About video_full_range_flag of H.264 decoder in i.MX6DL.

[keitanagashima]

Dear Sir or Madam,

Hello.

BSP : Android (jb4.2.2_1.1.0)

There is a header information [SPS(Sequence Parameter Set)] in the H.264 data.

And there is vui_parameters in SPS(Sequence Parameter Set).

Then, there is video_full_range_flag of the element of vui_parameters.

The intended function of "video_full_range_flag" is to tell the decoder that the content is using the full video range (Computer RGB) and the decoder should not expand the range otherwise clipping will occur.

[Q1]

Is the FSL's H.264 decoder changing RGB<->YUV processing by the value of this flag?

[Q2]

If Q1's answer is No, is it possible to process in the YUV change by the value of the flag?

Best Regards,

Keita

[eaglezhou · Accepted solution]

Hi, Keita

    vpu only output YUV buffer and it won't do RGB<->YUV conversion.

    anotherway, vpu can report the flag 'video_full_range_flag' through related register (but related api still not be exported by driver currently)

Eagle

[keitanagashima]

Hi Eagle,

Let me clarify my understanding.

------

vpu only output YUV buffer and it it doesn't need to do YUV<->RGB conversion.

Because there is not YUV→RGB conversion processing, there is not a code of YUV<->RGB conversion by video_full_range_flag.

------

Best Regards,

Keita

[eaglezhou]

Hi, Keita

    In fact, there are no implement of YUV<->RGB conversion in vpu RTL. e.g. vpu can only output YUV.

    I think the YUV<->RGB conversion should be post-process, not covered by vpu decoder.

    So, whatever the value of flag 'video_full_range_flag', vpu won't do YUV<->RGB conversion.

    Now, what vpu can do is report the flag value for post-process.

    The work flow is like:  video data -> (VPU) -> YUV -> (IPU/GPU/...) -> RGB.

Eagle

[keitanagashima]

Hi Eagle,

My customer understood the VPU isn't processing in the YUV->RGB conversion.

In the YUV -> RGB conversion with IPU/GPU as the Post processing of Decoder, is it changing processing by the value of video_full_range_flag?

Keita

[eaglezhou]

Hi, Keita

   As far as I know, GPU only support two CSC mode(601 and 709), while IPU is configurable.

   In such case, I think user need to compute related parameters themselves and configure them to IPU.

   robby (IPU) and XianzhongLi (GPU) can give more details info if necessary.

Eagle

[keitanagashima]

Dear Eagle,

Hello.

My customer tested H.264 clips with video_full_range_flag=0 or video_full_range_flag=1 in jb4.2.2_1.1.0.

If it change the convert processing with the video_full_range_flag, output display's brightness should change between 2 contents.

But, my customer wasn't seen the brightness difference.

So, we consider that video_full_range_flag isn't cared by jb4.2.2_1.1.0.

Keita

[eaglezhou]

Hi, Keita

    I think our release (include android) won't process flag 'video_full_range_flag' currently.

    - VPU ignore and doesn't report this flag to render

    - Render(IPU/GPU) don't have related CSC API as well

    - Fortunatelly, IPU seems have interface to allow user configure the CSC parameters (need to double confirm with Robby)

      In this case, user need to compute the parameters themselves.

Eagle

[xiezhiyong]

Hi,Eagle

>   - Render(IPU/GPU) don't have related CSC API as well

>   - Fortunatelly, IPU seems have interface to allow user configure the CSC parameters (need to double confirm with Robby)

Could you tell us which CSC GPU / IPU's API or register can set  CSC parameters?

Now we use the default setting.

Thansks

Xie Zhiyong

[keitanagashima]

Hi Eagle,

I apologies for the delay in replying to you.

I have an additional question.

> I think our release (include android) won't process flag 'video_full_range_flag' currently.

Why wasn't convert processing by Flag included?

Which is correct?

1. Originally android isn't supporting this Flag processing.

2. FSL didn't support it when FSL customized android.

3. Other things.

Best Regards,

keita

[eaglezhou]

Hi, Keita

   1. I am not sure whether original android support this flag

      customer can check it through try their clip on different android platform.

   2. We never considered this flag when we start to customize our android.

      In fact, this is the first time I hear the flag.

Eagle

[keitanagashima]

Could someone follow up the question?

Keita