[ADV7282A-M] Further details on I2P conversion.

Hi,

Could you tell me the status of these my questions?

Thank you!
Best regards.
Tamu

Hi Tamu San,

        Please find the below comments,

1. Could you tell us more details of I2P interpolation? 

       In linear interpolation, when an output sample falls between two input samples (horizontally or vertically), the output sample is computed by linearly interpolating between the two input samples. However, scaling to images smaller than one-half of the original still results in deleted samples.

      This results in uneven line spacing, which may result in visual artifacts.

      Please note that, An improvement in video quality of scaled images is possible using linear interpolation technique.

2.  Can we disable the "smoothing filter"?

        I2P does not contain any smoothing filter and also i don't see any smoothing filter block in ADV7282A-M.

        Try to adjust Chroma filter, Luma Filter, Chroma Transient Improvement, Digital Noise Reduction and Luma  Peaking Filter,
 and Comb filter sections. You may get some improvements.

3. Are there any register settings for removing or reducing this dot crawl phenomenon?

         By using 2D comb filter reduces we can reduce video noise (cross-color interference or color bleeding) and dot crawl (dot interference). 2D comb filters are good at separating the luma and chroma information.

Please note that, As per expert comment " Use a deinterlacer in your back-end processor rather than using the I2P block of the ADV7280. The backend processor will have to store an odd frame of video in a buffer, then store an even frame of video and then switch these two frames together to generate a progressive field. This will minimize interlaced to progressive errors but will add a delay to your system.

Be sure to introduce a line counter or similar software control to ensure that you do not get buffer overflows.

Also note that to use an interlaced to progressive converter in the back-end processor. You will need to store fields of video in memory and stitch these together to generate progressive video. This will add significant latency to the video. Also you will need to implement a control loop to ensure that the memory buffer does not get overloaded by the output from the ADV7280 (there are situations where ADV7280 will output fields that are too long/short). A line counter algorithm will do this well.

Thanks,

Poornima

Hi Tamu San,

        Please find the below comments,

1. Could you tell us more details of I2P interpolation? 

       In linear interpolation, when an output sample falls between two input samples (horizontally or vertically), the output sample is computed by linearly interpolating between the two input samples. However, scaling to images smaller than one-half of the original still results in deleted samples.

      This results in uneven line spacing, which may result in visual artifacts.

      Please note that, An improvement in video quality of scaled images is possible using linear interpolation technique.

2.  Can we disable the "smoothing filter"?

        I2P does not contain any smoothing filter and also i don't see any smoothing filter block in ADV7282A-M.

        Try to adjust Chroma filter, Luma Filter, Chroma Transient Improvement, Digital Noise Reduction and Luma  Peaking Filter,
 and Comb filter sections. You may get some improvements.

3. Are there any register settings for removing or reducing this dot crawl phenomenon?

         By using 2D comb filter reduces we can reduce video noise (cross-color interference or color bleeding) and dot crawl (dot interference). 2D comb filters are good at separating the luma and chroma information.

Please note that, As per expert comment " Use a deinterlacer in your back-end processor rather than using the I2P block of the ADV7280. The backend processor will have to store an odd frame of video in a buffer, then store an even frame of video and then switch these two frames together to generate a progressive field. This will minimize interlaced to progressive errors but will add a delay to your system.

Be sure to introduce a line counter or similar software control to ensure that you do not get buffer overflows.

Also note that to use an interlaced to progressive converter in the back-end processor. You will need to store fields of video in memory and stitch these together to generate progressive video. This will add significant latency to the video. Also you will need to implement a control loop to ensure that the memory buffer does not get overloaded by the output from the ADV7280 (there are situations where ADV7280 will output fields that are too long/short). A line counter algorithm will do this well.

Thanks,

Poornima

Hi Poornima-san,

Thank you for your reply!

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>>1. Could you tell us more details of I2P interpolation?
>In linear interpolation, when an output sample falls between two input samples (horizontally or vertically), the output sample is computed by linearly interpolating between the two input samples.
>However, scaling to images smaller than one-half of the original still results in deleted samples. This results in uneven line spacing, which may result in visual artifacts.
>Please note that, An improvement in video quality of scaled images is possible using linear interpolation technique.

=> The customer doesn't use scaler in the SoC.
     So the "scaling to images smaller" is not executed.
     Do you mean that the "linear interpolation" of ADV7282A-M is just only "outn = (inn–1 + inn+1) / 2"?
     (I think this is right because you said it as follows:)
     [ADV7282A-M] More details of the I2P interpolation. 

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>>2. Can we disable the "smoothing filter"?
>I2P does not any smoothing filter and also i don't see any smoothing filter block in ADV7282A-M.

