5.1 to stereo audio transitions.

[hbenthow]

For a scene in a fanedit with 5.1 Surround sound, I am using a stereo track from a CD. As I do not have a surround sound system, I do not know how well this will work. Could anyone give me an educated guess on whether or not a transition to a stereo audio track in an otherwise 5.1 movie will sound all right on a surround sound system? Will there be a drop in volume or other such jarring change?

 

[addiesin]

Good question. Dunno if I can answer it, but I can suggest a workaround if it doesn't sound right. To make the whole audio track stereo.

Open the video in Audacity 1.3 Beta (the version that can handle audio from video), figure out which one is the center channel (it is the one with all the voices) and pan the others left and right respectively, then mix it all down to a wav file. You could also use this method to mix down only the center channel, if you just want voices, or exclude the center channel completely if you want to have a "karaoke" esque effect, where the music and sound fx are still there but no vocals.

Of course this all depends on how the surround mix was done. In some cases this won't work because the music and sfx can be mixed into the center channel. That should not effect the finished stereo track if that's all you're doing.

Hope somebody else can give you more advice you can try before doing this!

 

[TV's Frink]

I did this a lot in my edit. Usually I just put the song in all five channels. You can get probably get away with only putting it in the R-L channels (or the center channel) as long as you are careful about what comes directly before and after. For instance, if you transition from a scene with a lot of surround activity to just the song in the front channels, it will be a lot more noticeable than if you transition from a scene with little or no surround activity. You can also play with fading in and out of the surrounds.

As far as volume levels go, I usually went off a visual clue first (the peak volume is shown for each track in the timeline in Vegas, not sure about other programs), then adjusted by listening on headphones. However, I found the best method was to listen on my 5.1 system once I was done to make sure there were no obvious changes in volume. I found a few things to fix that way. Maybe see if someone you know has a 5.1 system and will let you test your mix on it?

 

[hbenthow]

I don't know anyone who has a surround sound system, so i can't test it out.

To clarify, the track is a part of the score from "Bram Stoker's Dracula" (1992), and I fade from the part of the movie that has the very same music to part of the CD track. Thus, the same musical cue starts as 5.1 movie audio, then switches to stereo CD audio, before fading out. The reason that I am using the CD track is because I don't want the sound effects for that part, just the music.

 

[addiesin]

Hmm, your best bet is to play with it a lot and see if your video editing software can show you which audio channels have the music playing, and try to get your "new" track inserted into the same channels, and you're probably going to want to fade out the original audio while simultaneously fading in the new audio to avoid weird blips. If they're on separate tracks, it's easy enough, and if they're on the same track, crossfade will do the job.

EDIT: Once again, converting it all to stereo would be a lot easier, because then all you'd have to do is a simple crossfade, and if it's an edit you're making for yourself and you don't have a surround system, I'd suggest the easy route.

 

[june8]

You can use DBPowerAmp converter. You can convert any sound from stereo to 5.1/7.1 or vice versa. It has DSP effects to do this with channel counting and channel . Also has bith dept changing and resampling. Trial version doesn't allow to do everything but you may use to check out the results before you buy.

 

[geminigod]

It would help to respond if you gave more information about what editing program you are using. But I just had a re-realization working on my own edit along these lines, which is why this post caught my attention. Your post hints at an important issue that gets muddled with fanediting. I re-remembered how extremely important it is to be listening at the same level you are editing.

In other words, if mixing for 5.1, you really need to be listening in 5.1. And what I really mean by saying "mixing for 5.1" is that my final product will be rendered in 5.1. It matters not how many tracks are in my actual timeline. The fact that you have 6 tracks that match perfectly with the 6 audio channels is purely a coincidence of fanediting. It doesn't matter how many tracks I am working off of.

