Re: [Openvortex-dev] Low volume, distortion, etc

[Callum Lerwick]

> What is your motherboard chipset?  I have a MS-6163 BXMaster with
> i440BX.  The Vortex is sharing an IRQ with the video card, a Matrox
> G400.  My CPU is a Celeron-II 533 overclocked at 840mhz.

I have an Abit BH6 440BX based board, running a Celeron 800 at 992mhz, 
(124mhz bus).

00:07.2 USB Controller: Intel Corp. 82371AB/EB/MB PIIX4 USB (rev 01) 
(prog-if 00 [UHCI])
        Flags: bus master, medium devsel, latency 32, IRQ 9
00:07.3 Bridge: Intel Corp. 82371AB/EB/MB PIIX4 ACPI (rev 02)
        Flags: medium devsel, IRQ 9
00:0b.0 Ethernet controller: Lite-On Communications Inc LNE100TX (rev 20)
        Subsystem: Lite-On Communications Inc LNE100TX
        Flags: bus master, medium devsel, latency 32, IRQ 5
00:11.0 Multimedia audio controller: Aureal Semiconductor Vortex 2 (rev fe)
        Subsystem: Aureal Semiconductor AU8830 Vortex 3D Digital Audio 
Processor
        Flags: bus master, medium devsel, latency 32, IRQ 9
01:00.0 VGA compatible controller: nVidia Corporation NV5 [RIVA TNT2 
Ultra] (rev 11) (prog-if 00 [VGA])
        Subsystem: Guillemot Corporation Maxi Gamer Xentor 32
        Flags: bus master, 66Mhz, medium devsel, latency 248, IRQ 11

So its sharing with USB and ACPI. I only have my keyboard and mouse on 
USB, ACPI is disabled in the BIOS and not compiled in to Linux so 
shouldn't be doing anything. Doesn't seem to be related to 
mouse/keyboard use. Maybe its more along the lines of DMA bus 
contention, however heavy disk and net access don't seem to reliably 
trigger it either. Very strange.

> 2. the buffer for the left channel runs out due to CPU activity, poor
> granularity, etc; and the chip, without having received a signal to stop
> playing, barrels onward through memory, runs into the buffer for the
> right channel after passing through a little garbage (that's the "click/pop"
> you hear when the swapping happens), and continues playing the right

Personally I'm not getting any noticable pops. Its just swaps. Maybe I'm 
just getting the DMA buffers put right next to each other. (R/L are not 
interleaved?)

There is still some weirdness with the fragment sizes, relating to the 
sample rate. I can put xmms at a 400ms buffer time and 25ms period time, 
and play 44.1khz audio just fine, minus R/L swapping. Any lower and it 
starts getting crackley, as if its underrunning on every period and 
inserting silence. (Not a stuttering, which would be looping over the 
same buffer until the next comes in) Try and play a 32khz mp3 and I have 
to crank it all the way up to something like 5000ms buffer/500ms period 
to play without crackle.