背景

随着国产操作系统的推进，传统行业对Linux平台的呼声和需求越来越大，之前几年，我们发布了Linux平台运营商级的RTSP转RTMP推送模块、RTMP推送模块和RTSP、RTMP播放模块，前段时间，有开发者问我们，是不是可以在Linux平台实现轻量级RTSP服务，通过采集摄像头或者屏幕，在Linux平台实现类似于IPC的功能，便于第三方系统对接。

技术实现

轻量级RTSP服务实际上前几天我们在做Linux模块的时候，已经实现了，只是没有在demo上加这块，原因很简单，这块诉求一方面比较少，另一方面，我们windows、Android和iOS平台都有相关的接口和demo，接口调用基本类似。

废话不多说，上代码：

启动RTSP服务：

    bool StartRTSPService(NT_SmartPublisherSDKAPI* push_api){push_api->OpenRtspServer(&rtsp_server_handle_, 0);if (!rtsp_server_handle_){fprintf(stderr, "Create Rtsp Server failed..\n");return false;}else{int port = 18554;if (NT_ERC_OK != push_api->SetRtspServerPort(rtsp_server_handle_, port)){push_api->CloseRtspServer(rtsp_server_handle_);rtsp_server_handle_ = nullptr;fprintf(stderr, "Set Rtsp Server port failed, not in range..\n");return false;}//std::string user_name = "admin";//std::string password = "123456";//push_api->SetRtspServerUserNamePassword(rtsp_server_handle_, user_name.c_str(), password.c_str());//bool is_multicast = false;//push_api->SetRtspServerMulticast(rtsp_server_handle_, is_multicast ? 1 : 0);if (push_api->StartRtspServer(rtsp_server_handle_, 0) == 0) {fprintf(stdout, "Start Rtsp server succeed!\n");}else{push_api->CloseRtspServer(rtsp_server_handle_);rtsp_server_handle_ = nullptr;fprintf(stderr, "Start Rtsp server failed, please check if port in usage..");return false;}}return true;}

