ADV7281A-M video format detection feature

Hello,

I have questions below. Would you mind answering to my questions?

[Background / Concern]
We want to use NTSC J/M but lock is unstable when changing INSEL from 0xE to 0xF.
* Lock in the following order
   lock(NTSC4.43)-> unlock -> lock(NTSC J/M)

[Question]
1. Does ADV7281A-M lock only NTSC when "Autodetect enable" register(0x07) is set to 0x02 and "VID_SEL" is set to autodetect(default)?
2. If I set above condition, is NTSC limited to NTSC J/M?
3. Does the following condition solve the customer's issue?
    -> "VIL_SEL" is set to autodetect(default) and "Autodetect enable" is set to AD_NTSC_EN; NTSC autodetect enable?

4.Is there any concern when NTSC-M is input to ADV7281A-M with "Video Selection2" is set to default?
   Such as the brightness of the image is slightly different due to pedestal level incorrectly captured.

Best regards,
Gattu

  • 0
    •  Analog Employees 
    on Aug 19, 2021 2:23 PM

    Hi,

    1. Does ADV7281A-M lock only NTSC when "Autodetect enable" register(0x07) is set to 0x02 and "VID_SEL" is set to autodetect(default) ?

             If "Autodetect enable" register(0x07) is set to 0x02, ADV7281A part will adapt according to the input signal w.r.t PAL or NTSC.

    2. If I set above condition, is NTSC limited to NTSC J/M?

    3. Does the following condition solve the customer's issue?
        -> "VIL_SEL" is set to autodetect(default) and "Autodetect enable" is set to AD_NTSC_EN; NTSC autodetect enable?

                   Instead of configuring the "Autodetect enable"  register to 0x07 & try to configure "VID_SEL" register for particular input and let us know the result,

                     For PAL Input - 42 02 84 // PAL B/G/H/I/D

                    For NTSC-M  -  42 02 54 //NTSC-M

                     For NTSC-J -    42 02 44 //NTSC -J

    4.Is there any concern when NTSC-M is input to ADV7281A-M with "Video Selection2" is set to default?

        Such as the brightness of the image is slightly different due to pedestal level incorrectly captured.

               Yes,The main difference between NTSC-M and NTSC-J is that  the black level,

                       NTSC-M Black level: 7.5IRE
                       NTSC-J  Black level: 0IRE.

    Note:  IRE unit is nothing but an arbitrary unit used to describe the amplitude characteristics of a video signal.The black level and blanking level of the NTSC-J signal are identical (at 0 IRE) while in American NTSC, black level is slightly higher (7.5 IRE) than blanking level.

    Thanks,

    Poornima

  • Hi,

    >  If "Autodetect enable" register(0x07) is set to 0x02, ADV7281A part will adapt according to the input signal w.r.t PAL or NTSC.

    Reference manual UG-637 shows that if "Autodetect enable" register(0x07) is set to 0x02, ADV7281A-M will adapt to the NTSC only. Is it correct?

    Thanks,

    Gattu

  • 0
    •  Analog Employees 
    on Aug 24, 2021 8:12 AM in reply to gattu

    Hi,

    Reference manual UG-637 shows that if "Autodetect enable" register(0x07) is set to 0x02, ADV7281A-M will adapt to the NTSC only. Is it correct?

      Yes, by setting AD_NTSC_EN to 1 enables the detection of standard NTSC.

       But you can't adapt to the particular NTSC format like "NTSC J,NTSC M, NTSC M(pedestal), NTSC J(no pedestal), NTSC 4.43".

    Thanks,

    Poornima

  • Hi,

    Sorry for my late reply.
    I did several test in my lab to solve the issues and I would like to share with you.

    [issues]
    #1 Lock is unstable when changing INSEL from 0xE to 0xF
    *lock(NTSC4.43)-> unlock -> lock(NTSC J/M)
    #2 The black level differs between NTSC J and NTSC M when VID_SEL is the default.


    First, regarding VID_SEL setting what you mentioned befere, we tried to configur "VID_SEL" register for particular video standard but just setting VID_SEL, it couldn't resolve the incorrect lock on NTSC443. (Our input is NTSC L/M)
    And then, it seems that we can avoid unwanted locking to NTSC443 by setting Autodetect enable = NTSC(0x02). Please see the attached file in detail.

    Question #1
    Can the setting, "Autodetect enable" set to NTSC(0x02), solve our issue that the device lock to NTSC443 even though inputting NTSC J/M?


    Second, I understand the defference black level(IRE) and we did some test in my lab.
    The results are here,
    - There is defference in black level with VID_SEL=0000(default)
    - there is no defference between NTSC J and NTSC M in black level with VID_SEL=0001(include NTSC-M)

    Question #2
    Is it okay to input NTSC-J when VID_SEL is set to 0001 (include NTSC-M)?

    Regards,
    Gattu

    XLSX

  • 0
    •  Analog Employees 
    on Sep 2, 2021 11:44 AM in reply to gattu

    Hi,

    Ques #1:

      Please note that you should configure the registers according to your input streams & that is the reason we are getting the incorrect value in AD_Result status register(0x10).

      But in your case, you are giving NTSC4.43 input and you have configured the 0x07(Autodetect enable) register value as 0x02. So please leave it to default value '0x7F' and let us know the result for different streams of PAL & NTSC.

    Ques #2:

    Please refer below expert comment,

    Pedestal Mode:

     If CVBS source with a pedestal. Some CVBS video sources have a 7.5 IRE pedestal offset on the video. The ADV728x is not able to detect if a source has a pedestal or not. The result of this is that the output from the ADV728x is slightly too bright.

      But this can be fixed by indicating to the ADV728x that the CVBS has a pedestal. This can be done by modifying the vid_sel register bits. This basically performs a -7.5 IRE offset on the luma.  See "Video Standard Selection" section of UG-637.

    Thanks,

    Poornima