Hello,
We have a board with a dm368 and an Analog Devices adv7842. (Actually, we recently transitioned from the "standard" dm368 to the TMS320DM368ZCE48 that is rated for 486 MHz). We were somewhat unaware of the pixel clock rate limitations of the VPFE, and without realizing it, we have been "accidentally" supporting 1080p60 in our product (with the pixel clock at ~148 MHz) for some time now. We set up the resizer to resize the incoming video to 1280x720, and it just seems to work. But can anyone explain why this seems to work?
The reason for bringing this up now is we are now trying to support 1080 inputs at native resolution. 1080i25/30/50/60 and 1080p25/30 work fine. 1080p60 *mostly* works, but has occasional "glitches" where a video frame contains the lower part of a previous frame, which I suspect may be due to the pixel clock limitation, but I am not certain.
So, my questions are:
- Does the pixel clock limit (120 MHz) still apply if the image is being resized to a smaller size?
- Why does our first use case seem to work without issue, even though we're beyond the pixel clock upper limit?
- I don't actually need 50/60fps, and we do frame skipping anyway to output 25/30 fps. Given that, is there any way to "trick" the VPFE to divide the pixel clock frequency in half and effectively take every other frame? (Or any similar trickery to divide the frame rate in half?) We're also trying to see if there's a way to configure the adv7842 to skip every other frame.
Thanks!
