OpenHarmony 3.2 Beta多媒体系列—

一、简介

媒体子系统为开发者供给了媒体相关的很多功用，本文针对其间的视频录制功用做个具体的介绍。首要，我将经过媒体子系统供给的视频录制Test代码作为切入点，给大家梳理一下整个录制的流程。

二、目录

foundation/multimedia/camera_framework

├── frameworks
│   ├── js
│   │   └── camera_napi                            #napi完成
│   │       └── src
│   │           ├── input                          #Camera输入
│   │           ├── output                         #Camera输出
│   │           └── session                        #会话管理
│   └── native                                     #native完成
│       └── camera
│           ├── BUILD.gn
│           ├── src
│           │   ├── input                          #Camera输入
│           │   ├── output                         #Camera输出
│           │   └── session                        #会话管理
├── interfaces                                     #接口界说
│   ├── inner_api                                  #内部native完成
│   │   └── native
│   │       ├── camera
│   │       │   └── include
│   │       │       ├── input
│   │       │       ├── output
│   │       │       └── session
│   └── kits                                       #napi接口
│       └── js
│           └── camera_napi
│               ├── BUILD.gn
│               ├── include
│               │   ├── input
│               │   ├── output
│               │   └── session
│               └── @ohos.multimedia.camera.d.ts
└── services                                       #服务端
    └── camera_service
        ├── binder
        │   ├── base
        │   ├── client                             #IPC的客户端
        │   │   └── src
        │   └── server                             #IPC的服务端
        │       └── src
        └── src

三、录制的全体流程

四、Native接口运用

在OpenAtom OpenHarmony（以下简称“OpenHarmony”）系统中，多媒体子系统经过N-API接口供给给上层JS调用，N-API相当所以JS和Native之间的桥梁，在OpenHarmony源码中，供给了C++直接调用视频录制功用的例子，foundation/multimedia/camera_framework/interfaces/inner_api/native/test目录中。本文章首要参阅了camera_video.cpp文件中的视频录制流程。

首要依据camera_video.cpp的main办法，了解下视频录制的首要流程代码。

int main(int argc, char **argv)
{
    ......
    // 创立CameraManager实例
    sptr<CameraManager> camManagerObj = CameraManager::GetInstance();
    // 设置回调
    camManagerObj->SetCallback(std::make_shared<TestCameraMngerCallback>(testName));
    // 获取支撑的相机设备列表
    std::vector<sptr<CameraDevice>> cameraObjList = camManagerObj->GetSupportedCameras();
    // 创立收集会话
    sptr<CaptureSession> captureSession = camManagerObj->CreateCaptureSession();
    // 开端装备收集会话
    captureSession->BeginConfig();
    // 创立CameraInput
    sptr<CaptureInput> captureInput = camManagerObj->CreateCameraInput(cameraObjList[0]);
    sptr<CameraInput> cameraInput = (sptr<CameraInput> &)captureInput;
    // 敞开CameraInput
    cameraInput->Open();
    // 设置CameraInput的Error回调
    cameraInput->SetErrorCallback(std::make_shared<TestDeviceCallback>(testName));
    // 增加CameraInput实例到收集会话中
    ret = captureSession->AddInput(cameraInput);
    sptr<Surface> videoSurface = nullptr;
    std::shared_ptr<Recorder> recorder = nullptr;
    // 创立Video的Surface
    videoSurface = Surface::CreateSurfaceAsConsumer();
    sptr<SurfaceListener> videoListener = new SurfaceListener("Video", SurfaceType::VIDEO, g_videoFd, videoSurface);
    // 注册Surface的事件监听
    videoSurface->RegisterConsumerListener((sptr<IBufferConsumerListener> &)videoListener);
    // 视频的装备
    VideoProfile videoprofile = VideoProfile(static_cast<CameraFormat>(videoFormat), videosize, videoframerates);
    // 创立VideoOutput实例
    sptr<CaptureOutput> videoOutput = camManagerObj->CreateVideoOutput(videoprofile, videoSurface);
    // 设置VideoOutput的回调
    ((sptr<VideoOutput> &)videoOutput)->SetCallback(std::make_shared<TestVideoOutputCallback>(testName));
    // 增加videoOutput到收集会话中
    ret = captureSession->AddOutput(videoOutput);
    // 提交会话装备
    ret = captureSession->CommitConfig();
    // 开端录制
    ret = ((sptr<VideoOutput> &)videoOutput)->Start();
    sleep(videoPauseDuration);
    MEDIA_DEBUG_LOG("Resume video recording");
    // 暂停录制
    ret = ((sptr<VideoOutput> &)videoOutput)->Resume();
    MEDIA_DEBUG_LOG("Wait for 5 seconds before stop");
    sleep(videoCaptureDuration);
    MEDIA_DEBUG_LOG("Stop video recording");
    // 中止录制
    ret = ((sptr<VideoOutput> &)videoOutput)->Stop();
    MEDIA_DEBUG_LOG("Closing the session");
    // 中止收集会话
    ret = captureSession->Stop();
    MEDIA_DEBUG_LOG("Releasing the session");
    // 开释会话收集
    captureSession->Release();
    // Close video file
    TestUtils::SaveVideoFile(nullptr, 0, VideoSaveMode::CLOSE, g_videoFd);
    cameraInput->Release();
    camManagerObj->SetCallback(nullptr);
    return 0;
}

