codecs: h264decoder: Gap in field picture is not handled
Decoder should be robust against incomplete field pair
(need to address https://gitlab.freedesktop.org/gstreamer/gstreamer/-/blob/main/subprojects/gst-plugins-bad/gst-libs/gst/codecs/gsth264decoder.c#L1219)
Test file: field_gap.mkv
gst-launch-1.0 videotestsrc num-buffers=100 ! video/x-raw,format=NV12,framerate=30/1 ! interlace field-pattern=1 ! video/x-raw,interlace-mode=interleaved ! qsvh264enc ! video/x-h264,stream-format=byte-stream ! h264parse ! matroskamux ! filesink location=field_gap.mkv
Note that h264parse will split interlaced frame into two AUs (per field) and then the second field will be dropped by muxer because of unknown PTS.