Now to maybe answer your question more specifically, 1) Decide whether you are "mixing for stereo or 5.1" and set your project properties accordingly. (Based on what you have shared, I would recommend sticking with stereo and then your headphones will work well to edit with.) 2) just add the cd music as a new track to your timeline. If you are "mixing for stereo" then life is easy. You probably don't need to do anything, unless the CD music is broken up into 2 mono tracks, in which case you will have to assign a left and right to each track. If you are determined to keep the audio as 5.1 (even though you have no way to proof your work) you can approximate reasonably well by matching the panning on the CD track to the approximate difference in volume levels between the tracks assigned to front and rear that are playing music.

Note: Downmixing your 5.1 source audio to stereo, and then editing off of that is not a good way to go because then you limit your ability to manipulate the sound by not having the extra tracks to work off of. Again, remember the difference between tracks when mixing as opposed to channels when listening or rendering.

PS: Your mention of Dracula just reminded my that you had asked me to mess with a scene many months ago, didn't you? Sorry I never got back to you! I have been MIA for a few months. Whatever happened with that. Did you figure something out?

 

[hbenthow]

It would help to respond if you gave more information about what editing program you are using. But I just had a re-realization working on my own edit along these lines, which is why this post caught my attention. Your post hints at an important issue that gets muddled with fanediting. I re-remembered how extremely important it is to be listening at the same level you are editing.

In other words, if mixing for 5.1, you really need to be listening in 5.1. And what I really mean by saying "mixing for 5.1" is that my final product will be rendered in 5.1. It matters not how many tracks are in my actual timeline. The fact that you have 6 tracks that match perfectly with the 6 audio channels is purely a coincidence of fanediting. It doesn't matter how many tracks I am working off of.

Now to maybe answer your question more specifically, 1) Decide whether you are "mixing for stereo or 5.1" and set your project properties accordingly. (Based on what you have shared, I would recommend sticking with stereo and then your headphones will work well to edit with.) 2) just add the cd music as a new track to your timeline. If you are "mixing for stereo" then life is easy. You probably don't need to do anything, unless the CD music is broken up into 2 mono tracks, in which case you will have to assign a left and right to each track. If you are determined to keep the audio as 5.1 (even though you have no way to proof your work) you can approximate reasonably well by matching the panning on the CD track to the approximate difference in volume levels between the tracks assigned to front and rear that are playing music.

Note: Downmixing your 5.1 source audio to stereo, and then editing off of that is not a good way to go because then you limit your ability to manipulate the sound by not having the extra tracks to work off of. Again, remember the difference between tracks when mixing as opposed to channels when listening or rendering.

First of all, the program I am using is Womble MPEG Video Wizard.

I took something of a chance, and set the audio output to 5.1 for the whole track. I had been having some trouble with the transition, but I finally got it to go smoothly (at least on a stereo speaker system).

PS: Your mention of Dracula just reminded my that you had asked me to mess with a scene many months ago, didn't you? Sorry I never got back to you! I have been MIA for a few months. Whatever happened with that. Did you figure something out?

Well, I've been busy doing some audio editing and creating a new prologue, and real life has intervened as well, so I have never figured out how to use Avisynth or any of those other programs, or found any other way to restore the deleted scene.

 

[geminigod]

Your call. It won't be perfect, but the reality is that with a little bit of educated guessing it is possible to engineer rear sound without ever listening to it. As a rule of thumb, don't put much, if anything, to the rear. I added a whole bunch of stereo music to my current edit. I set the track that it all went into to ~75/25 ratio front to rear and frankly that might even be too much for a couple of the scenes.

Depending on how Womble manages the sound output while editing, you may still be better off temporarily changing your project properties to stereo. The thing that I realized today with Vegas is that it doesn't comprehend to downmix my sound when I plug in headphones as opposed to my 5.1 speakers. The only way to get the sound coming out of my editor to reflect a proper downmixed stereo sound is to change my project properties to stereo, regardless of whether I am mixing for 5.1 as the final product or not.

This discovery has prompted a new experiment to find out how much variation in sound there is in a stereo rendered track vs. a 5.1 track downmixed on the fly by hardware or software to stereo. Tests are still ongoing.