Welcome, Guest. Please login or register.

Author Topic: Amiga Stereo Effects!  (Read 4189 times)

Description:

0 Members and 1 Guest are viewing this topic.

Offline darkcoderTopic starter

  • Full Member
  • ***
  • Join Date: Sep 2002
  • Posts: 164
    • Show only replies by darkcoder
Amiga Stereo Effects!
« on: April 01, 2004, 11:51:21 AM »
Hello

 I would like to select the direction (left or right) from which a user perceives a sound.
 I am speaking about Paula direct coding, no AHI.
According to the Hardware Ref. Manual (HRM) audio channels 0 and 3 are associated to the Right Channel (R)
 while 1 and 2 to the Left one (L).
 After some experiments, it seems to me that the real situation is quite different:

 1) A2000 works as described in HRM
 2) A500, A600 and A1200 do the opposite, i.e. channels 0,3 come from L while 1,2 come form R
 3) A4000D is tricky.
    Here 0,3 come from the jack whose physical position, if one stands in front of the front panel of the case,
    is right. Such jack is colored in red, which usually means right. However, at least on my case, the jack is labelled "L" !!!!
    Of course 1,2 come from the left positioned jack, colored white BUT labelled "R"
 4) A4000T is even more tricky. I recall that on A4000T there is a video/audio module which is a daughterboard, and,
    at least with my Eagle tower case is "upside down", i.e., with components towards the bottom of the case. (is it the same with C=,
    AT and Quickpack towers?)
    So here 0,3 come from the jack physically  to the right, colored red and referenced as "right" in the manual (on the board there is no
    label).
    However, the A4000T has also a headphone connector. And if I use a headphone, then I hear channels 0,3 coming from the left!!!

 So I would like to ask you the following questions:
 Q1: Can anyone confirm or deny my results? Doing so many tests in one day, I could have done some mistake...

 Q2: What happens to A1000, A3000, A3000T, CDTV, CD32? To which jack are channels 0,3 associated?

 Q3: Suppose I want to produce sound from a specified jack. For example I could have a program playing a sound with a "left/right balance" volume command:
 selecting a gadget, I want to increase/decrease the volume of the right loudspeaker. What shoud I do?
     a) detect which Amiga model the program is running on (not easy, since it's not the question of detecting CPU or the chipset, but the motherboard!)
     b) choose one, I would say channels 0,3 coming from Left, since A500/A1200/A600 are the majority of Amiga models and assume the users of other models
        swap the connection of the audio jacks
     c) other ideas??

Q4: I can't see any rationale behind the choice of using different assignments on different models! Do you see any good reason?

I think this is a very strange situation. I really hope someone could help me to clarify my confused ideas!! :-)

The Dark Coder / Trinity
 

Offline that_punk_guy

  • Hero Member
  • *****
  • Join Date: Aug 2002
  • Posts: 4526
    • Show only replies by that_punk_guy
Re: Amiga Stereo Effects!
« Reply #1 on: April 01, 2004, 11:54:00 AM »
On both my A500 and A1200:

Channels 0 and 3 play through the left jack
Channels 1 and 2 play through the right jack

Other than that I can't help... :-?
 

Offline xeron

  • Hero Member
  • *****
  • Join Date: Mar 2002
  • Posts: 2533
    • Show only replies by xeron
    • http://www.petergordon.org.uk
Re: Amiga Stereo Effects!
« Reply #2 on: April 01, 2004, 11:54:36 AM »
Eh? I have 6 different Amigas and i'm pretty sure channels 0 & 3 come out of the left jack on all of them...

Certainly in Protracker and the like, the channels should go Left, Right, Right, Left.
Playstation Network ID: xeron6
 

Offline Karlos

  • Sockologist
  • Global Moderator
  • Hero Member
  • *****
  • Join Date: Nov 2002
  • Posts: 16867
  • Country: gb
  • Thanked: 4 times
    • Show only replies by Karlos
Re: Amiga Stereo Effects!
« Reply #3 on: April 01, 2004, 12:18:53 PM »
@darkcoder

Every amiga I have tinkered with follows the left = 0/3, right = 1/2 assignment. However, perhaps there are revisions that have this assignment inverted.

For your appication all I can suggest is having a "channel assignment" preference which simply chooses between the two assignments. When unset, it would assume the 0/3 = left, 1/2 = right assignment.

That way, the user can choose the assignment (perhaps they got their speakers the wrong way round or sth ;-) ) and evertbody is happy :-)
int p; // A
 

Offline Steady

Re: Amiga Stereo Effects!
« Reply #4 on: April 01, 2004, 01:35:37 PM »
Perhaps when you were testing the Amiga models with the 'reversed' output, you connected the speaker cabling back-to-front. Like the others wh replied, I've only known 0 & 3 to be the right channel, and 1 & 2 to be the left.

