camera recording流程

开始app调用到cameraservices

// start recording mode

status_t CameraService::Client::startRecording() {
    LOG1("startRecording (pid %d)", getCallingPid());
    return startCameraMode(CAMERA_RECORDING_MODE);
}

// start preview or recording

status_t CameraService::Client::startCameraMode(camera_mode mode) {
    LOG1("startCameraMode(%d)", mode);
    Mutex::Autolock lock(mLock);
    status_t result = checkPidAndHardware();
    if (result != NO_ERROR) return result;

    switch(mode) {
        case CAMERA_PREVIEW_MODE:
            if (mSurface == 0) {
                LOG1("mSurface is not set yet.");
                // still able to start preview in this case.

            }
            return startPreviewMode();
        case CAMERA_RECORDING_MODE:
            if (mSurface == 0) {
                LOGE("mSurface must be set before startRecordingMode.");
                return INVALID_OPERATION;
            }
            return startRecordingMode();
        default:
            return UNKNOWN_ERROR;
    }
}
           

status_t CameraService::Client::startRecordingMode() {
    LOG1("startRecordingMode");
    status_t result = NO_ERROR;

    // if recording has been enabled, nothing needs to be done

    if (mHardware->recordingEnabled()) {
        return NO_ERROR;
    }

    // if preview has not been started, start preview first

    if (!mHardware->previewEnabled()) {
        result = startPreviewMode();
        if (result != NO_ERROR) {
            return result;
        }
    }

    // start recording mode

    enableMsgType(CAMERA_MSG_VIDEO_FRAME);
    mCameraService->playSound(SOUND_RECORDING);
    result = mHardware->startRecording();  //调用hal recording.
    if (result != NO_ERROR) {
        LOGE("mHardware->startRecording() failed with status %d", result);
    }
    return result;
}
           

调用HAL 层的 previewthread 线程:

if (mRecordRunning == true && mMsgEnabled & CAMERA_MSG_VIDEO_FRAME) {
263 yuyv422_to_yuv420sp((unsigned char *)rawFramePointer,
264 (unsigned char *)mRecordingHeap->getBase(),
265 preview_width, preview_height);
266 LOGE(" ------- mRecordRunning --------");
267 mDataCbTimestamp(systemTime(SYSTEM_TIME_MONOTONIC), CAMERA_MSG_VIDEO_FRAME, mRecordingBuffer, mCallbackCookie);
268 }
           

使用回调函数： 回调到cameraservices .

void CameraService::Client::dataCallbackTimestamp(nsecs_t timestamp,
        int32_t msgType, const sp<IMemory>& dataPtr, void* user) {
    LOG2("dataCallbackTimestamp(%d)", msgType);

    sp<Client> client = getClientFromCookie(user);
    if (client == 0) return;
    if (!client->lockIfMessageWanted(msgType)) return;

    if (dataPtr == 0) {
        LOGE("Null data returned in data with timestamp callback");
        client->handleGenericNotify(CAMERA_MSG_ERROR, UNKNOWN_ERROR, 0);
        return;
    }

    client->handleGenericDataTimestamp(timestamp, msgType, dataPtr);
}
           

数据传给 client->handleGenericDataTimestamp(timestamp, msgType, dataPtr)

void CameraService::Client::handleGenericDataTimestamp(nsecs_t timestamp,
    int32_t msgType, const sp<IMemory>& dataPtr) {
    sp<ICameraClient> c = mCameraClient;
    mLock.unlock();
    if (c != 0) {
        c->dataCallbackTimestamp(timestamp, msgType, dataPtr);
    }
}
           

传给 frameworks/base/libs/camera/Camera.cpp

// callback from camera service when timestamped frame is ready

void Camera::dataCallbackTimestamp(nsecs_t timestamp, int32_t msgType, const sp<IMemory>& dataPtr)
{
    sp<CameraListener> listener;
    {
        Mutex::Autolock _l(mLock);
        listener = mListener;
    }
    if (listener != NULL) {
        listener->postDataTimestamp(timestamp, msgType, dataPtr);
    }
}
           

调用到 frameworks/base/media/libstagefright/CameraSource.cpp

frameworks/base/libs/camera/ICameraClient.cpp