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：
/** * 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：
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：
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。
