1 /*
2 * Copyright (c) 2017 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 "api/audio_codecs/opus/audio_decoder_opus.h"
12
13 #include <memory>
14 #include <utility>
15 #include <vector>
16
17 #include "absl/strings/match.h"
18 #include "modules/audio_coding/codecs/opus/audio_decoder_opus.h"
19
20 namespace webrtc {
21
IsOk() const22 bool AudioDecoderOpus::Config::IsOk() const {
23 if (sample_rate_hz != 16000 && sample_rate_hz != 48000) {
24 // Unsupported sample rate. (libopus supports a few other rates as
25 // well; we can add support for them when needed.)
26 return false;
27 }
28 if (num_channels != 1 && num_channels != 2) {
29 return false;
30 }
31 return true;
32 }
33
SdpToConfig(const SdpAudioFormat & format)34 absl::optional<AudioDecoderOpus::Config> AudioDecoderOpus::SdpToConfig(
35 const SdpAudioFormat& format) {
36 const auto num_channels = [&]() -> absl::optional<int> {
37 auto stereo = format.parameters.find("stereo");
38 if (stereo != format.parameters.end()) {
39 if (stereo->second == "0") {
40 return 1;
41 } else if (stereo->second == "1") {
42 return 2;
43 } else {
44 return absl::nullopt; // Bad stereo parameter.
45 }
46 }
47 return 1; // Default to mono.
48 }();
49 if (absl::EqualsIgnoreCase(format.name, "opus") &&
50 format.clockrate_hz == 48000 && format.num_channels == 2 &&
51 num_channels) {
52 Config config;
53 config.num_channels = *num_channels;
54 if (!config.IsOk()) {
55 RTC_DCHECK_NOTREACHED();
56 return absl::nullopt;
57 }
58 return config;
59 } else {
60 return absl::nullopt;
61 }
62 }
63
AppendSupportedDecoders(std::vector<AudioCodecSpec> * specs)64 void AudioDecoderOpus::AppendSupportedDecoders(
65 std::vector<AudioCodecSpec>* specs) {
66 AudioCodecInfo opus_info{48000, 1, 64000, 6000, 510000};
67 opus_info.allow_comfort_noise = false;
68 opus_info.supports_network_adaption = true;
69 SdpAudioFormat opus_format(
70 {"opus", 48000, 2, {{"minptime", "10"}, {"useinbandfec", "1"}}});
71 specs->push_back({std::move(opus_format), opus_info});
72 }
73
MakeAudioDecoder(Config config,absl::optional<AudioCodecPairId>,const FieldTrialsView * field_trials)74 std::unique_ptr<AudioDecoder> AudioDecoderOpus::MakeAudioDecoder(
75 Config config,
76 absl::optional<AudioCodecPairId> /*codec_pair_id*/,
77 const FieldTrialsView* field_trials) {
78 if (!config.IsOk()) {
79 RTC_DCHECK_NOTREACHED();
80 return nullptr;
81 }
82 return std::make_unique<AudioDecoderOpusImpl>(config.num_channels,
83 config.sample_rate_hz);
84 }
85
86 } // namespace webrtc
87