Possible or necessary to change TFF video to BFF?

[brassplyer]

Tweaking DVD video for someone and find the vob files and subsequent mpegs are top field first.

Is it possible or even necessary to change this to bottom field first?

Thanks.

[jagabo]

Possible, yes. Necessary, no.

[brassplyer]

Further searching led me to this script

# TFF (or BFF) interlaced YV12 video
ConvertToYUY2(interlaced=true)
Crop(0,1,-0,-0) # remove top scan line
AddBorders(0,0,0,1) # add one scan line to the bottom
# TFF converted to BFF (or BFF converted to TFF)
ConvertToYV12(interlaced=true)

[jagabo]

Yes, you can do that or:

SeparateFields()
Trim(1,0)
Weave()

But DVD supports both TFF and BFF so there's no reason to convert.

[DB83]

I also read (maybe I imagined it) that TFF produces the better player compatability.

I will even encode BFF (DV) as TFF mpeg2 for dvd. In fact that is all that procoder will allow (unless I missed something)

It might help if you also stated why you feel that you need to change this

[brassplyer]

It might help if you also stated why you feel that you need to change this

Just that BFF is the "norm" and wondered if there was any potential problem with video being TFF.

[jagabo]

BFF is not the norm. Almost all commercial interlaced DVD's I've seen are TFF.

[sanlyn]

BFF norm for DV. TFF norm for almost everything else.

[brassplyer]

Well 'ya learn something new everyday. The DVD's I've burned show up as BFF as does any DV video I've captured which is what I was going by. On one commercial DVD I checked that would actually let me see anything about the file info with Mediainfo it shows TFF.

So, why do they make the DVD's with TFF instead of BFF?

[jagabo]

Why does DV use BFF instead of TFF?