Editing existing footage audio and replacing it with your own question.

[movingzachb]

As many of you probably are aware there are many videos out there on Youtube that include actual movie footage with the voices actors edited out to substitute their own voice content.

As an example to best understand what I am asking: https://www.youtube.com/watch?v=KU_Jdts5rL0
In this video someone took actual movie footage and somehow used their own voice clips (of Donald Trump) for Darth Vader's voice to create a rather comical spoof. The voice audio is edited and substituted with different voice audio (but the background noise is kept). I think that the person who edited this created a background to go along with his own audio and just cross-faded it into the clip. I'm just not sure.

Please keep in mind I am not asking this so that I can break any copyright rules but I would like to learn how to do this to make my own. Apparently this video isn't breaking any copyrights.

What techniques are used or what audio editing methods are required to make this happen? I am new to video editing although I did some research on this before deciding to post this question. Apparently there is a way to strip the audio from movie file that has 5.1 audio and isolate the 'center channel' (as that is the channel that would most likely have only voice dialog) in portions of the movie by cutting it out and cross fading in your own audio. I read about it being possible with Audacity but I couldn't make sense of it.

I have learned that it very well all hinge on the center channel being strictly voice dialog and so it may not be a ideal to do this for everything but I still want to learn how to do it.

Then I read about the term 'demux/remux' where you would use a program to separate the audio tracks. It is all very confusing - although I have been pretty determined to try and understand how it works.

Very appreciative for any help with this.

[JVRaines]

A movie typically has synchronized video, audio and subtitle data streams. Muxing (short for "multiplexing") is the process of combining streams into one media file. Demuxing is the reverse: obtaining the streams in separate files. Remuxing is the round trip.

You can import a file with a 5.1 audio stream to Audacity and it will put each channel of that stream on a separate track. The Center channel will usually be the third one. Just replace it with your own material. Then you mix down to the appropriate stream format (probably AAC) and remux with the video stream into a new media file. There are lots of muxing tools in the Software Library.

[movingzachb]

A movie typically has synchronized video, audio and subtitle data streams. Muxing (short for "multiplexing") is the process of combining streams into one media file. Demuxing is the reverse: obtaining the streams in separate files. Remuxing is the round trip.

You can import a file with a 5.1 audio stream to Audacity and it will put each channel of that stream on a separate track. The Center channel will usually be the third one. Just replace it with your own material. Then you mix down to the appropriate stream format (probably AAC) and remux with the video stream into a new media file. There are lots of muxing tools in the Software Library.

So the 5.1 file could it be the actual video itself? What format would it need to be? Do I need to strip the audio first from the video file then import it into audacity?
When you import it do you select 'raw data" or just 'audio' I tried importing a video file into it and it gave me the option to select how many channels but not sure why or what to select.

[movingzachb]

I spent 4 hours last night researching this on my own and found a way to simply isolate the channel with dialog (actors voices) from the background (sound effects, music etc) in Audacity by importing it as an .mkv. The file was a .VOB file and I had to convert it to MKV to do this. Initially I tried doing this with VLC media player but it would not preserve the 6.1 channels.

After downloading several 'free' video converters (that actually were not really free) I found one that would convert the .VOB footage I wanted to a .MKV (with a water mark as I did not want to pay $59.95) however I only wanted the audio so I will make my edits to the voice dialog channel and then export it and attempt to match it up with the video.

I am still open to finding many other ways to do this and would like to know if there is a 'free' .VOB to .MKV converter that is REALLY free. Converting from a VOB to an MKV (to just edit the audio in audacity) seems to be the simplest way I can come up with. I am hoping this will work and that I can simply match up with the audio with the video in a video editor like Davinci Resolve that I am using now.

So the workflow plan up to now is:

1. Mount DVD or BluRay Disc after ripping it into an image file to the hard drive
2. Locate the desired footage from the mounted image (.vob file)
3. Convert .vob to a .mkv
4. Import a copy of this .mkv into a video editor (muting the audio)
5. In Audacity preferences set import export settings to 'Custom Mix)' (of course this assumes you have already installed FFMpeg 2.2.2 for Audacity).
6. Import (the original exported .mkv) it into audacity - it will import each channel into a separate track
7. Edit the track desired.
8. Export it to .wav
9. Import the .wav into the video editor and use that audio in lou of the existing (muted audio) matching it up to the footage.