SetPeriod Sound Issues

[LuMan]

I'm getting an odd error when trying to use the SetPeriod command in Blitz Basic to alter the pitch of a defined sound.

Here's the code, which creates a simple square wave and then tries to alter the pitch:

InitSound 0,128,450,0

For a=0 to 63
  SoundData 0,a,100
Next a

For a=64 to 128
  SoundData 0,a,-100
Next a

LoopSound 0,1
VWait 200

SetPeriod 0,250

LoopSound 0,1
VWait 200

Sound 0,1
End

It's dead simple, just a square wave, which sounds for 4 seconds (VWait 200)

However, when running the code all is well until the SetPeriod command is encountered. At this point I get an error saying "Illegal Chanel Mask". Bizarrely complete with mis-spelling of "Channel"... unless it is really something to do with perfume...

According to the Blitz manual, the SetPeriod command does not take a parameter for the audio channel, but purely a value for the pre-defined Period parameter of the Sound.

Any ideas?

[ReadOnlyCat]

First rule of debugging:
- strip the code to the bare minimum still exhibiting the bug

Do you still get the issue if you do:

InitSound 0, 128, 450, 0
For a=0 to 128
  SoundData 0, a, 100
Next a
LoopSound 0,1
SetPeriod 0, 250

If so, then try putting "127" in the loop instead of "128".

[LuMan]

The code works fine for the first part - although I did see a typo in my original post... The loop does go from 64 to 127, not 128

I've tried a number of different wave types - square, sine, saw, as well as loaded samples - and I always get the error when I try to amend the period....

[idrougge]

BUM7 says:
Syntax : SetPeriod Sound#,Period
Library : audiolib

Description:
Hmmm, not sure why we never included this command in the original
audiolib, SetPeriod simply allows the user to override the frequence
information (period) of the sound object after it has been loaded.

To alter a sound's pitch while playing programmers should hit the audio
hardware direct (hardware locations are listed at the back of the
reference manual).

[LuMan]

Hehe. OK, so the command isn't working properly, then. That's OK, so long as I know. Saves me hours of flogging a dead horse!!

Thanks for the heads-up, idrougge. Taking a look at the reference manual now...

UPDATE:
WOW! There's a lot of useful stuff in the reference section at the end of the Blitz Manual!
So, the following bit of code resets the period to 256, thus making the pitch of the note higher:

Move.w #$00ff, $dff0a6

Sorted

[idrougge]

I think the command you're looking for is Freq.

[LuMan]

Originally Posted by idrougge

I think the command you're looking for is Freq.

Hmm.. This may be in later updates of BB2 for that Amiga, but it's certainly not a command in the version I have. There's no reference in the Manual, and, while I can find a reference to it on the internet, the command throws an error when I try to compile.

[idrougge]

There's no reason not to run the Ultimate Blitz CD version unless you have a floppy-only system.

[LuMan]

Y'know, that's a good idea. I ought to dig it out, but I actually bought Blitz Basic 2 when if first came out and nostalgia sort of led me back to my original disk set.

I'll upgrade to the Ultimate version and make use of all those extra commands!!

[Mrs Beanbag]

Originally Posted by LuMan

So, the following bit of code resets the period to 256, thus making the pitch of the note higher:

Move.w #$00ff, $dff0a6

no, it sets it to 255...

[LuMan]

Originally Posted by Mrs Beanbag

no, it sets it to 255...

Ha! Er.. Deliberate mistake, to see if anyone was reading it... <ahem>..

[idrougge]

Found this in alt.sys.amiga.blitz…

>BUG2:
> SetPeriod
>
> SetPeriod Generates a false debugger error: Illegal Channel Mask.
> The strange thing is that the message persist even when your#
> sound number happens to be a legal channel mask.
> Also, if you specify a number not corresponding to an existing
> sound, you get an Uninitialized sound error.
> The only workaround is to set errors off and on before and after
> the command,
Fixed on BUM9 sort of, I think... a replacement library called XBaudiolib
was in Blitzlibs:Testlibs which fixes/updates many of the Acid sound
commands. It uses exactly the same command syntax as the Acid lib but has
XB before it e.g. XBSound...

[idrougge]

There's a fix to SetPeriod in http://aminet.net/package/dev/basic/BlitzLstJan02

[Anakirob]

This would be great, it's been a while since I coded in Blitz, but I recall telling my computer to get ****** every time I forgot to disable/re-enable the debugger around the Sound function. I'm curious as to which file contains the patch, is it this one:

BlitzLstJan02/attachments/mail_110/bugs2.2.bb2

I assume I just need to compile and run it.

[idrougge]

It's attachments/mail_56/libfixes.lha. It claims to fix exactly the problem of SetPeriod not working in debug mode.

[Amiga1992]

OK this was driving me insane.
How exactly do I patch this, then? I have the libfixes.lha file but no idea how to patch the program.
I have the Blitz Ultimate CD but installing from there using the installer gives me an error about some file being write protected. I never was able to use that installer. Do I have a bad CD?

[edit] as soon as I use setperiod, I hear noise in my audio channel. Must not be using it right.

[idrougge]

There is a fixed installer on Aminet. http://aminet.net/package/dev/blitz/ubbinstall

[Amiga1992]

Holy shit did they do nothing right? Thanks idrougge I'll have to try that.

[Daedalus]

Also, there's the http://ubb.plus version of the CD that might be worth looking at. It's a relatively recent update to the Blitz CD that includes all the major updates, a fixed installer and an updated manual.

As for changing the pitch of a sample, back in the '90s I used SetPeriod and it worked fine, so that bug probably crept in later on in a certain version of the libraries. But it was limited in that it only took effect the next time the sample was played, since it simply alters the period value associated with the sample. If that's all you need, you can easily modify the sound object's parameters directly using something like this:

*MySound.sound = Addr Sound(1)
*MySound\_period = 500

You'll need the bb2objtypes.res added to the compiler settings for the sound Newtype to be available.

If changing the pitch during the sample being played is the intended result, then the Freq command should do the job instead, or you can poke the desired period values directly into the chipset registers for the desired channels.

[Amiga1992]

Originally Posted by Daedalus

But it was limited in that it only took effect the next time the sample was played, since it simply alters the period value associated with the sample. If that's all you need, you can easily modify the sound object's parameters directly using something like this:

[...]
If changing the pitch during the sample being played is the intended result, then the Freq command should do the job instead, or you can poke the desired period values directly into the chipset registers for the desired channels.

Are you referring to this other thread I created? Because I tried to do this and I didn't get it to work. I'm gonna update that thread with the code I am using, maybe you can shed some light.