tts_receiver.h

// Copyright (c) 2010 The Chromium OS Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
//
// Defined an interface to be implemented for passing as a callback
// to receive synthesized audio data from the TTS engine.

#include <stdint.h>
#include <cstring>

#ifndef SPEECH_CLIENT_SYNTHESIS_SERVICE_TTS_RECEIVER_H_
#define SPEECH_CLIENT_SYNTHESIS_SERVICE_TTS_RECEIVER_H_

namespace speech_synthesis {

enum tts_synth_status {
  TTS_SYNTH_DONE = 0,         // Only the LAST call to Receive() for a given
                              // synthesis should have status = TTS_SYNTH_DONE.
  TTS_SYNTH_PENDING = 1
};

enum tts_callback_status {
  TTS_CALLBACK_CONTINUE = 1,  // The normal case: continue if there's more data.
  TTS_CALLBACK_HALT = 0,      // Stop synthesis.  The engine should
                              // return TTS_SUCCESS from SynthesizeText().
  TTS_CALLBACK_ERROR = 2      // Stop synthesis due to error.  The engine should
                              // return TTS_FAILURE from SynthesizeText().
};

template <class DataElement>
class TtsGenericDataReceiver {
 public:
  virtual ~TtsGenericDataReceiver() {}
  // Note that 'data' may be null if num_data_elements is zero;
  // this is often used with status = TTS_SYNTH_DONE to signal
  // the end of data.
  // TODO(fergus): refactor this to remove the status parameter
  // and instead use a separate Done() method.
  virtual tts_callback_status Receive(int rate, int num_channels,
      const DataElement* data, int num_data_elements,
      tts_synth_status status) = 0;
};

// For raw audio (linear 16 bit encoding).
typedef TtsGenericDataReceiver<int16_t> TtsDataReceiver;

// For compressed audio (arbitrary encoding).
typedef TtsGenericDataReceiver<char> TtsEncodedDataReceiver;
}

#endif  // SPEECH_CLIENT_SYNTHESIS_SERVICE_TTS_RECEIVER_H_