Adding audio to a DVD

[psydude]

So after mucking around for almost 2 hours I finally decided to post my question here, since I wasn't making a lot of headway. I hope someone can help me out. What I'm trying to do is a little bit complicated, so please bear with me:

I have a movie on DVD imported from the US. I have the same movie on a German VHS tape. Since a German DVD was never released (and I'm pretty sure never will be) and the quality of the tape is not all that good, I want to burn my own DVD, combining the video of the US DVD with the audio of the German tape. I already got the German audio on my computer. Now what do I do?

What I thought about doing:
-Ripping the US DVD and converting the movie to .mpg using DVDx or some similar program. This way I could change the framerate from NTSC to PAL (remember, the German tape and thus the audio is running at 25fps), and change the aspect ratio to an anamorphic format (I want to watch it on my projector later on).
-Adding the German audio and syncing it up with the video.
-Authoring a new DVD with this newly created video file using DVDStyler or a similar program.

Problem is, I'm not sure how I'd go about adding the audio and syncing it up. Also, I'd like to do as little encoding as possible so I don't lose too much quality. Can anyone point me in the right direction? Or is there maybe a more elegant way to do it all? By the way, I don't care about the extras, just the movie would be enough.

Any pointers would be greatly appreciated.

PS: The search function didn't work for me for some reason, so please don't kill me if this question has been asked before.

[Baldrick]

Demux the dvd to video and audio streams with PGCdemux.
Fix the audio. It will take time to get it synced...
Add back the old video with the new audio using muxman.
Add back the old menu with vobblanker.

See https://forum.videohelp.com/threads/277950-How-to-add-new-subtitles-to-an-existing-DVD and scroll down to method 2 and skip the subtitle part.

[hech54]

I wouldn't touch the video. I'd leave it as NTSC and only work with syncing up the audio to that NTSC material.

[AlanHK]

This way I could change the framerate from NTSC to PAL (remember, the German tape and thus the audio is running at 25fps), and change the aspect ratio to an anamorphic format (I want to watch it on my projector later on).

My advice: Don't change the video at all, you'll have to adjust the audio in any case.
You're opening a whole other can of worms converting video if you don't have to.

As for syncing the audio, I'd do it with Audacity.
Get the latest "beta" version, and install the ffmpeg plugins.

Then open the DVD audio track (probably AC3). You will use that as the timeline.
If it's multichannel, mix them all down to a single track.

Then "import" the VHS audio (presumably stereo).

In the simplest case you look for an obvious sound event near the beginning, and use the "Time Shift" tool to drag the VHS track to align the corresponding peaks exactly. Then find a similar event near the end.

Select the interval between the two events in the DVD track, note the exact duration. Now select the corresponding interval in the VHS track. Use the "Change Tempo" effect to change the duration to match exactly the DVD. That will set a percentage. But don't do it, copy the percent figure, click "cancel, select the entire VHS track, open Change Tempo again, paste in the percentage, and apply.

Now go back and check if the first events are aligned, you may have to adjust them with the time shift tool.

You might be done now, if the two videos were the same edit. But they may not be. Skip through it and see if the peaks are aligned all the way through. You may find that some scenes were cut differently, if so you will have to make similar adjustments to segments. You might even have to copy in some audio from the original track to cover if it isn't in the VHS version.

You might also have try the Noise Removal effect if there is a buzz or static on the VHS track.

When done mute the DVD track and export as AC3, 48000 Hz sampling rate.

[psydude]

Thank you all for your contributions.

I've done what AlanHK said, but unfortunately it didn't work out the way I hoped. The areas around the reference peaks are perfectly in sync, but most of the interval between them is still a little off. But at least it seems to be consistently off, although I'm not entirely sure yet. Oh well...Guess I'll have to fiddle around some more.

EDIT: Great...it's not consistent at all. Sometimes the sound is too early, sometimes far too late...and the two versions of the film are cut exactly the same. What the hell is going on? o_O How can it go from synced, to too early, to too late, to synced again?

[manono]

If the edits are exactly the same, then maybe all you have to do is convert the audio from its PAL source to fit the NTSC DVD. If true, about all you might have to do in addition is to add a delay to have them match exactly. Most days of my life I do similar things. BeSweet has PAL2NTSC presets. Make a WAV file first, at the same time doing the stretching, and then convert it back to AC3 audio with whatever you usually use for the purpose (not BeSweet if you can help it). There are other ways to do the same thing.

[AlanHK]

If the edits are exactly the same, then maybe all you have to do is convert the audio from its PAL source to fit the NTSC DVD. If true, about all you might have to do in addition is to add a delay to have them match exactly. Most days of my life I do similar things. BeSweet has PAL2NTSC presets. Make a WAV file first, at the same time doing the stretching, and then convert it back to AC3 audio with whatever you usually use for the purpose (not BeSweet if you can help it). There are other ways to do the same thing.

Audacity should already have done that with "Change Tempo", and as he says the reference points match, seems to have done it correctly.
But try it if you like.

EDIT: Great...it's not consistent at all. Sometimes the sound is too early, sometimes far too late...and the two versions of the film are cut exactly the same. What the hell is going on? o_O How can it go from synced, to too early, to too late, to synced again?

Could be inconsistent speed of your VHS player?

Anyway, if you have the patience you can select sections and stretch or shift them to match. You can copy segments to new tracks if that is more convenient and mix down later.

[psydude]

Okay, I found out what's causing the randomness I think. There are small "glitches" in the VHS recording which aren't really noticable if you watch the movie, but seem to be severe enough to mess up the audio. So I have no other choice but to fix everything by hand. Also, I think AlanHK is right about the inconsistent speed as well...sometimes the audio switches drastically from being too late to being too early, without there being a glitch (at least I don't see any). Oh well, that's gonna keep me busy for a couple of hours.

@AlanHK
By the way, is your explanation on how to sync up the audio posted as a HowTo on the site? Because if it is not, I'd like to write one up (with your permission of course) as it's really very helpful.

[AlanHK]

@AlanHK
By the way, is your explanation on how to sync up the audio posted as a HowTo on the site? Because if it is not, I'd like to write one up (with your permission of course) as it's really very helpful.

I may have read some hint,s but the details I worked out from experience.
So go ahead, if you can fix this track you should be an expert by the time you're done.

I don't know how familiar you are with Audacity, but splitting tracks into "clips" can be very useful for this kind of thing.
http://manual.audacityteam.org/index.php?title=Audacity_Tracks_and_Clips
The shortcut keys and such speed things up a lot once you learn them.

And when you have it synced, do try the "Noise reduction" effect, almost essential if from a VHS source I think.

[psydude]

Phew I'm finally done and actually quite happy with the results. Thanks for your help everyone! Nice to know there are still forums who offer more than just "RTFM" or "use google". I'll go ahead and write up a HowTo over the next few days so I can give something back to the community. And now if you'll excuse me, it's time for a victory dance.