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ADV7179 Display Two Images


We encountered the following problems in developing our product; could you help take a look, please?

The HDMI signal output by Hisilicon SOC is transmitted to ADV7604 and converted to BT656, and then input to ADV7179 and converted to CVBS signal output. May I ask if such a scheme is feasible?

And the Hisilicon SOC could not output 720x480P30 or 720x576P25 HDMI signals, it can only output 720x480P60 and 720x576P50 HDMI formats. Finally we tested and found that the signal output of ADV7179 had problems and showed two images.

If there is a problem with this design, any method to solve it?

Many thanks;


  • Hi,

     In analog out,there is no possible for  NTSC and PAL in progressive mode. So we can support only interlaced mode for cvbs and S-video out in ADV7179.

    Generally Composite video is an analog video signal format that carries standard-definition video (typically at 480i or 576i resolution) as a single channel and S-Video (also known as separate video and Y/C) is a signaling standard for standard definition video, typically 480i or 576i.

    And also none of the video encoders can do Progressive to Interlaced(480P to 480i or 625P to 625i).                     

    Note:In interlaced scanning each frame is scanned in two successive fields i.e odd and even field (each scan line is refreshed as half),So we can avoid the line flicker on sharp edges due to a too-low frame rate.



  • Got it; thanks Poornima for your help!