Injectable audio encoders: BuiltinAudioEncoderFactory

webrtc/modules/audio_coding/codecs/pcm16b/audio_encoder_pcm16b.cc

Index: webrtc/modules/audio_coding/codecs/pcm16b/audio_encoder_pcm16b.cc
diff --git a/webrtc/modules/audio_coding/codecs/pcm16b/audio_encoder_pcm16b.cc b/webrtc/modules/audio_coding/codecs/pcm16b/audio_encoder_pcm16b.cc
index cafd3e851bd376cf37aef2a9633b7bfa887fbcd7..442ea662dd336b89c562f61f74de412b2b4addf4 100644
--- a/webrtc/modules/audio_coding/codecs/pcm16b/audio_encoder_pcm16b.cc
+++ b/webrtc/modules/audio_coding/codecs/pcm16b/audio_encoder_pcm16b.cc
@@ -10,7 +10,11 @@
 
 #include "webrtc/modules/audio_coding/codecs/pcm16b/audio_encoder_pcm16b.h"
 
+#include <algorithm>
+
 #include "webrtc/base/checks.h"
+#include "webrtc/base/safe_conversions.h"
+#include "webrtc/base/string_to_number.h"
 #include "webrtc/common_types.h"
 #include "webrtc/modules/audio_coding/codecs/pcm16b/pcm16b.h"
 
@@ -40,6 +44,24 @@ AudioEncoderPcm16B::Config CreateConfig(const CodecInst& codec_inst) {
   config.payload_type = codec_inst.pltype;
   return config;
 }
+
+AudioEncoderPcm16B::Config CreateConfig(int payload_type,
+                                        const SdpAudioFormat& format) {
+  AudioEncoderPcm16B::Config config;
+  config.num_channels = format.num_channels;
+  config.sample_rate_hz = format.clockrate_hz;
+  config.frame_size_ms = 10;
+  auto ptime_iter = format.parameters.find("ptime");
+  if (ptime_iter != format.parameters.end()) {
+    auto ptime = rtc::StringToNumber<int>(ptime_iter->second);
+    if (ptime && *ptime > 0) {
+      const int whole_packets = *ptime / 10;
+      config.frame_size_ms = std::max(10, std::min(whole_packets * 10, 60));
+    }
+  }
+  config.payload_type = payload_type;
+  return config;
+}
 }  // namespace
 
 bool AudioEncoderPcm16B::Config::IsOk() const {
@@ -52,4 +74,23 @@ bool AudioEncoderPcm16B::Config::IsOk() const {
 AudioEncoderPcm16B::AudioEncoderPcm16B(const CodecInst& codec_inst)
     : AudioEncoderPcm16B(CreateConfig(codec_inst)) {}
 
+AudioEncoderPcm16B::AudioEncoderPcm16B(int payload_type,
+                                       const SdpAudioFormat& format)
+    : AudioEncoderPcm16B(CreateConfig(payload_type, format)) {}
+
+rtc::Optional<AudioCodecInfo> AudioEncoderPcm16B::QueryAudioEncoder(
+    const SdpAudioFormat& format) {
+  if (STR_CASE_CMP(format.name.c_str(), GetPayloadName()) == 0 &&
+      format.num_channels >= 1) {
+    Config config = CreateConfig(0, format);
+    if (config.IsOk()) {
+      return rtc::Optional<AudioCodecInfo>(
+          {config.sample_rate_hz, config.num_channels,
+           config.sample_rate_hz * 2 *
+               rtc::dchecked_cast<int>(config.num_channels)});
+    }
+  }
+  return rtc::Optional<AudioCodecInfo>();
+}
+
 }  // namespace webrtc