Re: sound header

[The Greene Family <topcoder@mindspring.com>]

At 12:27 PM 4/2/99 +1000, you wrote:
> I'm glad you agree with the OSS/ALSA part so we get something going in
>the short term (I'm talking a month or 2 here). Hopefully the rather
>blunt comments from others have made your realize that rewriting low
>level drivers is unrealistic (-:
> If the existing OSS/ALSA drivers are too inefficient or don't provide
>enough features, we should be hassling the OSS or ALSA developers to
>improve them, or contribute to their development, not reinvent our own.

I stated several times that I agree. :-)  Remember Derek = new to linux
programming.  It's not all to differennt thus far (i am used to DJGPP),
but, some stuff is way different. :-)

> Well playing a MOD, S3M etc is basically mixing the samples contained in
>the file in realtime, altering their pitch, volume & panning according to
>the pattern data. Do some research if you don't understand how they work,
>they are very important part of games, and almost the only format used in
>demos.

I understand how they work very well, thank you.

> OK, so this 'mixed' part is then passed to the mixer that combines it
>with the other 3d sounds that have been 'mixed'? <g>

Basically, yeah. :-)  I'm not a sound, pro just a guy who's been doing work
on his own for a few years. :-) I use different terms than other people
sometimes. :-)

> Sorry, I should have been clearer. You can output dolby encoded surround
>sound with a standard stereo sound card, but you require a surround sound
>decoder attached to your sound system to decode the 2 audio channels into
>the left, centre, right & surround speaker outputs. Virtually all videos,
>and most stereo TV broadcasts are encoded this way. If you don't have a
>surround decoder, it still works well with a stereo (2 speaker) system.
> Note this is quite a different matter from a soundcard that has 4 or more
>separate speaker outputs. This would require quite separate encoding, and
>would require driver-level support for the extra hardware channels.

That's why I had a big "Say wha?!" for that...most people i know with
decoders have 4 or more speakers.  So to me surround just isn't surround
with 2 speakers...I just can't identify with it like that. :-)

> OSS is quite easy to use, once you figure out the quirks. Using it for
>realtime applications is a bit trickier though. Basically you have to
>reduce the fragment size to somethign close to your audio update rate.
> Buffer underruns are a problem. My experiments just used a loop that
>waits till there is only one fragment playing, then calculated the next
>fragment - but we need something a bit more elegant than this <g>

My problem with my code right now (hopefully, it's working correctly, ioctl
is something I've used one other time and it's giving me headaches) is i'm
getting weird errors having to do with my class for the mixer, but it's
giving them in the ioctl.h file!!!!

>btw, IRC meets - why don't you just use the channel #gamedev  - I'm sure
>that's what the last meets used, and it's always empty. Personally I'd
>prefer IRCnet, but make up your own mind..

I say stick with it like this.  Works for me ya know?

Derek