Audio support

[azihassan]

In an attempt to enable audio support, I ran into two issues:

SDL_audiolib compilation errors

These were caused by the fact that it uses keywords instead of symbols for things like "and" or "or" and they don't compile for some reason. After checking it with chatgpt, I decided to circumvent it with:

find /opt/toolchains/dc/kos/devilutionX/build/_deps/sdl_audiolib-src/ -name '*.h' -or -name '*.cpp' | xargs sed -i 's/\bnot\b/!/g' && \
    find /opt/toolchains/dc/kos/devilutionX/build/_deps/sdl_audiolib-src/ -name '*.h' -or -name '*.cpp' | xargs sed -i 's/\bor\b/\|\|/g' && \
    find /opt/toolchains/dc/kos/devilutionX/build/_deps/sdl_audiolib-src/ -name '*.h' -or -name '*.cpp' | xargs sed -i 's/\band\b/\&\&/g'

Thread stack underrun

The game crashes after playing the intro (with sound) due to a thread stack underrun error that happens here. Ignoring this check results in the game playing with sound until the first loading screen, where it crashes with an out-of-memory error.

[glebm]

This is why:

https://github.com/KallistiOS/KallistiOS/blob/495e77fd60d5b09a1ad52a26cd4a7e73cd0d9d51/environ_base.sh#L51

-fno-operator-names disables support for and/or/not. However, and/or/not are part of the C++ and must not be disabled in an SDK that aims to be standards-compatible.

[glebm]

I've sent them a PR KallistiOS/KallistiOS#785

[gyrovorbis]

Absolutely right. Testing right now to make sure we don't have any kos-ports doing anything stupid which relied on that flag...

[gyrovorbis]

Ugh. You guys are like the 4th or so people recently who have overrun the main thread stack, revealing a fundamental shortcoming in KOS... you can configure any thread's stack size... except the built-in one...

For now, go modify this line: https://github.com/KallistiOS/KallistiOS/blob/495e77fd60d5b09a1ad52a26cd4a7e73cd0d9d51/kernel/arch/dreamcast/include/arch/arch.h#L71

Going to open a PR now to do this:

#ifndef THD_KERNEL_STACK_SIZE
#    define THD_KERNEL_STACK_SIZE (64 * 1024)
#endif

So that you guys can gracefully override this default noninvasively when you build KOS...

[glebm]

Thanks @gyrovorbis!

[azihassan]

Now that #7 is somewhat stable, I'm experimenting with sound again. I'll keep #7 open in case enabling sound impacts it. Here are some observations:

• Jan 28 build of kos (80a54c601e71dfeb44ec764583815ac353580205)
• Latest SDL-1.2, using SDL_AUDIO_DRIVER_DC and SDL_THREAD_DC. I also tried SDL_AUDIO_DRIVER_DC_STREAM but it has some skipping issues with the game
• Lowest audio settings (22k sample rate, 1 channel, 1k buffer size, 0 to 4 resampling quality, streaming virtually everything)
• With 32 MB enabled, it works out of the box
• With 16 MB, it crashes with an out-of-memory error when loading the town level
• I copied the sound config from rg99.cmake to stream audio files with a size larger than a certain threshold
  • Game fails to find barrel.wav. Bypassed by increasing FS_CD_MAX_FILES and FD_SETSIZE to 4096 in kos/include/kos/opts.h (KOS maintains open file handles for all the audio files it's going to stream maybe?)
  • No more OOM, but the streamed sfx are choppy and echoy. Preloaded sfx (like fbolt.wav) are more or less OK
    • Edit: actually fbolt is OK even while streamed, it looks like lightning spells are the worst offenders
  • Logging the .wav files shows that the town level loads about 6 or 7 MB of sound
    • Reduced by only loading the player's class sounds in multiplayer mode (will remove this change eventually when proper multiplayer is supported)
  • Logging memory usage shows that the sound data is loaded into RAM and not sound RAM (I think)
    • Is the buffer size setting relevant here? I'll trying increasing it
      • At 5120, there's a 1 second delay between actions and sounds
• Converting .wav files to yamaha ADPCM (ffmpeg -y -i diabdat/music/dintro.wav -acodec adpcm_yamaha build/data/diabdat/music/dintro.wav, thanks to Jan from discord for the tip) freezes the game when I interact with the main menu. Using adpcm_ms instead of adpcm_yamaha works and results in smaller sizes but the audio is still choppy
• Converting to mp3 also works (after rebuilding kos with this tip by @gyrovorbis) and gives even smaller files but I don't remember why I went back to wav, maybe no impact on audio quality

Here's a recording:

diablo-audio-2.mp4

I'll add more brain dumps as I learn more about sound stuff

[glebm]

Note that for PS2 we had some work-in-progress to do audio using PS2-specific functions

diasurgical#5238

This allowed us to use the audio RAM instead of RAM on the PS2

However, 2 MiB of audio RAM (same as on Dreamcast) was just a bit less than what the game needs

[azihassan]

Awesome thanks! I'll take a look

However, 2 MiB of audio RAM (same as on Dreamcast) was just a bit less than what the game needs

Oh OK, that's unfortunate. If sound effects can fit in audio RAM I would be find with streaming music, but in general I'm fine with topping off the sound RAM and streaming the rest