1/* 2 * Copyright (c) 2012 The WebRTC project authors. All Rights Reserved. 3 * 4 * Use of this source code is governed by a BSD-style license 5 * that can be found in the LICENSE file in the root of the source 6 * tree. An additional intellectual property rights grant can be found 7 * in the file PATENTS. All contributing project authors may 8 * be found in the AUTHORS file in the root of the source tree. 9 */ 10 11#include "webrtc/modules/audio_coding/neteq/timestamp_scaler.h" 12 13#include "webrtc/modules/audio_coding/neteq/decoder_database.h" 14#include "webrtc/modules/audio_coding/neteq/defines.h" 15#include "webrtc/system_wrappers/interface/logging.h" 16 17namespace webrtc { 18 19void TimestampScaler::ToInternal(Packet* packet) { 20 if (!packet) { 21 return; 22 } 23 packet->header.timestamp = ToInternal(packet->header.timestamp, 24 packet->header.payloadType); 25} 26 27void TimestampScaler::ToInternal(PacketList* packet_list) { 28 PacketList::iterator it; 29 for (it = packet_list->begin(); it != packet_list->end(); ++it) { 30 ToInternal(*it); 31 } 32} 33 34uint32_t TimestampScaler::ToInternal(uint32_t external_timestamp, 35 uint8_t rtp_payload_type) { 36 const DecoderDatabase::DecoderInfo* info = 37 decoder_database_.GetDecoderInfo(rtp_payload_type); 38 if (!info) { 39 // Payload type is unknown. Do not scale. 40 return external_timestamp; 41 } 42 switch (info->codec_type) { 43 case kDecoderG722: 44 case kDecoderG722_2ch: { 45 // Use timestamp scaling with factor 2 (two output samples per RTP 46 // timestamp). 47 numerator_ = 2; 48 denominator_ = 1; 49 break; 50 } 51 case kDecoderISACfb: 52 case kDecoderCNGswb48kHz: { 53 // Use timestamp scaling with factor 2/3 (32 kHz sample rate, but RTP 54 // timestamps run on 48 kHz). 55 // TODO(tlegrand): Remove scaling for kDecoderCNGswb48kHz once ACM has 56 // full 48 kHz support. 57 numerator_ = 2; 58 denominator_ = 3; 59 } 60 case kDecoderAVT: 61 case kDecoderCNGnb: 62 case kDecoderCNGwb: 63 case kDecoderCNGswb32kHz: { 64 // Do not change the timestamp scaling settings for DTMF or CNG. 65 break; 66 } 67 default: { 68 // Do not use timestamp scaling for any other codec. 69 numerator_ = 1; 70 denominator_ = 1; 71 break; 72 } 73 } 74 75 if (!(numerator_ == 1 && denominator_ == 1)) { 76 // We have a scale factor != 1. 77 if (!first_packet_received_) { 78 external_ref_ = external_timestamp; 79 internal_ref_ = external_timestamp; 80 first_packet_received_ = true; 81 } 82 int32_t external_diff = external_timestamp - external_ref_; 83 assert(denominator_ > 0); // Should not be possible. 84 external_ref_ = external_timestamp; 85 internal_ref_ += (external_diff * numerator_) / denominator_; 86 LOG(LS_VERBOSE) << "Converting timestamp: " << external_timestamp << 87 " -> " << internal_ref_; 88 return internal_ref_; 89 } else { 90 // No scaling. 91 return external_timestamp; 92 } 93} 94 95 96uint32_t TimestampScaler::ToExternal(uint32_t internal_timestamp) const { 97 if (!first_packet_received_ || (numerator_ == 1 && denominator_ == 1)) { 98 // Not initialized, or scale factor is 1. 99 return internal_timestamp; 100 } else { 101 int32_t internal_diff = internal_timestamp - internal_ref_; 102 assert(numerator_ > 0); // Should not be possible. 103 // Do not update references in this method. 104 // Switch |denominator_| and |numerator_| to convert the other way. 105 return external_ref_ + (internal_diff * denominator_) / numerator_; 106 } 107} 108 109} // namespace webrtc 110