;
|
|
int decoded_samples;
|
|
int plc_samples =
|
|
FrameSizePerChannel(kWebRtcOpusPlcFrameSizeMs, inst->sample_rate_hz);
|
|
|
|
if (inst->plc_use_prev_decoded_samples) {
|
|
/* The number of samples we ask for is |number_of_lost_frames| times
|
|
* |prev_decoded_samples_|. Limit the number of samples to maximum
|
|
* |MaxFrameSizePerChannel()|. */
|
|
plc_samples = inst->prev_decoded_samples;
|
|
const int max_samples_per_channel =
|
|
MaxFrameSizePerChannel(inst->sample_rate_hz);
|
|
plc_samples = plc_samples <= max_samples_per_channel
|
|
? plc_samples
|
|
: max_samples_per_channel;
|
|
}
|
|
decoded_samples =
|
|
DecodeNative(inst, NULL, 0, plc_samples, decoded, &audio_type, 0);
|
|
if (decoded_samples < 0) {
|
|
return -1;
|
|
}
|
|
|
|
return decoded_samples;
|
|
}
|
|
|
|
int WebRtcOpus_Decode(OpusDecInst* inst,
|
|
const uint8_t* encoded,
|
|
size_t encoded_bytes,
|
|
int16_t* decoded,
|
|
int16_t* audio_type) {
|
|
int decoded_samples;
|
|
|
|
if (encoded_bytes == 0) {
|
|
*audio_type = DetermineAudioType(inst, encoded_bytes);
|
|
decoded_samples = DecodePlc(inst, decoded);
|
|
} else {
|
|
decoded_samples = DecodeNative(inst, encoded, encoded_bytes,
|
|
MaxFrameSizePerChannel(inst->sample_rate_hz),
|
|
decoded, audio_type, 0);
|
|
}
|
|
if (decoded_samples < 0) {
|
|
return -1;
|
|
}
|
|
|
|
if (inst->plc_use_prev_decoded_samples) {
|
|
/* Update decoded sample memory, to be used by the PLC in case of losses. */
|
|
inst->prev_decoded_samples = decoded_samples;
|
|
}
|
|
|
|
return decoded_samples;
|
|
}
|
|
|
|
int WebRtcOpus_DecodeFec(OpusDecInst* inst,
|
|
const uint8_t* encoded,
|
|
size_t encoded_bytes,
|
|
int16_t* decoded,
|
|
int16_t* audio_type) {
|
|
int decoded_samples;
|
|
int fec_samples;
|
|
|
|
if (WebRtcOpus_PacketHasFec(encoded, encoded_bytes) != 1) {
|
|
return 0;
|
|
}
|
|
|
|
fec_samples =
|
|
opus_packet_get_samples_per_frame(encoded, inst->sample_rate_hz);
|
|
|
|
decoded_samples = DecodeNative(inst, encoded, encoded_bytes, fec_samples,
|
|
decoded, audio_type, 1);
|
|
if (decoded_samples < 0) {
|
|
return -1;
|
|
}
|
|
|
|
return decoded_samples;
|
|
}
|
|
|
|
int WebRtcOpus_DurationEst(OpusDecInst* inst,
|
|
const uint8_t* payload,
|
|
size_t payload_length_bytes) {
|
|
if (payload_length_bytes == 0) {
|
|
// WebRtcOpus_Decode calls PLC when payload length is zero. So we return
|
|
// PLC duration correspondingly.
|
|
return WebRtcOpus_PlcDuration(inst);
|
|
}
|
|
|
|
int frames, samples;
|
|
frames = opus_packet_get_nb_frames(
|
|
payload, static_cast<opus_int32>(payload_length_bytes));
|
|
if (frames < 0) {
|
|
/* Invalid payload data. */
|
|
return 0;
|
|
}
|
|
samples =
|
|
frames * opus_packet_get_samples_per_frame(payload, inst->sample_rate_hz);
|
|
if (samples > 120 * inst->sample_rate_hz / 1000) {
|
|
// More than 120 ms' worth of samples.
|
|
return 0;
|
|
}
|
|
return samples;
|
|
}
|
|
|
|
int WebRtcOpus_PlcDuration(OpusDecInst* inst) {
|
|
if (inst->plc_use_prev_decoded_samples) {
|
|
/* The number of samples we ask for is |number_of_lost_frames| times
|
|
* |prev_decoded_samples_|. Limit the number of samples to maximum
|
|
* |MaxFrameSizePerChannel()|. */
|
|
const int plc_samples = inst->prev_decoded_samples;
|
|
const int max_samples_per_channel =
|
|
MaxFrameSizePerChannel(inst->sample_rate_hz);
|
|
return plc_samples <= max_samples_per_channel ? plc_samples
|
|
: max_samples_per_channel;
|
|
}
|
|
return FrameSizePerChannel(kWebRtcOpusPlcFrameSizeMs, inst->sample_rate_hz);
|
|
}
|
|
|
|
int WebRtcOpus_FecDurationEst(const uint8_t* payload,
|
|
size_t payload_length_bytes,
|
|
int sample_rate_hz) {
|
|
if (WebRtcOpus_PacketHasFec(payload, payload_length_bytes) != 1) {
|
|
return 0;
|
|
}
|
|
const int samples =
|
|
opus_packet_get_samples_per_frame(payload, sample_rate_hz);
|
|
const int samples_per_ms = sample_rate_hz / 1000;
|
|
if (samples < 10 * samples_per_ms || samples > 120 * samples_per_ms) {
|
|
/* Invalid payload duration. */
|
|
return 0;
|
|
}
|
|
return samples;
|
|
}
|
|
|
|
int WebRtcOpus_NumSilkFrames(const uint8_t* payload) {
|
|
// For computing the payload length in ms, the sample rate is not important
|
|
// since it cancels out. We use 48 kHz, but any valid sample rate would work.
