Fold AudioEncoderMutable into AudioEncoder

webrtc/modules/audio_coding/codecs/audio_encoder.h

Index: webrtc/modules/audio_coding/codecs/audio_encoder.h
diff --git a/webrtc/modules/audio_coding/codecs/audio_encoder.h b/webrtc/modules/audio_coding/codecs/audio_encoder.h
index 0a40316b713025028fd67be64f9d75a08d124168..73b4468d4657ea5c58af8067435931f66e9a3351 100644
--- a/webrtc/modules/audio_coding/codecs/audio_encoder.h
+++ b/webrtc/modules/audio_coding/codecs/audio_encoder.h
@@ -23,18 +23,11 @@ namespace webrtc {
 class AudioEncoder {
  public:
   struct EncodedInfoLeaf {
-    EncodedInfoLeaf()
-        : encoded_bytes(0),
-          encoded_timestamp(0),
-          payload_type(0),
-          send_even_if_empty(false),
-          speech(true) {}
-
-    size_t encoded_bytes;
-    uint32_t encoded_timestamp;
-    int payload_type;
-    bool send_even_if_empty;
-    bool speech;
+    size_t encoded_bytes = 0;
+    uint32_t encoded_timestamp = 0;
+    int payload_type = 0;
+    bool send_even_if_empty = false;
+    bool speech = true;
   };
 
   // This is the main struct for auxiliary encoding information. Each encoded
@@ -54,26 +47,9 @@ class AudioEncoder {
     std::vector<EncodedInfoLeaf> redundant;
   };
 
-  virtual ~AudioEncoder() {}
+  virtual ~AudioEncoder() = default;
 
-  // Accepts one 10 ms block of input audio (i.e., sample_rate_hz() / 100 *
-  // num_channels() samples). Multi-channel audio must be sample-interleaved.
-  // The encoder produces zero or more bytes of output in |encoded| and
-  // returns additional encoding information.
-  // The caller is responsible for making sure that |max_encoded_bytes| is
-  // not smaller than the number of bytes actually produced by the encoder.
-  EncodedInfo Encode(uint32_t rtp_timestamp,
-                     const int16_t* audio,
-                     size_t num_samples_per_channel,
-                     size_t max_encoded_bytes,
-                     uint8_t* encoded);
-
-  // Return the input sample rate in Hz and the number of input channels.
-  // These are constants set at instantiation time.
-  virtual int SampleRateHz() const = 0;
-  virtual int NumChannels() const = 0;
-
-  // Return the maximum number of bytes that can be produced by the encoder
+  // Returns the maximum number of bytes that can be produced by the encoder
   // at each Encode() call. The caller can use the return value to determine
   // the size of the buffer that needs to be allocated. This value is allowed
   // to depend on encoder parameters like bitrate, frame size etc., so if
@@ -81,8 +57,13 @@ class AudioEncoder {
   // that the buffer is large enough by calling MaxEncodedBytes() again.
   virtual size_t MaxEncodedBytes() const = 0;
 
-  // Returns the rate with which the RTP timestamps are updated. By default,
-  // this is the same as sample_rate_hz().
+  // Returns the input sample rate in Hz and the number of input channels.
+  // These are constants set at instantiation time.
+  virtual int SampleRateHz() const = 0;
+  virtual int NumChannels() const = 0;
+
+  // Returns the rate at which the RTP timestamps are updated. The default
+  // implementation returns SampleRateHz().
   virtual int RtpTimestampRateHz() const;
 
   // Returns the number of 10 ms frames the encoder will put in the next
@@ -101,52 +82,74 @@ class AudioEncoder {
   // provided.
   virtual int GetTargetBitrate() const = 0;
 
-  // Changes the target bitrate. The implementation is free to alter this value,
-  // e.g., if the desired value is outside the valid range.
-  virtual void SetTargetBitrate(int bits_per_second) {}
-
-  // Tells the implementation what the projected packet loss rate is. The rate
-  // is in the range [0.0, 1.0]. This rate is typically used to adjust channel
-  // coding efforts, such as FEC.
-  virtual void SetProjectedPacketLossRate(double fraction) {}
+  // Accepts one 10 ms block of input audio (i.e., SampleRateHz() / 100 *
+  // NumChannels() samples). Multi-channel audio must be sample-interleaved.
+  // The encoder produces zero or more bytes of output in |encoded| and
+  // returns additional encoding information.
+  // The caller is responsible for making sure that |max_encoded_bytes| is
+  // not smaller than the number of bytes actually produced by the encoder.
+  // Encode() checks some preconditions, calls EncodeInternal() which does the
+  // actual work, and then checks some postconditions.
+  EncodedInfo Encode(uint32_t rtp_timestamp,
+                     const int16_t* audio,
+                     size_t num_samples_per_channel,
+                     size_t max_encoded_bytes,
+                     uint8_t* encoded);
 