开始发布RTSP流：

    NT_HANDLE StartPush(NT_SmartPublisherSDKAPI* push_api, const std::string& rtmp_url, int dst_fps){NT_INT32 pulse_device_number = 0;if (NT_ERC_OK == push_api->GetAuidoInputDeviceNumber(2, &pulse_device_number)){fprintf(stdout, "Pulse device num:%d\n", pulse_device_number);char device_name[512];for (auto i = 0; i < pulse_device_number; ++i){if (NT_ERC_OK == push_api->GetAuidoInputDeviceName(2, i, device_name, 512)){fprintf(stdout, "index:%d name:%s\n", i, device_name);}}}NT_INT32 alsa_device_number = 0;if (pulse_device_number < 1){if (NT_ERC_OK == push_api->GetAuidoInputDeviceNumber(1, &alsa_device_number)){fprintf(stdout, "Alsa device num:%d\n", alsa_device_number);char device_name[512];for (auto i = 0; i < alsa_device_number; ++i){if (NT_ERC_OK == push_api->GetAuidoInputDeviceName(1, i, device_name, 512)){fprintf(stdout, "index:%d name:%s\n", i, device_name);}}}}NT_INT32 capture_speaker_flag = 0;if ( NT_ERC_OK == push_api->IsCanCaptureSpeaker(2, &capture_speaker_flag) ){if (capture_speaker_flag)fprintf(stdout, "Support speaker capture\n");elsefprintf(stdout, "UnSupport speaker capture\n");}NT_INT32 is_support_window_capture = 0;if (NT_ERC_OK == push_api->IsCaptureXWindowSupported(NULL, &is_support_window_capture)){if (is_support_window_capture)fprintf(stdout, "Support window capture\n");elsefprintf(stdout, "UnSupport window capture\n");}if (is_support_window_capture){NT_INT32 win_count = 0;if (NT_ERC_OK == push_api->UpdateCaptureXWindowList(NULL, &win_count) && win_count > 0 ){fprintf(stdout, "X Capture Winows list++\n");for (auto i = 0; i < win_count; ++i){NT_UINT64 wid;char title[512];if (NT_ERC_OK == push_api->GetCaptureXWindowInfo(i, &wid, title, sizeof(title) / sizeof(char))){x_win_list.push_back(wid);fprintf(stdout, "wid:%llu, title:%s\n", wid, title);}}fprintf(stdout, "X Capture Winows list--\n");}}std::vector<CameraInfo> cameras;GetCameraInfo(push_api, cameras);if (!cameras.empty()){fprintf(stdout, "cameras count:%d\n", (int)cameras.size());for (const auto& c : cameras){fprintf(stdout, "camera name:%s, id:%s, cap_num:%d\n", c.name_.c_str(), c.id_.c_str(), (int)c.capabilities_.size());for (const auto& i : c.capabilities_){fprintf(stdout, "cap w:%d, h:%d, fps:%d\n", i.width_, i.height_, i.max_frame_rate_);}}}NT_UINT32 auido_option = NT_PB_E_AUDIO_OPTION_NO_AUDIO;if (pulse_device_number > 0 || alsa_device_number > 0){auido_option = NT_PB_E_AUDIO_OPTION_CAPTURE_MIC;}else if (capture_speaker_flag){auido_option = NT_PB_E_AUDIO_OPTION_CAPTURE_SPEAKER;}//auido_option = NT_PB_E_AUDIO_OPTION_CAPTURE_MIC_SPEAKER_MIXER;NT_UINT32 video_option = NT_PB_E_VIDEO_OPTION_SCREEN;if (!cameras.empty()){video_option = NT_PB_E_VIDEO_OPTION_CAMERA;}else if (is_support_window_capture){video_option = NT_PB_E_VIDEO_OPTION_WINDOW;}// video_option = NT_PB_E_VIDEO_OPTION_LAYER;//video_option = NT_PB_E_VIDEO_OPTION_NO_VIDEO;NT_HANDLE push_handle = nullptr;//if (NT_ERC_OK != push_api->Open(&push_handle, NT_PB_E_VIDEO_OPTION_LAYER, NT_PB_E_AUDIO_OPTION_CAPTURE_SPEAKER, 0, NULL))if (NT_ERC_OK != push_api->Open(&push_handle, video_option, auido_option, 0, NULL)){return nullptr;}push_api->SetEventCallBack(push_handle, nullptr, OnSDKEventHandle);//push_api->SetXDisplayName(push_handle, ":0");//push_api->SetXDisplayName(push_handle, NULL);// 视频层配置方式if (NT_PB_E_VIDEO_OPTION_LAYER == video_option){std::vector<std::shared_ptr<nt_pb_sdk::layer_conf_wrapper_base> > layer_confs;auto index = 0;第0层填充RGBA矩形, 目的是保证帧率, 颜色就填充全黑auto rgba_layer_c0 = std::make_shared<nt_pb_sdk::RGBARectangleLayerConfigWrapper>(index++, true, 0, 0, 1280, 720);rgba_layer_c0->conf_.red_ = 200;rgba_layer_c0->conf_.green_ = 200;rgba_layer_c0->conf_.blue_ = 200;rgba_layer_c0->conf_.alpha_ = 255;layer_confs.push_back(rgba_layer_c0);// 第一层为桌面层//auto screen_layer_c1 = std::make_shared<nt_pb_sdk::ScreenLayerConfigWrapper>(index++, true, 0, 0, 1280, 720);//screen_layer_c1->conf_.scale_filter_mode_ = 3;//layer_confs.push_back(screen_layer_c1);第一层为窗口if (!x_win_list.empty()){auto window_layer_c1 = std::make_shared<nt_pb_sdk::WindowLayerConfigWrapper>(index++, true, 0, 0, 640, 360);window_layer_c1->conf_.xwindow_ = x_win_list.back();layer_confs.push_back(window_layer_c1);}摄像头层if (!cameras.empty()){auto