How to deal with progressive scan video?

danimal wrote on 8/22/2001, 12:34 PM
My DV cam outputs progressive video, and I've noticed that if I try to edit and resave at the same resolution as the source (720x480) using for example the NTSC DV preset, the saved video just is not as smooth as the original. (Why does any 'rendering' take place by the way if all you're doing is cutting some parts and reassembling, shouldn't VF be smart enough to just copy the stream sections that haven't changed?) It almost seems like my 29.97 video is now playing at 15fps. Even if I output say, a 352x240 mpeg, I still get the jerky video. What's going on here?

Comments

SonyEPM wrote on 8/22/2001, 1:24 PM
You can create a progressive DV template- this may solve your problem.

Go to make movie/write file to disk/advanced render/choose avi>NTSC DV template/custom/video,

then set field order to "None(progressive)" then save that modified template as "NTSC DV Progressive".

Now you can choose this rendering template whenever you have progressive source material and want to print back out to progressive DV.

If you don't need to go back out to DV and just want computer playback, consider one of the Windows Media templates- compresses fast, looks great, small file sizes.
danimal wrote on 8/22/2001, 3:51 PM
Actually, that is what I was doing already, a NTSC DV Progressive template with the only difference being Field Order was set to None (Progressive). Ignore what I said about VF not just copying streams, I was thinking about a test I did outputting to interlace.

Getting back to progressive though, that is where it appears to be losing every other frame and output is jerky. A 4 minute clip saves in 45 seconds or so, so it is just copying the stream, but why does it apparently toss out every other frame?

Thanks
SonyEPM wrote on 8/22/2001, 4:26 PM
are you time-stretching video perhaps?
danimal wrote on 8/22/2001, 4:56 PM
It turns out that all the other clips are ok, but the one i was selecting loops in is somehow screwy. I imported it again and now it's smooth, so maybe I did stretch it after all. Is there some way to tell if a clip is stretched and drag it back to it's original length?
Chienworks wrote on 8/22/2001, 10:15 PM
If a clip is timestretched, there will be a sharp wavy line (like Charlie
Brown's shirt) behind the frames in the timeline. You can
right-mouse-button click on the clip, click properties from the pop-up
menu, and look at the General tab. The playback rate will tell you how
much the clip has been streched or compressed. Set this value back to
1.000 to have it play at the normal speed.
lungjian wrote on 10/15/2001, 6:46 PM
It's a Sony DV limitation. Sony DV camcorders only record 7.5 fps in Progressive mode. When it's interlaced, it's approximately equivalent to a 15 fps interlaced image. Canon DV camcorders capture 30 fps in Progressive mode. Most reviews of the Sonys seem to miss this fact. The Sonys are not ideal for progressive movies.