录制按钮

界面文件：

 

 主界面:OBSBasic.ui  中开始录制按钮的objectName 是   recordButton

槽函数：

void OBSBasic::on_recordButton_clicked()
{//1 输出模式是否被激活if (outputHandler->RecordingActive()) {bool confirm = config_get_bool(GetGlobalConfig(), "BasicWindow","WarnBeforeStoppingRecord");if (confirm && isVisible()) {QMessageBox::StandardButton button =OBSMessageBox::question(this, QTStr("ConfirmStopRecord.Title"),QTStr("ConfirmStopRecord.Text"),QMessageBox::Yes | QMessageBox::No,QMessageBox::No);if (button == QMessageBox::No) {ui->recordButton->setChecked(true);return;}}StopRecording();} else {if (!UIValidation::NoSourcesConfirmation(this)) {ui->recordButton->setChecked(false);return;}// 执行StartRecording();}
}

 调用堆栈：

 开始录制

void OBSBasic::StartRecording()
{if (outputHandler->RecordingActive())return;if (disableOutputsRef)return;// 1 检查磁盘是否有效if (!OutputPathValid()) {OutputPathInvalidMessage();ui->recordButton->setChecked(false);return;}//2 检查磁盘空间if (LowDiskSpace()) {DiskSpaceMessage();ui->recordButton->setChecked(false);return;}if (api)api->on_event(OBS_FRONTEND_EVENT_RECORDING_STARTING);SaveProject();//3 开始录制 if (!outputHandler->StartRecording())ui->recordButton->setChecked(false);
}// 简单输出
bool SimpleOutput::StartRecording()
{UpdateRecording();if (!ConfigureRecording(false))return false;if (!obs_output_start(fileOutput)) {QString error_reason;const char *error = obs_output_get_last_error(fileOutput);if (error)error_reason = QT_UTF8(error);elseerror_reason = QTStr("Output.StartFailedGeneric");QMessageBox::critical(main,QTStr("Output.StartRecordingFailed"),error_reason);return false;}return true;
}

调用libobs 

E:\opensrc\obs_src_19041\obs-studio-19141\obs-studio\libobs\obs-output.c

bool obs_output_start(obs_output_t *output)
{bool encoded;bool has_service;if (!obs_output_valid(output, "obs_output_start"))return false;if (!output->context.data)return false;has_service = (output->info.flags & OBS_OUTPUT_SERVICE) != 0;if (has_service && !obs_service_initialize(output->service, output))return false;encoded = (output->info.flags & OBS_OUTPUT_ENCODED) != 0;if (encoded && output->delay_sec) {return obs_output_delay_start(output);} else {if (obs_output_actual_start(output)) {do_output_signal(output, "starting");return true;}return false;}
}

停止录制：

void SimpleOutput::StopRecording(bool force)
{if (force)obs_output_force_stop(fileOutput);elseobs_output_stop(fileOutput);
}

调用的都是libobs.dll的导出 导出方法   obs.h中声明

/** Starts the output. */
EXPORT bool obs_output_start(obs_output_t *output);/** Stops the output. */
EXPORT void obs_output_stop(obs_output_t *output);

obs输出模式

高級输出

 

bool AdvancedOutput::StartRecording()
{const char *path;const char *recFormat;const char *filenameFormat;bool noSpace = false;bool overwriteIfExists = false;if (!useStreamEncoder) {if (!ffmpegOutput) {UpdateRecordingSettings();}} else if (!obs_output_active(streamOutput)) {UpdateStreamSettings();}UpdateAudioSettings();// 1 设置输出，ffmpeg 输出 or 录制输出if (!Active())SetupOutputs();//2 配置if (!ffmpegOutput || ffmpegRecording) {path = config_get_string(main->Config(), "AdvOut",ffmpegRecording ? "FFFilePath": "RecFilePath");recFormat = config_get_string(main->Config(), "AdvOut",ffmpegRecording ? "FFExtension": "RecFormat");filenameFormat = config_get_string(main->Config(), "Output","FilenameFormatting");overwriteIfExists = config_get_bool(main->Config(), "Output","OverwriteIfExists");noSpace = config_get_bool(main->Config(), "AdvOut",ffmpegRecording? "FFFileNameWithoutSpace": "RecFileNameWithoutSpace");string strPath = GetRecordingFilename(path, recFormat, noSpace,overwriteIfExists,filenameFormat,ffmpegRecording);obs_data_t *settings = obs_data_create();obs_data_set_string(settings, ffmpegRecording ? "url" : "path",strPath.c_str());obs_output_update(fileOutput, settings);obs_data_release(settings);}//3 startif (!obs_output_start(fileOutput)) {QString error_reason;const char *error = obs_output_get_last_error(fileOutput);if (error)error_reason = QT_UTF8(error);elseerror_reason = QTStr("Output.StartFailedGeneric");QMessageBox::critical(main,QTStr("Output.StartRecordingFailed"),error_reason);return false;}return true;
}

