352*480 mpg2 plays fine but lags when authored to DVD

[ozymango]

Okay, I dunno if this is a capture or author problem, but here goes --

I've got a Compro Videomate capture card, good picture when doing avi caps and even software mpeg caps (up to 352*480 mpeg2 on my system). That is, I can play the caps back using any player (e.g. Windows Media) and software DVD players, and the picture is good, there's no lag or strobing during fast motion scenes, minimal artifacts. Of course the aspect ratio is a bit weird. Most of my caps are 3500-4500 bps, seems to give a good balance between disc space and quality (just for simple "off the air" recording").

But if I "author" these to DVD (video_ts folder and then play back folder with dvd software player), the picture quality is still very good except during scenes of rapid motion -- the picture sort of "strobes" at that point, not exactly a lag ... almost looks like somebody's shaking the camera. I suppose it's a type of lag, though.

I burned a test to DVD to see if maybe my computer wasn't able to playback at speed but the burned DVD has the same problem. Again, "normal" movement is no problem, even reasonably quick movement is smooth, but very rapid movement, especially "jump" scenes (where something jumps into the frame) and you get the strobing/jittering for a second.

The original mpeg file doesn't exhibit any of this strobing/lagging, the motion is nice and smooth. And it's only when I capture directly to mpeg2 and then want to burn directly to DVD -- but then normally I capture 720*480 avi for anything I really want to keep and convert later, I've just started doing the 352*480 mpeg2 captures as a way to do quick off-air recordings.

I can capture at 352*480 mpeg2 software using about 60% of my processor; it'll peg the CPU at 720*480 so that's not an option.

So, any ideas as to what might be the problem here? It seems like it could be a bitrate issue but I've done 4500 bps encodes of 720*480 and never had a problem like this. Is it the encoder? If so, how come it plays smoothly as "stand-alone" mpeg2 but not when authored to DVD?

Oh, yeah, almost forgot the important part -- I've tried authoring using Ulead DVD Factory (bundled with my DVD burner) and it's worked great for other stuff (720*480) and it doesn't seem to be re-encoding the video in any way (it only takes a few seconds for it to "process" the orginal mpeg so I assume it's just parsing it somehow?). I also downoaded a trial of tmpgenc dvd author to see if that would make a difference, but still the same problems. Neither authoring program seems to do any re-encoding of the source mpeg file.

Any feedback (no matter how off the wall) is appreciated!

[Krispy Kritter]

352 x 480 is a valid dvd spec, so that most likely isn't the issue. Have you tried increasing the bitrate?

[GeorgeW]

are you capturing Field-based, or frame-based?

[ozymango]

are you capturing Field-based, or frame-based?

Uh ... I don't know. I'll check tonight and see what the default setting is. If it helps any, I'm using Compro Videomate PVR2 and there's a simple option for "Half DVD", the 352*480 setting, and maybe some buried advanced options.

This is a Philips chip based decoder; do you know of any other software capture drivers I might also try than the one that ships with this? (Compro drivers, proprietary I'm guessing).

And as for higher bit rate (previous poster), I was kinda thinking that too, so I'll try that. Thanks!

[ozymango]

Okay, I did some more testing last evening and the results are in --

I tried a 6000bps bitrate and the problem, as it is, is still there. It seems to be somewhat less but still on scenes of quick motion, the "strobing" is noticeable. Not monstrously so, but annoying anyway.

The only option I could find in the recording controls was a checkbox for "Deinterlace video." And it was unchecked, which is as it should be for sources to play back on TV, yes? However, immediately below the "Deinterlace video" checkbox is a line that's greyed out that contains the drop-down menu choice "frame capture." If I click the "deinterlace video" box, the greyed-out line says "field capture." ???

I've always had a plain composite input capture card before, never with built-in tuner, so I've never thought about deinterlacing options on capture. I understand that you do not want to capture TV deinterlaced if you ever intend to burn to DVD or play on a TV, correct? Perhaps the tuner part of this card is doing this automatically even without the option checked, could it be deinterlacing the video? Seems to me that would make sense in terms of the picture being smooth during pc playback as mpeg but "strobing" in DVD mode ...


Oh, drat, I should have tried capturing from my VCR's tuner to the line input of the card, not use the card's tuner, and see how it behaves -- I've captured plain avi files from my vcr playback to this card and converted to mpeg2 and those have played fine on DVD ... I think I'm on to something!

Thanks for the advice so far! And any more ideas, I'm still listening!

[ozymango]

Thanks again for the suggestions and I found the solution to my problem (or a solution anyway) --

I love my Compro Videomate tuner/capture card (software based encoding) but one glitch or issue or whatever -- when you record using the recording option from the included software tuner program, it records either mpeg1 or mpeg2 using its own encoder and it deinterlaces the output. I can't find anything about this in the docs or the website but what you end up with is very smooth video when playing back mpeg files on your computer as mpeg files but when exported to DVD files (vob), you get "strobing" because the interlace is fecked.

If I capture with the composite input from my VCR output (using the VCR as an external tuner), I get great captures that, when played back as mpeg2 files, have those little "lines" in the picture that I always found annoying whenever I watched rapid movement of captured video on my computer, but learned that this was because the video was interlaced and would play correctly on a TV screen.

Which is exactly the case -- the captured mpeg files don't look quite as smooth as mpeg files but look great when burned to DVD.

Anyway, I'm not sure this conclusion is 100% technically accurate but it does indeed explain a lot!