Latest progress and testing

When testing the latest versions on Hatari in TT High I did not manage to get any sound at all. This was a bit odd as I remembered EPSS had been working on the TT before. Also GemTwo tested on his real TT and it was exactly the same result, some flashing colours and no sound and even the MID file was just stuck at 0 when pressing play.

After some digging in the code, I found an check that was done if the DMA buffer had been overrun. When it was detected as overrun, it flashed the colours and try to reset the sound by stopping and starting it. This was the routine that was triggered all the time on the TT.

Trying to turn off the check at least got the MID file running when pressing play but still no sound at all.

I found some other code examples that was included in the EPSS Registered version that I managed to get sound with though, so not all hope is lost. But it sounded quite bad like it was playing the buffer two times and things like that so something is definitely not right here. At least that was on the Hatari. I might try this on a real TT to see if I get the same result.

But I think I recall the history of the development a bit here: When I first started coding on the EPSS I used my TT. And I designed it to utilize the feature that a Timer A interrupt was triggered when the Sound DMA buffer reach the end. This worked fine as far as I can remember. Then we wanted to use the EPSS in our Unit Seventeen demos. It was not really very demo-friendly to have a separate Timer A that was running so I tried to rewrite it to be able to run on the VBL without any Time A triggering end of sound buffer.

This was a bit difficult as we then have to ensure that the size of the play buffer was equal to how much could be played in the VBL. I Don’t think we ever solved this perfect and it might be some artifacts from then that now makes the EPSS not work on the TT. At least that is my theory for now.

We might release it anyway as it stands now, as it at least will be STe and Falcon compatible.

I might look to try to use Timer A for using the EPSS freestanding as a PRG or ACC for those that might want to use it on TT or possibly other environments where you run it on the VBL and then have a set of sound drivers that would be Time A enabled. But that approach might not work with linking it with Cubase with MROS, if they maybe use Timer A for their own purposes…


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