Sound Sync Saga Revisited - Weird Inconsistencies in Playback

[megamachine]

After the earlier thread I started on this topic, I remedied some problems by using TMPEnc to do some simple editing on a VCD encoded MPG captured from PAL VCR. But as I experiment more, I have discovered some vexing inconsistencies in the results. With hopes this is the right place to post these problems (if not, can some one recommend a better place?), let me describe the issue.

I use TMPGEnc to clip the intro and ending titles from a PAL VCD MPG, which does not cause sync problems. But, when I use it to clip out commercials within the program, I get several strange sync problems that are not present on the original MPG. Also, the edited MPG plays differently on PowerDVD than it does on WindowsMediaPlayer. I have run this several times to verify.

Here are the details. The program in question is an hour documentary with three commercial breaks separating four segments. After taking out the commercial breaks with the "cut currently selected area" function, the edited file displays several different sync problems within the two players noted above. In playback on PowerDVD, there is a gradually expanding delay between sound and picture, with the sound coming perhaps 100ms before the picture by the end of the program, although it is in sync at the beginning. In WMP, the sound stays in sync throughout. However, in both players the third clipped segment is severely out of sync, in a different ratio than the sections before or after. On another trial, on playback in WMP, the picture is ahead of the sound, from the beginning. In the second edited section, after the first commercial cut, there’s also a strange skipping/repeating effect, as if the sound and audio are trying to catch up to one another, which suddenly stops toward the end of the section. At that point, the sound and picture are closer to being in sync, with a very slight delay, again with the picture almost imperceptibly ahead of the sound. In the next section, the larger gap between sound and picture returns, again with the picture ahead of the sound. The last section has perfect sync in sound and picture. In PDVD, the first section is in sync. In the second section, the skipping effect returns for about 5 minutes, then the section returns to being in sync. In the next section, the sound and picture are out of sync, with picture being ahead of the sound. In the last section, the sound and picture are also out of sync, with the picture ahead of the sound, very slightly, but then it drifts to the sound being ahead of the picture. Whew!

All I want to do is clip out titles and commercials from a program captured from VCR, but I can't seem to get it right. With apologies for the verbose post, can anyone recommend a way to do this, within or without TMPEnc? With many humble thanks to you all.

[setarip]

"I use TMPGEnc to clip the intro and ending titles from a PAL VCD MPG"

"All I want to do is clip out titles and commercials from a program captured from VCR"


Surely, your initial capture is NOT as VCD. Is it in MPEG-1, MPEG-2, or .AVI format?

What software, with what video and audio settings, are you using for capturing?

[megamachine]

I am using CapWiz from ADS Tech Instant DVD, and initially used VideoStudio6 for editing, though now I am using TMPGEnc Plus. I have a laptop so can't use an internal capture card. In addition to selecting between PAL and NTSC, there are four settings in the capture software: VCD (MPEG-1, 44.1Khz sound, 25fps, 350x288) and then three DVD settings (MPEG-2 with choice of 44 or 48 audio, and quality settings at 3mbs, 4mbs, 5mbs). I am using the VCD capture setting from VCR, and the captured PAL VCD video plays perfectly in Windows Media Player and PowerDVD. It is only when I render the edited video that I get the problems noted above. For rendering, I select PAL VCD on TMGPEnc Plus and VideoStudio, which both seem to have fixed settings. I was using VideoStudio to do the edits, but found it cumbersome, though there were fewer sync problems. I find TMPGEnc much easier to work with, but have noticed worse sync problems.

An update. Instead of clipping out the commercials in TMPGEnc all at once, I tried creating four separate clips and then merging them. That worked somewhat better, though in some cases the same sync and skipping problems arose. Based on that, I am guessing that there might be something related to the length of the segment I am removing that in some cases throws off the sync in the rest of the clip. It is not consistent, and only happens sometimes. Maybe what I need is a way to insure that the video and audio remaine lined up when I clip out the commercial breaks. I'm shooting in the dark, and really don't have a clue. Thanks for any light you can shed on this. Best wishes.

[setarip]

"VCD (MPEG-1, 44.1Khz sound, 25fps, 350x288)"

I assume this is merely a typo - and it's actually 352x288, which is the proper resolution for a PAL MPEG1-VideoCD-compliant file.




1) Quickly check to see that the audiostream is, in fact, MPEG1-compliant .MP2 format by doing the following:

TMPGEnc>>MPEGTools>>Demultiplex

Load your file



2) You might want to try the following:

BEFORE doing any editing, load your MPEG1-VideoCD-format file into TMPGEnc as follows:

TMPGEnc>>MPEGTools>>Merge&Cut

Set the mode to "MPEG1-VideoCD" (NOT "plain vanilla" MPEG-1)

Save with a new filename

Use this new file for editing

[rsquirell]

or you could do it the easy way...a tape to tape and cut out the commercials before you even capture.

