Mpeg1 To Mpeg2 Loss of Sync

[carnage2004]

I realise there have been many many posts about sync going out and how to fix this. I feel my problem is slighty different to anyone elses.

In a nut shell i want to stop this so i dont have to fix it, so i will expain whats going on.

Mpegs are either downloaded or captured, tested and play fine. Then i use ulead Video studio 7 to convert them to mpeg2 (i have tried tmpenc and the same outcome occurs) mind you this is only sometimes and doesnt have to be a massive file for this to occur.

Ok back to the thesis :P 6 out of 10 times the conversion is fine. But sometimes the sync gradually goes out, from the original ok file. If it is a captured file i am converting to mpeg2 i have to lower the quality of the capture until i find one that canconvert without the voice out. so this isnt a capture problem........ its a conversion problem. I am totally stumped and tried calling ulead about this. The responce was drop the quality from mpeg2

I have plenty of ram, A fast cpu (celeron 2600 ghz) also have new hard drives so thats not the problem.

I dont use Avi files due to them going very jerky when converting to mpeg2 so its an mpeg1 to mpeg2 problem... sometimes its even an mpeg2 to mpeg2 problem with changing the resolution. ....... any ideas??

[petar]

My first guess would be the frame rate. Check what's the frame rate of the original files. Are you encoding at the same one or you're changing it?

[carnage2004]

ok thats the thing im unsure how to actually check the frame rate of the original file. And your suggesting ... to check it and make sure the mpeg2 conversion is the same framerate .. eg pal or ntsc

[petar]

There are plenty of tools that can check the frame rate of a video. Just to name few: VirtualDub (with the MPEG mod), VideoToolBox, ReStream...
You mentioned you use TMPGEnc. You can check it with the MPEG tools of this application as well. Click on Multiplex or De-multiplex and open a video. You don't need to mux or de-mux anything, it just that when you open the video it tells you the frame rate, among other information.

[mats.hogberg]

...another not that stupid q is: Why do you convert from mpg1 to mpg2? You'll only loose quality in the process, if that's the only alteration you do to the video.

/Mats

[bottle-necked]

Playing a video file with Windows Media Player or Power DVD player, etc, and saying it's ok and in sync is meaningless information. The real and true test of sync is playing the video file in VirtualDub, and in this case of MPEG2, VirtualDub MPEG2 or Mod. If VirtualDub will play the file in sync then I would believe it is truly in sync, but just because Media Player plays it ok isn't telling me much at all.

Good luck.

[carnage2004]

Virtual dub wouldnt play it at all..................

secondly some of these files are only available on mpeg1 format. I was under the impression that the file needed to be converted to mpeg2 to be dvd playable

[carnage2004]

ok the file i am trying to convert ...

MPEG-1 Video 320x240 29.97 fps 1500 kps
MPEG-1 Audio Audio Layer-2 44100Hz 192 kps

[carnage2004]

ahh virtual dub came up with an error, and only displays half the file. Does this mean its cactus or fixable

[mikeny]

Sometimes this works:

1.Demux your mpeg 1 into m1v and mp2 with TmpgEnc
2.Convert mp2 to 48000 Hz. with BeSweet or FFmpegGui
3. Load your m1v into VirtualDub and check the total time of the file. You can move the slider all the way to the right to check.
4. Now open the new mp2 with Goldwave. Check the time of the mp2. Is it different? If yes, then:
5. Use the 'time-warp' function in Goldwave to match the time of the m1v as reported by VirtualDub.
6. Save corrected sound file as wav with Goldwave.
7. Now you can load the m1v and wav into VirtualDub and preview the output. Is it in synch? If so:
8 Use audio editor BeSweet or FFmpegGui to convert .wav to .mp2
9. Load both files into TmpgEnc DVD Author (the .m1v and the .mp2) You should be able to check here if they are in synch as you can preview it. I think it's in the edit part or chapter cut.
10. You could burn with the TmpgEnc DVD Author Writing Tool if the .vobs are in synch.

This way, you are not reencoding the mpeg and thus, you're not losing quality as mats.hogberg said.

[carnage2004]

just tried your thesis........... conveted to mv1 and its saying there is only 40 mins of video, but the file goes for 1 hour and 49 mins. Some error ust be doing this

[mats.hogberg]

If you're doing a NTSC DVD, you can use the XVCD mpgs (that's what you got) and author them as DVD with TMPGEnc DVD Author without atlering them in any way before authoring. If this works, and if they'll play all the way if TDA accepts it as source mtrl, depends on how seriously your mpg is damaged.

/Mats