以上是视频录制的全体流程，其进程首要经过Camera模块支撑的才能来完成，其间涉及几个重要的类：CaptureSession、CameraInput、VideoOutput。CaptureSession是整个进程的控制者，CameraInput和VideoOutput相当所以设备的输入和输出。

五、调用流程

后续首要针对上面的调用流程，梳理具体的调用流程，便利我们对了解视频录制的整理架构有一个愈加深化的了解。

创立CameraManager实例

经过CameraManager::GetInstance()获取CameraManager的实例，后续的一些接口都是经过该实例进行调用的。GetInstance运用了单例形式，在OpenHarmony代码中这种办法很常见。

sptr<CameraManager> &CameraManager::GetInstance()
{
    if (CameraManager::cameraManager_ == nullptr) {
        MEDIA_INFO_LOG("Initializing camera manager for first time!");
        CameraManager::cameraManager_ = new(std::nothrow) CameraManager();
        if (CameraManager::cameraManager_ == nullptr) {
            MEDIA_ERR_LOG("CameraManager::GetInstance failed to new CameraManager");
        }
    }
    return CameraManager::cameraManager_;
}

获取支撑的相机设备列表

经过调用CameraManager的GetSupportedCameras()接口，获取设备支撑的CameraDevice列表。跟踪代码能够发现serviceProxy_->GetCameras终究会调用到Camera服务端的对应接口。

std::vector<sptr<CameraDevice>> CameraManager::GetSupportedCameras()
{
    CAMERA_SYNC_TRACE;
    std::lock_guard<std::mutex> lock(mutex_);
    std::vector<std::string> cameraIds;
    std::vector<std::shared_ptr<Camera::CameraMetadata>> cameraAbilityList;
    int32_t retCode = -1;
    sptr<CameraDevice> cameraObj = nullptr;
    int32_t index = 0;
    if (cameraObjList.size() > 0) {
        cameraObjList.clear();
    }
    if (serviceProxy_ == nullptr) {
        MEDIA_ERR_LOG("CameraManager::GetCameras serviceProxy_ is null, returning empty list!");
        return cameraObjList;
    }
    std::vector<sptr<CameraDevice>> supportedCameras;
    retCode = serviceProxy_->GetCameras(cameraIds, cameraAbilityList);
    if (retCode == CAMERA_OK) {
        for (auto& it : cameraIds) {
            cameraObj = new(std::nothrow) CameraDevice(it, cameraAbilityList[index++]);
            if (cameraObj == nullptr) {
                MEDIA_ERR_LOG("CameraManager::GetCameras new CameraDevice failed for id={public}%s", it.c_str());
                continue;
            }
            supportedCameras.emplace_back(cameraObj);
        }
    } else {
        MEDIA_ERR_LOG("CameraManager::GetCameras failed!, retCode: %{public}d", retCode);
    }
    ChooseDeFaultCameras(supportedCameras);
    return cameraObjList;
}

