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    Invelos Forums->DVD Profiler: Plugins Page: 1  Previous   Next
Tool: MonoCheck
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DVD Profiler Unlimited RegistrantStar ContributorGSyren
Profiling since 2001
Registered: March 14, 2007
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Sweden Posts: 4,245
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My search for a way to determine if 2-channel audio track is mono or stereo led me pretty much nowhere, so I decided to try to write a program to help. The result is MonoCheck.
(Yes, it's that small!)

It compares the left and right channel of the audio output from your PC when you play a movie at a normal volume. It can determine if a track is actually mono.

You can read all about it in the online help.
My freeware tools for DVD Profiler users.
Gunnar
DVD Profiler Unlimited RegistrantStar ContributorGSyren
Profiling since 2001
Registered: March 14, 2007
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Sweden Posts: 4,245
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If it wasn't clear why I thought we needed a way to identify 2-channel mono, here it is.

From the Audio section in the rules:
Quote:
Note: Select Mono for both 1-channel and 2-channel mono.


Media players seem to always report 2-channel audio as stereo, which leads to a lot of profiles, especially for older movies, having the wrong information.

When in doubt - MonoCheck

PS For a brief moment I considered calling the program The MonoLisa, because it's a masterpiece. 
PPS Do read the help file before contributing! It really holds important information.
My freeware tools for DVD Profiler users.
Gunnar
 Last edited: by GSyren
DVD Profiler Unlimited RegistrantStar ContributorGSyren
Profiling since 2001
Registered: March 14, 2007
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I found that the "noise" level limit for the prediction needed a bit of tweaking.
Stereo tracks with very limited stereo effects could be reported as M2 (2-channel mono).
You would still see the values changing, so you should realize that it's probably not mono, but still ...

Fixed in MonoCheck 1.0.1
My freeware tools for DVD Profiler users.
Gunnar
DVD Profiler Unlimited RegistrantStar ContributorNexus the Sixth
Aficionado since 1999
Registered: March 13, 2007
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Nice tool!

For additional visual verification you could also try this: Soundcard Scope

I haven't tested it on DVDs but it works well enough comparing mono and stereo tracks on Spotify, for example with The Beatles "1" (Remastered).

For older recordings you will sometimes see variations in the input signals due to channel noise but the differences are generally much smaller than for real stereo.
DVD Profiler Unlimited RegistrantStar ContributorGSyren
Profiling since 2001
Registered: March 14, 2007
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Sweden Posts: 4,245
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For those who are interested.

How it works in detail

MonoCheck uses a .Net audio library called NAudio in order to monitor the output from the PC's soundcard. This gives MonoCheck a floating point value for the left and right channel, and it computes the difference between these two values.

In theory, if the sound is mono there should be no difference, so the value should be zero. If it is 1-channel mono, then it probably is zero, unless the sound card introduces changes in the audio streams. If it is 2-channel stereo, then we have two separate channels encoded on the disc, and the encoding may introduce some slight variations, especially if it is not a lossless encoding.

So, a standard Dolby 2-channel mono track will definitely have some very minor differences. A stereo track will have much larger differences, but it will still be a very small value. What MonoCheck attempts to do is to magnify that value to the point where the integer part is still zero for a mono recording, but well above zero for a stereo recording. That way, the user should be able to see the displayed value stay at zero when it is mono, and vary quite noticeably when it is stereo.

Internally MonoCheck also keeps track of the highest raw value of the difference, in order to determine with some degree of accuracy if the track is 1-channel mono, 2-channel mono or stereo.

So, there are two things that has had to be determined by trial-and-error; the multiplier for the displayed value, and the threshold for the raw value. This means that MonoCheck is probably not 100% perfect, and may never be. But it should still be good enough to give a reliable result.


Currently the magnifier still seems to need a little tweaking. I have noticed that mono tracks may "spill over" and occasionally display 1 instead of 0. But that should not be enough to fool anyone into thinking that it is stereo. Stereo shows much larger values.

