Yadif - normal or double frame rate

[pooksahib]

Hi. I'm working on a cheapo DVD and QTGMC gave the output a strange wobbly effect at certain points. I then used Yadif and the result was fine. My question is about frame-rate - QTGMC's default is 'double' whereas the default for Yadif is 'single'. I always assume (rightly or wrongly) that 'default' = 'recommended'.

If you were using Yadif would you go single or double?

[manono]

Depends on the source. Maybe neither. You should know by now to include an untouched video sample when asking questions.

I always assume (rightly or wrongly) that 'default' = 'recommended'.

Wrongly.

[jagabo]

Hi. I'm working on a cheapo DVD and QTGMC gave the output a strange wobbly effect at certain points.

Then you probably did something wrong.

My question is about frame-rate - QTGMC's default is 'double' whereas the default for Yadif is 'single'. I always assume (rightly or wrongly) that 'default' = 'recommended'.

If you were using Yadif would you go single or double?

If your video is really interlaced and you want smooth motion on playback use double. If you have playback limitations use single.

But, as manono pointed out, you need to figure out exactly what your source is before deciding to deinterlace.

[pooksahib]

Thanks. DGIndex and MediaInfo both called it interlaced and, on frame by frame, so did I although the 'combs' were very small. I'm happy with the result of 'double yadif'.

[jagabo]

Thanks. DGIndex and MediaInfo both called it interlaced

That only tell you how it's encoded. It doesn't tell you if the frames are interlaced.

and, on frame by frame, so did I although the 'combs' were very small. I'm happy with the result of 'double yadif'.

That also may not mean it's interlaced. Step through field by field during a horizontal a panning shot. If there is motion with every field it's really interlaced. If there's only motion every two fields it's really progressive and TFM() is a better choice than QTGMC() or Yadif(mode=1).

[pooksahib]

Thanks again, jagabo. After running SeparateFields(), I'm sticking with yadif. I can't think of what the 'something wrong' could be as regards QTGMC - I scripted it in the same way I always have. At the end of the day, it's a cheap DVD that I'm not too bothered about and the yadif result is fine.

[jagabo]

Certainly there are some types of images that cause problems for QTGMC. But the also usually cause worse problems for Yadif. Closely spaced thin horizontal lines (like widow shades in the background), for example.

Could you upload a short segment of the original video that shows the wobbly effect after QTGMC? I'm curious to see exactly what you're talking about.

[pooksahib]

Sorry, jagabo, I can't. Neither the VOBs nor the mpg I created with VOB2MPG will open in an editor. Like I said, the DVD's a cheapo and must have problems of its own. However, I previewed it again with QTGMC and the wobbly effect has now been replaced with a juddery effect. Yadif still does the job though which means I remain happy.

[jagabo]

You indicated you were able to open the VOB file with DgIndex. You should be able to mark and demux a short segment with that. A juddery effect from QTGMC is probably the wrong field order.

[pooksahib]

Hey, you're right. Adding assumeTFF() before QTGMC did the trick. You have my grateful thanks.

[_Al_]

I always assume (rightly or wrongly) that 'default' = 'recommended'.

so in this case also as you can see QTGMC uses Bottom Field First as default, so "recommended" as per say is not applicable ...