I think you can safely program as the RKM says.
 

Offline darkcoderTopic starter

  • Full Member
  • ***
  • Join Date: Sep 2002
  • Posts: 164
    • Show only replies by darkcoder
Re: Amiga Stereo Effects!
« Reply #5 on: April 01, 2004, 02:33:36 PM »
@steady & Karlos

If you read each other's reply, you'll see that you have different outcomes!

To do the tests, I did the following: I put both cables in the Amiga's jacks. BUt I only inserted one of the cables in the loudspeakers jack.
So, when testing for example channel 0, the sound come ony if the left (or right in the case of A2000, A4000) was connected.
Also, note what happens to the 4000D: there for sure there is a mistake, eithr in the color of the jack, or in the label on the case.

Please, consider that I spent a day doing tests, so althoug errors are possible, I checked things twice before writing...
Can you please spacify your Amiga models?

Darky
The Dark Coder / Trinity
 

Offline nOw2

  • Full Member
  • ***
  • Join Date: Jul 2002
  • Posts: 194
    • Show only replies by nOw2
Re: Amiga Stereo Effects!
« Reply #6 on: April 01, 2004, 03:07:03 PM »
Oh god, is it April already?

Quote

Also, note what happens to the 4000D: there for sure there is a mistake, eithr in the color of the jack, or in the label on the case.


Audio is completely standardised.

0,3 come out of the left/white/L jack.
1,2 come out of the right/red/R jack.

Any other situation, and someone's been playing or replacing components. Or it's the 1st of April. The only possible confusion assuming standard equipment is that some Amiga models are designed such that left is on the left viewed from the front of the machine, not the back.

Quote

Can you please spacify your Amiga models?


All of them.
 

Offline Steady

Re: Amiga Stereo Effects!
« Reply #7 on: April 01, 2004, 04:47:59 PM »
Dang!!!

I looked at the left and right designations repeatedly before typing in my answer in the knowledge that I would probably go dyslexic... and I still stuffed it up! :roll:

It was basically a longwinded way of saying the RKM is right. Follow that.
 

Offline darkcoderTopic starter

  • Full Member
  • ***
  • Join Date: Sep 2002
  • Posts: 164
    • Show only replies by darkcoder
Re: Amiga Stereo Effects!
« Reply #8 on: April 01, 2004, 07:15:06 PM »
Hi

 I really choose the wrong day... :-(
 I am not joking, really!
 Maybe I did some mistake in the tests, but I'am not joking.

 @ Steady:

 HRM is surely wrong, it states that channel 0-3 comes from the right.
 Almost everyone here said channel 0-3 comes from the left.
The Dark Coder / Trinity
 

Offline Thomas

Re: Amiga Stereo Effects!
« Reply #9 on: April 02, 2004, 02:19:47 PM »

Well, I never read this section of the RKRM very carefully and now I am really surprised.

From what I learned in my early Amiga days (more than 15 years ago) and never was proven wrong, channels 0 and 3 go to the left, channels 1 and 2 to the right and the audio connectors on the A4000 are labelled correctly and coloured wrong (red = left and white = right).

Well, this means either the RKRM is wrong or my world view is about to be reversed :-)

Bye,
Thomas

Offline darkcoderTopic starter

  • Full Member
  • ***
  • Join Date: Sep 2002
  • Posts: 164
    • Show only replies by darkcoder
Re: Amiga Stereo Effects!
« Reply #10 on: April 05, 2004, 12:09:07 PM »
Hello

  First of all I say again this no joke!!
  I will never post anything the 1st of april...
  except jokes!! :-D

 @Thomas I think you should update your "world view"!

 I posted the same message in comp.sys.amiga.hardware and got a reply from Dave Haynie!!!

Here is what he writes:
-------------------------------------------------------
> I am speaking about Paula direct coding, no AHI.
>According to the Hardware Ref. Manual (HRM) audio channels 0 and 3 are
>associated to the Right Channel (R) while 1 and 2 to the Left one (L).

That's the plan...

> 1) A2000 works as described in HRM

I did it pretty much the way the A1000 did it, though using George
Robbins' cheaper anti-imaging filter.

> 2) A500, A600 and A1200 do the opposite, i.e. channels 0,3 come from L
>while 1,2 come form R

Sounds like they screwed these up. I never checked, myself.


> 3) A4000D is tricky.
>    Here 0,3 come from the jack whose physical position, if one stands in
>front of the front panel of the case, is right. Such jack is colored in red, which usually means right.
>However, at least on my case, the jack is labelled "L" !!!!
>    Of course 1,2 come from the left positioned jack, colored white BUT
>labelled "R"

Sounds like the motherboard is built correctly, the case labelled
incorrectly.