录制

 

 为什么不使用ffmepeg命令行录制

•  1 录制窗口鼠标闪烁
• 2 无法处理屏幕分辨率非100%时的区域的录制不全
• 3 热插拔时，无法更改采集源
• 4 无法录制DirectUi窗口（无窗口句柄）

FFmpeg

Builds - CODEX FFMPEG @ gyan.dev

 链接：https://pan.baidu.com/s/1owwUbNEUzXQMARaOlfRH3w?pwd=yy3j 
提取码：yy3j

OBS采集模块

• 显示器采集：core中的 libobs-d3d11和 libos-winrt  以及    duplicator-monitor-capture.c
• 窗口采集：win-capture      window-capture.c
•  游戏采集：game-capture.c
• 采集卡采集：decklink
• 摄像头采集：win-dshow

窗口采集方式

 

BitBlt的采集效率比较低，且只能采集一些有窗口句柄的窗口，无窗口句柄得用WGC。例如谷歌浏览器，VSCode 等都是无句柄窗口，这些窗口用BitBlt采集，显示都是黑色的

 

 E:\opensrc\obs_src_19041\obs-studio-19141\obs-studio\plugins\win-capture\window-capture.c

enum window_capture_method {METHOD_AUTO,METHOD_BITBLT,METHOD_WGC,
};

具体使用哪种方式根据窗口特点，在自动模式下：当是以下窗口是使用wgc 否则使用bltblt，

static const char *wgc_partial_match_classes[] = {"Chrome","Mozilla",NULL,
};static const char *wgc_whole_match_classes[] = {"ApplicationFrameWindow","Windows.UI.Core.CoreWindow","XLMAIN",        /* excel*/"PPTFrameClass", /* powerpoint */"OpusApp",       /* word */NULL,
};

choose_method(enum window_capture_method method, bool wgc_supported,const char *current_class)
{if (!wgc_supported)return METHOD_BITBLT;if (method != METHOD_AUTO)return method;if (!current_class)return METHOD_BITBLT;const char **class = wgc_partial_match_classes;while (*class) {if (astrstri(current_class, *class) != NULL) {return METHOD_WGC;}class ++;}class = wgc_whole_match_classes;while (*class) {if (astrcmpi(current_class, *class) == 0) {return METHOD_WGC;}class ++;}return METHOD_BITBLT;
}

采集方式如上；

 WGC本质是使用到d3d11采集，GPU

 

 Windows.Graphics.Capture Namespace - Windows UWP applications | Microsoft Learn

E:\opensrc\obs_src_19041\obs-studio-19141\obs-studio\plugins\win-capture\window-capture.c

 

 桌面采集

 Advances to the display Infrastructure - Windows drivers | Microsoft Learn

Desktop duplication - Windows drivers | Microsoft Learn 

 

两种采集方式：

enum display_capture_method {METHOD_AUTO,METHOD_DXGI,METHOD_WGC,
};

