Get decoded data

Autonomous Machines Jetson & Embedded Systems Jetson Xavier NX
1

I use 14_multivideo_decode in mmapi.
My decided data format is YUV420.
I need to get the data and convert into ABGR format.
Then I tried to use NvBufferTransform, but an error occured with “NvMapMemCacheMaint Bad parameter”.
What shoud I do ?

A part of my code is as below.

    //declaration
    input_params.payloadType = NvBufferPayload_SurfArray;
    input_params.width = crop.c.width;
    input_params.height = crop.c.height;
    input_params.layout = NvBufferLayout_Pitch;
    input_params.colorFormat = NvBufferColorFormat_ABGR32;
    input_params.nvbuf_tag = NvBufferTag_NONE;

    ret = NvBufferCreateEx(&ctx->transform_fd, &input_params);
    //process
    NvBufferTransformParams transParams;
	memset(&transParams, 0, sizeof(NvBufferTransformParams));
	transParams.transform_flag = NVBUFFER_TRANSFORM_FILTER;
	transParams.transform_filter = NvBufferTransform_Filter_Smart;
	transParams.src_rect.width = ctx->display_width;
	transParams.src_rect.height = ctx->display_height;
	transParams.dst_rect.width = ctx->display_width;
	transParams.dst_rect.height = ctx->display_height;
	
	cv::Mat src = cv::Mat::zeros(ctx->display_height, ctx->display_width, CV_8UC4);
	cv::Mat image;
	void * ptr_top;
	uint8_t *ptr_cur;
	if (-1 == NvBufferTransform(ctx->dmabuff_fd[v4l2_buf.index], ctx->transform_fd, &transParams))
	NvBufferMemMap(ctx->transform_fd, 0, NvBufferMem_Read_Write, &ptr_top);   //ptr_top is void*
	NvBufferMemSyncForCpu(ctx->transform_fd, 0, &ptr_top);
	memcpy(src.data, ptr_top, ctx->display_height * ctx->display_width  * 4);
	cv::cvtColor(src, image, cv::COLOR_BGRA2BGR);
3

Hi,

This works like:

	if (-1 == NvBufferTransform(ctx->dmabuff_fd[v4l2_buf.index], ctx->transform_fd, &transParams))
{
	NvBufferMemMap(ctx->transform_fd, 0, NvBufferMem_Read_Write, &ptr_top); //ptr_top is void*
}
	NvBufferMemSyncForCpu(ctx->transform_fd, 0, &ptr_top);

Not sure but probably NvBufferTransform() succeeds and then it does not call NvBufferMemMap().

4

Thanks for your reply.
I found the wrong code.
I modified it but it doesn’t work as expected.
The data in “image” is collapsed.

if (-1 == NvBufferTransform(ctx->dmabuff_fd[v4l2_buf.index], ctx->transform_fd, &transParams))
{
     //error check
}
NvBufferMemMap(ctx->transform_fd, 0, NvBufferMem_Read_Write, &ptr_top);   //ptr_top is void*
NvBufferMemSyncForCpu(ctx->transform_fd, 0, &ptr_top);
5

Hi,
You may dump ctx->transform_fd through dump_dmabuf() and check the data in YUV viewer. Check if the data is correct.