Add opus audio codec support in remoting

remoting/codec/audio_encoder_opus.h

+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef REMOTING_CODEC_AUDIO_ENCODER_OPUS_H_
+#define REMOTING_CODEC_AUDIO_ENCODER_OPUS_H_
+
+#include "remoting/codec/audio_encoder.h"
+
+#include "remoting/proto/audio.pb.h"
+
+struct OpusEncoder;
+
+namespace media {
+class AudioBus;
+class MultiChannelResampler;
+}  // namespace media
+
+namespace remoting {
+
+class AudioPacket;
+
+class AudioEncoderOpus : public AudioEncoder {
+ public:
+  AudioEncoderOpus();
+  virtual ~AudioEncoderOpus();
+
+  // AudioEncoder interface.
+  virtual scoped_ptr<AudioPacket> Encode(
+      scoped_ptr<AudioPacket> packet) OVERRIDE;
+
+ private:
+  void InitEncoder();
+  void DestroyEncoder();
+  bool ResetForPacket(AudioPacket* packet);
+
+  void ResamplerRead(media::AudioBus* audio_bus);
+
+  int sampling_rate_;
+  AudioPacket::Channels channels_;
+  OpusEncoder* encoder_;
+
+  int frame_size_;
+  scoped_ptr<media::MultiChannelResampler> resampler_;
+  scoped_array<char> resample_buffer_;
+
+  // Used to pass packet to the ResamplerRead() callback.
+  const char* resampling_data_;
+  int resampling_data_size_;
+  int resampling_data_pos_;
+
+  // Left-over unencoded samples from the previous AudioPacket.
+  scoped_array<int16> leftover_buffer_;

[Wez, 2012/10/19 01:51:32]

nit: Rather than a separate |leftover_buffer_|, why not store the partially-read
AudioPacket here, with an indication of how far into it we've read so far, and
avoid the extra copying?

[Sergey Ulanov, 2012/10/19 20:54:30]

We need to handle the case when we receive a sequence of small packets, so
storing just one AudioPacket may not be enough and we will need to copy some
data anyway to handle this case. Having just one buffer simplifies
implementation.

+  int leftover_buffer_size_;
+  int leftover_samples_;
+
+  DISALLOW_COPY_AND_ASSIGN(AudioEncoderOpus);
+};
+
+}  // namespace remoting
+
+#endif  // REMOTING_CODEC_AUDIO_ENCODER_OPUS_H_