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source: webrtc/webrtc/modules/audio_coding/neteq4/timestamp_scaler.cc @ 0:4bda6873e34c

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Last change on this file since 0:4bda6873e34c was 0:4bda6873e34c, checked in by Michael Prittie <mprittie@…>, 6 years ago

Scrubbed password for publication.

File size: 3.5 KB
Line 
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/neteq4/timestamp_scaler.h"
12
13#include "webrtc/modules/audio_coding/neteq4/decoder_database.h"
14#include "webrtc/modules/audio_coding/neteq4/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 kDecoderOpus:
52    case kDecoderOpus_2ch:
53    case kDecoderISACfb:
54    case kDecoderCNGswb48kHz: {
55      // Use timestamp scaling with factor 2/3 (32 kHz sample rate, but RTP
56      // timestamps run on 48 kHz).
57      // TODO(tlegrand): Remove scaling for kDecoderCNGswb48kHz once ACM has
58      // full 48 kHz support.
59      numerator_ = 2;
60      denominator_ = 3;
61    }
62    case kDecoderAVT:
63    case kDecoderCNGnb:
64    case kDecoderCNGwb:
65    case kDecoderCNGswb32kHz: {
66      // Do not change the timestamp scaling settings for DTMF or CNG.
67      break;
68    }
69    default: {
70      // Do not use timestamp scaling for any other codec.
71      numerator_ = 1;
72      denominator_ = 1;
73      break;
74    }
75  }
76
77  if (!(numerator_ == 1 && denominator_ == 1)) {
78    // We have a scale factor != 1.
79    if (!first_packet_received_) {
80      external_ref_ = external_timestamp;
81      internal_ref_ = external_timestamp;
82      first_packet_received_ = true;
83    }
84    int32_t external_diff = external_timestamp - external_ref_;
85    assert(denominator_ > 0);  // Should not be possible.
86    external_ref_ = external_timestamp;
87    internal_ref_ += (external_diff * numerator_) / denominator_;
88    LOG(LS_VERBOSE) << "Converting timestamp: " << external_timestamp <<
89        " -> " << internal_ref_;
90    return internal_ref_;
91  } else {
92    // No scaling.
93    return external_timestamp;
94  }
95}
96
97
98uint32_t TimestampScaler::ToExternal(uint32_t internal_timestamp) const {
99  if (!first_packet_received_ || (numerator_ == 1 && denominator_ == 1)) {
100    // Not initialized, or scale factor is 1.
101    return internal_timestamp;
102  } else {
103    int32_t internal_diff = internal_timestamp - internal_ref_;
104    assert(numerator_ > 0);  // Should not be possible.
105    // Do not update references in this method.
106    // Switch |denominator_| and |numerator_| to convert the other way.
107    return external_ref_ + (internal_diff * denominator_) / numerator_;
108  }
109}
110
111}  // namespace webrtc
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