采集方式的选择：

bool obs_module_load(void)
{struct win_version_info ver;bool win8_or_above = false;char *config_dir;//1 确定windows 版本struct win_version_info win1903 = {.major = 10, .minor = 0, .build = 18362, .revis = 0};config_dir = obs_module_config_path(NULL);if (config_dir) {os_mkdirs(config_dir);bfree(config_dir);}get_win_ver(&ver);// 2 win8win8_or_above = ver.major > 6 || (ver.major == 6 && ver.minor >= 2);// 3 使用d3dobs_enter_graphics();graphics_uses_d3d11 = gs_get_device_type() == GS_DEVICE_DIRECT3D_11;obs_leave_graphics();// 4 支持wgcif (graphics_uses_d3d11)wgc_supported = win_version_compare(&ver, &win1903) >= 0;// 5 选择使用duplicator_capture_info (wgc)或monitor_capture_info(gdi)  if (win8_or_above && graphics_uses_d3d11)obs_register_source(&duplicator_capture_info);elseobs_register_source(&monitor_capture_info);obs_register_source(&window_capture_info);char *config_path = obs_module_config_path(NULL);init_hook_files();init_hooks_thread =CreateThread(NULL, 0, init_hooks, config_path, 0, NULL);obs_register_source(&game_capture_info);return true;
}

 E:\opensrc\obs_src_19041\obs-studio-19141\obs-studio\plugins\win-capture\duplicator-monitor-capture.c

static void duplicator_capture_tick(void *data, float seconds)
{struct duplicator_capture *capture = data;/* completely shut down monitor capture if not in use, otherwise it can* sometimes generate system lag when a game is in fullscreen mode */if (!obs_source_showing(capture->source)) {if (capture->showing) {obs_enter_graphics();free_capture_data(capture);obs_leave_graphics();capture->showing = false;}return;}/* always try to load the capture immediately when the source is first* shown */if (!capture->showing) {capture->reset_timeout = RESET_INTERVAL_SEC;}obs_enter_graphics();// 采集模式选择      if (capture->method == METHOD_WGC) {//wgcif (capture->reset_wgc && capture->capture_winrt) {capture->exports.winrt_capture_free(capture->capture_winrt);capture->capture_winrt = NULL;capture->reset_wgc = false;capture->reset_timeout = RESET_INTERVAL_SEC;}if (!capture->capture_winrt) {capture->reset_timeout += seconds;if (capture->reset_timeout >= RESET_INTERVAL_SEC) {capture->capture_winrt =capture->exports.winrt_capture_init_monitor(capture->capture_cursor,capture->handle);capture->reset_timeout = 0.0f;}}} else {if (capture->capture_winrt) {capture->exports.winrt_capture_free(capture->capture_winrt);capture->capture_winrt = NULL;}if (!capture->duplicator) {capture->reset_timeout += seconds;//桌面复制if (capture->reset_timeout >= RESET_INTERVAL_SEC) {capture->duplicator = gs_duplicator_create(capture->dxgi_index);capture->reset_timeout = 0.0f;}}if (capture->duplicator) {if (capture->capture_cursor)cursor_capture(&capture->cursor_data);if (!gs_duplicator_update_frame(capture->duplicator)) {free_capture_data(capture);} else if (capture->width == 0) {reset_capture_data(capture);}}}obs_leave_graphics();if (!capture->showing)capture->showing = true;UNUSED_PARAMETER(seconds);
}

默认会走到桌面复制

 

 当选择 windows 10 則使用wgc

 BitBlt x264 采集

四个线程：

• video_thread:视频编码和输出线程，后面简称“video 线程，负责视频编码和输出
• obs_graphics_thread:视频渲染线程，后面简称“graphics 线程，也就是源合成音视频、生成原始视频帧、显示到窗口（预览）等功能
• audio_thread: 音频编码和输出线程，后面简称“audio 线程
• CaptureThread:音频采集

  当点击开始录制按钮时，在ffmpeg_mux_start 中,raw_active被设置为ture,obs_graphics_thread post信号量，video_thread接收到信号量后，编码输出

点击开始录制后：

video_thread线程的创建过程：

ResetVideo

   AttemptToResetVideo

        --obs_reset_video

             -- obs_init_video 

                       --video_output_open(&video->video, &vi);

