OMPT as converter

[Sam_Zen]

I admit it's a bit late, but I discovered the advantages of the RC3 mix mode recently.
I re-saved some files with that mode, and the enhancement was impressive.

So I decided to convert my collection of older tracking modules, all MOD or XM format.
MOD doesn't have such a mix mode, so has to be converted to another format anyway.
XM does have the mix mode. All files had the 'original' or RC2 mix, so should be re-saved as well.
I chose to convert both types to the IT format, because it's closer to ongoing developments of OMPT.
(and for my convenience, because it can export a quad WAV file properly)

Quite a job with 170 to go..
So I was looking for some standard actions in the procedure, to program myself to do it efficiently.
First of all, it wasn't going to be a matter of : open - pick RC3 - and save again.
All files had different values at the volume sliders of the General tab, so I needed a standard setting.
So far, I chose for Initial global : 128, VSTi : 0 (no plugins of course), and Sample : 48.

But more things appeared to ask attention in this process.
Under the Mix level RC3 (Song properties) is also 'Miscellaneous flags'. I did "100" as default.
Lineair frequency slides on or off ? I have no idea.

Another peculiar aspect : the MOD format with its standard panning per channel L-R-R-L etc.
When opened, the Initial Pan sliders (Gen. tab) have a value of 64 (L) or 192 (R).
They are greyed out, so can't be changed. But as soon as the IT conversion takes place,
these values become valid. In some cases this resulted in a slightly narrow panorama.

This mass conversion has led to the removal of my old collection from the server.
So the links to these files, like those in the list of my profile, are no longer valid.

[Saga Musix]

To address some points individually...

So I decided to convert my collection of older tracking modules, all MOD or XM format.

This is not always a good idea, since most effects (pattern commands) sound slightly different in all formats. But yeah, the differences are subtle in most cases.

(and for my convenience, because it can export a quad WAV file properly)

Uh, but quad output should work for IT just like XM. Or did you maybe spot a bug here? Please elaborate.

All files had different values at the volume sliders of the General tab, so I needed a standard setting.

Well, since the global volume can be modified in the patterns, it's not too wise to change it during such a process. Unless you don't use Wxx and Vxx commands (Gxx and Hxx in XM, I believe) of course.
For compatibility with players which calculate the sample volume correctly, the sample volume should be around 32-48, or else it might distort in schism and other trackers.

Under the Mix level RC3 (Song properties) is also 'Miscellaneous flags'. I did "100" as default.

If the tunes were not composed in MPT, this is the way to go. And I'd even recommend using this setting if they were composed in MPT, but are intended to be listened to in XMPlay or other players as well.

Lineair frequency slides on or off ? I have no idea.

Just leave it. Tone portamento will sound wrong in an already finished song if you change it. ANd as a general advice, it should be enabled when composing new modules, however it is not possible to use it in MOD and S3M, as they both use Amiga slides, not Linear slides.

But as soon as the IT conversion takes place,
these values become valid. In some cases this resulted in a slightly narrow panorama.

You just imagine that, panning is handled exactly the same in all formats. Maybe you imagine it because the C-5 frequency goes slightly up (I think there's a bug in NTSC/PAL frequency conversion)?

[Sam_Zen]

effects (pattern commands) sound slightly different in all formats. But yeah, the differences are subtle in most cases.

Subtle enough after checking 170 files to decide to do it.

quad output should work for IT just like XM. Or did you maybe spot a bug here? Please elaborate.

Before hijacking this thread : I like to elaborate, and I was already planning to post a seperate topic about this.

it's not too wise to change it during such a process. Unless you don't use Wxx and Vxx commands

I didn't use any of those codes, so no problem

the sample volume should be around 32-48

So I'm a bit at the high end with my 48..
I tested with XMPlay and Foobar2000, all ok, no distortion.

it is not possible to use it in MOD and S3M, as they both use Amiga slides, not Linear slides

I don't think I used tone porta in a MOD, only in XM to provide phasing, but I'll check.

You just imagine that, panning is handled exactly the same in all formats

Quite right, at a second listen it appeared to be my imagination. Nothing narrower.

On the other hand it gave the opportunity to artificially 'widen' the panorama by changing the panning value per channel.
From the default 64 - 192 to 0 - 255.

Another aspect to mention : IT files are, as average, 1/8 smaller than the MOD or XM version.
To illustrate this conversion, some random picked examples :

* Blacklight Kids - 12 CH : the before MOD version  and the  after IT version

* Klass - 4 CH : the before MOD version  and the  after IT version

[Saga Musix]

I tested with XMPlay and Foobar2000, all ok, no distortion.

That's the wrong players to test, because XMPlay will automatically adjust the master volume (i.e. the sample amplification) so that modules never distort / are always as loud as possible). So it actually ignores this slider.

I don't think I used tone porta in a MOD, only in XM to provide phasing, but I'll check.

Well, as I said it's not a problem anyway if you don't touch the value. When converting from MOD to IT, linear slides are of course left off, and when converting from XM to IT, the value will not be changed.
Your track "Blacklight Kids" uses them (pattern 15), btw, so you DID use it in a MOD.

Another aspect to mention : IT files are, as average, 1/8 smaller than the MOD or XM version.

That's because the IT format uses a quite efficient way to compress patterns. Impulse Tracker itself was also possible to compress samples using a unique compression algorithm, but I think no tracker apart from IT itself can save such IT files (all trackers I know can load such samples, though).
Since the XM format saves samples as delta values, they compress slightly better than uncompressed IT samples, though.

[Sam_Zen]

Thanks Jojo, for the additional information.

[oxxi]

I also like switching between the no interpolation, and polyphase to give tunes a different sound. OPMT is the best!

[Saga Musix]

That doesn't have anything to do with converting modules, though...

[oxxi]

yeah, not really but this post just reminded me of that.

[Saga Musix]

Quoting something from above which I missed... Sample volume 48 is the "high end", it's just a typical value (and actually the default one). Depending on the module, even 64 will still sound ok.

[Sam_Zen]

the sample volume should be around 32-48

That's why I mentioned 'high end'. I noticed now that 48 is the one that pops up in most cases.
Maybe 64 is possible, but not with my tracks. I would get lotsa distorted conversions.
I guess because I already payed attention to the max volume of the original modules.

[Saga Musix]

Well, neither MOD nor XM have a dedicate amp value for sample volume, so if you tracks distort with anything about 48, you probably use a lot of duplicated channels.

[Sam_Zen]

My tracks didn't distort at 48, so it was sufficient for me.
I seldomly used duplicated channels to crank up the volume, if that's what you mean.

Additional info about the S3M format :
This differs from the MOD or XM situation.
- VSTi vol is greyed out
- Initial Pan (channels) is already active, with saved values.