I would like to create a disc with six mono channels to use for testing 5.1 processors and receivers. The reason for such a disc, if it can be made and will work, is to know that all six channels are working properly. I am assuming that it has to be a DVD disc, but I do not know that for sure. A regular 5.1 disc will not have the same material in all six channels at the same time and so it is entirely possible that those channels that do not appear to be working properly merely have no material at the moment or have very quiet material compared to a main channel, like the center channel for example. By having a disc with six channels that are separate and independent, but all the same, one can quickly determine whether the processor or receiver is operating properly.
As such, I would like to take a mono signal and place it on all six channels. I would use music passages or songs and not test tones.
If the disc can be created and works properly, then one should be able to adjust the channels to the point where the volume of the passage is the same for each channel. This also requires matching speakers (six of them). If the channels cannot be made equal in sound volume and quality with this disc and the speakers do match, then there is a problem in the processor or the receiver. Even if the speakers do not match perfectly, the sound should be close in all of them.
In short, this disc would let you quickly if you had, for example, a bad amplifier channel, or some other problem that was preventing the signal from getting all the way to the speaker.
I do know how to turn a stereo CD into a mono disc and I have the mono Beatles box set, so I can get the digital mono material that has the entire musical passage or song in just one channel.
I would appreciate any help or guidance.
You may have some shaky assumptions about how Dolby Digital works. It’s most efficient when you have a theatrical presentation with the monolog in the center, the car crash on left and right, the explosion in the LFE and birds chirping in the rear channels, but nowhere it is written that you have to do that. I had a test ac3 file of a woman walking “around the room” talking and announcing the points of the compass as she went. “I’m standing on the Left Rear now. This is the Left Rear.”
It was intended as a speaker test. I think it came with a sound card I bought. You can probably go online and find something like that already made up.
A more evil thing that Dolby does is Dial Norm. There is a limited range of loudnesses that can be accommodated by a sound system. In order to recreate reality as closely as possible, Dolby adjusts volume on the fly during the performance. You may have never noticed that on a commercial movie.
Done properly, this gives you the explosion that rattles the dinnerware and moves your shirt, but the dialog is at a perfect volume.
That’s the good news. The bad news if you have to produce that control during the making of the surround file. If you don’t, it may kick in at the default volume points instead of where you intended. This drags you to using a professional video editing package like Premier or Final Cut (the old Final Cut) which has sliders and controls for Dolby.
As with MP3, Dolby gets you at the generator step, not the playback step. Neither is free.
Then there’s the matter of the LFE. Low Frequency Effects only passes sounds that a pipe organ, earthquakes and explosions can generate. It will not pass dialog or any meaningful music.
Here’s one that has a pre-baked surround test.
http://www.lynnemusic.com/surround.html
Koz
Thanks. I do not necessarily know what I am doing so I appreciate the basic information. I think you can see what I want to do. I just want to have a handy test disc so I do not have to hope I get to a good spot in a movie and so I do not have to take forever to get through the previews and menus and over to the spot that gives me a good test.