[megamachine]

Yes, that was a typo, sorry. I checked the file in De-multiplex:

video_stream 0x00 MPEG-1 Video 352x288 25fps 1148kbs

audio_stream 0x00 MPEG-1 Audio Layer-2 44100Hz 224kbs

Both of those streams are checked. There is also a third line for "padding_stream," which is not checked and has no data.

In Simple De-multiplex, the files are appended with .m1v and mp2.

I'll try saving the file in TMPGEnc as an MPEG-VCD before editing and see how that works. I'd like to do this work on my laptop if possible, but the suggestion to edit the tapes before capturing made me think about something that may or may not be related to the problems I am having. The tape from which I am capturing the video in question may be a dubbed or recycled tape (borrowed from a buddy), which made me hesitant to dub it again, but I also began to wonder if the quality or generation of the tape has a bearing on how well it is captured. In retrospect, it seems that the files captured from store bought or first generation tapes worked better in editing. Just a thought.

[megamachine]

Just a quick update. I tried first saving the file as MPEG-1 VCD before editing it, and ended up with the same out of sync end product. But the really strange thing is the inconsistency. I cut the hour program into four parts and edited the commercials from each part and saved each part separately as an MPEG-1 VCD. The third and fourth parts play fine, with no sync problems, but the first and second parts have different degrees of audio/video sync, depending on the method used to edit and render, and it is always there, but only on those two parts of the same original video, which, before editing, displayed no sync problems at all.

[setarip]

Just curious - In addition to your statement that the tape source is re-used, was it recorded at SP, LP, or EP? My thinking is that anything other than SP might present a problem...

[rsquirell]

At the risk of making this too complicated...when you do a tape-to-tape you need another VCR or camcorder. You can control the media going into the other device ( ie. buy a new tape) and the speed (SP). All you do with the original tape is play it while you record with the new...when you hit an ad you stop, back up the new tape to where it fades to black before the commercial...play the old tape until you see where the show begins again and start your new tape. Never do you re-dub the original. But if the original is an old shakey SLP, then you have an old shakey SLP issue and may need to have the tape remastered by a professional who has the equipment (or go check out the library to see if they have the movie there.)

[megamachine]

I returned the tape to the person I borrowed it from, but I believe it was recorded SP. It may have been one of those really thin tapes, where they squeeze 180 or 240 minutes or more onto the reels, and the quality of the original was noticeably worse than other tapes I used. I know about tape to tape dubbing, and have access to a double VCR, but's it's NTSC and the tape in question is PAL. In any case, on dubbing tapes, I noticed that often the second or third generation suffers in quality, especially the sound. Besides that, I like messing with digital solutions, so part of this is the challenge of solving a problem, not just getting the final product, which of course I could easily do with tape. I can also cave and buy the DVD of the program, but I am in this to learn. Anyway, using the same method that I described earlier, I captured another program from a different tape and edited it and there is very little trouble with sync, just a slight problem that can be adjusted in TMPGEnc. That tape was first generation, store bought, while the earlier one was home recorded, perhaps on a recycled tape that has been re-recorded, and there was some loss of quality already. Both are PAL, both are SP, and I use the same capture and editing method, yet the results differ. So if you guys think it is a problem related to the quality of the tape I am using, I trust your judgment and will leave it aside for other work. I just wanted to see if it was something in my procedures or in my setup that I was doing wrong. With thanks and best wishes.

[rsquirell]

We were bombarded by a rash of posts on related issues on the Dazzle DVC-150 forum last night. TMPGenc DVD Author appearantly does an excellent job of cutting out commercials, but it's not going to help with your multiple synch problem. Old tapes will often play on analog TV's which are more tolerant of synch problems associated with LP tapes...and the same tape will capture jerky in digital (which is intolerant.) They mention machines which can correct the problem, but they start at $300. If the tape is irreplaceable a professional can remaster it for a reasonable price.

[megamachine]

Interesting, what is the address for that forum? I just got TMPGEnc DVD Authoring, and like it already (I just wish they had more designs and layouts to choose from). I will mess with that and see if I can just cut the commercials there while authoring, and skip the intermediate stage of using TMPGEnc Plus for that. I wonder if DVD Author can remove noise around the edges of the video. I find I need that on some captures from VCR. It does sound like my problem is a tape quality problem. The program in question is replaceable, and if I really need it I can even get the DVD. As I go through my own tape collection, I'll need to decide which ones I really need on digital and which can stay on tape, and so at some point I might want to look into that device you noted. Thanks for taking time to read and respond to my posts.