webrtc 讀寫文件操作4------- 錄音播放文件

1、接口函數：兩個函數的主要區別 主要是寫流還是寫文件。

其他參數：採用的編解碼個格式。

 int StartRecordingPlayout(int channel,
                            const char* fileNameUTF8,
                            CodecInst* compression = NULL,
                            int maxSizeBytes = -1) override;

  int StartRecordingPlayout(int channel,
                            OutStream* stream,
                            CodecInst* compression = NULL) override;

2、channel 值如果爲-1，就在output_mixer 層錄音混音後的音頻，如果channel 爲其他值在錄音對應通道的音頻

int VoEFileImpl::StartRecordingPlayout(int channel,
                                       const char* fileNameUTF8,
                                       CodecInst* compression,
                                       int maxSizeBytes) {
  WEBRTC_TRACE(kTraceApiCall, kTraceVoice, VoEId(_shared->instance_id(), -1),
               "StartRecordingPlayout(channel=%d, fileNameUTF8=%s, "
               "compression, maxSizeBytes=%d)",
               channel, fileNameUTF8, maxSizeBytes);
  static_assert(1024 == FileWrapper::kMaxFileNameSize, "");

  if (!_shared->statistics().Initialized()) {
    _shared->SetLastError(VE_NOT_INITED, kTraceError);
    return -1;
  }
  if (channel == -1) {
    return _shared->output_mixer()->StartRecordingPlayout(fileNameUTF8,
                                                          compression);
  } else {
    // Add file after demultiplexing <=> affects one channel only
    voe::ChannelOwner ch = _shared->channel_manager().GetChannel(channel);
    voe::Channel* channelPtr = ch.channel();
    if (channelPtr == NULL) {
      _shared->SetLastError(VE_CHANNEL_NOT_VALID, kTraceError,
                            "StartRecordingPlayout() failed to locate channel");
      return -1;
    }
    return channelPtr->StartRecordingPlayout(fileNameUTF8, compression);
  }
}

3、創建fileplayer 類型進行編碼以及寫文件

int Channel::StartRecordingPlayout(const char* fileName,
                                   const CodecInst* codecInst) {
  WEBRTC_TRACE(kTraceInfo, kTraceVoice, VoEId(_instanceId, _channelId),
               "Channel::StartRecordingPlayout(fileName=%s)", fileName);

  if (_outputFileRecording) {
    WEBRTC_TRACE(kTraceWarning, kTraceVoice, VoEId(_instanceId, -1),
                 "StartRecordingPlayout() is already recording");
    return 0;
  }

  FileFormats format;
  const uint32_t notificationTime(0);  // Not supported in VoE
  CodecInst dummyCodec = {100, "L16", 16000, 320, 1, 320000};

  if ((codecInst != NULL) &&
      ((codecInst->channels < 1) || (codecInst->channels > 2))) {
    _engineStatisticsPtr->SetLastError(
        VE_BAD_ARGUMENT, kTraceError,
        "StartRecordingPlayout() invalid compression");
    return (-1);
  }
  if (codecInst == NULL) {
    format = kFileFormatPcm16kHzFile;
    codecInst = &dummyCodec;
  } else if ((STR_CASE_CMP(codecInst->plname, "L16") == 0) ||
             (STR_CASE_CMP(codecInst->plname, "PCMU") == 0) ||
             (STR_CASE_CMP(codecInst->plname, "PCMA") == 0)) {
    format = kFileFormatWavFile;
  } else {
    format = kFileFormatCompressedFile;
  }

  rtc::CritScope cs(&_fileCritSect);

  // Destroy the old instance
  if (output_file_recorder_) {
    output_file_recorder_->RegisterModuleFileCallback(NULL);
    output_file_recorder_.reset();
  }

  output_file_recorder_ = FileRecorder::CreateFileRecorder(
      _outputFileRecorderId, (const FileFormats)format);
  if (!output_file_recorder_) {
    _engineStatisticsPtr->SetLastError(
        VE_INVALID_ARGUMENT, kTraceError,
        "StartRecordingPlayout() fileRecorder format isnot correct");
    return -1;
  }

  if (output_file_recorder_->StartRecordingAudioFile(
          fileName, (const CodecInst&)*codecInst, notificationTime) != 0) {
    _engineStatisticsPtr->SetLastError(
        VE_BAD_FILE, kTraceError,
        "StartRecordingAudioFile() failed to start file recording");
    output_file_recorder_->StopRecording();
    output_file_recorder_.reset();
    return -1;
  }
  output_file_recorder_->RegisterModuleFileCallback(this);
  _outputFileRecording = true;

  return 0;
}