Android平台GB28181设备接入，语音广播功能非常重要，本文要介绍的，不是语音广播的流程，语音广播流程，之前的blog也有非常详细的分享，感兴趣的可以参考官方规范书的交互流程：
语音广播这块，有开发者提出这样的诉求，如何适时调节语音广播的音量？
因为我们的语音广播，audio的播放，是基于我们RTMP、RTSP直播播放模块设计实现的，对应的接口如下：
代码语言：javascript复制 /**
* 设置播放音量
*
* @param handle: return value from SmartPlayerOpen()
*
* @param volume: 范围是[0, 100], 0是静音，100是最大音量, 默认是100
*
* @return {0} if successful
*/
public native int SmartPlayerSetAudioVolume(long handle, int volume);如果需要实时调节音量，只要加个音量调节的SeekBar即可：
代码语言：javascript复制 audioVolumeBar.setOnSeekBarChangeListener(new SeekBar.OnSeekBarChangeListener() {
@Override
public void onProgressChanged(SeekBar seekBar, int i, boolean b) {
}
@Override
public void onStartTrackingTouch(SeekBar seekBar) {
}
@Override
public void onStopTrackingTouch(SeekBar seekBar) {
curAudioVolume = seekBar.getProgress();
audioVolumeText.setText("当前音量: " curAudioVolume);
if(playerHandle != 0)
{
libPlayer.SmartPlayerSetAudioVolume(playerHandle, curAudioVolume);
}
}
});如果需要在启动播放的时候，给个默认的初始音量，可以在StartAudioPlay()的时候，设置即可：
代码语言：javascript复制 private boolean startAudioPlay() {
if (player_handle_ != 0 )
return false;
player_handle_ = lib_player_.SmartPlayerOpen(context_);
if (player_handle_ == 0)
return false;
lib_player_.SetSmartPlayerEventCallbackV2(player_handle_,new EventHandePlayerV2());
// 缓存大小可以调整
lib_player_.SmartPlayerSetBuffer(player_handle_, 0);
// lib_player_.SmartPlayerSetFastStartup(player_handle_, 0);
// set report download speed(默认2秒一次回调 用户可自行调整report间隔)
lib_player_.SmartPlayerSetReportDownloadSpeed(player_handle_, 1, 20);
lib_player_.SmartPlayerClearRtpReceivers(player_handle_);
lib_player_.SmartPlayerAddRtpReceiver(player_handle_, rtp_receiver_handle_);
lib_player_.SmartPlayerSetSurface(player_handle_, null);
// lib_player_.SmartPlayerSetRenderScaleMode(player_handle_, 1);
lib_player_.SmartPlayerSetAudioOutputType(player_handle_, 1);
lib_player_.SmartPlayerSetMute(player_handle_, 0);
lib_player_.SmartPlayerSetAudioVolume(player_handle_, 100);
lib_player_.SmartPlayerSetExternalAudioOutput(player_handle_, new PlayerExternalPCMOutput());
lib_player_.SmartPlayerSetUrl(player_handle_, "rtp://ntinternal/rtpreceiver/implemention0");
if (0 != lib_player_.SmartPlayerStartPlay(player_handle_)) {
lib_player_.SmartPlayerClose(player_handle_);
player_handle_ = 0;
Log.e(TAG, "start audio paly failed");
return false;
}
lib_player_.SmartPlayerSetAudioDataCallback(player_handle_, new PlayerAudioDataOutput());
lib_player_.SmartPlayerSetPullStreamAudioTranscodeAAC(player_handle_, 0);
if (0 ==lib_player_.SmartPlayerStartPullStream(player_handle_) ) {
// 启动定时器，长时间收不到音频数据，则停止播放，发送BYE
last_received_audio_data_time_.set(SystemClock.elapsedRealtime());
handler_.postDelayed(new AudioPlayerPCMTimer(player_handle_), AudioPlayerPCMTimer.INTERVAL_MS);
}
return true;
}如果需要静音，audio volume设置为0即可，以上是大概的接口设计和调用逻辑，感兴趣的开发者，可以自行尝试。
