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adv7842 SDP deinterlacing

Question asked by mbu on Mar 3, 2014
Latest reply on Apr 25, 2014 by raymondcarter

We are using the built in de-interlacer in the adv7842 for Composite/S-video.

 

We are having problems to obtain a stable image on the de-interlaced result.

It seems to be jumping one line between the frames. It looks very much like the problem described in:

http://ez.analog.com/message/112544#112544

 

The output from the adv7842 is fed into an fpga where we have added a format-measure functionality and

we can observe the actual format coming from the adv7842.

 

I have tried a lot of combinations on the registers in SDP-IO 0xa8, 0xa9, 0xaa, 0xab, 0xac, 0axd, 0xae, 0xaf

(VSYNC_ADJUST and DE_VERTICAL_ADJUST) and I can adjust the two frames in relation to each other.

 

Keeping SDP-IO 0xa8 -> 0xaf to default (4) the output is on every frame:

vid measure format                 720x576 (864x624)
     horizontal                     fp = 12, +sync = 64, bp = 68
     vertical                       fp = 5, +sync = 4, bp = 39

But now the image jumps vertically one line between the frames.

 

The best result I have had is if I set for instance:

SDP-IO

0xa8 = 5

0xa9 = 4

0xaa = 4

0xab = 4

0xac = 5

0xad = 4

0xae = 4

0xaf = 4

 

Now the de-interlaced result is changing with one line between the frames:

 

vid measure format                 720x576 (864x625)
      horizontal                     fp = 12, +sync = 64, bp = 68
      vertical                       fp = 6, +sync = 4, bp = 39

 

vid measure format                 720x575 (864x623)
      horizontal                     fp = 12, +sync = 64, bp = 68
      vertical                       fp = 5, +sync = 3, bp = 40

 

But combined resulting image now looks stable, so the de-interlaced frames do match.

 

However this is causing us problems in the further signal-path, we do down-sample the input to 420 and

require an even number of lines on the input, or at least the same number of lines on every frame.

 

Attached file shows register settings for IO, SDP and SDP-IO maps.

 

Do you have some settings which can generate a stable format out and an even number of lines ?

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