创立收集会话

下面是比较重要的环节，经过调用CameraManager的CreateCaptureSession接口创立收集会话。CameraManager创立收集会话，是经过serviceProxy_->CreateCaptureSession办法进行调用，这儿涉及到了OpenHarmony中的IPC的调用，serviceProxy_是远端服务在本地的代理，经过这个代理能够调用到具体的服务端，这儿是HCameraService。

sptr<CaptureSession> CameraManager::CreateCaptureSession()
{
    CAMERA_SYNC_TRACE;
    sptr<ICaptureSession> captureSession = nullptr;
    sptr<CaptureSession> result = nullptr;
    int32_t retCode = CAMERA_OK;
    if (serviceProxy_ == nullptr) {
        MEDIA_ERR_LOG("CameraManager::CreateCaptureSession serviceProxy_ is null");
        return nullptr;
    }
    retCode = serviceProxy_->CreateCaptureSession(captureSession);
    if (retCode == CAMERA_OK && captureSession != nullptr) {
        result = new(std::nothrow) CaptureSession(captureSession);
        if (result == nullptr) {
            MEDIA_ERR_LOG("Failed to new CaptureSession");
        }
    } else {
        MEDIA_ERR_LOG("Failed to get capture session object from hcamera service!, %{public}d", retCode);
    }
    return result;
}

代码终究来到HCameraService::CreateCaptureSession中，该办法中new了一个HCaptureSession目标，而且将该目标传递给了参数session，所以前面的captureSession目标便是这儿new出来的HCaptureSession，前面的CameraManager的CreateCaptureSession()办法中将captureSession封装成CaptureSession目标返回给应用层运用。

int32_t HCameraService::CreateCaptureSession(sptr<ICaptureSession> &session)
{
    CAMERA_SYNC_TRACE;
    sptr<HCaptureSession> captureSession;
    if (streamOperatorCallback_ == nullptr) {
        streamOperatorCallback_ = new(std::nothrow) StreamOperatorCallback();
        if (streamOperatorCallback_ == nullptr) {
            MEDIA_ERR_LOG("HCameraService::CreateCaptureSession streamOperatorCallback_ allocation failed");
            return CAMERA_ALLOC_ERROR;
        }
    }
    std::lock_guard<std::mutex> lock(mutex_);
    OHOS::Security::AccessToken::AccessTokenID callerToken = IPCSkeleton::GetCallingTokenID();
    captureSession = new(std::nothrow) HCaptureSession(cameraHostManager_, streamOperatorCallback_, callerToken);
    if (captureSession == nullptr) {
        MEDIA_ERR_LOG("HCameraService::CreateCaptureSession HCaptureSession allocation failed");
        return CAMERA_ALLOC_ERROR;
    }
    session = captureSession;
    return CAMERA_OK;
}

开端装备收集会话

调用CaptureSession的BeginConfig进行收集会话的装备作业。这个作业终究调用到被封装的HCaptureSession中。

int32_t HCaptureSession::BeginConfig()
{
    CAMERA_SYNC_TRACE;
    if (curState_ == CaptureSessionState::SESSION_CONFIG_INPROGRESS) {
        MEDIA_ERR_LOG("HCaptureSession::BeginConfig Already in config inprogress state!");
        return CAMERA_INVALID_STATE;
    }
    std::lock_guard<std::mutex> lock(sessionLock_);
    prevState_ = curState_;
    curState_ = CaptureSessionState::SESSION_CONFIG_INPROGRESS;
    tempCameraDevices_.clear();
    tempStreams_.clear();
    deletedStreamIds_.clear();
    return CAMERA_OK;
}

