How to cut audio chunks and synchronize it to video

[Nightwolf4321]

I'm looking for the appropiate program to do the follwing tasks.

I have a collection of a series with 4 chapters in each DVD. They have 2 audio tracks. I want to backup them but in the process I want to remove the second audio to insert a 3rd audio that I recorded from TV. I need a program to cut out the commercials from the audio I recorded and help me to sinchronize them with the video. I want to use a copy of the fisrt audio to insert in it the chunks of my recorded audios because I want to use the opening and ending of the first audio.

Hope you understand what I want.

Thanks.

[Scorpion King]

I know you can do the audio like that in Ulead VideoStudio because I've done it before. It's a chore.... but doable.

Take your time. lol

Good luck.

[Baldrick]

You need to use several tools and it's gonna take time to get it synced.

Demux / Split the audio from the dvd with pgxdemux, see https://www.videohelp.com/guides.php?guideid=937#937

Then use a video editor and add the video and audio tracks to sync, maybe mpeg video wizard.

You could also use audio editor like goldwave but it's harder to sync against the video.

[machf]

Sure, I've done that.

First you need to demux the different components of every chapter of the DVD (video, audio, subtitles). You decide whether you want to do them all at once, or one by one.

Next you need to convert the original audio (the one you want to keep) and the one you recorded from TV to stereo .wav files (I'm assuming your TV recording only has stereo audio). There are different programs which can do that part.

Then you can use Cool Edit, Audacity or some other program that will allow you to open both files at the same time and display the waveforms for better reference. Actually, you'll need THREE audio files open at the same time: the original in stereo .WAV format (used for reference), a copy of it (where you're going to paste over the new audio), and the audio you recorded (from which you're going to copy chunks). If you don't mind overwriting the original .WAV file, you can work with just two windows.

If your TV recording is an AVI file, I'd also suggest you open it in VirtualDubMod, and at the same time open the original video (after demuxing it to an .m2v file) in another instance of VDM. That way you can check first which frame of the original corresponds to which one in your AVI (especially, those right at the start and at the end of the commercial break), and use that as reference to seek the proper times in the audio files.

Check if the audio levels of both files are the same, if they are not you'll have to either increase or decrease the amplitude of your TV recording's audio until it matches the original. Unless the original is playing too low in your opinion and the recording plays well, then you'd do the opposite.

Then you check the audio corresponding to the scene you're going to overwrite, paying attention to the start and end times, and the total duration. Check also for door slams, explosions or other non-vocal noises that are easily noticeable and take note of their times. Go to the new audio and check the same spots (start, end, noticeable sounds). The duration (end minus start) should be the same in bith cases, and the difference in times between both audio files should be the same for all events corresponding to the same scene (if not, there's a commercial break you missed, or an additional scene that isn't present on one of the versions, or something like that). Once you've verified that, select the audio between the start and end of the scene in both audios, delete the one from the original audio and paste a copy of the other one at the same spot. Repeat for all the other scenes, and for all episodes.

Once you're done with that, in order to replace the audio streams on the DVD, I suppose first you'll need to encode the audio you've built to Dolby AC3 format, in order to be able to remux it with the rest to put it back on the DVD.

In order to place everything back replacing the original DVD structure, I think there are some guides here, take a look around.

I remember I did that for the first two "Justice League" movies, they came out pretty well. The first one had an additional scene that the three-part broadcast didn't include, it would have been perfect if there was no dialog, but Wonder Woman says "Forgive me, mother" at some point (just three words!), and I had no option but to leave that dialog from the original audio.

With "Kelly's Heroes" it's proving to be more difficult, as my TV recording is a different cut from the one used for the DVD release. My "Where Eagles Dare" recording, OTOH, only seems to have a few black frames in between some scenes, possibly where commercials were originally meant to be inserted, but aside from that, it's very close to the DVD release. I have to finish doing it some time...

EDIT: wow, it took me some time to type all this... when I started, there were no answers yet.

[GTRBudda]

Having done this myself a couple of times, I've found there's another issue to watch out for. Two recordings from two different sources might not run for the same duration. In other words, once you line up the audio files so the wave forms match peak for peak around the start of your file, they may be out of sync, ahead or behind of the matching peaks, at the end. If any of your recording comes from tape, that's almost certainly the case. It's easy enough to fix in Audacity by changing the sample rate. For the track where you might need to change the duration, click the track name -> set rate -> other. Then change the rate up or down to increase or decrease the duration of the track. For example, if the rate you start with is 44100 Hz, change to 44102 to make it shorter, or 44098 to make it longer (even numbers only in Audacity). Depending on the difference in duration, you'll need to experiment with different rates to bring the tracks in line. Small changes like this won't be noticeable in the playback. There's a guide here on how to do this with a different editor, though I can't recall which one.

Another helpful tool is JR Screen ruler. Good for aligning the wave peaks.
http://www.spadixbd.com/freetools/?referrer=JRulerUser

[machf]

Right, I forgot to mention that... good that you did.
I mean, that was the whole point of checking the start, end and other points, and I didn't mention what to do if they don't match... bummer.

BTW, when you convert the audios to .wav files, it's a good idea to make them both 48kHz, 16-bit, stereo, since that's what you'll be using to encode for DVD later.

[GTRBudda]

Tonde mo nai, I'm in the middle of the same kind of project right now and it was on my mind.

I should clarify something I said, also. When I wrote, "Small changes like this won't be noticeable in the playback", I meant small changes in sample rate won't cause a noticeable change in pitch, the sound will be the same. It makes a surprising difference in sync though.

[Alex_ander]

As mentioned, there are just 2 things to be fixed: time delay and duration. The most time consuming thing is determining the right values. You can find/calculate both values using a software allowing easy shifting audio vs MPEG video on time-line for preview. Womble MPEG Video Wizard is very good and fast at this. It allows fine adjustment by typing audio delay value. Generally you have to first sync audio/video close to the beginning to find the delay value, then move audio to sync it in the end and thus find the difference in video vs audio duration. You'll have to convert your DVD to MPEG file for previewing on time-line.
Time delay can be adjusted in a sound editor by adding silence (or cutting audio) in the beginning and time duration - by time stretching (e.g. Sony SoundForge editor has this filter). Then you can encode audio and reauthor the DVD.

[Nightwolf4321]

Thank you very much for all of your suggestions. I'll try all of them.