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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。
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。
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。
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。
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。
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。
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。
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);
- }
- }
- });
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();
- }
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) {
-
- }
- });
- 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;
- }
9. 同屏延迟,能不能做到毫秒级
废话不多说,上视频,延迟毫秒级。
安卓采集屏幕至轻量级RTSP服务|推送RTMP整体毫秒级延迟
Windows不在话下,Android平台需要高版本支持,高版本是可以采集到扬声器数据的,我们也实现了相关的demo,可以同时采集麦克风和扬声器的audio,单独推送或者同时混音输出。
当然可以,我们同屏采集端,支持采集编码png或jpg格式输出。
其实一个好的无纸化同屏系统,需要考虑的有整体组网、分辨率、码率、实时延迟、音视频同步和连续性等各个指标,做容易,做好难,上述抛砖引玉,未能面面俱到,感兴趣的开发者,可以跟我单独交流。
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