[FFmpeg-user] Capture from USB Dazzle: Interlaced or not interlaced. FFV1 level3 vs h264

[Andy Furniss]

MrNice wrote:

> To confirm I have an interlaced USB video, I tried
>
> ./ffmpeg -debug 1 -f v4l2 -ts mono2abs -channel 1 -video_size
> 720x576 -pix_fmt yuyv422 -thread_queue_size 512 -i /dev/video0 -c:v
> libx264 -preset slow -qp 0 -flags +ilme+ildct -aspect 4:3 -pix_fmt
> yuv422p

This doesn't confirm v4l passes interlaced flags as it seems -flags
+ilme+ildct tells libx264 to encode as interlaced. It seems to default
to tff - so it's only luck if it works = source was really tff.

I wasn't testing with v4l, it was a yuyv422 interlaced file (in avi
flagged as progressive).

for me the output was identical using -flags +ilme+ildct or -x264opts
tff=1 (used .mp4 to md5sum as mkv never md5sums the same due to guid).

The latter of course allowing easily to change to bff-1 as required,
though I guess there are many ways in practice.

Maybe someone could confirm that -flags +ilme+ildct is truly the same
in the case of libx264.

As you are using 422 remember if you ever convert to 420 be sure to use
scale=interl=1 or your chroma will be messed up. You may also need to
avoid using any -target xxxx.