If you’re like me, and you have a lot of video footage on video tape that you want to have on DVD, you might want to take a look at tinkering with the soundtrack to bring it more in line with the soundtrack options available with newer technology. Some cleanup options are available, and, depending on the source material and the amount of time and effort you’re prepared to invest, it’s sometimes even possible to make a simulated 5.1 sound track.
I’d suggest that you take care of making a digital copy of your source material first, and make a backup. Tapes wear out, and sourcing good quality devices to play them on is getting harder – VHS recorders/players haven’t been manufactured for a couple of years now, so you’ll have to do the best you can with what you can find. I have two VHS machines in reasonable working order, both of which are plugged into DVD recorders. You might not be so lucky.
The next step, once you’ve created a digital copy of your source material and a backup, and imported it to your computer, is to make a working copy of your source material.
I find it easier to work on the video first. A minimalist approach works well for initial editing and cleanup, particularly if you’re just starting out with conversion. The goal is to preserve the memories, without necessarily showing off your video production skills, and without losing anything you might want to refer to later. Because I had a habit of reusing camera tapes, I sometimes find short bursts of unrelated material mixed into the footage I review – now is a good time to remove this material from my working copy.
The next step is consider your options for producing a quality soundtrack. At the very least, you should keep a copy of the original soundtrack. The number of people I know with a full home theatre system complete with surround sound are in the minority – many rely on the speakers in their TV, laptop, or phone. As well as this, nearly all of the footage that I recorded prior to 2004 is mono, making it harder to craft a convincing 5.1 soundtrack.
With a 2.0 stereo sound source, it is possible to use the differences between the left and right channels to create a simulation of a 5.1 surround soundtrack. I have described one such process elsewhere.
Over the years, I’ve recorded a number of events on my camcorder for other people. In recent months, I’ve made a 5.1 surround sound audio track available on several DVDs I’ve made. Although not as accurate as making a proper mix of material from multiple sound sources, it is possible to create a passable simulation of full surround sound from 2.0 stereo source – this relies on the two stereo channels not being identical, and making use of the differences between the two channels.
Important note: the results you get depends on the quality and nature of your source material and how much effort you are prepared to make. The following notes assume that your source material has a regular two channel stereo soundtrack, as commonly found on CDs and MP3 files. Making an acceptable 5.1 sound mix from a mono source requires a modified approach.
I use Audacity as the basic framework for manipulating the soundtrack on my video files. I have the channel mixer plugin installed, to assist in the remixing process. This is available as a Nyquist Effect Plugin. Depending on the file format you export your remixed soundtrack, you might need to install the ffmpeg import/export library. – don’t forget to set Audacity to export use a custom mix instead of stereo or mono.
- Open Audacity
- Import/open your video files – this should give you a two soundtracks organized as as a stereo pair
- Normalize your soundtrack with the Effect->Normalize
- Duplicate your stereo source so that you four stereo pairs of soundtracks. The first will become the front left and front right channels, the second pair will become the centre channel, the third pair will become your bass/LFE channel, and the fourth pair will become your left rear and right rear channels.
- [Optional] Select the first stereo pair, and select the Effect->Vocal Reduction and Isolation effect. For the action, choose remove center. Click on OK. Be patient, this can take a while for longer clips.
- Select the second stereo pair, and select the Effect->Vocal Reduction and Isolation effect. For the action, choose isolate center. Click on OK. Be patient, this can take a while for longer clips. Then choose mix->mix tracks to mono.
- Select the next stereo pair. Use mix->mix tracks to mono. Then use Effect->Low pass filter. Keep in mind that the LFE channel is commonly designed for freuencies of 120Hz and lower, so you might want to check the setting before clicking OK.
- Select the last stereo pair. Lately I’ve been using the channel mixer plugin for this stage of processing. The decoding matrixes described on Wikipedia might be a useful starting place for choosing the values to use. Because Audacity’s plugin uses percentages, you’ll have to multiply the figures on Wikipedia by 100.
- You should now have the following: 1 stereo pair, 2 mono tracks, and 1 stereo pair.
- Export the resultant mix into your preferred format.