Why does my DVD made from interlaced DV "shimmer" with movement?

[absinthe]

Hey all,

I'm no newbie when it comes to video processing in general, but I've just made from first DVD from a captured DV source (interlaced home video DV camera - NTSC).

I captured with WinDV, wrote an AviSynth script to put two films together and fade in/out between segments, encoded MPEG2 with CCE (and the audio, too), authored with TMPGEnc DVD Author, created an ISO image with PgcEdit (mkisofs), and burned with DVD Decrypter.

I did not blend the fields. I figured, hey I'll be watching it on interlaced TV, so why do that? I'm fairly sure I had CCE configured correctly, though to be honest this was my first time encoding an interlaced source. It was definitely set for 29.97 fps, block scanning order set to 'alternate,' intra block DC precision set to 10, and quantizer characteristics 32. I maximized the bitrate to fill out a whole DVD, avg. bitrate @7600.

Everything went great until I actually watched the video. The shimmering is terrible, with any movement at all, even slow panning of the camera.

There's a DV-to-DVD guide here: http://www.doom9.org/index.html?/dv/guide.html - that describes separating the fields for separate processing and putting them back together, as well as using the Reinterpolate411 filter for colorspace conversion. Do those steps eliminate this shimmer effect?

thx,

-abs

[absinthe]

No one has ideas?????

It doesn't seem to shimmer when I play it back on the computer, by the way.

-abs

[Guest]

I don't know what you mean by "shimmer".

Did you get the field order correct? Did you deinterlace inadvertently? Did you encode as interlaced source and output?

[absinthe]

By shimmer, I mean there appears to be a "flickering" effect with movement, even slight movement. Oddly, it doesn't show up on the computer. But it does on three different DVD players and 2 different TVs.

The video is definitely bottom-first, but as far as I know CCE doesn't have a setting to specify that. I simply selected "alternate" in the quality settings, which you're supposed to do for an interlaced source. Output video setting was for 29.97, 4x3 AR.

When the encode was done, I made a d2v file from it with DgIndex, and it was still bottom-field first, so I assumed it was okay.

-abs

[Guest]

I suggest you ask the mod to move this to the CCE forum.

[absinthe]

Good suggestion.

Before I did the whole video with CCE, I did a 1-minute sample with just a quick pass in TMPGEnc, just to make sure my script was working right. When I burned that little sample and played it back, there was no flicker. Maybe I'll just try the whole process with TMPGEnc instead. If it comes out normally, then I must be doing something wrong with CCE.

-abs

[gnuz187]

If you're describing this shimmering correctly I believe it occurs when you play an interlaced "bottom field first" video that's flagged as "upper field first" or vice-versa on a television. Since NTSC DV is interlaced and bottom field first, when encoding that to DVD MPEG-2 you should put a check mark beside the "Upper Field First" option in CCE 2.5 or set the "Offset Line" value to 1 in CCE-2.67 or CCE-Basic. Read questions Q10 and Q11 in the the CCE FAQ for an explanation.

[absinthe]

Thanks!

I've checked out the FAQ and I feel sure this is it. I never would've figured out that setting. It's a bit more straightforward in TMPGEnc.

Thanks again,

-abs

[WorBry]

My DV sources are all PAL Type II (captured from a Sony DCR-PC115E mini-DV camcorder)but I have experienced something similar to the shimmering (more of a shaky/jerkiness) when I've needed to convert to NTSC DVD using TMPGenc 3.0 Express. The effect is barely noticeable on PC playback (at least in PowerDVD) but quite evident on TV playback with standalone DVD-player (multisystem) particularly on panning and zooming scenes. Friends in North America who I send these NTSC DVD's to have also remarked on the jerkiness when played on their NTSC set-tops. I definitely have the source field order set correctly as BFF, although its worth noting that if you use the Matrox DV/DVCAM vfw codec for decompression the field order (at least with my Pal sources) is reversed and you have to set the source to TFF in TMPGenc 3.0Express (or else reverse the order back to BFF using the AVS filter ReverseFieldDominance). The only remedy I've found for these "jerkies" is to deinterlace (in TMPGenc). This contrary to my normal practice with PAL DVD encodes, which I always keep interlaced and which play perfectly smoothly on both PC and TV. If there is a good explanation and better solution for this I'd appreciate some advice also.

[absinthe]

There is no good solution to your problem, at least not without some hardware. Your PAL video moves at 25 fps, whereas interlaced NTSC will move at 29.970 fps. There's not much to do with this kind of conversion except deinterlace your PAL video, slow down the framerate to 23.976 (keeping your audio in sync), and make a DVD, during which process pulldown flags will be added so that on television playback the video will be interlaced again, playing at 29.970. I'm sure that's what TMPGEnc is doing for you.

