Audio Sync issue -again

[baldrick45]

I last posted about a DVD which produced a back up which worked fine but on conversion for a PSP went horribly out of sync. Turned out to be largely a Ripguard issue.

This time I'm struggling with almost the direct reverse. I've an Xvid AVI which plays perfectly but I wanted to burn it to DVD for the kids to watch on a standalone player. I routinely use ConvertXtoDVD for this and have generally beeen very well pleased but this time the soundtrack is badly unsync'd.

Gspot reports an Xvid video file and VBR mp3 soundtrack. Tmpgenc Express tells me that the movie is 1h 31m 8 sec 88 ms long while the soundtrack is only 1h 25m 2s 82 ms long. Divfix and RepairDivx report no errors in the AVI.

I can see one obvious problem. The AVI opens with a two 20C Fox logo's. The first (in the AVI is silent and lasts for approx 30-31 secs) the second starts with the usual "Dum, de de Dah ..." fanfare but in the conversion process the sound always starts from the first logo. (but what about the other missing minutes? sound on the AVI stops with the final frame)

I've used VDM to export a Wav, trimed the AVI to cut out the first logo sequence but when I remux the sync is still goneby at least 3-5 seconds. Rerunning these editted files through ConvertXtoDVD doesn't work either, nor does rerunning ConvertXDVD the original AVI file but with a 30500 ms audio offset (not even close to sync'd). I've tried playing with syncview to measure the amount which we are out of sync but I guess I don't know how to use that tool properly and I don't get any consistent figures from it.

I've also played around and demuxed the VOB's created by ConvertXtoDVD to get a M2V file with no audio track at all but a very satisfactory video quality. But playing around with this within Tmpgenc and the various Wav's, AC3s and MP2s created from the sound file gave no better results.

Assuming that I go back to the original AVI file (or the M2V) and the VDM demuxed Wav, what should I be trying to do here and with what tools? I'm a noob to this game but quite am quite tech savvy and hate to give up where I know I have a good video sorce and sound track but just can't get the two to play together.

That said, I'm concerned the gross differences in run times between the audio and video indicate some other nasties in the mix which I haven't even begun to battle yet. So if your recommendation is that life is too short for struggles like this then I'll forget it and move on. But you all like a challenge ... Dont you?

[guns1inger]

Try this. Export the audio as uncompressed PCM using virtualdubmod. Now import the wav file and disable the mp3 audio. Test play the avi. If the audio is out of sync, use the Audio Skew facility (under Interleaving in the Stream List) to adjust the audio start point until it is in sync. Once you it lined up, use ConvertXtoDVD to finish it off.

To date I have had only one VBR audio avi that I could not repair. It didn't matter how I tried to line it up because it drifted in and out of sync throughout. It is the only one to beat me so far, ismply because it wasn't worth the effort to repair.

[baldrick45]

At the risk of sounding very dim.

Could you step me through extracting the uncompressed WAV? This is what I'm trying at the minute.

I'm using VDM 1.5.10.2

I load the AVI, I click no when prompted to rewrite the VBR audio header.

Under Video Settings I'm set to full processing. I select Streams -> Stream List and see a single audio stream.

I right click on the audio stream and select "full processing" then click on the save wav button.

Is this correct? I haven't been doing the "right click -> full processing" thing before which might explain a lot.

Baldrick45

[baldrick45]

OK

I extracted an uncompressed Wav as outliined above - 900 Meg+ in size but still 1hr 26 mins as opposed to 1 hr 31 mins for the video.

VDM lets me disable the original mp3 audio stream and add in this one but when I try and preview it I hear no sound unless I let the whole audio trackbe dubbed in and yet again the sound starts with the start of the AVI not with the 2nd logo.

I trimmed out the first logo and in TMPGENC Express added in the new soundtrack. It lets me preview the end result and dynamically play around with the audio offset. This way I can get the audio spot on at the start with approx 500ms delay but it seems to run off as I go through with an offset of 1200ms needed at the end of the movie.

How do I try and correct this?

Thanks

Baldrick45

[SDeC]

Since you now have a separate WAV file (make sure it is a standard, uncompressed WAV), you should really use SyncView before doing anything else.

Load the avi as the Video Source, and load the WAV as the Audio Source. SyncView makes it easy to (1) shift the audio earlier or later, and (2) preview the result in real time. Once you have found a satisfactory Audio Sync (offset) value, jump to early, middle and late scenes and test for consistency. If you find some scenes are in sync but others are not, then you've got a bit of a mess on your hands.

Assuming you have a good audio track and a good video track, use SyncView's WAV Export Tool to write yet another WAV file: one that is perfectly sized and correctly aligned for the target video stream.

You are then ready to begin restoring the AVI

Regards,

- SD

[baldrick45]

Yep, I've got a mess!

An audio offset of -680ms applied to a version of the AVI trimmed to lose the first Studio logo is practically perfectly in sync till about 2/3 of the way though then it slips off sync quickly to finish over two seconds out again!

Sod it! Life is too short for some fights. I guess that wisdom is knowing that sometimes it's easier to walk away!

Baldrick45

[baldrick45]

Well wudaya know !

In desperaton and as a last throw of the dice I just ran the original AVI through TMPGENC Express (ver 3.0.4.24) It took forever (8h 35 min) but what came out was a fullly compliant Mpeg file WHICH WAS PERFECTLY IN SYNC THE WHOLE WAY THROUGH.

I fed this straight into TMPGENC DVD author (ConvertXtoDVD would have taken the MPG too but I wanted to take no chances on it doing an additional transcode of the file and reducing the video quality or re-introducing audio errors) and 20 mins later I had a near perfect DVD.

I would never have thought to try TMPGENC for converting a dodgy VBR MP3 stream. I always believed it was really just a good, but slow, video codec. But if anyone else finds their standard AVI conversion prog is letting them down, its definitely worth giving it a try!

Thanks to everyone who offfered advice.

Baldrick45