topic Re: Stream encoding in i.MX Processors

Stream encoding

Lunsheng — Fri, 09 Jun 2023 13:35:22 GMT

Hi all,

I am now using the libimxvpuapi on an imx8m plus board to do YUV2H264 encoding. I refer to example/encode-example.c. However, I encountered the failure to allocate dma buffer at the line of function call imx_dma_buffer_allocate() as below:

ctx->stream_buffer = imx_dma_buffer_allocate(
ctx->allocator,
ctx->enc_global_info->min_required_stream_buffer_size,
ctx->enc_global_info->required_stream_buffer_physaddr_alignment,
0
);

I get a exception at this call and a print "Bus error" without any detailed informaiton.

Would you please help check what the root cause it is?

Thank you!

Re: Stream encoding

Bio_TICFSL — Mon, 12 Jun 2023 14:45:58 GMT

Hello,

You are using a processor instruction with an address that does not satisfy its alignment requirements. Check your code to avoid this bus error.

Regards

Re: Stream encoding

Lunsheng — Fri, 16 Jun 2023 15:03:33 GMT

Thank you for your reply.

According to the comment in the code as below:

/* Creates a new DMA buffer allocator.

* This uses one of the several available i.MX DMA allocators internally. Which

* one is used is determined by the build configuration of libimxdmabuffer.

* @Param error If this pointer is non-NULL, and if an error occurs, then the integer

* the pointer refers to is set to an error code from errno.h. If creating

* the allocator succeeds, the integer is not modified.

* @return Pointer to the newly created DMA allocator, or NULL in case of an error.

ImxDmaBufferAllocator* imx_dma_buffer_allocator_new(int *error);

It seems that the only thing being related to the allocation of dma buffer is the allocator. When I compiled the libimxdmabuffer, I did not specified which allocator to used because I have no idea which one I should use.

Question: I am now using imx8m plus, what allocator should I use?

Thank you!