# Error running nppiRGBToYUV420\_8u\_C3P3R on discrete GPU

**URL:** <https://forums.developer.nvidia.com/t/error-running-nppirgbtoyuv420-8u-c3p3r-on-discrete-gpu/272412>\
**Category:** GPU-Accelerated Libraries\
**Tags:** npp\
**Created:** [November 10, 2023, 8:14am UTC](https://forums.developer.nvidia.com/t/error-running-nppirgbtoyuv420-8u-c3p3r-on-discrete-gpu/272412 "2023-11-10T08:14:48Z")\
**Posts on this page:** 6\
**Page:** 1

<div class="post-metadata">

**Author:** ![liviolima80](https://developer.download.nvidia.com/images/forums/profile-default-devtalk-84.png) [@liviolima80](https://forums.developer.nvidia.com/u/liviolima80)\
**Post date:** [November 10, 2023, 8:14am UTC](https://forums.developer.nvidia.com/t/error-running-nppirgbtoyuv420-8u-c3p3r-on-discrete-gpu/272412/1 "2023-11-10T08:14:48Z")

</div>

Good morning,  
I have the following code

==============================================================================

int W=1920;  
int H=1200;  
int nSrcStep = W;

cudaMallocManaged(&ptr\_RGBCUDA, (3 \* W \* H));  
cudaMallocManaged(&ptr\_YCbCrCUDA, (3 \* W \* H) / 2);

Npp8u\* pYCbCrDst[3];  
pYCbCrDst[0] = (Npp8u\*)ptr\_YCbCrCUDA;  
pYCbCrDst[1] = (Npp8u\*)((long)ptr\_YCbCrCUDA + (long)nSrcStep \* (long)h);  
pYCbCrDst[2] = (Npp8u\*)((long)ptr\_YCbCrCUDA + (long)nSrcStep \* (long)h + (long)(nSrcStep \* h / 4));

int steps[3];  
steps[0] = nSrcStep;  
steps[1] = nSrcStep / 2;  
steps[2] = nSrcStep / 2;

stat = nppiRGBToYUV420\_8u\_C3P3R((Npp8u\*)ptr\_RGBCUDA, 3 \* W, pYCbCrDst, steps, oSizeROI);  
if (stat == NPP\_SUCCESS)  
{  
cerr = cudaMemcpy(ptr\_YCbCrHost, ptr\_YCbCrCUDA, (3 \* W \* H) / 2, cudaMemcpyDeviceToHost);  
printf(“\nnppiRGBToYUV420\_8u\_C3P3R result %i %i\n\n”, stat, cerr);  
}  
else printf(“\nnppiRGBToYUV420\_8u\_C3P3R error %i\n\n”, stat);

=====================================================================================

I’m testing the following code on two different hardware:

- Jetson Orin Nano and AGX with Jetpack 5.1.1 (Cuda version 11.4)
- Laptop with NVIDIA GeForce RTX 3050, Windows 11, driver version 536.99, Cuda version 12.2

If I run the code on Jetson Orin Nano everything works correctly. If I run the code on Laptop I have nppiRGBToYUV420\_8u\_C3P3R function that returns NPP\_SUCCESS, but the following cudaMemcpy returns error 700 (cudaErrorIllegalAddress).

I tried to debug the code using compute-sanitizer and the result is that I had a lot of error lines like this

========= Invalid **global** write of size 1 bytes  
========= at 0x910 in void ImageColorConversionKernel\_4XX\_8u\<(NppColorModel)0, (NppPixelFormat)3, (NppColorModel)4, (NppPixelFormat)12\>(const unsigned char \*, const unsigned char \*, const unsigned char \*, const unsigned char \*, int, int, int, unsigned char \*, unsigned char \*, unsigned char \*, unsigned char \*, int, int, int, unsigned int, unsigned int)  
========= by thread (11,1,0) in block (1,2,0)  
========= Address 0xa3462b is out of bounds

It seems is something related to memory access, but I cannot understand where is the issue

Regards

---

<div class="post-metadata">

**Author:** ![Robert\_Crovella](https://sea2.discourse-cdn.com/nvidia/user_avatar/forums.developer.nvidia.com/robert_crovella/32/14043_2.png) [@Robert\_Crovella](https://forums.developer.nvidia.com/u/Robert_Crovella)\
**Post date:** [November 15, 2023, 3:02pm UTC](https://forums.developer.nvidia.com/t/error-running-nppirgbtoyuv420-8u-c3p3r-on-discrete-gpu/272412/2 "2023-11-15T15:02:14Z")

</div>

You have not provided a complete code that I can test, and omitted important items.

