I've been experimenting with the new audio configuration in the latest release of the Indivision Tool and I found some things which I thought might be helpful to share. Apologies once more for the wall of text, and again none of this is a complaint. I think you will already know most of this but hopefully some of it might be useful info to others or to help for ongoing investigations.
At present the audio works great for me when configured at the 96kHz bitrate on the 4 HDTV's I've tested but at that bitrate only. The sound is not quite identical to the original analogue out but it is very good and very clean as you'd expect from digital – I don’t mind the filtering personally but I know that’s a subjective thing. I think I have noticed a little lag when I run the digital and analogue sound side-by-side but not so much that anything seems out of sync with what's happening on screen.
Sound seem to work fine for me in the Workbench, and in ProTracker, OctaMED and EaglePlayer, regardless of format (I think that’s because EaglePlayer processes all audio through the same pipeline before sending it on to Paula).
I've tried a couple of hundred or so games over the last few days (not exhaustively), and the audio seems to work great for a heck of a lot of them, the list below is the exceptions I found...
As a few other folks have noted, audio does not seem to work for me in any of the Turrican games after the initial Rainbow Arts/Factor 5 splash screen. I get no audio at all in B.C.Kid, , X-Out and Z-Out. Audio in R-Type and Denaris/Katakis seems fine.
Sound doesn’t seem to work for me in Rainbow Islands, Uridium 2, Fire and Ice, or Virocop. I think all were written by Andrew Braybrook/Graftgold so might all have the similar audio routines?
No audio in Xenon, Xenon 2, Cadaver, or Speedball 2 but Speedball, Gods, Magic Pockets, and Chaos Engine all seem fine and have full sound as far as I can tell.
No audio in Shadow of the Beast 1, Beast 3, Brian The Lion, or Puggsy. Audio seems fine in Beast 2, Agony, Awesome, Killing Game Show, Leander (maybe a missing sound effect in title music?), Lemmings, Lemmings 2, Obitus, Ork.
Audio seems to work for me in Rick Dangerous and Switchblade 2 but not in Rick Dangerous 2 or Switchblade.
From what I read in some of the other posts, I think you're already working something to improve compatability which I think will probrably fix most of the above. The next games I found are a bit different in that they have audio but it doesn't seem complete so I guess these might be a slightly different issue...
Dune has audio but only channels 1 and 2 seem to be output, channels 3 and 4 are missing – I played the Dune intro MOD in ProTracker to compare and it’s definitely channels 3 and 4 which are missing, so one from each stereo side.
No audio in Monkey Island 1 (TFMX like Turrican etc.?) but Monkey Island 2 and Indy Jones and The Fate of Atlantis have audio but are again missing notes/sounds – again it sounds to me like they're missing channels but I can’t be sure.
Same with Another World: About half of the audio is missing during the intro, no drums, most sfx missing – I don’t have the mod file for this one so I can’t be certain if it’s whole channels bit it is missing part of the audio for sure. Flashback seems fine, as do Future Wars, and Operation Stealth.
Frontier is another game with partial audio, you can hear it during the intro. Again this sounds like it’s missing a channel on each side.
New Zealand Story’s audio works on the title screen and intro but cuts out when starting a game after the walrus kidnaps the kiwis.
Rocket Ranger also seems to be missing some notes/channels.
The HDTV displays are now very occasionally (maybe after 1-2 hours or so) losing video sync and blinking out, which is something I've not seen since I swapped out my bad HDMI cable. I haven't changed my setup at all since the HDMI cable swap, I’ve only updated the Indivision firmware and Tool, so I think it might be something in the new firmware causing, it may even be the audio and my constantly messing with the settings to try things causing it – it only happens occasionally, once it starts the screen blinking out happens every few seconds for 5-6 times, then subsides but comes back again after a few minutes. Power cycling the Amiga also seems to stop it. I need to investigate this a little more as it hasn't happened since I unplugged the USB network adapter from my RapidRoad earlier today.
I've also noticed a little more pixel noise/errors on the Workbench since the latest update, not at all as bad as it was with the initial firmware but it seems to happen more frequently than it did in 1.4. I think it’s bad reads of the pixels on the Amiga side as they’re too big to be just moise on the output display. They seem more likely to happen if I launch something like DOpus4 which makes a clone of the Workbench screen, and they definitely occur more if I am copying something from the pcmcia slot (using a cf card and adapter).
At the moment I'm running the Workbench in DBLPAL progressive, 64 colours, and the Mk3 is set to scan that at 640x576 50Hz in SHiRes, and scale up to 1920x1080p50. Activating the CCKLine pull up seems to lessen the errors and gets rid of them most of the time, but not all of them, all of the time.
The slight screen zoom when in non-DVI mode, which moves both the Workbench border and the Indivision overlay partly off the screen still appears to be present. It’s not just a translation, it’s definitely being scaled slightly – I don’t know if the HDTVs are doing it due to there being less lines in the picture, or if it’s the Indivision scaling things differently in non-DVI mode. Also, the VSync ripple which happens every 10-12 seconds is still there, in both DVI and non-DVI mode – so something odd is going on with that. It might well be the TVs doing it and not the Indivision but the same thing does not happen when I plug in a Raspberry Pi or my PC’s graphics card into the same HDTV and set those to 50Hz modes. The PC graphics card might be interpolating the frames and smoothing things out but there's no way the Raspberry Pis are doing that, they're not powerful enough. If I try to activate VSync or Auto-Resolution (or both), I lose the picture completely and all TVs report an unsupported resolution.
Additionally, I've noticed that when I cycle through the audio/DVI modes on the Advanced options modal window in quick succession, the Indivision Tool sometimes seems to get itself into a state where it thinks it has already saved/synced changes I’ve made, when it has not. I have to quit out of it and redo them when this happens.
With all that said, I am really enjoying the great digital picture quality and the experimental audio too, so and thank you for all your hard work and efforts. I just hope some of the above is useful information.