Line data    Source code

       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/system_wrappers/include/logging.h"
      15             : 
      16             : namespace webrtc {
      17             : 
      18           0 : void TimestampScaler::Reset() {
      19           0 :   first_packet_received_ = false;
      20           0 : }
      21             : 
      22           0 : void TimestampScaler::ToInternal(Packet* packet) {
      23           0 :   if (!packet) {
      24           0 :     return;
      25             :   }
      26           0 :   packet->timestamp = ToInternal(packet->timestamp, packet->payload_type);
      27             : }
      28             : 
      29           0 : void TimestampScaler::ToInternal(PacketList* packet_list) {
      30           0 :   PacketList::iterator it;
      31           0 :   for (it = packet_list->begin(); it != packet_list->end(); ++it) {
      32           0 :     ToInternal(&(*it));
      33             :   }
      34           0 : }
      35             : 
      36           0 : uint32_t TimestampScaler::ToInternal(uint32_t external_timestamp,
      37             :                                      uint8_t rtp_payload_type) {
      38             :   const DecoderDatabase::DecoderInfo* info =
      39           0 :       decoder_database_.GetDecoderInfo(rtp_payload_type);
      40           0 :   if (!info) {
      41             :     // Payload type is unknown. Do not scale.
      42           0 :     return external_timestamp;
      43             :   }
      44           0 :   if (!(info->IsComfortNoise() || info->IsDtmf())) {
      45             :     // Do not change the timestamp scaling settings for DTMF or CNG.
      46           0 :     numerator_ = info->SampleRateHz();
      47           0 :     if (info->GetFormat().clockrate_hz == 0) {
      48             :       // If the clockrate is invalid (i.e. with an old-style external codec)
      49             :       // we cannot do any timestamp scaling.
      50           0 :       denominator_ = numerator_;
      51             :     } else {
      52           0 :       denominator_ = info->GetFormat().clockrate_hz;
      53             :     }
      54             :   }
      55           0 :   if (numerator_ != denominator_) {
      56             :     // We have a scale factor != 1.
      57           0 :     if (!first_packet_received_) {
      58           0 :       external_ref_ = external_timestamp;
      59           0 :       internal_ref_ = external_timestamp;
      60           0 :       first_packet_received_ = true;
      61             :     }
      62           0 :     const int64_t external_diff = int64_t{external_timestamp} - external_ref_;
      63           0 :     assert(denominator_ > 0);  // Should not be possible.
      64           0 :     external_ref_ = external_timestamp;
      65           0 :     internal_ref_ += (external_diff * numerator_) / denominator_;
      66           0 :     return internal_ref_;
      67             :   } else {
      68             :     // No scaling.
      69           0 :     return external_timestamp;
      70             :   }
      71             : }
      72             : 
      73             : 
      74           0 : uint32_t TimestampScaler::ToExternal(uint32_t internal_timestamp) const {
      75           0 :   if (!first_packet_received_ || (numerator_ == denominator_)) {
      76             :     // Not initialized, or scale factor is 1.
      77           0 :     return internal_timestamp;
      78             :   } else {
      79           0 :     const int64_t internal_diff = int64_t{internal_timestamp} - internal_ref_;
      80           0 :     assert(numerator_ > 0);  // Should not be possible.
      81             :     // Do not update references in this method.
      82             :     // Switch |denominator_| and |numerator_| to convert the other way.
      83           0 :     return external_ref_ + (internal_diff * denominator_) / numerator_;
      84             :   }
      85             : }
      86             : 
      87             : }  // namespace webrtc