When I build a complete code like this around what you have shown, I get no errors:

```auto
# cat t88.cu
#include <npp.h>
#include <cstdio>

int main(){

  int W=1920;
  int H=1200;
  int h = H;
  int nSrcStep = W;
  Npp8u *ptr_RGBCUDA, *ptr_YCbCrCUDA, *ptr_YCbCrHost;
  cudaMallocManaged(&ptr_RGBCUDA, (3 * W * H));
  cudaMallocManaged(&ptr_YCbCrCUDA, (3 * W * H) / 2);
  cudaMallocManaged(&ptr_YCbCrHost, (3 * W * H) / 2);

  Npp8u* pYCbCrDst[3];
  pYCbCrDst[0] = (Npp8u*)ptr_YCbCrCUDA;
  pYCbCrDst[1] = (Npp8u*)((size_t)ptr_YCbCrCUDA + (size_t)nSrcStep * (size_t)h);
  pYCbCrDst[2] = (Npp8u*)((size_t)ptr_YCbCrCUDA + (size_t)nSrcStep * (size_t)h + (size_t)(nSrcStep * h / 4));

  int steps[3];
  steps[0] = nSrcStep;
  steps[1] = nSrcStep / 2;
  steps[2] = nSrcStep / 2;
  NppiSize oSizeROI = {W, H};
  NppStatus stat = nppiRGBToYUV420_8u_C3P3R((Npp8u*)ptr_RGBCUDA, 3 * W, pYCbCrDst, steps, oSizeROI);
  if (stat == NPP_SUCCESS)
  {
    cudaError_t cerr = cudaMemcpy(ptr_YCbCrHost, ptr_YCbCrCUDA, (3 * W * H) / 2, cudaMemcpyDeviceToHost);
    printf("\nnppiRGBToYUV420_8u_C3P3R result %i %i\n\n", stat, cerr);
  }
  else printf("\nnppiRGBToYUV420_8u_C3P3R error %i\n\n", stat);
}
# nvcc -o t88 t88.cu -lnppicc
# compute-sanitizer ./t88
========= COMPUTE-SANITIZER

nppiRGBToYUV420_8u_C3P3R result 0 0

========= ERROR SUMMARY: 0 errors
#

```

CUDA 12.2, L40 GPU, Ubuntu 22.04

(note, for posterity I have edited the above code to include the “fix” from below, switching from `(long)` casting to `(size_t)` casting.)

---

<div class="post-metadata">

**Author:** ![liviolima80](https://developer.download.nvidia.com/images/forums/profile-default-devtalk-84.png) [@liviolima80](https://forums.developer.nvidia.com/u/liviolima80)\
**Post date:** [January 3, 2024, 8:15am UTC](https://forums.developer.nvidia.com/t/error-running-nppirgbtoyuv420-8u-c3p3r-on-discrete-gpu/272412/3 "2024-01-03T08:15:44Z")

</div>

Hi @Robert_Crovella ,  
sorry for the late reply.

I took exactly the same code you provide and I used with a “Cuda 12.1 Runtime Project” under Visual Studio 2022. If I run it I had exactly the same error

nppiRGBToYUV420\_8u\_C3P3R result 0 700

My settings are CUDA 12.1, NVIDIA GeForce RTX 3050 Laptop GPU, Windows 11Pro

Best regards

---

<div class="post-metadata">

**Author:** ![Robert\_Crovella](https://sea2.discourse-cdn.com/nvidia/user_avatar/forums.developer.nvidia.com/robert_crovella/32/14043_2.png) [@Robert\_Crovella](https://forums.developer.nvidia.com/u/Robert_Crovella)\
**Post date:** [January 3, 2024, 7:42pm UTC](https://forums.developer.nvidia.com/t/error-running-nppirgbtoyuv420-8u-c3p3r-on-discrete-gpu/272412/4 "2024-01-03T19:42:38Z")

</div>

on [windows](https://stackoverflow.com/questions/384502/what-is-the-bit-size-of-long-on-64-bit-windows), `long` is a 32-bit type. Try casting to a 64-bit type.

```
pYCbCrDst[1] = (Npp8u*)((size_t)ptr_YCbCrCUDA + (size_t)nSrcStep * (size_t)h);
pYCbCrDst[2] = (Npp8u*)((size_t)ptr_YCbCrCUDA + (size_t)nSrcStep * (size_t)h + (size_t)(nSrcStep * h / 4));

```

A clue is here:

> [@liviolima80](#):
>
> ========= Address 0xa3462b is out of bounds

That is a suspiciously small value for an address/pointer, and if you compare that numerical value to the numerical value of the `ptr_YCbCrCUDA` pointer after it is allocated, I think you will find an obvious discrepancy.

---

<div class="post-metadata">

**Author:** ![liviolima80](https://developer.download.nvidia.com/images/forums/profile-default-devtalk-84.png) [@liviolima80](https://forums.developer.nvidia.com/u/liviolima80)\
**Post date:** [January 4, 2024, 2:45pm UTC](https://forums.developer.nvidia.com/t/error-running-nppirgbtoyuv420-8u-c3p3r-on-discrete-gpu/272412/5 "2024-01-04T14:45:09Z")

</div>

Thank you @Robert_Crovella,  
finally I fix my issue

Regards

---

<div class="post-metadata">

**Author:** ![system](https://sea2.discourse-cdn.com/nvidia/user_avatar/forums.developer.nvidia.com/system/32/68080_2.png) [@system](https://forums.developer.nvidia.com/u/system)\
**Post date:** [January 18, 2024, 2:45pm UTC](https://forums.developer.nvidia.com/t/error-running-nppirgbtoyuv420-8u-c3p3r-on-discrete-gpu/272412/6 "2024-01-18T14:45:17Z")

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