Get image frames from NvBufSurfaceParams** bufferList

Accelerated Computing Intelligent Video Analytics DeepStream SDK
1

Hi,

How to extract image frames from NvMOTFrame->NvBufSurfaceParams->NvBufSurfacePlaneParams->?

Can you give me reference code?

2

For accessing frame buffer, you can refer to this, https://devtalk.nvidia.com/default/topic/1061205/deepstream-sdk/rtsp-camera-access-frame-issue/post/5377678/#5377678, it’s similar.

3

I get the following error while using that code mentioned in your link

NvMOTStatus NvMOT_Process(NvMOTContextHandle contextHandle,NvMOTProcessParams *pParams,NvMOTTrackedObjBatch *pTrackedObjectsBatch)

{

NvBufSurfaceParams* buf_list = fr->bufferList[0];

NvBufSurfaceMappedAddr mapd_addr = buf_list->mappedAddr;
cv::Mat bgr_frame = cv::Mat (cv::Size( 640, 368), CV_8UC3);
cv::Mat in_mat =cv::Mat (368, 640,CV_8UC4, mapd_addr.addr[0],1920);
cv::cvtColor (in_mat, bgr_frame, cv::COLOR_RGB2BGR);
cv::imwrite("./img1.png",in_mat);

return NvMOTStatus_OK;
}

error:

what():  OpenCV(4.2.0-dev) opencv/opencv/modules/core/include/opencv2/core/mat.inl.hpp:548: error: (-215:Assertion failed) total() == 0 || data != NULL in function 'Mat'
4

Did you sync GPU buffer hereby buf_list for CPU access before creating cv Mat buffer?
NvBufSurfaceSyncForCpu(NvBufSurface *surf, int index, int plane)

5

Previous err was due to

pQuery->colorFormats[0] = NVBUF_COLOR_FORMAT_RGBA;

in NvMOT_Query,

Now I get frames but it is full of stripes I have attached actual and result frame.

My code is

NvMOTStatus NvMOT_Process(NvMOTContextHandle contextHandle,NvMOTProcessParams *pParams,NvMOTTrackedObjBatch *pTrackedObjectsBatch)

{

NvBufSurfaceParams* buf_list = fr->bufferList[0];

NvBufSurfaceMappedAddr mapd_addr = buf_list->mappedAddr;
cv::Mat bgr_frame = cv::Mat (cv::Size( 640, 368), CV_8UC4);
cv::Mat in_mat =cv::Mat (368, 640,CV_8UC4, mapd_addr.addr[0],1920);
cv::cvtColor (in_mat, bgr_frame, cv::COLOR_RGBA2BGR);
cv::imwrite("./result.png",in_mat);

return NvMOTStatus_OK;
}

help me to convert image

original.jpg
original.jpg1920×1080 567 KB

result.png

original.jpg
original.jpg1920×1080 575 KB

6

Can you extract your source which can compile and run in our environments for a further check?
or if not possible please check below 2 points:
1 as before mentioned, Did you sync GPU buffer hereby buf_list for CPU access before creating cv Mat buffer?
NvBufSurfaceSyncForCpu(NvBufSurface surf, int index, int plane)
2 cv::Mat in_mat =cv::Mat (368, 640,CV_8UC4, mapd_addr.addr[0],1920);
are you sure your buffer color format is RGBA? if yes, the pitch should be width pixels bytes per pixel (640*4)

7

yes, my width is 1280 and pitch is 5120, finally I got the frame :) Thank you.

8

I am facing the same issue and I am a little puzzled on how to read frame data off of NvBufSurfaceParams**, and how you I can call NvBufSurfaceSyncForCpu with an NvBufSurfaceParams** rather than an NvBufSurface.