camera_layer_c1 = std::make_shared<nt_pb_sdk::CameraLayerConfigWrapper>(index++, true,640, 0, 640, 360);strcpy(camera_layer_c1->conf_.device_unique_id_, cameras.front().id_.c_str());camera_layer_c1->conf_.is_flip_horizontal_ = 0;camera_layer_c1->conf_.is_flip_vertical_ = 0;camera_layer_c1->conf_.rotate_degress_ = 0;layer_confs.push_back(camera_layer_c1);if (cameras.size() > 1){auto camera_layer_c2 = std::make_shared<nt_pb_sdk::CameraLayerConfigWrapper>(index++, true,640, 0, 320, 240);strcpy(camera_layer_c2->conf_.device_unique_id_, cameras.back().id_.c_str());camera_layer_c2->conf_.is_flip_horizontal_ = 0;camera_layer_c2->conf_.is_flip_vertical_ = 0;camera_layer_c2->conf_.rotate_degress_ = 0;layer_confs.push_back(camera_layer_c2);}}auto image_layer1 = std::make_shared<nt_pb_sdk::ImageLayerConfigWrapper>(index++, true, 650, 120, 324, 300);strcpy(image_layer1->conf_.file_name_utf8_, "./testpng/tca.png");layer_confs.push_back(image_layer1);auto image_layer2 = std::make_shared<nt_pb_sdk::ImageLayerConfigWrapper>(index++, true, 120, 380, 182, 138);strcpy(image_layer2->conf_.file_name_utf8_, "./testpng/t4.png");layer_confs.push_back(image_layer2);std::vector<const NT_PB_LayerBaseConfig* > layer_base_confs;for (const auto& i : layer_confs){layer_base_confs.push_back(i->getBase());}if (NT_ERC_OK != push_api->SetLayersConfig(push_handle, 0, layer_base_confs.data(),layer_base_confs.size(), 0, nullptr)){push_api->Close(push_handle);push_handle = nullptr;return nullptr;}}// push_api->SetScreenClip(push_handle, 0, 0, 1280, 720);if (video_option == NT_PB_E_VIDEO_OPTION_CAMERA){if (!cameras.empty()){push_api->SetVideoCaptureDeviceBaseParameter(push_handle, cameras.front().id_.c_str(),640, 480);//push_api->FlipVerticalCamera(push_handle, 1);//push_api->FlipHorizontalCamera(push_handle, 1);//push_api->RotateCamera(push_handle, 0);}}if (video_option == NT_PB_E_VIDEO_OPTION_WINDOW){if (!x_win_list.empty()){//push_api->SetCaptureXWindow(push_handle, x_win_list[0]);push_api->SetCaptureXWindow(push_handle, x_win_list.back());}}push_api->SetFrameRate(push_handle, dst_fps); // 帧率设置push_api->SetVideoEncoder(push_handle, 0, 1, NT_MEDIA_CODEC_ID_H264, 0);push_api->SetVideoBitRate(push_handle, 2000);  // 平均码率2000kbpspush_api->SetVideoQuality(push_handle, 26); push_api->SetVideoMaxBitRate(push_handle, 4000); // 最大码率4000kbps// openh264 配置特定参数push_api->SetVideoEncoderSpecialInt32Option(push_handle, "usage_type", 0); //0是摄像头编码, 1是屏幕编码push_api->SetVideoEncoderSpecialInt32Option(push_handle, "rc_mode", 1); // 0是质量模式, 1是码率模式push_api->SetVideoEncoderSpecialInt32Option(push_handle, "enable_frame_skip", 0); // 0是关闭跳帧, 1是打开跳帧push_api->SetVideoKeyFrameInterval(push_handle, dst_fps*2); // 关键帧间隔push_api->SetVideoEncoderProfile(push_handle, 3); // H264 highpush_api->SetVideoEncoderSpeed(push_handle, 3); // 编码速度设置到3if (pulse_device_number > 0){push_api->SetAudioInputLayer(push_handle, 2);push_api->SetAuidoInputDeviceId(push_handle, 0);}else if (alsa_device_number > 0){push_api->SetAudioInputLayer(push_handle, 1);push_api->SetAuidoInputDeviceId(push_handle, 0);}push_api->SetEchoCancellation(push_handle, 1, 0);push_api->SetNoiseSuppression(push_handle, 1);push_api->SetAGC(push_handle, 1);push_api->SetVAD(push_handle, 1);push_api->SetInputAudioVolume(push_handle, 0, 1.0);push_api->SetInputAudioVolume(push_handle, 1, 0.2);// 音频配置push_api->SetPublisherAudioCodecType(push_handle, 1);//push_api->SetMute(push_handle, 1);if ( NT_ERC_OK != push_api->SetURL(push_handle, rtmp_url.c_str(), NULL) ){push_api->Close(push_handle);push_handle = nullptr;return nullptr;}//启动轻量级RTSP服务bool is_rtsp_service_started = StartRTSPService(push_api);if (is_rtsp_service_started){if (!rtsp_server_handle_){fprintf(stderr, "StartRtspStream rtsp server handle is null..");return nullptr;}std::string rtsp_stream_name = "stream1";push_api->SetRtspStreamName(push_handle, rtsp_stream_name.c_str());push_api->ClearRtspStreamServer(push_handle);push_api->AddRtspStreamServer(push_handle, rtsp_server_handle_, 0);if (NT_ERC_OK != push_api->StartRtspStream(push_handle, 0)){push_api->Close(push_handle);push_handle = nullptr;return nullptr;}fprintf(stdout, "StartRtspStream succeed..\n");}return push_handle;}
}