=> This is not my main question.
     The main question of No.2 is "Could you tell us why the bottom of one black line affects all of top 5 red line?".
     This is what I want to know by my question 2.

Also, I think that there is the "smoothing filter" in ADV7282A-M because the expert said it as follows:
https://ez.analog.com/video/f/q-a/9323/adv7280-deinterlacing-question/7255#7255
The expert comments : "A smoothing filter is also applied to reduce the effect of low angle noise (i.e. jaggies)."

So I think that an answer for my question 2("Could you tell us why the bottom of one black line affects all of top 5 red line?") is that
the "smoothing filter" is multi-tap filtering and it is applied across multiple 5 lines, and it causes the bottom of one black line affects all of top 5 red line.
Is this right?
Please see my attached file "ADV7282A_M_I2P_Conversion_Questions.xlsx" on my first comment on this thread.

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>>3. Are there any register settings for removing or reducing this dot crawl phenomenon?
>By using 2D comb filter reduces we can reduce video noise (cross-color interference or color bleeding) and dot crawl (dot interference).
>2D comb filters are good at separating the luma and chroma information.

=> Thank you!
     Could you tell me which registers of ADV7282A-M you mean?
     If possible, please tell me the related register's address and bit(s). I think it very helpful for the customers.

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>Please note that, As per expert comment " Use a deinterlacer in your back-end processor rather than using the I2P block of the ADV7280.

=>I asked the customer whether this is possible or not.
    He said this is not possible because the SoC he is using can not receive interlace video.
    So he has to use deinterlacer block of ADV7282A-M.
    He tries to improve the image quality in this situation. So he asks these three questions to us.

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Thank you!
Best regards.
Tamu

Hi Tamu San,

       Please find the below comments,

As per expert comment, Usually we will get image artifacts when we enable I2P feature So this is an known issue and the solutions been suggested in the thread (+) ADV7280-M with CVBS Analog - Deinterlacing Issue - Q&A - Video - EngineerZone to come out of such artifacts.

Also to avoid such image artifacts expert suggested to use ADV7186 part.

ADV7186 part can perform frame based deinterlacing which should avoid the artifacts that we are seeing in the ADV7280 (the ADV7280 uses line based deinterlacing).

Note the tradeoff here is that the ADV7186 is more expensive and complex than the ADV7280. Also the frame based deinterlacing will generate a significant latency through the system. This is usually not desirable for automotive safety applications.

 However, scaling to images smaller than one-half of the original still results in deleted samples. This results in uneven line spacing, which may result in visual artifacts.

    This is something we explained about I2P protocol by using line interpolation technique that are explained in video-demy5.pdf

     There is no scaler or any such functionality that are performed in I2P algorithm.

   Generally, I2P operates in two basic modes: Scan line duplication and Scan line interpolation,

   Please note that the I2P core in the ADV7280 is designed to use a line doubling technique to convert Interlaced video to Progressive video.

Could you tell me which registers of ADV7282A-M you mean ?

    There are lot of filtering registers (Chroma filter, Luma Filter, Chroma Transient Improvement, Digital Noise Reduction and Luma Peaking Filter, and Comb filter) which are available in ADV7282A-M manuals So i don't know the exact values about improvement and also in our eval board we keep this filtering register value as default one.

Below are the register configuration that we are enabling in our eval board to support I2P functionality.

     84 5B 00 ; Advanced Timing Enabled

     84 55 80 ; Enable I2P .

As per my understanding Smoothing filter is an separate filter that we need to integrate according to our requirement and i don't see such filter in the ADV7280A-M part.

Thanks,

Poornima

Hi Poornima-san,

Thank you for your reply.
About question3, I could understand. Thank you so much.

I told about ADV7186 to the customer.
But he can't accept it because he requires a video decoder with MIPI output, ADV7186 is too expensive and he doesn't have enough time to change his design.

The customer is going to try to improve these artefacts by image processing of SoC after the SoC receives MIPI video progressive data from the ADV7282A-M.
The SoC can not receive an interlace video. And the SoC can receive the video data by only MIPI port.
So he has to use ADV7282A-M and deinterlacer(I2P) in it.
So he asks us these questions about the more details of I2P interpolation in order to improve the image quality of the guide lines by SoC.

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About question 1:
>>1. Could you tell us more details of I2P interpolation?

Does the I2P interpolation of ADV7282A-M is just only "outn = (inn–1 + inn+1) / 2"?
(I think this is right because you said it as follows:)
ez.analog.com/.../adv7282a-m-more-details-of-the-i2p-interpolation
If this is right, I told it to the customer and this quesion1 may be closed.