创立CameraInput

应用层经过camManagerObj->CreateCameraInput(cameraObjList[0])的办法进行CameraInput的创立，cameraObjList[0]便是前面获取支撑设备的第一个。依据CameraDevice创立对应的CameraInput目标。

sptr<CameraInput> CameraManager::CreateCameraInput(sptr<CameraDevice> &camera)
{
    CAMERA_SYNC_TRACE;
    sptr<CameraInput> cameraInput = nullptr;
    sptr<ICameraDeviceService> deviceObj = nullptr;
    if (camera != nullptr) {
        deviceObj = CreateCameraDevice(camera->GetID());
        if (deviceObj != nullptr) {
            cameraInput = new(std::nothrow) CameraInput(deviceObj, camera);
            if (cameraInput == nullptr) {
                MEDIA_ERR_LOG("failed to new CameraInput Returning null in CreateCameraInput");
                return cameraInput;
            }
        } else {
            MEDIA_ERR_LOG("Returning null in CreateCameraInput");
        }
    } else {
        MEDIA_ERR_LOG("CameraManager::CreateCameraInput: Camera object is null");
    }
    return cameraInput;
}

敞开CameraInput

调用了CameraInput的Open办法，进行输入设备的启动打开。

void CameraInput::Open()
{
    int32_t retCode = deviceObj_->Open();
    if (retCode != CAMERA_OK) {
        MEDIA_ERR_LOG("Failed to open Camera Input, retCode: %{public}d", retCode);
    }
}

增加CameraInput实例到收集会话中

经过调用captureSession的AddInput办法，将创立的CameraInput目标增加到收集会话的输入中，这样收集会话就知道收集输入的设备。

int32_t CaptureSession::AddInput(sptr<CaptureInput> &input)
{
    CAMERA_SYNC_TRACE;
    if (input == nullptr) {
        MEDIA_ERR_LOG("CaptureSession::AddInput input is null");
        return CAMERA_INVALID_ARG;
    }
    input->SetSession(this);
    inputDevice_ = input;
    return captureSession_->AddInput(((sptr<CameraInput> &)input)->GetCameraDevice());
}

终究调用到HCaptureSession的AddInput办法，该办法中核心的代码是tempCameraDevices_.emplace_back(localCameraDevice)，将需求增加的CameraDevice插入到tempCameraDevices_容器中。

int32_t HCaptureSession::AddInput(sptr<ICameraDeviceService> cameraDevice)
{
    CAMERA_SYNC_TRACE;
    sptr<HCameraDevice> localCameraDevice = nullptr;
    if (cameraDevice == nullptr) {
        MEDIA_ERR_LOG("HCaptureSession::AddInput cameraDevice is null");
        return CAMERA_INVALID_ARG;
    }
    if (curState_ != CaptureSessionState::SESSION_CONFIG_INPROGRESS) {
        MEDIA_ERR_LOG("HCaptureSession::AddInput Need to call BeginConfig before adding input");
        return CAMERA_INVALID_STATE;
    }
    if (!tempCameraDevices_.empty() || (cameraDevice_ != nullptr && !cameraDevice_->IsReleaseCameraDevice())) {
        MEDIA_ERR_LOG("HCaptureSession::AddInput Only one input is supported");
        return CAMERA_INVALID_SESSION_CFG;
    }
    localCameraDevice = static_cast<HCameraDevice*>(cameraDevice.GetRefPtr());
    if (cameraDevice_ == localCameraDevice) {
        cameraDevice_->SetReleaseCameraDevice(false);
    } else {
        tempCameraDevices_.emplace_back(localCameraDevice);
        CAMERA_SYSEVENT_STATISTIC(CreateMsg("CaptureSession::AddInput"));
    }
    sptr<IStreamOperator> streamOperator;
    int32_t rc = localCameraDevice->GetStreamOperator(streamOperatorCallback_, streamOperator);
    if (rc != CAMERA_OK) {
        MEDIA_ERR_LOG("HCaptureSession::GetCameraDevice GetStreamOperator returned %{public}d", rc);
        localCameraDevice->Close();
        return rc;
    }
    return CAMERA_OK;
}

