Meaning of return values of the cuvidVideoParser callbacks + request for nvidia to update the docs

I had an issue where a h264 video with idr only frames was decoding just fine, but a h264 file with idr, b and p resulted in the typical h264 decode error garbage. After spending too much time I found the solution somewhere I didn’t expect.

I expected that the callbacks that you set on the CUVIDPARSERPARAMS should return 0 on success and < 0 on failure like most C/C++ functions do. And tbh, I expected that the parser would actually ignore the return values or would use them and returning an error would cause a failure. But I couldn’t find any info on this in the header or documentation.

It turns out this is not really the case. When my sequence callback returns 0 (as in success when following the convention that is used in C/C++) the h264 with idr only frames works fine. But this somehow causes h264 videos with other nals then idr to be decoded incorrectly.

So the fix was to return 1 from my sequence callback instead of 0.

@nvidia could you document this somewhere in the nvcuvid.h file?

It’s always good to improve the documentation but it’s pretty obvious from even a cursory look at the sample code.


int NvDecoder::HandlePictureDecode(CUVIDPICPARAMS *pPicParams) {
    if (!m_hDecoder) 
        NVDEC_THROW_ERROR("Decoder not initialized.", CUDA_ERROR_NOT_INITIALIZED);
        return false;

    NVDEC_API_CALL(cuvidDecodePicture(m_hDecoder, pPicParams));
    return 1;

Hi Roxlu,

Thank you for your feedback. We will improve the documentation.

Ryan Park