Delinterlacing does not work correctly on the Raspberry Pi 4

  • I appreciate the work done on delinterlacing, however I've had to turn it off because it's not working correctly. The problem is that when turned on, jitter is introduced by the delinterlacing functionality. One way this is evidenced is by the way horizontal crawls, frequently used on news programs, jitters as the text moves from right to left.

    IMHO, I believe the problem is caused by the delinterlacing algorithm reversing the field order. I say this because as the author of digital compositing software, I've seen the same artifact when my code inadvertently reversed the field order. I fixed the problem by making sure the field order was correct.

  • There is a debug feature to force the field order:

    linux/bcm2835-v4l2-codec.c at 8e1110a580887f4b82303b9354c25d7e2ff5860e · raspberrypi/linux
    Kernel source tree for Raspberry Pi-provided kernel builds. Issues unrelated to the linux kernel should be posted on the community forum at…
    github.com

    Try running "find /sys -name field_override" to find the location of the debug node.

    When video is running you can poke 8 (TB) or 9 (BT) to force the field order. e.g.

    echo 8 > /sys/.../field_order

    Does one of those look better than the default?

    But, as Hias says, a sample file would be useful.