88 lines
2.9 KiB
C++
88 lines
2.9 KiB
C++
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/*
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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/neteq/timestamp_scaler.h"
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#include "api/audio_codecs/audio_format.h"
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#include "modules/audio_coding/neteq/decoder_database.h"
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#include "rtc_base/checks.h"
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namespace webrtc {
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void TimestampScaler::Reset() {
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first_packet_received_ = false;
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}
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void TimestampScaler::ToInternal(Packet* packet) {
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if (!packet) {
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return;
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}
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packet->timestamp = ToInternal(packet->timestamp, packet->payload_type);
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}
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void TimestampScaler::ToInternal(PacketList* packet_list) {
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PacketList::iterator it;
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for (it = packet_list->begin(); it != packet_list->end(); ++it) {
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ToInternal(&(*it));
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}
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}
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uint32_t TimestampScaler::ToInternal(uint32_t external_timestamp,
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uint8_t rtp_payload_type) {
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const DecoderDatabase::DecoderInfo* info =
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decoder_database_.GetDecoderInfo(rtp_payload_type);
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if (!info) {
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// Payload type is unknown. Do not scale.
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return external_timestamp;
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}
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if (!(info->IsComfortNoise() || info->IsDtmf())) {
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// Do not change the timestamp scaling settings for DTMF or CNG.
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numerator_ = info->SampleRateHz();
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if (info->GetFormat().clockrate_hz == 0) {
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// If the clockrate is invalid (i.e. with an old-style external codec)
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// we cannot do any timestamp scaling.
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denominator_ = numerator_;
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} else {
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denominator_ = info->GetFormat().clockrate_hz;
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}
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}
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if (numerator_ != denominator_) {
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// We have a scale factor != 1.
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if (!first_packet_received_) {
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external_ref_ = external_timestamp;
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internal_ref_ = external_timestamp;
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first_packet_received_ = true;
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}
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const int64_t external_diff = int64_t{external_timestamp} - external_ref_;
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RTC_DCHECK_GT(denominator_, 0);
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external_ref_ = external_timestamp;
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internal_ref_ += (external_diff * numerator_) / denominator_;
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return internal_ref_;
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} else {
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// No scaling.
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return external_timestamp;
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}
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}
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uint32_t TimestampScaler::ToExternal(uint32_t internal_timestamp) const {
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if (!first_packet_received_ || (numerator_ == denominator_)) {
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// Not initialized, or scale factor is 1.
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return internal_timestamp;
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} else {
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const int64_t internal_diff = int64_t{internal_timestamp} - internal_ref_;
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RTC_DCHECK_GT(numerator_, 0);
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// Do not update references in this method.
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// Switch |denominator_| and |numerator_| to convert the other way.
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return external_ref_ + (internal_diff * denominator_) / numerator_;
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}
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}
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} // namespace webrtc
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