Question about CD audio

[Captain FPGA]

I heard CD audio wasn't implemented yet. Which is confusing to me since I used to think CD audio was all PS1 games had. But apparently there is separate audio used for things like full motion video that music is missing from the core. I'm sure the dev is aware of this and doing everything within their power to make it work.

That said I thought the Mister had trouble with CD audio that's why the Ao486 core was lacking this feature. The Mister just didn't have enough on the hardware side to utilize it.

Then I saw the Saturn core (WIP) running the fmv for Sonic 3D Blast music and all! So I guess what I'm asking is this, can sound be achieved with full motion video on PSX just like the Saturn core and if so might this pave the way for adding music for other cores like the Ao486? I have a feeling the latter is a tall order since it's based off of different architecture. My initial understanding giving that PC core music is impossible but after seeing the Saturn core I am less sure.

[softtest9]

The SPU allows for sequenced (MIDI-like) music with ADPCM/BRR compressed samples. It is kind of a successor to the SPC700 in the SNES (both chips designed by Sony). A lot of games make use of this feature, and then there are also prerecorded compressed music formats like ADX used in some games.

As for CD audio, we already have it with PC-Engine CD and Sega CD. Also from the readme at https://github.com/MiSTer-devel/PSX_MiSTer

"CD : 50%

single track only
no audio yet"

So yeah, CD audio is missing because the CDROM part of the PSX core is incomplete. I would imagine that it gets implemented soon-ish. Why it's missing in ao486 I don't know. It could be a lack of developer interest or because of ao486's design flaws that make the core difficult to improve.

[Captain FPGA]

Ah-hah! So CD audio is on the way for PSX and it's at the halfway point. That was fast!

You're right for some reason I did not think about the Sega CD that has all kinds of FMVs accompanied by sound. So we know the Mister can handle it. Still leaves a big question mark on the Ao486. Maybe I'll ask over there.

Had no idea SNES shared a sound chip with PSX. Learn something new every day.

[zakk4223]

AO486 is already tight in both FPGA resources AND timing. It may just be that getting it in there was going to push things over the edge. That core is already in a state where it doesn't necessarily successfully compile every time. Almost any feature you think 'why doesn't ao486 do this?' the answer is FPGA resources/timing failures.

[FoxbatStargazer]

I recall something like the current CD audio cores kind of "cheat?" Like the ARM chip needs to be used to stream redbook tracks into a buffer as needed, which the FPGA side then works on. So that's not a method easily transplanted from/to pure FPGA environments.

[Stupid Dufus]

Here's a list (may be incomplete, not sure) of games that offer red book audio for PS1
https://tme.miraheze.org/wiki/List_of_P ... dio_tracks

[pgimeno]

Definitely incomplete. I've used the CD of Sentinel Returns just to listen to that awesome John Carpenter's OST (and it's not on the list).

Also, it seems inaccurate. Dino Crisis 2 does not have any CD/DA tracks at all, for one.

[Captain FPGA]

AO486 is already tight in both FPGA resources AND timing. It may just be that getting it in there was going to push things over the edge. That core is already in a state where it doesn't necessarily successfully compile every time. Almost any feature you think 'why doesn't ao486 do this?' the answer is FPGA resources/timing failures.

I see so it's probable the Mister tapped out it's power level for such a core. It's a lot to ask after all making the Mister run something as elaborate as the Doom machine.