Android平台实现无纸化同屏并推送RTMP或轻量级RTSP服务(毫秒级延迟)

原创

音视频牛哥

修改于 2024-06-18 13:11:46

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文章被收录于专栏：RTSP/RTMP直播相关RTSP/RTMP直播相关

技术背景

在写这篇文章之前，实际上几年之前，我们就有非常稳定的无纸化同屏的模块，本文借demo更新，算是做个新的总结，废话不多说，先看图，本文以Android平台屏幕实时采集推送，Windows播放为例，和大家做个技术分享。

技术考量指标

本文以大牛直播SDK前些年实现的Android同屏采集推送为例，大概介绍下一些技术考量指标。

1. 轻量级RTSP服务还是RTMP？

我们在做无纸化同屏的时候，问的最多的是，能不能不要自建服务，直接主讲人或教师端，直接启动轻量级RTSP服务，其他终端拉流，如果是小并发，比如5人内的小范围的同屏，Windows平台走轻量级RTSP无可厚非，如果是30-60甚至100人的会议室，建议走RTMP。

2. 推送分辨率和码率选择

我们接触到好多设备，性能一般，但是屏幕是高分屏，甚至可以采集到4K的，考虑到实时编码和并发环境下，AP的承载能力，一般建议选择适合自己的分辨率码率即可，不要只追求高分辨率高码率，导致组网困难，单个或双通道AP压力大，一般建议控制在1920*1080分辨率内，码率控制在1-5M。

3. 软编码还是硬编码

Windows平台，一般优先考虑软编，因为大多Windows性能瓶颈不太大，超过1080P可以考虑硬编，Android平台建议直接硬编码。

4. 高分屏采集编码效率低怎么办

高分屏，不管是Windows还是Android，采集后的数据，建议先压缩，再编码，Windows平台我们可以设置压缩比例（scale rate），Android平台亦可，比如采集原始屏幕，或者缩放后的屏幕，具体见下图：

  /* BackgroudService.java
   * Author: daniusdk.com
   */ 
  private void createScreenEnvironment() {

        sreenWindowWidth = mWindowManager.getDefaultDisplay().getWidth();
        screenWindowHeight = mWindowManager.getDefaultDisplay().getHeight();

        Log.i(TAG, "screenWindowWidth: " + sreenWindowWidth + ",screenWindowHeight: "
                + screenWindowHeight);

        if (sreenWindowWidth > 800)
        {
            if (screen_resolution_type_ == SCREEN_RESOLUTION_STANDARD)
            {
                scale_rate = SCALE_RATE_HALF;
                sreenWindowWidth = align(sreenWindowWidth / 2, 16);
                screenWindowHeight = align(screenWindowHeight / 2, 16);
            }
            else if(screen_resolution_type_ == SCREEN_RESOLUTION_LOW)
            {
                scale_rate = SCALE_RATE_TWO_FIFTHS;
                sreenWindowWidth = align(sreenWindowWidth * 2 / 5, 16);
                screenWindowHeight = align(screenWindowHeight * 2 / 5, 16);
            }
        }

        Log.i(TAG, "After adjust mWindowWidth: " + sreenWindowWidth + ", mWindowHeight: " + screenWindowHeight);

        int pf = mWindowManager.getDefaultDisplay().getPixelFormat();
        Log.i(TAG, "display format:" + pf);

        DisplayMetrics displayMetrics = new DisplayMetrics();
        mWindowManager.getDefaultDisplay().getMetrics(displayMetrics);
        mScreenDensity = displayMetrics.densityDpi;

        mImageReader = ImageReader.newInstance(sreenWindowWidth,
                screenWindowHeight, 0x1, 6);

        mMediaProjectionManager = (MediaProjectionManager) getSystemService(Context.MEDIA_PROJECTION_SERVICE);
    }