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About question 2:
>I2P does not any smoothing filter and also i don't see any smoothing filter block in ADV7282A-M.
>As per my understanding Smoothing filter is an separate filter that we need to integrate according to our requirement and i don't see such filter in the ADV7280A-M part.

The Device Manual UG-1176 says as follows:
"Edge adaptive technology minimizes video defects on low angle lines." on the page 35 as follows:

So I think that ADV7282A-M has a function to minimize video defects on low angle lines for the deinterlaced video.

My question2 is "If your answer is that only "outn = (inn–1 + inn+1) / 2" is right for Q1 question, could you tell us why the bottom of one black line affects all of top 5 red line?".
Please see my attached file "ADV7282A_M_I2P_Conversion_Questions.xlsx" on my first comment on this thread.

I think that the "Edge adaptive technology" function has multi-tap filtering and it is applied across multiple 5 lines, and it causes the bottom of one black line affects all of top 5 red line.
Is this right?
If this is right, I'll tell it to the customer and I think this quesion2 will be closed.

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Sorry for many times. And thank you for your support!

Thank you!
Best regards.
Tamu

Hi Tamu San,

        Please find the below comment,

Does the I2P interpolation of ADV7282A-M is just only "outn = (inn–1 + inn+1) / 2"?

       YES, this equation is equivalent to generate a new scan lines between two input scan lines. Generally, in linear interpolation the new scan lines are generated by averaging the previous and next active scan lines (i.e  (inn–1 + inn+1) / 2 ).

       Also ADV7280 de-interlacer is basically a line doubler with some Edge adaptive technology to clean up low angle edges but i am not sure whether this technology has multi tap filtering and this technology is affecting all the top 5 red lines.

      Please let me know, What type of visual effect are you getting at output after I2P conversation. If Possible Please share the output image.

Thanks,

Poornima

Hi Poornima-san,

Thank you for your reply.
About question1, I could understand. Thank you so much.

> Also ADV7280 de-interlacer is basically a line doubler with some Edge adaptive technology to clean up low angle edges
> but i am not sure whether this technology has multi tap filtering and this technology is affecting all the top 5 red lines.
> Please let me know, What type of visual effect are you getting at output after I2P conversation. If Possible Please share the output image.

=> Please see about the output image as follows:

I have already sent these image in the attached file "ADV7282A_M_I2P_Conversion_Questions.xlsx" on my first comment on this thread.
Please see the attached file "ADV7282A_M_I2P_Conversion_Questions.xlsx" again.

About the "phenomenon 1-1",
I think that the "Edge adaptive technology" function has multi-tap filtering and it is applied across multiple 5 lines, and it causes the bottom of one black line affects all of top 5 red line.
In other words, I think that the "phenomenon 1-1" (All the top 5 red lines are blackish overall) is caused by the multi-tap filtering of Edge adaptive technology.
Is this right?
If this is right, I'll tell it to the customer and I think this quesion2 will be closed.
(The customer just wants to know why the bottom of one black line affects all of top 5 red line in order to try to improve these phenomenon by image processing of the SoC.
So If the reason is clarified, I think the customer will be satisfied and this question2 will be closed.)

I'm sorry for many times. And thank you very much for your support!

Thank you!
Best regards.
Tamu

Hi Tamu San,

        ADV7280 related manuals does not contain any details about edge adaptive technology but this technology details we got it from Internet.

        In edge adaptive processing where pixels are interpolated along an edge to remove the appearance of "jaggies" (jagged edges) and here multiple edges are filtered to get the better video quality, So it seems the edge adaptive technology function has multi-tap filtering & this might be the reason where multiple lines get affected from bottom line.

        Note: Typically here, Multiple edges are filtered along to determine which one is the strongest. As the number of detection edges increases, so does the video quality. Therefore, the proper selection of directions is critical to achieving the highest image quality, with special attention being paid to shallow or low-angle directions. The result is sharp detail with less flicker and fewer artifacts.

Thanks,

Poornima

Hi Poornima-san,

Thank you for your reply!
About question2, I could almost understand. Thank you so much.

I think this is the last question.

Can we disable the only "Edge adaptive technology" (and multi-tap filtering) while the I2P function (deinterlacer) is used?
If we can disable it, please let us know how to set it to be disabled.
If it can not be disabled, it's OK, please let me know it.

Thank you!
Best regards.
Tamu

Hi Tamu San,

         Edge adaptive seems to be an inbuilt technology for I2P functionality So i don't think we can disable it.

         But we can disable the other filtering registers like Chroma filter, Luma Filter, Chroma Transient Improvement, Digital Noise Reduction and Luma Peaking Filter, and Comb filter.

Thanks,

Poornima

Thank you !