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DIY Dolby Digital and DTS test tone CD


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4 replies to this topic

#1 of 5 Jonathan M

Jonathan M

    Second Unit

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  • Join Date: Jul 23 2002

Posted March 26 2003 - 10:40 AM

Hi all,

Just thought I'd share a method I've discovered for creating testtone CDs with Dolby Digital and DTS surround multichannel tones allowed.

Basically it involves creating the various tones/pink noise etc. that you want as a WAV file, and then converting up to 6 mono wave files into a single Dolby Digital or DTS WAV file.

These encoded wavs are basically an AC3 or DTS stream, padded out to correct for bitrate, and written with the correct header to an Audio CDR(W).

You play them on a standard dvd player or cd player with optical out, and your receiver SHOULD pick up the stream as the appropriate type and decode as if it was a DVD. You must be careful about volume, as if your receiver doesn't pick up the stream correctly, you'll get 0dB noise output - not nice for speakers or ears!

Too encode, you can use SoftEncode for DD and SurCode for DTS. A free option is available with BeSweet for DD, but no free option for DTS encoding, other than obtaining it via a dodgy download.

This enables you to test your bass management to the extreme, by putting test tones and MLS signals in any of the channels including the .1 LFE channel, and seeing how it directed etc.

I will over the next week or so performing frequency analysis using MLS signals to see what is happening to the management of bass in my NAD T752.

Hope this helps someone!
"Price and quality are not correlated"

DIY Home Theatre

#2 of 5 Karl FS

Karl FS

    Extra

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  • Join Date: Feb 07 2003

Posted March 26 2003 - 05:01 PM

sounds like a cool idea... how about posting some of the wav files here when you're done? I'd love to send some localized test signals to my new tempest I just built.

#3 of 5 Jonathan M

Jonathan M

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  • Join Date: Jul 23 2002

Posted March 27 2003 - 09:24 AM

I am currently experimenting with MLS signals to see how the compression schemes of both DD and DTS effect the frequency response. Assuming I can get them to work, this will mean we can simply record on a computer the output from any preamp/processor or receiver with pre-outs, and plot up a frequency response.

I will be willing to post the compressed files to the net once I get the process down, assuming there is a demand for it.

What sort of tones would people be interested in, and what tracks would you like them on? (All at once, Just mains, Just centre, LFE only etc. etc.)
"Price and quality are not correlated"

DIY Home Theatre

#4 of 5 Jon G.

Jon G.

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Posted March 27 2003 - 11:34 AM

Wow, that's cool. If you could do it (and I know that's a big if), test tones for DTS-ES and DD-EX would be a god-send. I'd love 7 individual tones for the 6.1 channels in DTS-ES and DD-EX...

#5 of 5 Jonathan M

Jonathan M

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  • Join Date: Jul 23 2002

Posted March 27 2003 - 11:47 AM

DD EX probably wouldn't be too hard, as it just a matrixed version. How good it turns out the "discrete" rear centre might be questionable, though.

DTS ES is not possible at this time. It relies on a DTS CD Audio track, which AFAIK is only 5.1 at this stage.

What type of tones is everyone wanting - just pure sines, or a warble signal, sweep, noise etc.?
"Price and quality are not correlated"

DIY Home Theatre