If anyone has a PC setup with more than 2 audio channels, for example 5.1, I would very much like to know if MonoCheck works there as well. I have not been able to test that.
My freeware tools for DVD Profiler users.
Gunnar
DVD Profiler Unlimited RegistrantStar ContributorT!M
Profiling since Dec. 2000
Registered: March 13, 2007
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Brilliant tool! 
DVD Profiler Unlimited RegistrantFrodonf
Registered: March 14, 2007
Canada Posts: 225
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Wow!
Great tool!

Thanks GSyren 
Certainty of death...
Small chance of success...
What are we waiting for ?!
DVD Profiler Unlimited RegistrantStar ContributorGSyren
Profiling since 2001
Registered: March 14, 2007
Reputation: Highest Rating
Sweden Posts: 4,245
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MonoCheck version 2

Just a reminder why I created the first version of MonoCheck. From the rules:
Quote:
Select Mono for both 1-channel and 2-channel mono.

It's often hard to distinguish mono from stereo. MonoCheck version 1 was based on the assumption that 2-channel mono tracks would be identical, so if you took the volume from one and subtracted the volume from the other, they would cancel out. Unfortunately audio mastering isn't always that exact, which made MonoCheck less than reliable.

When I decided to revisit the problem with determining mono or stereo, I realized that I had really been overthinking the problem the first time around. So I simplified the solution down to this:


It's really just two volume meters in parallel. If you see the volume bars move unsynchronized, it's a stereo track. If they are always synchronized it's mono. If the mono sound isn't perfectly balanced, one bar may be slightly shorter than the other, but they'll still move the same way.

Right click anywhere in the program and you'll get a context menu that gives you access to the settings, and to the help file.
My freeware tools for DVD Profiler users.
Gunnar
DVD Profiler Unlimited RegistrantStar Contributordee1959jay
Registered: March 19, 2007
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Brilliant as always. Many thanks, Gunnar!   
DVD Profiler Unlimited RegistrantStar ContributorGSyren
Profiling since 2001
Registered: March 14, 2007
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Quoting dee1959jay:
Quote:
Brilliant as always. Many thanks, Gunnar!   

Thanks! Glad to know someone finds it useful! 
My freeware tools for DVD Profiler users.
Gunnar
DVD Profiler Desktop and Mobile RegistrantStar Contributormreeder50
I was outta bullets
Registered: March 29, 2007
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It is absolutely useful.
Marty - Registered July 10, 2004, User since 2002.
DVD Profiler Unlimited RegistrantStar ContributorObiKen
Registered: October 22, 2015
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I tried MonoCheck v2 and liked it very much, its a simple but effective tool and I will be using it from now on.
Bravo Zulu to GSyren.
DVD Profiler Unlimited RegistrantStar ContributorGSyren
Profiling since 2001
Registered: March 14, 2007
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Sweden Posts: 4,245
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Thanks Marty and ObiKen! 
My freeware tools for DVD Profiler users.
Gunnar
DVD Profiler Unlimited RegistrantStar Contributorrdodolak
Registered: March 18, 2007
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Quoting Nexus the Sixth:
Quote:
Nice tool!

For additional visual verification you could also try this: Soundcard Scope

I haven't tested it on DVDs but it works well enough comparing mono and stereo tracks on Spotify, for example with The Beatles "1" (Remastered).

For older recordings you will sometimes see variations in the input signals due to channel noise but the differences are generally much smaller than for real stereo.


Audacity is another tool that can be used to visualize the channels.

https://www.audacityteam.org/
DVD Profiler Unlimited RegistrantStar ContributorGSyren
Profiling since 2001
Registered: March 14, 2007
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Sweden Posts: 4,245
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Yes, I'm sure that there are several other tools that can do the same thing.

The advantage with MonoCheck is that it is small, so you can keep it on top of your mediaplayer while you're auditing a profile.
And since it is a single function tool, it's extremely easy to use.
My freeware tools for DVD Profiler users.
Gunnar
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