Does stereo to surround makes sense for captures?

[Chainmax]

After reading a portion of the "99% Complete List..." thread and Eye of Horus's own thread on stereo to surround I get the impression that this is only applicable to music. Would it make any sense to use it for audio on analog captures?

[ursamtl]

Originally posted by Chainmax
After reading a portion of the "99% Complete List..." thread and Eye of Horus's own thread on stereo to surround I get the impression that this is only applicable to music. Would it make any sense to use it for audio on analog captures?

Hi Chainmax,

Although the focus of most surround methods presented here has been on music, I see no reason why the techniques should not work for any stereophonic source, whether it's a digital source or an analog capture. By the way, when you say "analog captures" what do you mean, live recordings of sounds from microphones? Transfers from old analog movie soundtracks? Even if you're taking about movies, give them a try. I mentioned before in this forum how I used to hook up speakers across the positive leads of my amp in the late 70's to get the difference signal between the two channels and create a pseudo-surround system (an engineer called David Hafler discovered this circuit). This wasn't just for music. Stereo movie soundtracks sounded great through this as well. Dialog is usually mixed to center, so it came out of the center, and the ambient background music sounded huge with the surround effect. It might not have been discrete 5.1, but it sounded good.

Remember that the results will always depend on the quality of the source you feed and to a certain extent on the technique used for recording. If the stereo-to 5.1 method you use extracts existing ambience from the recording, then true stereo recordings (meaning recordings made with a proper stereo microphone or two mikes) will certainly work better than recordings where mono sounds have simply been panned to different positions between the two speakers. If the method you choose adds artificial processing, convolution, delays, filters, etc., then this doesn't matter as much, but then you're at the mercy of the person who chose the artificial processing. Some like lots of reverb, others like delay, etc., etc.

In the end, all you can do is try and if you like it, great. If not, try something different! :)

[KpeX]

ursamtl makes some good points. The main reason I think most of the stereo to 5.1 efforts are focused on music is because 5.1 music sources are much less common than for movies and TV.

Ultimately your own ears should be the judge to this question - but if you try every stereo to 5.1 method you'll be busy for a while ;).

If the capture is a somewhat recent movie (and many TV shows now as well), it most likely already has a Pro Logic soundtrack, and if your receiver supports dolby PL this may be the easiest solution. If the capture source does not contain Pro Logic, or the pro logic sound doesn't satisfy you, then start firing up some bidules, batch files, & surround processing methods :).

[Chainmax]

ursamtl: by "analog captures" I mean stuff captured from TV or VHS to my computer. BTW, thanks for the reply, I never would have thought about your "hooking up the speakers across the positive leads of the amp" method :).

KpeX: the thing is that there are so many different methods, and they all seem very tricky...I don't suppose there's a relatively simple method that most people here agree with?

[KpeX]

Well for simplicity I'd have to suggest UpmixGUI (http://forum.doom9.org/showthread.php?s=&threadid=75445&) or the original UpmiX - but I may be biased in that respect ;). Also this method will not result in any advanced 5.1 effects, simply a reproduction of the channels over 5.1.

But I don't think there's any one method that everyone agrees on by any means.

[Chainmax]

Originally posted by KpeX
Also this method will not result in any advanced 5.1 effects, simply a reproduction of the channels over 5.1.
What exactly does that mean? Also, are those advanced 5.1 effects available on the more complex guides?

[ursamtl]

Originally posted by Chainmax
ursamtl: by "analog captures" I mean stuff captured from TV or VHS to my computer. BTW, thanks for the reply, I never would have thought about your "hooking up the speakers across the positive leads of the amp" method :).
I found it in an old "1001 Electronic Projects" magazine when I was a teenager. You have to be careful with it, however, because it can present your amp/receiver with some strange impedance loads. I've never had a problem with it and I used the same circuit up until I got a proper 5.1 system. I even used it in addition to a Dolby Pro Logic circuit and proper surround speakers.

As Kpex says, try some of the methods out. His original Upmix is in fact a good starting point.

