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ADV212: Delay in Video

Hi all,

I am using ADV212 for video compression.

I have read from adv212 FAQ that in encoder it takes 1.5 Filed delay and in decoder it takes

1.5 field.

it means  delay should be 3 filed( 60 MS). but i have observed more delay in video(around 1Sec).

what i am doing is that as i get field from encoder i fed  it to decoder without buffer.

Does image index play any role in delay or might be another factor?

I have doubt that in decoder first field should be odd with zero image index.

Is it like that or any other reason for it.

with regards

JSH

  • Hi JS,

    Worst case for the encode/decode itself is 1.5 times the tile time. (field or frame).  There isn't enough internal memory to buffer more than a few frames unless they are black frames so 1 sec isn't really possible.

    Are you using master or slave mode synchs?

    You really need buffering between encoder and decoder since they won't necessarily be ready at the same time.

    Image index is ignored in the decoder so it wouldn't be a factor.  If the FIELD pin, in slave mode, doesnt match the polarity of codestream, you will add latency as well.

    Dave

  • Hi david,

    Decoder  is in master mode and i am feeding compressed packets only.

    I am not using HVF pin. I am using embedded EAV/SAV in video encoder(ADV7311) for displaying

    the video.

    with regards

    JSH

  • Hi JS,

    Master mode should eliminate most of the conflicts.  Without the FIELD pin, it will start expecting the field polarity to match what you set it to in the PICFG options.  If that was wrong you would add another field of latency at most though if you are alternating field polarity as you should.  If field polarity is not alternating, then it will simply throw away the data until if gets the polarity it's expecting.

    Bottom line is that there isn't enough memory to buffer for a 1 sec latency regardless unless all you have is black frames, so something else is going on in your system I think.

    Dave

  • Hi david,

    delay problem solved.

    when video is lock i have reset the part.

    now i don't feel delay.

    with regards

  • Hi JSH

    I have the same Problem. Can you explain what you exactly did to solve it?

    Regards

    M. H.