chromecast/media/cma/decoder/cast_audio_decoder.h

// Copyright 2015 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 CHROMECAST_MEDIA_CMA_DECODER_CAST_AUDIO_DECODER_H_
#define CHROMECAST_MEDIA_CMA_DECODER_CAST_AUDIO_DECODER_H_

#include <memory>

#include "base/callback.h"
#include "base/memory/ref_counted.h"
#include "media/base/channel_layout.h"

namespace base {
class SingleThreadTaskRunner;
}  // namespace base

namespace chromecast {
namespace media {
struct AudioConfig;
class DecoderBufferBase;

// Audio decoder interface.
class CastAudioDecoder {
 public:
  enum Status {
    kDecodeOk,
    kDecodeError,
  };

  enum OutputFormat {
    kOutputSigned16,     // Output signed 16-bit interleaved samples.
    kOutputPlanarFloat,  // Output planar float samples.
  };

  // The callback that is called when the decoder initialization is complete.
  // |success| is true if initialization was successful; if |success| is false
  // then the CastAudioDecoder instance is unusable and should be destroyed.
  typedef base::OnceCallback<void(bool success)> InitializedCallback;

  // Callback called when a buffer has been decoded. |config| is the actual
  // config of the buffer, which may differ from the config indicated the the
  // wrapper format.
  typedef base::OnceCallback<void(
      Status status,
      const AudioConfig& config,
      scoped_refptr<media::DecoderBufferBase> decoded)>
      DecodeCallback;

  // Creates a CastAudioDecoder instance for the given |config|. Decoding must
  // occur on the same thread as |task_runner|. Returns an empty unique_ptr if
  // the decoder could not be created. |initialized_callback| will be called
  // once initialization completes (either successfully, or if it failed).
  // The callback will not be called after the CastAudioDecoder instance is
  // destroyed.
  static std::unique_ptr<CastAudioDecoder> Create(
      scoped_refptr<base::SingleThreadTaskRunner> task_runner,
      const media::AudioConfig& config,
      OutputFormat output_format,
      ::media::ChannelLayout output_channel_layout,
      InitializedCallback initialized_callback);

  // Given a CastAudioDecoder::OutputFormat, return the size of each sample in
  // that OutputFormat in bytes.
  static int OutputFormatSizeInBytes(CastAudioDecoder::OutputFormat format);

  // Get output channel layout to be used by CastAudioDecoder from |config|.
  static ::media::ChannelLayout OutputChannelLayoutFromConfig(
      const AudioConfig& config);

  virtual ~CastAudioDecoder() = default;

  // Converts encoded data to the |output_format|. Must be called on the same
  // thread as |task_runner|. Decoded data will be passed to |decode_callback|.
  // It is OK to call Decode before the |initialized_callback| has been called;
  // those buffers will be queued until initialization completes, at which point
  // they will be decoded in order (if initialization was successful), or
  // ignored if initialization failed. The |decode_callback| will not be called
  // after the CastAudioDecoder instance is destroyed.
  // It is OK to pass an end-of-stream DecoderBuffer as |data|.
  virtual void Decode(scoped_refptr<media::DecoderBufferBase> data,
                      DecodeCallback decode_callback) = 0;
};

}  // namespace media
}  // namespace chromecast

#endif  // CHROMECAST_MEDIA_CMA_DECODER_CAST_AUDIO_DECODER_H_