> 4) A4000T is even more tricky. I recall that on A4000T there is a
>video/audio module which is a daughterboard,

I actually worked a little on the A4000 audio, so let's see. The
daughterboard is easy to explain: we were moving toward the use of
more standard PC casework, but ATX had not yet been invented. So where
do you put the ports? You put 'em on plug-in cards, of course.

>    So here 0,3 come from the jack physically  to the right, colored red and
>referenced as "right" in the manual (on the board there is no
>    label).
>    However, the A4000T has also a headphone connector. And if I use a
>headphone, then I hear channels 0,3 coming from the left!!!

Sounds like that's done wrong. The built-in speaker, of course, is
mono.

> Q3: Suppose I want to produce sound from a specified jack. For example I
>could have a program playing a sound with a "left/right balance" volume
>command:

I don't think left/right balance was major concern. No one imagined
you'd want to allocate two Paula channels for one stereo channel,
simply to allow for balance. This was actually addressed, poorly, in
AAA, where you could select L or R for each of the 8 audio channels.
But not a L/R mix, which would have been the right answer.. and fairly
easy to do, too.

>     a) detect which Amiga model the program is running on (not easy, since
>it's not the question of detecting CPU or the chipset, but the motherboard!)
>     b) choose one, I would say channels 0,3 coming from Left, since
>A500/A1200/A600 are the majority of Amiga models and assume the users of
>other models swap the connection of the audio jacks
>     c) other ideas??

First time you run the program, play a sound on what you think is the
left channel. As the user "do you hear this on the left or the right".
Store that in your PROGDIR: and adjust accordingly. This way, you also
address the users of properly (or non-ambiguously) speced audio jacks
who've managed to wire them backwards, anyway.

>Q4: I can't see any rationale behind the choice of using different
>assignments on different models! Do you see any good reason?

Someone make a mistake, and copied it forward to subsequent models
("someone" would probably have to be or George, though I'm not sure,
Greg may have done the headphone jack in the A4000T, or it may have
been me -- I was mainly doing AAA and other "advanced" stuff in the
A4000 days, but I did help out on Zorro and some of the analog audio
stuff).

Dave Haynie       | Chief Toady, Frog Pond Media Consulting
dhaynie@jersey.net| Take Back Freedom! Bush no more in 2004!
"Deathbed Vigil" now on DVD! See http://www.frogpondmedia.com :-D  :-D
The Dark Coder / Trinity
 

Offline DeQuevedo

  • Full Member
  • ***
  • Join Date: Jun 2002
  • Posts: 220
    • Show only replies by DeQuevedo
Re: Amiga Stereo Effects!
« Reply #11 on: April 05, 2004, 01:35:46 PM »
Hi Ppl

Sure Amiga sound is associated this way : 0-3=R and 1-2=L

May be some amiga model have been screwed up internally, but I have found some units with the L/R RCA connectors mounted inversed (white/red color code)

This may be the easiest explantion

-DeQ

---------------------------------------

-Have Fun infected Incubes!
 

Offline Thomas

Re: Amiga Stereo Effects!
« Reply #12 on: April 05, 2004, 03:10:45 PM »

Well, I started with an A500, so this is the reason for my view. And most coders seem to do it the same way. E.g. if you play Heretic2 with the speakers connected the "correct" way, stereo effects are reversed.

I think Dave's suggestion to add an option for the user to decide which way he likes most is the best way.

Bye,
Thomas

Offline Thematic

  • Jr. Member
  • **
  • Join Date: Aug 2003
  • Posts: 69
    • Show only replies by Thematic
Re: Amiga Stereo Effects!
« Reply #13 on: April 25, 2004, 12:11:49 AM »
This part of the Reference Manual(s) is erroneous. That's exactly why AHI has the env var AHIpaulaSwapChannels; I have it set, because most of the programs that I use, expect the audio cables to be crossed.

But I've connected them to a cheap mixer so if need be I just turn the dials.
So you have the strings in your palm. Do you know what they are for?
 

Offline Calgor

  • Newbie
  • *
  • Join Date: May 2007
  • Posts: 13
    • Show only replies by Calgor
Re: Amiga Stereo Effects!
« Reply #14 on: June 19, 2011, 02:50:07 PM »
I came across this problem that my A3000 had channels 0,3 right and channels 1,2 left and my A1200 was the opposite.

Note that in fact the RKRM Hardware Reference Manuals themselves contradict each other!

Hardware Reference Manual (1st Edition 1986): Page 136: Channels 0,3 left and Channels 1,2 right.
Hardware Reference Manual (3rd Edition 1991): Page 137: Channels 1,2 left and Channels 0,3 right.

Looks like whomever wrote the later manual (be it starting from 2nd or 3rd edition) swapped them around for some reason given that the details are in the same respective sections of the manuals.  I do not have the 2nd edition to check that.