                                    --pthread_create(&out->thread, NULL, video_thread   创建video线程

                        --pthread_create(&video->video_thread, NULL, obs_graphics_thread, obs);创建视频渲染线程

在obs_graphics_thread中，通过while (obs_graphics_thread_loop(&context)) 处理任务：

当帧准备好后，通过 output_video_data 调用video_output_unlock_frame  发送信号量

通知video线程开始工作 ：

video线程拿到信号量进入while循环

video_output_cur_frame 处理当前视频帧

 

scale_video_output 做scale 处理,采集到rgb转yuv,等

input->callback是static void receive_video(void *param, struct video_data *frame)

做视频编码：

 

进入具体的编码方式：obs_x264_encode

static bool obs_x264_encode(void *data, struct encoder_frame *frame,struct encoder_packet *packet,bool *received_packet)
{struct obs_x264 *obsx264 = data;x264_nal_t *nals;int nal_count;int ret;x264_picture_t pic, pic_out;if (!frame || !packet || !received_packet)return false;if (frame)init_pic_data(obsx264, &pic, frame);ret = x264_encoder_encode(obsx264->context, &nals, &nal_count,(frame ? &pic : NULL), &pic_out);if (ret < 0) {warn("encode failed");return false;}*received_packet = (nal_count != 0);parse_packet(obsx264, packet, nals, nal_count, &pic_out);return true;
}

 其中：x264_encoder_encode 是依赖中的接口

E:\opensrc\obs_src_19041\dependencies2019\win32\include\x264.h

 

结束录制

主线程调用堆栈：

     obs-ffmpeg.dll!ffmpeg_mux_stop(void * data, unsigned __int64 ts) 

     obs.dll!obs_output_actual_stop(obs_output * output, bool force, unsigned __int64 ts) 

     obs.dll!obs_output_stop(obs_output * output) 

     obs32.exe!SimpleOutput::StopRecording(bool force) 

     obs32.exe!OBSBasic::StopRecording()

ucrtbased.dll线程 obs_x264_destroy：x64销毁

 音频设备初始化以及音频采集线程创建

E:\opensrc\obs_src_19041\obs-studio-19141\obs-studio\plugins\win-wasapi\win-wasapi.cpp

static void *CreateWASAPISource(obs_data_t *settings, obs_source_t *source,bool input)
{try {return new WASAPISource(settings, source, input);} catch (const char *error) {blog(LOG_ERROR, "[CreateWASAPISource] %s", error);}return nullptr;
}

 com初始化

WASAPISource::WASAPISource(obs_data_t *settings, obs_source_t *source_,bool input): source(source_), isInputDevice(input)
{UpdateSettings(settings);stopSignal = CreateEvent(nullptr, true, false, nullptr);if (!stopSignal.Valid())throw "Could not create stop signal";receiveSignal = CreateEvent(nullptr, false, false, nullptr);if (!receiveSignal.Valid())throw "Could not create receive signal";Start();
}inline void WASAPISource::Start()
{if (!TryInitialize()) {blog(LOG_INFO,"[WASAPISource::WASAPISource] ""Device '%s' not found.  Waiting for device",device_id.c_str());Reconnect();}
}......void WASAPISource::Initialize()
{HRESULT res;//初始化comres = CoCreateInstance(__uuidof(MMDeviceEnumerator), nullptr,CLSCTX_ALL, __uuidof(IMMDeviceEnumerator),(void **)enumerator.Assign());if (FAILED(res))throw HRError("Failed to create enumerator", res);if (!InitDevice())return;device_name = GetDeviceName(device);if (!notify) {notify = new WASAPINotify(this);enumerator->RegisterEndpointNotificationCallback(notify);}HRESULT resSample;IPropertyStore *store = nullptr;PWAVEFORMATEX deviceFormatProperties;PROPVARIANT prop;resSample = device->OpenPropertyStore(STGM_READ, &store);if (!FAILED(resSample)) {resSample =store->GetValue(PKEY_AudioEngine_DeviceFormat, &prop);if (!FAILED(resSample)) {if (prop.vt != VT_EMPTY && prop.blob.pBlobData) {deviceFormatProperties =(PWAVEFORMATEX)prop.blob.pBlobData;device_sample = std::to_string(deviceFormatProperties->nSamplesPerSec);}}store->Release();}InitClient();if (!isInputDevice)InitRender();InitCapture();
}

