double buffered dmasound player in stos

[mlynn1974]

I have written a double buffered DMA sound player in STOS.
It uses DMA Sound so it is really only STE compatible, but Steem will play it just fine. It also uses gemdos fopen\fread\fseek\fclose (see my other post).

It is a prototype for such a routine which I might try to write in assembly (with STFM compatibility).
I know it clicks a little bit when the samples swap buffers but it is better than nothing.
It can play samples larger than physical memory e.g. an STE with 512k can play a 1.7Mb sample running off a hard disk or virtual hard disk in Steem.

You can download my prototype demo here (1.38Mb):
http://www.lynn3686.com/download/stos/motd1.zip
This plays the old Match of the Day tune with some player statistics showing. The music is sampled at 12.5kHz, 8-bit, signed using Audicity.
I haven't tested this on a real STE yet. I have just developed it in STOS using Steem 3.2

[OverlordMRK]

That sounds really clear for 12.5Khz, nice. When you mean write in assembly, are you meaning to create an actual extension for STOS? STFM compatibility would be good for this in STOS as well as STE. I presume because of processor time and access speed, it would be limited to having just a game title screen and the music playing in the background? But still, that would be pretty neat regardless!

[thomas3]

This is really cool! Thanks!

[mlynn1974]

When you mean write in assembly, are you meaning to create an actual extension for STOS?

No I was thinking of writing the whole routine in assembly. I don't know how to write a full extension from scratch. STOS is fine for a quick prototype.

I think the demo code like a scroller or sprites would have to run on the VBL interrupt to guarantee execution. This isn't possible\practical in STOS. The disk loader would have to run on the main loop because disk i/o in an interrupt would block the main loop. I think this is how the Kinky Boots demo by POV works.

>it would be limited to having just a game title screen and the music playing in the background?
Yes for long tunes MOD format is better, but for sample demos this technique is good.

[MiggyMog]

Cool. There are some details on making an extension in the stos gamemaker's manual but there are supposedly details mising. There is an example with the missing link extension on the disk. You can get it in exxos' s site