main函数调用如下：

/** Author: daniusdk.com
*/
int main(int argc, char *argv[])
{//signal(SIGINT, &OnSigIntHandler);//signal(SIGFPE, &OnSigIntHandler);struct sigaction act;sigemptyset(&act.sa_mask);act.sa_sigaction = OnSaSigaction;act.sa_flags = SA_SIGINFO;sigaction(SIGINT, &act, NULL);sigaction(SIGFPE, &act, NULL);XInitThreads(); // X支持多线程, 必须调用auto display = XOpenDisplay(nullptr);if (!display){fprintf(stderr, "Cannot connect to X server\n");return 0;}auto screen = DefaultScreen(display);auto root = XRootWindow(display, screen);XWindowAttributes root_win_att;if (!XGetWindowAttributes(display, root, &root_win_att)){fprintf(stderr, "Get Root window attri failed\n");XCloseDisplay(display);return 0;}int main_w = root_win_att.width / 2, main_h = root_win_att.height / 2;auto black_pixel = BlackPixel(display, screen);auto white_pixel = WhitePixel(display, screen);auto main_wid = XCreateSimpleWindow(display, root, 0, 0, main_w, main_h, 0, white_pixel, black_pixel);if (!main_wid){fprintf(stderr, "Cannot Create Main Window\n");XCloseDisplay(display);return 0;}XSelectInput(display, main_wid, StructureNotifyMask | KeyPressMask);auto sub_wid = CreateSubWindow(display, screen, main_wid);if (!sub_wid){fprintf(stderr, "Cannot Create Render Window\n");XDestroyWindow(display, main_wid);XCloseDisplay(display);return 0;}XMapWindow(display, main_wid);XStoreName(display, main_wid, "Video Preview");XMapWindow(display, sub_wid);LogInit();NT_SmartPublisherSDKAPI push_api;if (!PushSDKInit(push_api)){XDestroyWindow(display, sub_wid);XDestroyWindow(display, main_wid);XCloseDisplay(display);return 0;}auto push_handle = StartPush(&push_api, "rtmp://192.168.0.103:1935/hls/test1", 30);if (!push_handle){fprintf(stderr, "start push failed.\n");XDestroyWindow(display, sub_wid);XDestroyWindow(display, main_wid);XCloseDisplay(display);push_api.UnInit();return 0;}// 开启预览，也可以不开启, 根据需求来push_api.SetPreviewXWindow(push_handle, "", sub_wid);push_api.StartPreview(push_handle, 0, nullptr);// auto push_handle1 = StartPush(&push_api, "rtmp://192.168.0.154:1935/live/test1", 30);while (!g_is_exit){while (MY_X11_Pending(display, 10)){XEvent xev;memset(&xev, 0, sizeof(xev));XNextEvent(display, &xev);if (xev.type == ConfigureNotify){if (xev.xconfigure.window == main_wid){if (xev.xconfigure.width != main_w || xev.xconfigure.height != main_h){main_w = xev.xconfigure.width;main_h = xev.xconfigure.height;XMoveResizeWindow(display, sub_wid, 0, 0, main_w - 4, main_h - 4);}}}else if (xev.type == KeyPress){if (xev.xkey.keycode == XKeysymToKeycode(display, XK_Escape)){fprintf(stdout, "ESC Key Press\n");g_is_exit = true;}}if (g_is_exit)break;}}fprintf(stdout, "Skip run loop, is_exit:%d\n", g_is_exit);push_api.StopPreview(push_handle);push_api.StopRtspStream(push_handle);push_api.StopRtspServer(rtsp_server_handle_);push_api.CloseRtspServer(rtsp_server_handle_);rtsp_server_handle_ = nullptr;push_api.Close(push_handle);push_handle = nullptr;XDestroyWindow(display, sub_wid);XDestroyWindow(display, main_wid);XCloseDisplay(display);push_api.UnInit();fprintf(stdout, "SDK UnInit..\n");return 0;
}