创建音频采集线程CaptureThread

 

bool WASAPISource::ProcessCaptureData()
{HRESULT res;LPBYTE buffer;UINT32 frames;DWORD flags;UINT64 pos, ts;UINT captureSize = 0;while (true) {// 获取采集的数据包大小res = capture->GetNextPacketSize(&captureSize);if (FAILED(res)) {if (res != AUDCLNT_E_DEVICE_INVALIDATED)blog(LOG_WARNING,"[WASAPISource::GetCaptureData]"" capture->GetNextPacketSize"" failed: %lX",res);return false;}if (!captureSize)break;//获取音频数据res = capture->GetBuffer(&buffer, &frames, &flags, &pos, &ts);if (FAILED(res)) {if (res != AUDCLNT_E_DEVICE_INVALIDATED)blog(LOG_WARNING,"[WASAPISource::GetCaptureData]"" capture->GetBuffer"" failed: %lX",res);return false;}obs_source_audio data = {};data.data[0] = (const uint8_t *)buffer;data.frames = (uint32_t)frames;data.speakers = speakers;data.samples_per_sec = sampleRate;data.format = format;data.timestamp = useDeviceTiming ? ts * 100 : os_gettime_ns();if (!useDeviceTiming)data.timestamp -= util_mul_div64(frames, 1000000000ULL,sampleRate);//音频数据处理obs_source_output_audio(source, &data);capture->ReleaseBuffer(frames);}return true;
}

 audio_thread

 

 

 

 

static void input_and_output(struct audio_output *audio, uint64_t audio_time,uint64_t prev_time)
{size_t bytes = AUDIO_OUTPUT_FRAMES * audio->block_size;struct audio_output_data data[MAX_AUDIO_MIXES];uint32_t active_mixes = 0;uint64_t new_ts = 0;bool success;memset(data, 0, sizeof(data));#ifdef DEBUG_AUDIOblog(LOG_DEBUG, "audio_time: %llu, prev_time: %llu, bytes: %lu",audio_time, prev_time, bytes);
#endif/* get mixers */pthread_mutex_lock(&audio->input_mutex);for (size_t i = 0; i < MAX_AUDIO_MIXES; i++) {if (audio->mixes[i].inputs.num)active_mixes |= (1 << i);}pthread_mutex_unlock(&audio->input_mutex);/* clear mix buffers */for (size_t mix_idx = 0; mix_idx < MAX_AUDIO_MIXES; mix_idx++) {struct audio_mix *mix = &audio->mixes[mix_idx];memset(mix->buffer, 0, sizeof(mix->buffer));for (size_t i = 0; i < audio->planes; i++)data[mix_idx].data[i] = mix->buffer[i];}/* get new audio data */success = audio->input_cb(audio->input_param, prev_time, audio_time,&new_ts, active_mixes, data);if (!success)return;/* clamps audio data to -1.0..1.0 */clamp_audio_output(audio, bytes);/* output */for (size_t i = 0; i < MAX_AUDIO_MIXES; i++)do_audio_output(audio, i, new_ts, AUDIO_OUTPUT_FRAMES);
}

最后调用到do_audio_output

static const char *receive_audio_name = "receive_audio";
static void receive_audio(void *param, size_t mix_idx, struct audio_data *in)
{profile_start(receive_audio_name);struct obs_encoder *encoder = param;struct audio_data audio = *in;if (!encoder->first_received) {encoder->first_raw_ts = audio.timestamp;encoder->first_received = true;clear_audio(encoder);}if (audio_pause_check(&encoder->pause, &audio, encoder->samplerate))goto end;if (!buffer_audio(encoder, &audio))goto end;while (encoder->audio_input_buffer[0].size >=encoder->framesize_bytes) {if (!send_audio_data(encoder)) {break;}}UNUSED_PARAMETER(mix_idx);end:profile_end(receive_audio_name);
}

 send_audio_data 中进行编码