创立Video的Surface

经过Surface::CreateSurfaceAsConsumer创立Surface。

sptr<Surface> Surface::CreateSurfaceAsConsumer(std::string name, bool isShared)
{
    sptr<ConsumerSurface> surf = new ConsumerSurface(name, isShared);
    GSError ret = surf->Init();
    if (ret != GSERROR_OK) {
        BLOGE("Failure, Reason: consumer surf init failed");
        return nullptr;
    }
    return surf;
}

创立VideoOutput实例

经过调用CameraManager的CreateVideoOutput来创立VideoOutput实例。

sptr<VideoOutput> CameraManager::CreateVideoOutput(VideoProfile &profile, sptr<Surface> &surface)
{
    CAMERA_SYNC_TRACE;
    sptr<IStreamRepeat> streamRepeat = nullptr;
    sptr<VideoOutput> result = nullptr;
    int32_t retCode = CAMERA_OK;
    camera_format_t metaFormat;
    metaFormat = GetCameraMetadataFormat(profile.GetCameraFormat());
    retCode = serviceProxy_->CreateVideoOutput(surface->GetProducer(), metaFormat,
                                               profile.GetSize().width, profile.GetSize().height, streamRepeat);
    if (retCode == CAMERA_OK) {
        result = new(std::nothrow) VideoOutput(streamRepeat);
        if (result == nullptr) {
            MEDIA_ERR_LOG("Failed to new VideoOutput");
        } else {
            std::vector<int32_t> videoFrameRates = profile.GetFrameRates();
            if (videoFrameRates.size() >= 2) { // vaild frame rate range length is 2
                result->SetFrameRateRange(videoFrameRates[0], videoFrameRates[1]);
            }
            POWERMGR_SYSEVENT_CAMERA_CONFIG(VIDEO,
                                            profile.GetSize().width,
                                            profile.GetSize().height);
        }
    } else {
        MEDIA_ERR_LOG("VideoOutpout: Failed to get stream repeat object from hcamera service! %{public}d", retCode);
    }
    return result;
}

该办法中经过IPC的调用终究调用到了HCameraService的CreateVideoOutput(surface->GetProducer(), format, streamRepeat)。

sptr<VideoOutput> CameraManager::CreateVideoOutput(VideoProfile &profile, sptr<Surface> &surface)
{
    CAMERA_SYNC_TRACE;
    sptr<IStreamRepeat> streamRepeat = nullptr;
    sptr<VideoOutput> result = nullptr;
    int32_t retCode = CAMERA_OK;
    camera_format_t metaFormat;
    metaFormat = GetCameraMetadataFormat(profile.GetCameraFormat());
    retCode = serviceProxy_->CreateVideoOutput(surface->GetProducer(), metaFormat,
                                               profile.GetSize().width, profile.GetSize().height, streamRepeat);
    if (retCode == CAMERA_OK) {
        result = new(std::nothrow) VideoOutput(streamRepeat);
        if (result == nullptr) {
            MEDIA_ERR_LOG("Failed to new VideoOutput");
        } else {
            std::vector<int32_t> videoFrameRates = profile.GetFrameRates();
            if (videoFrameRates.size() >= 2) { // vaild frame rate range length is 2
                result->SetFrameRateRange(videoFrameRates[0], videoFrameRates[1]);
            }
            POWERMGR_SYSEVENT_CAMERA_CONFIG(VIDEO,
                                            profile.GetSize().width,
                                            profile.GetSize().height);
        }
    } else {
        MEDIA_ERR_LOG("VideoOutpout: Failed to get stream repeat object from hcamera service! %{public}d", retCode);
    }
    return result;
}

