Test files for ambio processor development

[mosc]

Here are a couple of test files developed by Robin Miller to aid in the development of ambiophonic processors.

One is a recording of Robin speaking and panned left, right, and center. This is a good test of the processors with and coloration.

The other file is a dirac pulse at 44100 Hz. Play this though your processor and record the output. Robin has agreed to analyze these output files on his system.

The ultimate verification is, of course, the sonic results.

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dirac-pulse.wav
Description:	dirac pulse copyright 2008 by Robin Miller	Download
Filename:	dirac-pulse.wav
Filesize:	1.18 MB
Downloaded:	256 Time(s)

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speech-left-right-center.wav
Description:	Left - Center - Right speech copyright 2008 by Robin Miller	Download
Filename:	speech-left-right-center.wav
Filesize:	5.37 MB
Downloaded:	269 Time(s)

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[DrJustice]

I guess the Dirac test/verify is for the RACE version, and not yours?

DJ
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[mosc]

[DrJustice]

You mean Robin Miller will analyze a Dirac processed by your version of the ambiophonic processor? (it wil have a totally different impulse response than the RACE one)

Edit: if not perhaps you can generate a test file, using your VST, from that Dirac pulse?

DJ
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[mosc]

There are differences between mine and the RACE processor, of course. He'll look a the response for things that look flakey. It's just a sanity check.

I'll record my VST's response and post it, for reference though.

[durwood]

Of all the different ambio plugins I have tested they all seem to have a slight issue, unless it is intentional.

Using the l-r-c track, when I hear the L or R vocal, the "s" from stage originates from the center. It is a bit distracting and not sure if it is intended but it smears the location. Like I said they all seem to do it, past and present ones.

To verify I wasn't crazy, I monitored it with a stereo goniometer both before and after the plugin and it is visible in the meter too, only on the output side. Singal going in is intact. Can this be corrected?

I also noticed the center location is very precise, but the L an R are not as precise. Again input side is good, output is where I notice it. Is this an artifact or intentional to give it more ambiance? No adjustment I could do seemed to correct it.

[mosc]

[durwood]

Yep I understand both speakers work in conjunction with each other to move the location around just as with ambisonics.

I need to try to capture screen shots on the goniometer though maybe to explain the centered 's' on non-centered signal. I don't think that should happen and if we could improve that I would feel much better about it. I hope it is not a necessary evil, it's a wee bit distracting and maybe not totally noticeable or masked with complex music but now that I know it is there I can't miss it.

[durwood]

I was able to capture what I was talking about. Two things.

1) The centering of the beginning and ending of the word "stage" only on the output side when supposed to be L or R

2) The diffuse/loose L and R rather than a strongly defined L or R. Maybe this is needed for ambiance? I wonder if it could be too coloring for some folks?

The good is you can see the output is wider than the stereo signal and since the speakers are more centralized and away from walls it sounds wider than the stereo signal even though stereo speaker placement is already set further apart.

Left


Center


Right (with "stage" word)


Right before "stage" is said

[mosc]

What you are seeing is the effect of whitish noise in the word "stage". Imagine, for discussion, that you play white noise in the L channel and the same signal delayed by some small amount in the R. Your stereo vector scope should show a perfect X pattern, but it will probably not. Instead you might see a fuzzy X with a cluster in the center.

A vertical line on the vector scope indicates the same signal in the L and R channels (mono or uncorrelated). It might be expected that as the signals are noise, they will randomly be exactly the same, or close to the same. This distribution will explain the "globular cluster" in the center and the fuzziness of the images.

[mosc]