5. Android横竖屏自动适配

Android平台，如果是pad采集，基本就是横屏采集，如果手机端，需要确保横竖屏模式下都可以正常采集。

4. 为什么要考虑补帧

Android的时候，一定的采集模式下，屏幕如果没有变化，不会一直有实时屏幕数据回调下来，这时候，为了保持帧率或数据采集的完整性，建议补帧。

5. 异常网络处理、事件回调机制

网络状态，不管是推送端，还是播放端，都是需要有实时的状态回调，确保客户端可以实时感知网络状态。

backgroudService.SetEventListener(new EventListener() {
                  @Override
                  public void onPublisherEventCallback(long handle, int id, long param1, long param2, String param3, String param4, Object param5) {
                      String publisher_event = "";

                      switch (id) {
                          case NTSmartEventID.EVENT_DANIULIVE_ERC_PUBLISHER_STARTED:
                              publisher_event = "开始..";
                              break;
                          case NTSmartEventID.EVENT_DANIULIVE_ERC_PUBLISHER_CONNECTING:
                              publisher_event = "连接中..";
                              break;
                          case NTSmartEventID.EVENT_DANIULIVE_ERC_PUBLISHER_CONNECTION_FAILED:
                              publisher_event = "连接失败..";
                              break;
                          case NTSmartEventID.EVENT_DANIULIVE_ERC_PUBLISHER_CONNECTED:
                              publisher_event = "连接成功..";
                              break;
                          case NTSmartEventID.EVENT_DANIULIVE_ERC_PUBLISHER_DISCONNECTED:
                              publisher_event = "连接断开..";
                              break;
                          case NTSmartEventID.EVENT_DANIULIVE_ERC_PUBLISHER_STOP:
                              publisher_event = "关闭..";
                              break;
                          case NTSmartEventID.EVENT_DANIULIVE_ERC_PUBLISHER_RECORDER_START_NEW_FILE:
                              publisher_event = "开始一个新的录像文件 : " + param3;
                              break;
                          case NTSmartEventID.EVENT_DANIULIVE_ERC_PUBLISHER_ONE_RECORDER_FILE_FINISHED:
                              publisher_event = "已生成一个录像文件 : " + param3;
                              break;

                          case NTSmartEventID.EVENT_DANIULIVE_ERC_PUBLISHER_SEND_DELAY:
                              publisher_event = "发送时延: " + param1 + " 帧数:" + param2;
                              break;

                          case NTSmartEventID.EVENT_DANIULIVE_ERC_PUBLISHER_CAPTURE_IMAGE:
                              publisher_event = "快照: " + param1 + " 路径：" + param3;

                              if (param1 == 0) {
                                  publisher_event = publisher_event + "截取快照成功..";
                              } else {
                                  publisher_event = publisher_event + "截取快照失败..";
                              }
                              break;
                          case NTSmartEventID.EVENT_DANIULIVE_ERC_PUBLISHER_RTSP_URL:
                              publisher_event = "RTSP服务URL: " + param3;
                              break;
                          case NTSmartEventID.EVENT_DANIULIVE_ERC_PUSH_RTSP_SERVER_RESPONSE_STATUS_CODE:
                              publisher_event = "RTSP status code received, codeID: " + param1 + ", RTSP URL: " + param3;
                              break;
                          case NTSmartEventID.EVENT_DANIULIVE_ERC_PUSH_RTSP_SERVER_NOT_SUPPORT:
                              publisher_event = "服务器不支持RTSP推送, 推送的RTSP URL: " + param3;
                              break;
                      }

                      String str = "当前状态：" + publisher_event;

                      Log.i(TAG, str);

                      if (handler_ != null) {
                          Message message = new Message();
                          message.what = PUBLISHER_EVENT_MSG;
                          message.obj = publisher_event;
                          handler_.sendMessage(message);
                      }
                  }
            });

6. 采集到的数据可以按需录像吗

可以，而且很有必要，同屏的时候，如果需要把开会或教授内容实时保存下来，可以随时启动录像。

    public boolean startRecorder()
    {
        Log.i(TAG, "onClick startRecorder..");

        if(!stream_publisher_.is_publishing())
        {
            startCaptureScreen();
        }

        if (layer_post_thread_ != null)
            layer_post_thread_.update_layers();

        if (stream_publisher_.is_recording()) {
            stopRecorder();
            return false;
        }

        InitAndSetConfig();

