Interlaced or not?

[MarcN]

Hello

I have ripped a PAL DVD with DVDDecrypter and now I want to index it with DGIndex (V 1.2.1). DGIndex reports the VOBs to be interlaced:

Frame Type: Interlaced
Frame Struct: Field
Field Order: Bottom

However the video does not look to be interlaced during playback in DGIndex, nor when I load the .avs (created by GKnot, without any deinterlacing filters turned on, of course) in VDub. So I guessed it’s actually progressive video just marked ‘interlaced’.

BUT if I stop the playback in DGIndex (pressing ESC) the still frame IS always interlaced.
Is this just a display error from DGIndex or could there be a deinterlacing filter I missed?

Thanks allot,
Marc.

[The Geek]

What DVD was it ? Was it a video DVD with movie content ?

Movies are progressive, however, they can be (and maybe are) encoded interlaced. Since both fields belong to the same frame, you can weave the fields and get a perfect frame, rather than with 'true' interlaced footage, where the fields are shot at different times.

So, if it's a movie DVD, it's interlaced even though it doesn't have the comb effect.

The Geek

[MarcN]

Oops, forgot to mention that.

Yes, it’s a movie. No apparent combing during Vdub- and DGIndex-playback, only after stopping DGIndex. Skipping through the movie with the left/right keys in DGIndex also shows no combing.

Marc

[The Geek]

Then DGIndex displays the wrong fields when stopping. Both fields from the same frame result in a perfect frame, no combing.

The Geek

[Guest]

Your clip is field structure. Hitting ESC does an immediate thread kill on the decode thread. I suppose that could happen between two fields of a frame, giving the result you describe. I'll add it to the work list.

[MarcN]

Thanks for the clarification!

Do I have to treat field structured video differently than frame structured one? I’m asking especially about the colour conversion from YV12 to YUY2. Another movie DVD (PAL) I ripped also looked progressive and was marked ‘interlaced’ but the frame structure was ‘Frame’. There I added the line

ConvertToYUY2 (interlaced=true)

to the .avs.

Was that correct and should I do the same with frame struct = ‘Field’?

Thanks
Marc

[scharfis_brain]

do never rely on a programs output regarding interlacing.
use your eyes.

so: if there are combs visible -> interlaced / combed -> treat source interlaced
if no combs visible -> progressive -> treat source
as progressive (ignore what the program tells you!)

[Guest]

Pure progressive material can be, and often is, encoded as interlaced. The key is the setting of the progressive_frame flag. When it is set to interlaced, you need to upsample to YUY2 as interlaced. The latest DGDcode has a mode which allows it to automatically upsample correctly per frame by following the progressive_frame flag. You set upConv=true.

[MarcN]

Thanks again!

I will let DGDcode do the colour conversion from now on.
One thing less to worry about

Marc

[Spyn]

dgindex display interlaced for most of my PAL dvd cause only the begin credits are interlaced but the movie is not interlaced at all.

[scharfis_brain]

Originally posted by neuron2
Pure progressive material can be, and often is, encoded as interlaced. The key is the setting of the progressive_frame flag. When it is set to interlaced, you need to upsample to YUY2 as interlaced. The latest DGDcode has a mode which allows it to automatically upsample correctly per frame by following the progressive_frame flag. You set upConv=true.

No!
Even interlaced subsampled YV12 with progressive Frame contents should be treaten as progressive YV12.

That was one of the reasons for me to do the motion adaptive YV12 <-> YUY2 sampling.