progressive footage encoded as interlaced mpeg2

[misapito]

Hi,
I am a newbie to this forum but have been converting my home videos to DVD for a couple of years. In fact, I am about caught up with that task just to see the technology changing. Anyways, since my old hi8 camcorder is now dead, I have been capturing some video with my digital camera, which does a surprisingly good job. It outputs progressive footage of course. My dilema is that my mpeg2 encoder only gives interlaced output. So, I am thinking it won't look good when shown on a progressive capable system (ie flat panel screen), which I hope to upgrade to soon.

Can I take my mpeg2 interlaced output and simply change the header info using something like Restream so that it will play as progressive? Both fields are made from the same progressive frame so I was hoping this would be all there was to it, but I know better. Please fill me in!

[JohnnyMalaria]

If your camera is progressive (what make/model is it?), it doesn't actually matter if the MPEG2 is interlaced. A modern progressive display will create a progressive frame anyway from the interlaced input. And, as you point out, both fields come from the same progressive source.

I suppose there might be some quality reduction if the display applies a specific deinterlacing algorithm but I can't imagine it would be of any importance.

[manono]

I suppose there might be some quality reduction if the display applies a specific deinterlacing algorithm...

That's right. Depending on what's handling the video, the player or the TV, a bad one may be doing some deinterlacing rather than just outputting the progressive frames as is, and could conceivably degrade the output. What I don't quite get is misapito's statement that it's impossible to get progressive output from his encoder. As far as I know, that statement is incorrect. I'd be curious which encoder he's using, and if it's really true I'd suggest the use of a better encoder.

[misapito]

Thanks for your reply.

I will try to clarify my concerns -- when you display progressive video on a interlace device (TV) there is a comb effect every time there is motion. Not much that can be done to fix that. Would it not follow that if progressive material is displayed as interlaced on a progressive capable display it too will have the comb interlaced look with motion? The display would be showing the two fields at a slightly different times. If the display saw a progressive flag it would show the two fields simultaneously -- no motion comb???

[edDV]

Thanks for your reply.

I will try to clarify my concerns -- when you display progressive video on a interlace device (TV) there is a comb effect every time there is motion. Not much that can be done to fix that. Would it not follow that if progressive material is displayed as interlaced on a progressive capable display it too will have the comb interlaced look with motion? The display would be showing the two fields at a slightly different times. If the display saw a progressive flag it would show the two fields simultaneously -- no motion comb???

Are you talking about telecine of 24fps film to 29.97fps video? If so this explains it all.
http://www.dvdfile.com/news/special_report/production_a_z/3_2_pulldown.htm

[manono]

when you display progressive video on a interlace device (TV) there is a comb effect every time there is motion.

Eh? Maybe I'm not understanding you, but what makes you think that progressive video shows combing on an interlaced display. For example, most Hollywood movies on DVD are encoded progressively, but if you ever see any interlacing something's very wrong.

Would it not follow that if progressive material is displayed as interlaced on a progressive capable display it too will have the comb interlaced look with motion?

No. If both fields are from the same point in time, how can there be any combing? There's nothing really wrong with encoding progressive material as interlaced. The vast majority of movies on PAL DVDs are encoded as interlaced and they're from progressive sources (usually). Even if it's really interlaced video, a progressive display (or the player feeding into it) has deinterlacers that can take care of it. What you don't want to do is to encode real interlaced material as progressive (although it happens sometimes), because then any sort of flag reading player or display will screw up.

I don't know; much of your post makes no sense at all (to me). Maybe edDV's link will help.

[misapito]

I first notice the comb effect when I watched a slide show on my TV. During a constant speed horizontal pan the defect is very noticeable. Then I started examining progressively recorded DVD material and upon careful inspection could see that in the horizontal motion the comb effect would appear on my TV, something I had not noticed before. Playing them on my friends system using a LCD display there were no problems.

I play my interlaced home videos on my TV or his system and all is well, but when I play video that I recorded with my digital camera (progressive) and render to DVD, I see the "comb" in horizontal motion. I use Pinnacle 9 to encode, but have to use the interlaced setting. (there is a progressive encode button, but it is useless. It discards one one of the fields no matter the input material and kills the resolution). So, I end up with progressive material that is encoded as interlace and I believe that is what is giving me the unwanted defect. I thought a simple header change would solve my problems. I changed the Mpeg2 header using Restream to progressive and authored a dvd with both the original clip and the modified one. The both look the same - bad.

[edDV]

Define (make and model number) of the following so we have a clue:

"TV",
DVD Player
connection method DVD player to TV
digital camera
MPeg2 encoder that is always interlace
method of making stills to DVD
how are you panning a still?
are these progressively recorded DVDs store bought or made by you?

"video recorded with digital camera"
what camera?
what frame size?
what frame rate?
How did you transfer the camera movie file to the editor?

Most digital cameras record at 12-25fps with small frame sizes and very high compression (usually MJPEG). These must be interpolated to 720x480i @29.97 fps for a normal DVD or 720x480p @23.976fps for progressive DVD*. To play the latter progressive, you need a progressive DVD player and progressive TV that are properly connected (YPbPr or HDMI) and configured. If your TV is a normal interlace CRT, a progressive DVD player will make the frame rate conversion from 23.976p to interlace 29.97i **.

Give more info. Changing the header is not going to fix your problem.


* see What is DVD? above left.
Now there is a way to "trick" progressive on to a 29.97fps 480i DVD by extracting both fields from a 480p 29.97fps stream but that is guessing an answer.

** actually a non-progressive DVD player will convert 23.976 progressive to 29.97 interlace as well but will always assume film source use the telecine (insert pad fields) method.

[manono]

And a sample of the video that gives you problems might help as well.

If you don't know how to get a sample, open a VOB in DGIndex, use the [ and ] buttons to isolate a small 10-seconds-with-movement section. File->Save Project and Demux Video. Then upload the M2V somewhere and give us the link.

[misapito]

Thank you for your posts, I have not had time to reply, but did get a potential clue to the error of my ways from your comments and questions. Since I've never connected my DVD player in progressive mode before I just connected it to my friends HDTV using an s-video cable. I will try my video samples again on his system using the component video cables, which I believe is the correct way to connect up for progressive viewing. BTW, my friend only has his HDTV connected to his computer, that is why I needed to connect up the dvd player. I will report back with the results.