[Sycho]

if your captouring a movie use the Pro Logic II upmixing guide, i highly recommend it over the other guides for movies

[Chainmax]

Sycho, is this (http://forum.doom9.org/showthread.php?threadid=57736&highlight=Pro+Logic+upmixing+guide) the guide you're talking about?

[ursamtl]

Originally posted by Chainmax
Sycho, is this (http://forum.doom9.org/showthread.php?threadid=57736&highlight=Pro+Logic+upmixing+guide) the guide you're talking about?

As I wrote in the other thread, why not just play your two-channel audio on your 5.1 system and switch on the DPLII? It will give you the same result with a LOT less work! Virtually all 5.1 receivers have at least DPL and more than likely DPLII. For non-Dolby encoded material (meaning your analog capture) there really isn't much technical difference between DPLI & II. The first time you read Dolby's technical literature, it seems like there's a difference, but after you think about it or play around with equipment featuring DPLII, you come to realize that it's mostly marketing hype.

Like I said, much easier to hit the switch! :)

Regards,
Steve.

[joshbm]

Originally posted by ursamtl

Like I said, much easier to hit the switch! :)


Yes, but how many average-joe people know what they're doing to flip to DPLII :). Unless encoding for yourself and you know that your own player supports DPLII Upmixing, which is probably the case :p. BUT If not, it wouldn't necessarily be easier to encode your stereo source to 5.1 using DPLII upmixing, but it would be less hassle when viewing your DVD video-- which honestly isn't too bad, but when I create DVD's for other people, I like to make it as easy as possible for them to just put in the DVD and go. Instead of saying "Oh and by the way, to make my DVD play something similar to 5.1 sound, see if your DVD player supports Dolby Prologic II." The reply you would get would be :confused:.

;)

Regards,
- Joshbm

[ursamtl]

Originally posted by joshbm
Yes, but how many average-joe people know what they're doing to flip to DPLII :). Unless encoding for yourself and you know that your own player supports DPLII Upmixing, which is probably the case :p. BUT If not, it wouldn't necessarily be easier to encode your stereo source to 5.1 using DPLII upmixing, but it would be less hassle when viewing your DVD video-- which honestly isn't too bad, but when I create DVD's for other people, I like to make it as easy as possible for them to just put in the DVD and go. Instead of saying "Oh and by the way, to make my DVD play something similar to 5.1 sound, see if your DVD player supports Dolby Prologic II." The reply you would get would be :confused:.

;)

Regards,
- Joshbm

A valid point. I've been focused mainly on upmixing for music to burn AC3 or DTS surround CDs for my own personal use. For a DVD soundtrack that will go to others, yes it would make sense to do a 5.1 AC3 upmix, provided the method gave you the results you wanted. If the listener's receiver is setup properly, etc., then by default the 5.1 AC3 mix will play. If not, he or she will get a downmixed version in DPLI or II, or else a plain stereo version.

A DTS 5.1 track by itself wouldn't be advisable, however, because on some receivers, you'd end up with no sound at all unless the user specifically switched to DTS.

There are several good PDFs with guidelines for preparing mixes that will work for everyone at www.dolby.com. For DTS info, www.dtsonline.com is the place to go.

Ciao,
Steve.

[joshbm]

Originally posted by ursamtl
There are several good PDFs with guidelines for preparing mixes that will work for everyone at www.dolby.com. For DTS info, www.dtsonline.com is the place to go.

Ciao,
Steve.

Could you direct me where to go on Dolby's site? lol :p, I've been looking around for a while and can't seem to find these documents.

Thanks!
Josh

[ursamtl]

Hi Josh,

You can find the Dolby stuff in their Information > Technical Information menu or at http://www.dolby.com/resources/tech_library/index.cfm. This consists of a fairly extensive bunch of PDFs. For DTS, check out http://www.dtsonline.com/pro-audio/ for an authoring guide or http://www.dtsonline.com/technology/technical_literature.php for some technical white papers.

Happy reading!

Steve.