It "shimmers" on TV because it's being "telecined" by the DVD player as if it were a progressive image, but it never was a progressive image. It started out interlaced and you deinterlaced it. Every frame is therefore comprised of two fields which originated a split-second apart in time.

I would imagine it looks relatively normal on the computer because the computer (I believe) will just play progressive images (i.e. at 23.976).

- Two things you can do -

1. The best solution would be to have your NTSC-land friends get multisystem (PAL/NTSC) DVD players. They're cheap!

2. Short of that, let them watch the videos on computers. And if you're going to do that, I'd just encode to a different format altogether. I'm an XviD fan, myself. Computers will play things back properly at any framerate.

-abs

[Guest]

Originally posted by absinthe
Your PAL video moves at 25 fps, whereas interlaced NTSC will move at 29.970 fps. There's not much to do with this kind of conversion except deinterlace your PAL video, slow down the framerate to 23.976 (keeping your audio in sync), and make a DVD, during which process pulldown flags will be added so that on television playback the video will be interlaced again, playing at 29.970.

There's no need anymore to reduce the frame rate to 23.976. DGPulldown will convert directly from 25fps by adding just the right pulldown flags. You'll need to deinterlace it if necessary, of course.

[WorBry]

Hi Absinthe and Neuron2,

Thanks so much for replying and your advice.

Until now I'd been encoding at a high bitrate; 2-pass VBR, av 8850 kbps, max 9250, min 3400 (GOP I=1, P=5, I=0) with AC3 audio, 224 (using the TMPGenc AC3 plugin). Since my last post, I've played around with different bitrates. Interstingly, lowering the settings to av 7000, max 8000, min 2800 (GOP I=1, P=7, I=0) with PCM audio, greatly reduced the jerkiness without only a slight loss in quality (at least, to my critical eye). I've yet to try the lower bitrate settings with AC3 audio.

I have, for quite some time been exploring the various other formats, including DivX, XviD, VP6, RV10, NeroDigital and now of course AVC/H264, but quite honestly, to get anywhere near the quality of DVD you have to encode at very high bitrates (at least 2500 kbps) and not everyone has a PC powerful enough to playback (smoothly) at these rates. For me VP6 (soon VP7) or XviD (with sharp matrix) remain the most impressive, although the x264 (AVC) codec is also developing at a phenomenal rate. I was also quite impressed with Nero's AVC - while the trial lasted. For sending short, low res clips by email however, I prefer RV10, which has a low CPU demand, and of course many people have RealPlayer already installed. WMV? - forget it.

I will do some more DVD tests based on your suggestions.

Thanks again.

[Guest]

>you have to encode at very high bitrates (at least 2500 kbps)

2500 kbps is not a "very high bitrate".

[WorBry]

True, although I did say "at least". For my PAL DV sources, DivX (5.2.1 slow setting, single BF) at full res (720x544 or 528 as preferred) and 97% quality (Quant 2) requires in excess of 5000kbps. For my own archives, I'm encoding at 3500 - 3800 to acheive around 55-60% compressibility, using a fairly straightforward script AVISource>ConvertToYUY2(interlaced=true)>KernelDeint(order=0,sharp=true), LanczosResize(720,544),Undot()with FastRecompress in VDub (audio MP3 128 CBR). 2500kbps would be about the minimum I would use with VP6 to acheive comparable results, but the CPU demand (at least on my PC AMDXP2800/1GBDDR) is nearly twice that of DivX and XviD. As I commented, not everyone has a PC capable of playing back such files (I avoided saying, "higher bitrate files")which is a big consideration when you distribute home videos to a varied audience. Of course, I'm going way off topic here.

Again, thanks for the "pulldown" advice. I'll give DGPullDown a go.

[2Bdecided]

You could try real PAL>NTSC converson...

http://forum.doom9.org/showthread.ph...0&pagenumber=4

(slow, but it works well - see the post from scharfis_brain 6th February 2005 02:25)

and you could avoid video bitrates above 8Mbps which (apparently) seem to upset some DVD players (though I can't remember where I read that figure, so take it with a pinch of salt!).

Hope this helps.

Cheers,
David.

[PhillipWyllie]

I got the shimering effect when I capped The Simpsons from CH4(uk-pal). The solution was to use the smart deinterlacer plugin in virtual dub( on the avi!).