NvBufferTransform causes Segmentation fault

[praxidike97]

I want to convert an image from RGBA to YUV420 on the Orin. According to various threads on this forum this should be possible using the NvBufferTransform method. Somehow I cannot get this to work, I get a Segmentation fault no matter what.
I put together a minimal example. In this example I don’t try to do color conversion but just any transformation at all but it still fails with a Segmentation fault:

int dmaFd1;
int dmaFd2;
unsigned long out_buf_size;
unsigned char *out_buf;
int width = 100;
int height = 100;

NvBufferCreateParams paramsCreate1 = {.width = width,
                                   .height = height,
                                   .payloadType = NvBufferPayload_SurfArray,
                                   .layout = NvBufferLayout_BlockLinear,
                                   .colorFormat = NvBufferColorFormat_GRAY8,
                                   .nvbuf_tag = NvBufferTag_NONE};

NvBufferCreateParams paramsCreate2 = {.width = width,
                                  .height = height,
                                  .payloadType = NvBufferPayload_SurfArray,
                                  .layout = NvBufferLayout_BlockLinear,
                                  .colorFormat = NvBufferColorFormat_GRAY8,
                                  .nvbuf_tag = NvBufferTag_NONE};

NvBufferCreateEx(&dmaFd1, &paramsCreate1);
NvBufferCreateEx(&dmaFd2, &paramsCreate2);

unsigned char *dummy_data = new unsigned char[width * height];
for (int i = 0; i < width * height; i++){
    dummy_data[i] = 42;
}

Raw2NvBuffer(dummy_data, 0, width, height, dmaFd1);

NvBufferTransformParams paramsTransform;
paramsTransform.transform_flag = NVBUFFER_TRANSFORM_FLIP;
paramsTransform.transform_flip = NvBufferTransform_None;
int retNv = NvBufferTransform(dmaFd1, dmaFd2, &paramsTransform);

Any ideas what’s wrong here?

[DaneLLL]

Hi,
NvBuffer APIs are deprecated on Jetpack 5 releases. Please call NvBufSurfTransform(). NvBufSurface APIs are defined in

/usr/src/jetson_multimedia_api/include/nvbufsurftransform.h
/usr/src/jetson_multimedia_api/include/nvbufsurface.h

[praxidike97]

Hey, thanks for the quick reply!
I tried NvBufSurfTransform() and it seems to work. The problem is that after the transformation I have to perform a JPEG encoding. From what I read there is no straight-forward way to use the hardware JPEG encoder with a NvBufSurface right? It can only be used with an NvBuffer as shown in /usr/src/jetson_multimedia_api/samples/05_jpeg_encode.

What is the recommanded way here? Use NvBufferTransform even though it is deprecated so that I get an NvBuffer object? Or is there a way to encode a NvBufSurface that I overlooked?

[DaneLLL]

Hi,
Do you install the samples through SDKManager? All Jetpack 5 samples should be based on NvBufSurface APIs.

[praxidike97]

I am not really sure, got the Orin provided by my company. Can you point me to any resources regarding JPEG encoding?

Even on the NVidia page (https://docs.nvidia.com/jetson/l4t-multimedia/l4t_mm_05_jpeg_encode.html) it says that the JPEG encoder takes an NvBuffer. Or is this outdated?

[DaneLLL]

Hi,
The content may not be well updated. Please directly refer to the sample:

/usr/src/jetson_multimedia_api/samples/05_jpeg_encode/

[praxidike97]

I did take a look at this sample, but it still uses NvBuffer. So, there is currently no way to encode a NvBufSurface ?

Nvm, I figured it out. I just looked at encodeFromBuffer and not encodeFromFd. The latter works with the new API.

[DaneLLL]

Hi,
Please check if you use Jetpack 5.1.1 or 5.1.2 and install the samples through SDKManager. You shall see NvBufSurface APIs are called, such as NvBufSurf::NvAllocate(), NvBufSurf::NvTransform()

[praxidike97]

Yeah, I did so, works now, thanks