[FFmpeg-user] encoding bff input to mov labels the output as progressive

[Dave Rice]

Hi all,

I am encoding bff v210 video to other codecs (uncomrpessed, ffv1, prores, j2k) in quicktime. Also the input is identified as bff the output is identified as progressive unless I force it with -vf setfield=bff. For the test below I'm using ffmpeg 2.0 built on July 19th, 2013.

Here is a command to create a sample bff input:

ffmpeg -f lavfi -i mandelbrot=s=720x486:r=ntsc -t 5 -c:v v210 -vf setfield=bff v210bff.mov

Checking with mediainfo:

mediainfo --inform="Video;%ScanType%,%ScanOrder%" v210bff.mov
Interlaced,BFF

When I encode like (same codec in and out):
ffmpeg -i v210bff.mov -c:v v210 v210bff-2-v210.mov

Then the output shows this in mediainfo:
mediainfo --inform="Video;%ScanType%,%ScanOrder%" v210bff-2-v210.mov 
Progressive,

I can force the output to bff with:
ffmpeg -i v210bff.mov -c:v v210 -vf setfield=bff v210bff-2-v210forced-bff.mov

but from reading past threads of the quicktime 'fiel' atom it seems that preserving the field order is the intent although not the default behavior that I'm getting. If I don't check to see if the input is bff (using ffmbc or mediainfo) and then include setfield=bff then the resulting progressive output causes playback issues on interlaced monitors.

I can put this into the tracker but wanted to check that my test process and expectations are sane.

Dave Rice