Question, i.MX6Q USB data transfer is wrong while playing video

[Aemj]

Dear team,

I would like to ask about the issue of USB data transfer which my customer faces.

On the customer’s board, USB camera is connected to i.MX6Q. And they use Android4.0(based on your androidBSP) for OS.

They saw the camera data seemed to be corrupted or missing when i.MX6 was playing H.264 video at 60fps(the resolution was QVGA).

When the frame rate of playing video was 30fps, the USB camera’s data seemed to be OK.

This phenomenon of USB camera data is also seen when Hello-gl2, sample program included in NDK, is executed on i.MX6.

From the above, they believe the cause of this issue is related to the internal BUS load of i.MX6.

Do you have any ideas on the cause of this issue?

On the customer’s board, The USB camera data needs to be captured correctly even when the video is playing at 60fps simultaneously.

Thanks,

Miyamoto

[Yuri]

Miyamoto,

Your idea, that “the cause of this issue is related to the internal BUS load of i.MX6” is quite reasonable.

If system / memory bus  load is high, because many modules, using DMA, are working simultaneously

(VPU, DMA, IPU, GPU, SD as system storage)  some data may be lost because of modules FIFO over-/under-load. 

You may try the following in order to improve situation : 

1) disable bus frequency feature. Take a look at section 17 (How do I enable or disable 

    the bus frequency feature?) of the “Android_Frequently_Asked_Questions.pdf” in Android
    documentation.  

2) to optimize memory usage. Please refer to    

“Memory Management on i.MX6 Android” 

https://community.freescale.com/docs/DOC-93591

The following material may be useful

   “Memory Issue in i.MX5 Android”

< https://community.freescale.com/servlet/JiveServlet/previewBody/

93334-102-1-2448/iMX5%20Android%20GB%20Memory%20Usage%20and%20Optimization.pdf >

Have a great day,

Yuri

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