Jerky VCD?

[rhegedus]

Dear all,

I've noticed that some VCDs I create from MPGs created from AVIs using TMPGEnc and VirtualDub (for the wav file) have jerky motion when panning or when there is a lot of movement going on. I have created the MPG using the TMPGEnc wizard using a CBR of 1150kbps.

I'm watching the VCDs on a JVC XV-S300BK, which has played VCDs made from VHS capture or from ready made MPGs without a problem but then again, the VCDs I've created play fine in my PC.

The strange thing is that when the jerkyness occurs, it is just about less than every second. When TMPGEnc converts AVI to MPG, it does so in 18-frame cycles (i.e. you only see every eighteenth frame when viewed in preview) - most of my AVIs are 23.9 or 25 fps, so it would appear that the jerkyness is linked to the way TMPGEnc works.

I know this isn't a PC problem (P4 2.26, 1G DDR etc), so what is left for me to do to eliminate the jerkyness? I've tried changing to bitrate by +/- 200, but this hasn't had any noticable effect.

Can I 'tweek' TMPEnc to eliminate this pheneomenon? Or what am I doing wrong?

Many thanks,

Rob

[geek rock]

is the jerkiness present in the original AVI files? could just be a low frame rate in the original AVI's..

[0 kewl]

Most likely you used TMPGEnc to convert the framerate which TMPGEnc is not good at. Better convert the framerate beforehand using this guide:

http://www.vcdhelp.com/forum/userguides/78178.php

[rhegedus]

Nope, the original AVIs are all 23.976 or 25fps and I stick to the same frame rate when converting. There's no jerkyness in the original AVI or the MPG producedwhen I view it on the PC.



Rob

[gll99]

Its interesting that in the same sentence you mention a pal and an ntsc framerate standard. Could that be the source of your problem????

[0 kewl]

If you really are converting Pal->Pal and NTSC->NTSC like you said and if your DVD player does support both standards, then there are 2 things i can think of:

1) You got XviD AVIs as original source
2) Sometimes AVIs with AC3 for sound can create that kind of problem but in that case you would have more problems even when loading them into TMPGEnc

Jerkyness when panning or a lot of movement could also point to Interlacing problems.

Lastly - i had problem like that when i made XVCD and tried to play in player that supports pure VCD, but i assume it is not the case here.

[rhegedus]

You mean that if I try to play the resulting files (if they are 23.976fps) in a PAL sys (25fps) then I have to change the fps?

This would be a simple(?) solution I hope.....

Rob

[0 kewl]

If your player supports NTSC (23.976 fps) then no need to convert 23.976 to 25 fps, if it doesn't - then that IS your problem. In this case you need to convert your framerate to 25 fps using the guide i mentioned.

[rhegedus]

I'll give it a go!

Thanks for the help.

Rob

[puertorican138]

rhegedus, it could also be a field order problem. Try changing the field order and see if that helps.

[kjmacke]

Some players don't like 23.976 frame rate. My apex is that way so I encode in 29.97 even if the source is 23.976. Have not had a jerky problem ever since.

[puertorican138]

I have an APEX (1500) and it doesn't like 23.976fps either, unless I encode it with 3:2 Pulldown. APEX models don't like the 23.976 frame-rate.

[vcdfreak]

How about trying different GOP structures? Try to adjust the number of B pictures from (0-3) and compare the result.

Since you are running at low bitrate, you cannot afford to max out I pictures leaving no Bs or Ps. You can experiment with high bitrate with more Is and a bit of Ps with no Bs. Slowly decrease the number of Ps and compare the result.
If your player can support 7-8Mbps of bitrate, you can max out Is with no/minimum Bs and Ps.

[rhegedus]

Thanks for all the info, folks - much appreciated!!!

I've managed to convert the avi video to 25fps, but I'm having trouble with the audio conversion. I've read the guide on framerate conversion, but BeSweet is not the friendliest program there is. The guide refers to a slightly different version and therefore, some of the tabs aren't there. Ho hum.

Anybody fancy giving a step-by-step for v0.6 b61?

Rob

[Hot Rats]

I am having the same problem, but this is even before I get the file to VCD. If I view the mpeg on my PC after conversion, it has the jerkiness that rhegedus has described. The avi I am converting is 23.9 fps and I am not altering the framerate.

Whatever the problem is, it's nothing to do with my VCD player. It's definitely something to do with the way tmpgenc is converting the file (not that I'm an expert).

I'd love to find a solution to this one!

Hot Rats

[0 kewl]

Rhegedus,

Use GoldWave to upsample your audio to match the lenth of your 25 fps video.

1) File->Open... (to open your extracted WAV sound)
2) Effects->Pitch...->tick Scale radiobutton (if not already ticked) and change the number in the box to 1.0427 (for 23.976->25 conversion)
3) Press OK
4) Wait until the WAV is upsampled
5) File->Save as...->choose .WAV as file type and a new name for your file
6) Press Save

Now you can load your 25 fps AVI video and the new WAV into TMPGEnc for encoding.

Hot Rats,

What template did you use to encode your VCD?


Regards.

[greengate69]

Not that I particularly understand how it works, but I got round a similar problem by setting the "Motion Search Precision" from "normal" to "Highest (Very slow)" ander the "Video" tab in TMPGEnc. This takes a lot longer, but the end result was very smooth. Might be worth a try.

[rhegedus]

Dear All,

Thanks to your help, I think I've managed to eliminate the jerky VCD problem!

You are right in that it appears to be a frame rate issue, since conversion with VirtualDub and Goldwave (thanks O kewl) and changing the motion search precision (thanks greengate69) has sorted the problem out.

I'm not sure which of the above proceedures was responsible (or maybe it was both), but I'm not going to mess about with it.

Either way, I'm now happily watching smooooooth VCDs!!!

Thanks again!

Rob

[twist0105]

You know, I just had a similar problem...

Long story short, TMPGEnc wasn't working with framerates properly. I know you are not supposed to do framerate conversions in it; however, it seemed to be ignoring my output framerate setting and doing it at whatever dang rate it felt like. Highly annoying. Anyone know why TMPGEnc would do this? The only reason for this I can suggest is that I loaded the VCD template and then modified it; maybe it didn't like that. On another comp the same file converted perfectly.

[VCDHunter]

I'm having a terrible time with Tmpgenc recently. All the mpgs it creates now suffer from a terrible video pause - the audio continues but the video will puse for maybe 20 seconds and then catch up. It's doing this with every downloaded avi (divx or just avi) and even some mpegs. I'm just trying out Panasonic MPEG1 encoder to see if this will fix the problems. The other way I got around this was to encode in Tmpgenc incorrectlt (maybe altering the framerate) then come to burning the cd Nero will encode the video stream again. I do this double encoding to retain the widescreen aspect of the image as nero seems to cut and compress the image. I've used Tmpgenc for ages and its always been good to me until now.

[rhegedus]

Strangely, just when I thought I had it cracked, TMPGEnc starts acting up.

I've got an avi of Donnie Darko, 23.97 fps. Extracted the wav (and changed the pitch etc) and changed the framerate to 25fps with VirtualDub.

When I load it into TMPGEnc, it comes up as 30fps and the mpeg produced shakes like a shitting dog! Can I manually override this?

Rob

[rhegedus]

Just tried an old version of TNPGEnc - works fine! Tried the latest version - works fine also. Maybe TMPGEnc gets 'corrupted' with use - who knows!

Rob