        ConfigRecorderParam();

        boolean start_ret = stream_publisher_.StartRecorder();
        if (!start_ret) {
            stream_publisher_.try_release();
            Log.e(TAG, "Failed to start recorder.");
            return false;
        }

        startAudioRecorder();
        startLayerPostThread();

        return true;
    }

    //停止录像
    public void stopRecorder() {
        stream_publisher_.StopRecorder();
        stream_publisher_.try_release();

        if (!stream_publisher_.is_publishing())
            stopAudioRecorder();
    }

7. 文字、图片水印

需要而且建议支持，比如实时时间、学校或公司logo等。

        //水印效果选择++++++++++
        watermarkSelctor = (Spinner) findViewById(R.id.watermarkSelctor);
        watermarkSelctor.setEnabled(false);
        final String[] watermarks = new String[]{"图片水印", "全部水印", "文字水印", "不加水印"};

        ArrayAdapter<String> adapterWatermark = new ArrayAdapter<String>(this,
                android.R.layout.simple_spinner_item, watermarks);

        adapterWatermark.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);

        watermarkSelctor.setAdapter(adapterWatermark);

        watermarkSelctor.setSelection(3,true);
        watemarkType = 3;   //默认不加水印

        watermarkSelctor.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {

            @Override
            public void onItemSelected(AdapterView<?> parent, View view,
                                       int position, long id) {

                watemarkType = position;

                Log.i(TAG, "[水印类型]Currently choosing: " + watermarks[position] + ", watemarkType: " + watemarkType);

                if(backgroudService !=null) {
                    backgroudService.updateWatermarker(watemarkType);
                }
            }

            @Override
            public void onNothingSelected(AdapterView<?> parent) {

            }
        });

8. 可以同时启动轻量级RTSP服务吗

    public boolean startRtspService(int port)
    {
        Log.i(TAG, "startRtspService++");

        rtsp_handle_ = lib_publisher_.OpenRtspServer(0);

        if (rtsp_handle_ == 0) {
            Log.e(TAG, "创建rtsp server实例失败! 请检查SDK有效性");
        } else {
            if (lib_publisher_.SetRtspServerPort(rtsp_handle_, port) != 0) {
                lib_publisher_.CloseRtspServer(rtsp_handle_);
                rtsp_handle_ = 0;
                Log.e(TAG, "创建rtsp server端口失败! 请检查端口是否重复或者端口不在范围内!");
            }

            if (lib_publisher_.StartRtspServer(rtsp_handle_, 0) == 0) {
                Log.i(TAG, "启动rtsp server 成功!");
            } else {
                lib_publisher_.CloseRtspServer(rtsp_handle_);
                rtsp_handle_ = 0;
                Log.e(TAG, "启动rtsp server失败! 请检查设置的端口是否被占用!");
            }

            isRTSPServiceRunning = true;
        }

        return true;
    }

    //停止RTSP服务
    public void stopRtspService() {
        Log.i(TAG, "stopRtspService++");
        if(!isRTSPServiceRunning)
        {
            return;
        }
        if (lib_publisher_ != null && rtsp_handle_ != 0) {
            lib_publisher_.StopRtspServer(rtsp_handle_);
            lib_publisher_.CloseRtspServer(rtsp_handle_);
            rtsp_handle_ = 0;
        }

        isRTSPServiceRunning = false;
    }

    public boolean startRtspPublisher(){
        Log.i(TAG, "startRtspPublisher++");

        if(!stream_publisher_.is_publishing())
        {
            startCaptureScreen();
        }

        InitAndSetConfig();

        String rtsp_stream_name = "stream1";
        stream_publisher_.SetRtspStreamName(rtsp_stream_name);
        stream_publisher_.ClearRtspStreamServer();

        stream_publisher_.AddRtspStreamServer(rtsp_handle_);

        if (!stream_publisher_.StartRtspStream()) {
            stream_publisher_.try_release();
            Log.e(TAG, "调用发布rtsp流接口失败!");
            return false;
        }

        startAudioRecorder();
        startLayerPostThread();

        return true;
    }

    //停止发布RTSP流
    public void stopRtspPublisher() {
        Log.i(TAG, "stopRtspPublisher++");
        stream_publisher_.StopRtspStream();
        stream_publisher_.try_release();

        if (!stream_publisher_.is_publishing())
            stopAudioRecorder();
    }

    public int getRtspSessionNumbers(){
        int session_numbers = 0;
        if (lib_publisher_ != null && rtsp_handle_ != 0) {
            session_numbers = lib_publisher_.GetRtspServerClientSessionNumbers(rtsp_handle_);
            Log.i(TAG, "GetRtspSessionNumbers: " + session_numbers);
        }

        return session_numbers;
    }