can progress MPEG2 video be DVD compliant?

[sohr]

Hi...

Simple question here:

Can a 720x480 MPEG2 file (@29.97 fps) be DVD-compliant if it is non-interlaced (i.e. progressive)? Or do I have to reconvert to 720x480 interlaced?

Thanks!

[guns1inger]

Many studio disks are progressive, with the player outputting an interlaced signal. I believe that NTSC progressive disks are 23.976 with a 2:3 pulldown though.

Try dropping it into your authoring software to see if it complains.

[sohr]

Thanks, I wasn't aware that there was a different framerate for NTSC progressive.

So if I want to make a DVD-compliant MPEG2 for NTSC, my choices are

720x480 @ 29.97 fps interlaced...

OR

720x480 @ 23.976 fps progressive.

Right?

Is there any noticable difference in picture quality or compressionability between the two formats?

Thanks!

[BJ_M]

29.97 progressive is also DVD compliant - but your dvd player will not output it this way

[sohr]

29.97 progressive is also DVD compliant - but your dvd player will not output it this way

So essentially it'd be a waste of drive space? I'm assuming the progressive MPEG2 would need more drive space than the same MPEG in interlaced mode, right?

Basically, I'm just wondering what the best quality settings are to use when I convert my MPEG2s to DVD-compliant MPEG2s in TMPENGenc Xpress.

I don't want to use the DVD output source type in Xpress, since it will try to fit each MPEG2 into a 4.7 GB drive... but I'm not done editing the MPEGS so I would like to keep as much quality as possible for now.

[MpegEncoder]

29.97 progressive is also DVD compliant - but your dvd player will not output it this way

Doesn't this depend on the player and the setup? Progressive scan DVD players could output a progressive signal is configured and connected that way.

[bugster]

29.97 progressive is also DVD compliant - but your dvd player will not output it this way

So essentially it'd be a waste of drive space? I'm assuming the progressive MPEG2 would need more drive space than the same MPEG in interlaced mode, right?

Not quite right. The size of an mpeg is determined by its bitrate and playing time. The frame rate and reolution etc have no effect. Waht is does mean is that for a given bitrate, a 29.97fps mpeg has less bits per frame than a 23.97fps mpeg. This can cause a reduction in quality which can only be recovered by increasing the bitrate and so increasing filesize.

Progressive/interlaced is not an issue though. Both require the same amount of data. Remember, 29.97 FRAMES per second is really 59.98 FIELDS per second when interlaced. Each field being half a frame.

[sohr]

Thanks, bugster.

So if quality is my main goal, I would be better off encoding to 720x480 @ 23.97 fps progressive for my final encode?

Currently, my MPEG2 files are 1280x720 @ 59.96 fps so I thought the conversion to 720x480 @ 29.97 would make the most sense (since it would only need to resize and cut every other frame to get the framerate right). But if that doesn't provide the best quality, maybe I should switch?

[BJ_M]

29.97 progressive is also DVD compliant - but your dvd player will not output it this way

Doesn't this depend on the player and the setup? Progressive scan DVD players could output a progressive signal is configured and connected that way.

nope

[BJ_M]

Thanks, bugster.

So if quality is my main goal, I would be better off encoding to 720x480 @ 23.97 fps progressive for my final encode?

Currently, my MPEG2 files are 1280x720 @ 59.96 fps so I thought the conversion to 720x480 @ 29.97 would make the most sense (since it would only need to resize and cut every other frame to get the framerate right). But if that doesn't provide the best quality, maybe I should switch?

nope - not always true -- it depends on your source, if this was shot as interlaced and/is a interlaced source, best quality is still keeping it interlaced ..

ONLY if this is a film source - should it be progressive , except in a few rare cases ...

[lordsmurf]

VCD is 29.97 progressive ....

I've converted up to 352x480 progressive many times when restoring older VCD source, and some other odd digital sources.

It plays everywhere.

Whatever that's worth.

My anal-retentive DVDit! PE says it compliant.

[sohr]

ONLY if this is a film source - should it be progressive , except in a few rare cases ...

Ok.. this was originally a 720p high-def stream. Does that qualify as one of the rare cases?

[BJ_M]

that would clasify as film source - or HD Video

that should stay as 23.976 + pulldown

[sohr]

that would clasify as film source - or HD Video

that should stay as 23.976 + pulldown

Ok. so the fact it was originaly 59.96 fps doesn't make moving to 29.97 fps any better instead? Just checking...

[BJ_M]

720p ussually means 24fps .....

you sure it doesnt have pulldown ? or is it true 30fps ?

[sohr]

Actually, not sure.

AVIcodec tells me its a 1280x720 MPG2 file @ 59.940 fps. It's straight out of an ATI HDTV Wonder card...

[sohr]

Well, I've given the NTSC standard of 23.97 fps progressive at 720x480 a try.

Picture quality at the same bitrate is markedly better... however, in areas of the screen where there is fixed text (such as a static banner at the the top of the video), it "flickers" or bobs. I don't see this when using the 29.97 fps option in interlaced mode.

Is there some way to correct for this? Maybe use a difference de-interlace method?

I tried using VirtualDub to recreate the problem, since it allows you to apply filters and preview the output without having to commit to anything. However, I noticed the flicker or bobbing in the fixed text areas even with no filters applied to my original file, even though they are not there in the source...

Any suggestions?