音视频选项，可设置的类型如下：

/*定义Video源选项*/
typedef enum _NT_PB_E_VIDEO_OPTION
{NT_PB_E_VIDEO_OPTION_NO_VIDEO = 0x0,NT_PB_E_VIDEO_OPTION_SCREEN   = 0x1, // 采集屏幕NT_PB_E_VIDEO_OPTION_CAMERA      = 0x2, // 摄像头采集NT_PB_E_VIDEO_OPTION_LAYER    = 0x3, // 视频合并，比如桌面叠加摄像头等NT_PB_E_VIDEO_OPTION_ENCODED_DATA = 0x4, // 已经编码的视频数据，目前支持H264NT_PB_E_VIDEO_OPTION_WINDOW   = 0x5, // 采集窗口
} NT_PB_E_VIDEO_OPTION;/*定义Auido源选项*/
typedef enum _NT_PB_E_AUDIO_OPTION
{NT_PB_E_AUDIO_OPTION_NO_AUDIO                    = 0x0,NT_PB_E_AUDIO_OPTION_CAPTURE_MIC                = 0x1, // 采集麦克风音频NT_PB_E_AUDIO_OPTION_CAPTURE_SPEAKER            = 0x2, // 采集扬声器NT_PB_E_AUDIO_OPTION_CAPTURE_MIC_SPEAKER_MIXER    = 0x3, // 麦克风扬声器混音NT_PB_E_AUDIO_OPTION_ENCODED_DATA                = 0x4, // 编码后的音频数据，目前支持AAC, speex宽带(wideband mode)NT_PB_E_AUDIO_OPTION_EXTERNAL_PCM_DATA            = 0x5, /*外部PCM数据*/NT_PB_E_AUDIO_OPTION_MIC_EXTERNAL_PCM_MIXER     = 0x6, /* 麦克风和外部PCM数据混音 当前只支持一路外部音频和内置麦克风混音*/NT_PB_E_AUDIO_OPTION_TWO_EXTERNAL_PCM_MIXER     = 0x7, /* 两路外部PCM数据混音*/
} NT_PB_E_AUDIO_OPTION;

调用流程和Windows平台轻量级RTSP服务基本一致（实际上接口本身几无差别）。

总结

Linux平台轻量级RTSP服务，对我们来说，轻车熟路了，主要是demo展示这块，整体编码性能和延迟，配合我们的RTSP播放器测试下来，几百毫秒，可完全满足无纸化同屏、教育类等传统行业技术诉求。