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/ilbc/audio_encoder_ilbc.h"
12
13 #include <memory>
14 #include <vector>
15
16 #include "common_types.h" // NOLINT(build/include)
17 #include "modules/audio_coding/codecs/ilbc/audio_encoder_ilbc.h"
18 #include "rtc_base/numerics/safe_conversions.h"
19 #include "rtc_base/numerics/safe_minmax.h"
20 #include "rtc_base/ptr_util.h"
21 #include "rtc_base/string_to_number.h"
22
23 namespace webrtc {
24 namespace {
GetIlbcBitrate(int ptime)25 int GetIlbcBitrate(int ptime) {
26 switch (ptime) {
27 case 20:
28 case 40:
29 // 38 bytes per frame of 20 ms => 15200 bits/s.
30 return 15200;
31 case 30:
32 case 60:
33 // 50 bytes per frame of 30 ms => (approx) 13333 bits/s.
34 return 13333;
35 default:
36 FATAL();
37 }
38 }
39 } // namespace
40
SdpToConfig(const SdpAudioFormat & format)41 rtc::Optional<AudioEncoderIlbcConfig> AudioEncoderIlbc::SdpToConfig(
42 const SdpAudioFormat& format) {
43 if (STR_CASE_CMP(format.name.c_str(), "ILBC") != 0 ||
44 format.clockrate_hz != 8000 || format.num_channels != 1) {
45 return rtc::nullopt;
46 }
47
48 AudioEncoderIlbcConfig config;
49 auto ptime_iter = format.parameters.find("ptime");
50 if (ptime_iter != format.parameters.end()) {
51 auto ptime = rtc::StringToNumber<int>(ptime_iter->second);
52 if (ptime && *ptime > 0) {
53 const int whole_packets = *ptime / 10;
54 config.frame_size_ms = rtc::SafeClamp<int>(whole_packets * 10, 20, 60);
55 }
56 }
57 return config.IsOk() ? rtc::Optional<AudioEncoderIlbcConfig>(config)
58 : rtc::nullopt;
59 }
60
AppendSupportedEncoders(std::vector<AudioCodecSpec> * specs)61 void AudioEncoderIlbc::AppendSupportedEncoders(
62 std::vector<AudioCodecSpec>* specs) {
63 const SdpAudioFormat fmt = {"ILBC", 8000, 1};
64 const AudioCodecInfo info = QueryAudioEncoder(*SdpToConfig(fmt));
65 specs->push_back({fmt, info});
66 }
67
QueryAudioEncoder(const AudioEncoderIlbcConfig & config)68 AudioCodecInfo AudioEncoderIlbc::QueryAudioEncoder(
69 const AudioEncoderIlbcConfig& config) {
70 RTC_DCHECK(config.IsOk());
71 return {8000, 1, GetIlbcBitrate(config.frame_size_ms)};
72 }
73
MakeAudioEncoder(const AudioEncoderIlbcConfig & config,int payload_type)74 std::unique_ptr<AudioEncoder> AudioEncoderIlbc::MakeAudioEncoder(
75 const AudioEncoderIlbcConfig& config,
76 int payload_type) {
77 RTC_DCHECK(config.IsOk());
78 return rtc::MakeUnique<AudioEncoderIlbcImpl>(config, payload_type);
79 }
80
81 } // namespace webrtc
82