|
|
int payload_length_ms =
|
|
opus_packet_get_samples_per_frame(payload, 48000) / 48;
|
|
if (payload_length_ms < 10)
|
|
payload_length_ms = 10;
|
|
|
|
int silk_frames;
|
|
switch (payload_length_ms) {
|
|
case 10:
|
|
case 20:
|
|
silk_frames = 1;
|
|
break;
|
|
case 40:
|
|
silk_frames = 2;
|
|
break;
|
|
case 60:
|
|
silk_frames = 3;
|
|
break;
|
|
default:
|
|
return 0; // It is actually even an invalid packet.
|
|
}
|
|
return silk_frames;
|
|
}
|
|
|
|
// This method is based on Definition of the Opus Audio Codec
|
|
// (https://tools.ietf.org/html/rfc6716). Basically, this method is based on
|
|
// parsing the LP layer of an Opus packet, particularly the LBRR flag.
|
|
int WebRtcOpus_PacketHasFec(const uint8_t* payload,
|
|
size_t payload_length_bytes) {
|
|
if (payload == NULL || payload_length_bytes == 0)
|
|
return 0;
|
|
|
|
// In CELT_ONLY mode, packets should not have FEC.
|
|
if (payload[0] & 0x80)
|
|
return 0;
|
|
|
|
int silk_frames = WebRtcOpus_NumSilkFrames(payload);
|
|
if (silk_frames == 0)
|
|
return 0; // Not valid.
|
|
|
|
const int channels = opus_packet_get_nb_channels(payload);
|
|
RTC_DCHECK(channels == 1 || channels == 2);
|
|
|
|
// Max number of frames in an Opus packet is 48.
|
|
opus_int16 frame_sizes[48];
|
|
const unsigned char* frame_data[48];
|
|
|
|
// Parse packet to get the frames. But we only care about the first frame,
|
|
// since we can only decode the FEC from the first one.
|
|
if (opus_packet_parse(payload, static_cast<opus_int32>(payload_length_bytes),
|
|
NULL, frame_data, frame_sizes, NULL) < 0) {
|
|
return 0;
|
|
}
|
|
|
|
if (frame_sizes[0] < 1) {
|
|
return 0;
|
|
}
|
|
|
|
// A frame starts with the LP layer. The LP layer begins with two to eight
|
|
// header bits.These consist of one VAD bit per SILK frame (up to 3),
|
|
// followed by a single flag indicating the presence of LBRR frames.
|
|
// For a stereo packet, these first flags correspond to the mid channel, and
|
|
// a second set of flags is included for the side channel. Because these are
|
|
// the first symbols decoded by the range coder and because they are coded
|
|
// as binary values with uniform probability, they can be extracted directly
|
|
// from the most significant bits of the first byte of compressed data.
|
|
for (int n = 0; n < channels; n++) {
|
|
// The LBRR bit for channel 1 is on the (|silk_frames| + 1)-th bit, and
|
|
// that of channel 2 is on the |(|silk_frames| + 1) * 2 + 1|-th bit.
|
|
if (frame_data[0][0] & (0x80 >> ((n + 1) * (silk_frames + 1) - 1)))
|
|
return 1;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
int WebRtcOpus_PacketHasVoiceActivity(const uint8_t* payload,
|
|
size_t payload_length_bytes) {
|
|
if (payload == NULL || payload_length_bytes == 0)
|
|
return 0;
|
|
|
|
// In CELT_ONLY mode we can not determine whether there is VAD.
|
|
if (payload[0] & 0x80)
|
|
return -1;
|
|
|
|
int silk_frames = WebRtcOpus_NumSilkFrames(payload);
|
|
if (silk_frames == 0)
|
|
return 0;
|
|
|
|
const int channels = opus_packet_get_nb_channels(payload);
|
|
RTC_DCHECK(channels == 1 || channels == 2);
|
|
|
|
// Max number of frames in an Opus packet is 48.
|
|
opus_int16 frame_sizes[48];
|
|
const unsigned char* frame_data[48];
|
|
|
|
// Parse packet to get the frames.
|
|
int frames =
|
|
opus_packet_parse(payload, static_cast<opus_int32>(payload_length_bytes),
|
|
NULL, frame_data, frame_sizes, NULL);
|
|
if (frames < 0)
|
|
return -1;
|
|
|
|
// Iterate over all Opus frames which may contain multiple SILK frames.
|
|
for (int frame = 0; frame < frames; frame++) {
|
|
if (frame_sizes[frame] < 1) {
|
|
continue;
|
|
}
|
|
if (frame_data[frame][0] >> (8 - silk_frames))
|
|
return 1;
|
|
if (channels == 2 &&
|
|
(frame_data[frame][0] << (silk_frames + 1)) >> (8 - silk_frames))
|
|
return 1;
|
|
}
|
|
|
|
return 0;
|
|
}
|