-  // This is the encode function that the inherited classes must implement. It
-  // is called from Encode in the base class.
   virtual EncodedInfo EncodeInternal(uint32_t rtp_timestamp,
                                      const int16_t* audio,
                                      size_t max_encoded_bytes,
                                      uint8_t* encoded) = 0;
-};
 
-class AudioEncoderMutable : public AudioEncoder {
- public:
-  enum Application { kApplicationSpeech, kApplicationAudio };
-
-  // Discards unprocessed audio data.
+  // Resets the encoder to its starting state, discarding any input that has
+  // been fed to the encoder but not yet emitted in a packet.
   virtual void Reset() = 0;
 
-  // Enables codec-internal FEC, if the implementation supports it.
-  virtual bool SetFec(bool enable) = 0;
-
-  // Enables or disables codec-internal VAD/DTX, if the implementation supports
-  // it.
-  virtual bool SetDtx(bool enable) = 0;
-
-  // Sets the application mode. The implementation is free to disregard this
-  // setting.
-  virtual bool SetApplication(Application application) = 0;
-
-  // Sets an upper limit on the payload size produced by the encoder. The
-  // implementation is free to disregard this setting.
-  virtual void SetMaxPayloadSize(int max_payload_size_bytes) = 0;
-
-  // Sets the maximum rate which the codec may not exceed for any packet.
-  virtual void SetMaxRate(int max_rate_bps) = 0;
-
-  // Informs the encoder about the maximum sample rate which the decoder will
-  // use when decoding the bitstream. The implementation is free to disregard
-  // this hint.
-  virtual bool SetMaxPlaybackRate(int frequency_hz) = 0;
+  // Enables or disables codec-internal FEC (forward error correction). Returns
+  // true if the codec was able to comply. The default implementation returns
+  // true when asked to disable FEC and false when asked to enable it (meaning
+  // that FEC isn't supported).
+  virtual bool SetFec(bool enable);
+
+  // Enables or disables codec-internal VAD/DTX. Returns true if the codec was
+  // able to comply. The default implementation returns true when asked to
+  // disable DTX and false when asked to enable it (meaning that DTX isn't
+  // supported).
+  virtual bool SetDtx(bool enable);
+
+  // Sets the application mode. Returns true if the codec was able to comply.
+  // The default implementation just returns false.
+  enum class Application { kSpeech, kAudio };
+  virtual bool SetApplication(Application application);
+
+  // Tells the encoder about the highest sample rate the decoder is expected to
+  // use when decoding the bitstream. The encoder would typically use this
+  // information to adjust the quality of the encoding. The default
+  // implementation just returns true.
+  // TODO(kwiberg): Change return value to void, since it doesn't matter
+  // whether the encoder approved of the max playback rate or not.
+  virtual bool SetMaxPlaybackRate(int frequency_hz);
+
+  // Tells the encoder what the projected packet loss rate is. The rate is in
+  // the range [0.0, 1.0]. The encoder would typically use this information to
+  // adjust channel coding efforts, such as FEC. The default implementation
+  // does nothing.
+  virtual void SetProjectedPacketLossRate(double fraction);
+
+  // Tells the encoder what average bitrate we'd like it to produce. The
+  // encoder is free to adjust or disregard the given bitrate (the default
+  // implementation does the latter).
+  virtual void SetTargetBitrate(int target_bps);
+
+  // Sets the maximum bitrate which must not be exceeded for any packet. The
+  // encoder is free to adjust or disregard this value (the default
+  // implementation does the latter).
+  virtual void SetMaxBitrate(int max_bps);
+
+  // Sets an upper limit on the size of packet payloads produced by the
+  // encoder. The encoder is free to adjust or disregard this value (the
+  // default implementation does the latter).
+  virtual void SetMaxPayloadSize(int max_payload_size_bytes);
 };
 }  // namespace webrtc
 #endif  // WEBRTC_MODULES_AUDIO_CODING_CODECS_AUDIO_ENCODER_H_