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YUV420 to YUV422 Conversion

Manoj R
Intellectual 390 points

Hi,

I am working on a video decoder,the output of the decoder is yuv420 format.But i understand that display drivers in OMAP 3530 support only 422 format.I've the following questions on this.

1) Is there any option to display 420 format with some other drivers ??

2Is there any hardware support for the conversion

2) I would like to do the conversion outside of the decoder as it'll be a huge overhead.I would like to know how do i use EDMA from ARM side.I've used it in many places in DSP in the decoder.But i don't know how do i do this from ARM side.Is accessing the resigeters and other things is the same way as from DSP ??

Thanks & Regards,

Manoj

  • 0
    TI__Expert 8180 points

    Hi,

    Yes, display driver supports 4:2:2 format only. you will have to do conversion from 4:2:0 to 4:2:2 outside of display context and provide the converted buffer to display driver for display. OMAP hardware doesn't support this feature.

     

    You may want to refer to the link -

    http://www.ti.com/sc/docs/psheets/abstract/apps/spraak3b.htm

    This document explains how to convert 4:2:2 to 4:2:0 format using Resizer driver in detail for DM6446, same is applicable for OMAP. You will have to use similar thing for converting 4:2:0 to 4:2:2 color format.

    Thanks,

    Vaibhav

  • 0 in reply to Vaibhav Hiremath
    Intellectual 390 points

    Hi Vaibhav,

    Thanks for ur response.

    One more query i've is , so which one will be more efficient ?? doing the 422 to 420 conversion using resizer or ARM or DSP??

    Also when i went through the doc u shared ,i was a bit confused about how to specify the output format ?? I could see only the input format being mentioned.

    Please clarify.

    Thanks & Regards,

    Manoj

     

  • 0 in reply to Manoj R
    TI__Expert 8180 points

    Hi Manoj,

    Let me clarify your question on documentation first,

    Please note that, we are trying to achieve 4:2:0 to 4:2:2 and vice a versa by playing with coefficients. So there will not be direct configuration where you can say my input is this and give me that output. Resizer driver doesn't convert format, it barely resizes the image.

     

    Now which one to use for this conversion, actually it's bit trade-off,

    If you use Resizer hardware, then you will have to follow some hardware constraints. (Please refer to the Resizer Spec). With Software you will end up utilizing CPU cycles.You will have to choose depending on your use-case.

    Personnely I am really not sure about how SW (either on DSP or ARM)  behaves in terms of CPU utilization and stuff, so will not be able to assist you on this.

    Thanks,

    Vaibhav