HCameraService的CreateVideoOutput办法中首要创立了HStreamRepeat，而且经过参数传递给前面的CameraManager运用，CameraManager经过传递的HStreamRepeat目标，进行封装，创立出VideoOutput目标。

增加videoOutput到收集会话中，而且提交收集会话

该过程类似增加CameraInput到收集会话的进程，能够参阅前面的流程。

开端录制

经过调用VideoOutput的Start进行录制的操作。

int32_t VideoOutput::Start()
{
    return static_cast<IStreamRepeat *>(GetStream().GetRefPtr())->Start();
}

该办法中会调用到HStreamRepeat的Start办法。

int32_t HStreamRepeat::Start()
{
    CAMERA_SYNC_TRACE;
    if (streamOperator_ == nullptr) {
        return CAMERA_INVALID_STATE;
    }
    if (curCaptureID_ != 0) {
        MEDIA_ERR_LOG("HStreamRepeat::Start, Already started with captureID: %{public}d", curCaptureID_);
        return CAMERA_INVALID_STATE;
    }
    int32_t ret = AllocateCaptureId(curCaptureID_);
    if (ret != CAMERA_OK) {
        MEDIA_ERR_LOG("HStreamRepeat::Start Failed to allocate a captureId");
        return ret;
    }
    std::vector<uint8_t> ability;
    OHOS::Camera::MetadataUtils::ConvertMetadataToVec(cameraAbility_, ability);
    CaptureInfo captureInfo;
    captureInfo.streamIds_ = {streamId_};
    captureInfo.captureSetting_ = ability;
    captureInfo.enableShutterCallback_ = false;
    MEDIA_INFO_LOG("HStreamRepeat::Start Starting with capture ID: %{public}d", curCaptureID_);
    CamRetCode rc = (CamRetCode)(streamOperator_->Capture(curCaptureID_, captureInfo, true));
    if (rc != HDI::Camera::V1_0::NO_ERROR) {
        ReleaseCaptureId(curCaptureID_);
        curCaptureID_ = 0;
        MEDIA_ERR_LOG("HStreamRepeat::Start Failed with error Code:%{public}d", rc);
        ret = HdiToServiceError(rc);
    }
    return ret;
}

核心的代码是streamOperator_->Capture，其间最终一个参数true，表示收集连续数据。

录制完毕，保存录制文件

六、总结

本文首要对OpenHarmony 3.2 Beta多媒体子系统的视频录制进行介绍，首要梳理了全体的录制流程，然后对录制进程中的首要过程进行了具体地剖析。视频录制首要分为以下几个过程：

（1）获取CameraManager实例。

（2）创立收集会话CaptureSession。

（3）创立CameraInput实例，而且将输入设备增加到CaptureSession中。

（4）创立Video录制需求的Surface。

（5）创立VideoOutput实例，而且将输出增加到CaptureSession中。

（6）提交收集会话的装备。

（7）调用VideoOutput的Start办法，进行视频的录制。

（8）录制完毕，保存录制的文件。

关于OpenHarmony 3.2 Beta多媒体系列开发，我之前还分享过

《OpenHarmony 3.2 Beta源码剖析之MediaLibrary》

《OpenHarmony 3.2 Beta多媒体系列——音视频播放框架》

《OpenHarmony 3.2 Beta多媒体系列——音视频播放gstreamer》

这几篇文章，欢迎感兴趣的开发者进行阅读。

OpenHarmony 3.2 Beta多媒体系列——视频录制

一、简介

二、目录

三、录制的全体流程

四、Native接口运用

五、调用流程

六、总结

作者信息

OpenHarmony 3.2 Beta多媒体系列——视频录制

一、简介

二、目录

三、录制的全体流程

四、Native接口运用

五、调用流程

六、总结

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作者信息