NvJPEGEncoder-encodeFromBuffer-tegra_multimedia_api

Hi,
I am using NvJPEGEncoder, And I meet some problems.
I use the function “encodeFromBuffer” to encode the image.But I do not know how to transfer my buffer of YUV420 data to “NvBuffer”.Dose anyone know how to fix this problem. Thank you!

below is the base code

unsigned long size = JPEG_BUFFER_SIZE;
        unsigned char *buffer = out_nvimage;
        NvBuffer nvbuf(V4L2_PIX_FMT_NV12M, DST_WIDTH, DST_HIGHT, 0);
        nvbuf.allocateMemory();
        //auto ret = read_video_frame(( char*)out_nvimage, *nvbuf);
        m_JpegEncoder->encodeFromBuffer(nvbuf, JCS_YCbCr, &buffer, size,40);

Hi,
We have a reference sample 05_jpeg_encode. Please check

/usr/src/tegra_multimedia_api/samples/05_jpeg_encode/