AudioDecoder: New method SampleRateHz, + implementations for our codecs

webrtc/modules/audio_coding/codecs/g711/audio_decoder_pcm.h

Index: webrtc/modules/audio_coding/codecs/g711/audio_decoder_pcm.h
diff --git a/webrtc/modules/audio_coding/codecs/g711/audio_decoder_pcm.h b/webrtc/modules/audio_coding/codecs/g711/audio_decoder_pcm.h
index 7a627e757c972f4a1454d32a27969b538cbb8a84..cc5776868aba26b5c8819c27feed5e87d0aae33a 100644
--- a/webrtc/modules/audio_coding/codecs/g711/audio_decoder_pcm.h
+++ b/webrtc/modules/audio_coding/codecs/g711/audio_decoder_pcm.h
@@ -19,11 +19,13 @@ namespace webrtc {
 
 class AudioDecoderPcmU final : public AudioDecoder {
  public:
-  explicit AudioDecoderPcmU(size_t num_channels) : num_channels_(num_channels) {
+  explicit AudioDecoderPcmU(int sample_rate_hz, size_t num_channels)

[hlundin-webrtc, 2016/05/30 14:10:17]

Even though not a technical necessity, I think PCM u/A are defined to be 8000 Hz
codecs. You should be able to hard-code 8000 Hz into these codecs and skip the
new ctor parameter.

[kwiberg-webrtc, 2016/05/31 08:26:05]

Done.

+      : sample_rate_hz_(sample_rate_hz), num_channels_(num_channels) {
     RTC_DCHECK_GE(num_channels, 1u);
   }
   void Reset() override;
   int PacketDuration(const uint8_t* encoded, size_t encoded_len) const override;
+  int SampleRateHz() const override;
   size_t Channels() const override;
 
  protected:
@@ -34,17 +36,20 @@ class AudioDecoderPcmU final : public AudioDecoder {
                      SpeechType* speech_type) override;
 
  private:
+  const int sample_rate_hz_;
   const size_t num_channels_;
   RTC_DISALLOW_COPY_AND_ASSIGN(AudioDecoderPcmU);
 };
 
 class AudioDecoderPcmA final : public AudioDecoder {
  public:
-  explicit AudioDecoderPcmA(size_t num_channels) : num_channels_(num_channels) {
+  explicit AudioDecoderPcmA(int sample_rate_hz, size_t num_channels)
+      : sample_rate_hz_(sample_rate_hz), num_channels_(num_channels) {
     RTC_DCHECK_GE(num_channels, 1u);
   }
   void Reset() override;
   int PacketDuration(const uint8_t* encoded, size_t encoded_len) const override;
+  int SampleRateHz() const override;
   size_t Channels() const override;
 
  protected:
@@ -55,6 +60,7 @@ class AudioDecoderPcmA final : public AudioDecoder {
                      SpeechType* speech_type) override;
 
  private:
+  const int sample_rate_hz_;
   const size_t num_channels_;
   RTC_DISALLOW_COPY_AND_ASSIGN(AudioDecoderPcmA);
 };