AnsweredAssumed Answered

ADV7441A output issue

Question asked by kai on Mar 26, 2012
Latest reply on Jun 14, 2012 by mattp

Hi There,

We are trying to use ADV7441A as component video decoder, the output of ADV7441A is in the form of 16 bit YCbCr 4:2:2 format .

The video setup is: Component video -> ADV7441A -> 16 bit 656 bus -> Video processing chip  (Compressing to H.264 or MPEG2) -> save the video stream output into the local harddisk as TS stream file.

Symptom: The room fan power connect to the same power bar as the ADV7441A board, and the final video output will show the issue if we switch the room fan a few times.  We could also replicate the issue by removing the GROUND of the Y input signal. 

We did several experiments for narrowing down it: 

1. The analog component input shows the instantaneous noise when the room fan switching,  the amplitude of noise vary from 300mv-1V. 

2. The output file shows the permanent color shift issue after the instantaneous noise. The color shift is gone once we restart the video processor. That implies the issue is caused by video processor i think rather than ADV7441A chip. Somehow the noise pass through ADV7441A trigger the video processor into bad stage, and processor doesn't even know there is issue. There is nothing can be done on the video processor side at this point, so we have to think about how to optimize/change something on ADV7441A chip to avoid such kind of scenario happen. 

 

Please see the attached output snapshot to show the issue.

Any idea on it? 

video_output_shift.jpg

cheers,

Kai,


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