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TVP5146M2 Video Quality Issues

Brad Nelson1
Prodigy 10 points
Other Parts Discussed in Thread: TVP5146M2, AM3517, TVP5146

We are having issues with video quality while using the TVP5146M2 to get video data into an AM3517 processor.  The AM3517 captures NTSC video, and then displays it via an HDMI interface.

There's nothing that jumps out as wrong with the video, but when we compare the same camera going through our device to an HDMI monitor, side by side with an NTSC monitor getting the video signal directly, it is apparent that the video quality is diminished.  Vertical lines in particular appear to be slightly blurred.  For example, a fence post in the distance is not readily visible going through our device and HDMI monitor, but it can be seen on the NTSC monitor.

We've tested many things - anti-aliasing circuit, software, etc, and pretty much have it nailed down to the TVP chip.  Grabbing a frame straight from the TVP chip before it is sent out to the HDMI monitor, and then looking at it on a computer monitor confirms the HDMI monitor and output circuitry are not part of the problem.  We're not sure where to look next.

The board is about to go through a revision, and we'd like to find this issue.  Where should I be looking to try and find this problem?

  • 0
    TI__Mastermind 43875 points

    What is the monitor native display resolution and what is the AM3517 output display resolution?

    Feeding the video source directly in to the monitor means you will be basically comparing the monitor's video decoder to the TVP5146 decoder and it may simply be that the monitor has a higher quality decoder, i.e. this may be a limitation of the TVP. Additionally, the monitor will potentially have a higher quality scaler to scle from the NTSC source input to the native monitor resolution, whereas passing through the AM3517 will likely be using a linear interpolation scaler.

    Try experimenting with the luma processing control registers (07h & 08h).

    Try experimenting with the chroma processing register at 0eh.

    Try experimenting with the CTI corning and gain registers at 2eh.

    BR,

    Steve