[SDL] SDL 1.3 audio update...

[Bob Pendleton]

Thank you for this major update! Three cheers for Ryan!

		Bob Pendleton

On Fri, 2006-09-01 at 03:59 -0400, Ryan C. Gordon wrote:
> (long email, sorry.)
> 
> Okay, lots of SDL 1.3 work on the audio subsystem hit Subversion today. 
> I'm still doing the work to add 32-bit datatypes in this batch.
> 
> 
> First, SDL_LoadWAV() now handles float32 and int32 .wav files. On this 
> box (Linux/amd64 with ALSA), I can use the loopwave.c test on a float32 
> .wav file and it plays fine.
> 
> The following backends were updated. Please note that most of these 
> systems I can't even compile, let alone test, and way too many had no 
> documentation available that I could find...so I made some best-guesses. 
> If it broke, send a patch and/or complain loudly.
> 
> alsa: int32 and float32 are supported directly in the drivers.
> amiga: int32 support added (google suggests AHIST_S32S, etc exist)
> baudio: int32 and float32 support added (and some others!)
> dart: No 32 bit support, but will now use SDL's converters if device 
> opened for anything other than U8 or S16LSB (failure before).
> dc: No 32-bit support, but will now use SDL's converters if device 
> opened for anything but 8 or 16 bit data (failure before).
> dmedia: float32 support, fallbacks for other things (failure before).
> macosx: float32 and int32 support added. float32 is the fastpath on Mac 
> OS X, and apps should favor it on this platform when possible (but the 
> other formats will still work).
> macrom: int32/float32 support added. Is OS 9 support going away?
> mint: one of the codepaths appears to support int32, based on #defines 
> in the headers. The rest I just tried to make sure that unexpected 
> AudioSpec values get weeded out. I touched a lot more code than I was 
> comfortable with here. Someone should check it: revision #2728.
> mme: Added int32 support, since you feed it a .wav header, but I don't 
> know if the system can actually handle this. I could also feed it a .wav 
> header with float32 support, but I couldn't find any indication that the 
> system wouldn't barf on this the same way SDL_LoadWAV did until earlier 
> today.
> nto: Added int32/float32 ... isn't this just ALSA? Why's it a seperate 
> backend?
> windib: Added int32 (see notes about mme).
> windx5: Added int32 (see notes about mme).
> 
> Several drivers had clamps added for > 2 channel output, since the 
> drivers don't (or don't appear to) support more than stereo output.
> 
> bsd, paudio, sun, and ums got no updates, even though they might be able 
> to use at least int32. Documentation found on google wasn't clear or 
> didn't exist. If they can't handle 32-bit data directly, they'll still 
> work if SDL_OpenAudio() requests a 32-bit type...SDL will transparently 
> convert as necessary. But it may be performance we're leaving on the 
> table because I don't know if it's safe to put a "32" into a field or I 
> don't know the magic enum name. People that know: please speak up!
> 
> dummy and disk just use whatever. No changes needed.
> 
> dsp and dma didn't change: the OpenSound docs suggest that there is 
> int32 and float32 support, but either strongly urged you not to use it 
> or said the symbols were placeholders. The headers on my Linux box 
> didn't have the symbols, so OSS loses out here for now. SDL will convert 
> to 16-bit at a higher level in these cases.
> 
> Others, like esd, arts, and nas, didn't change because they don't 
> support 32-bit data and seemed well written (higher level will convert 
> data to something it does support before feeding the driver).
> 
> 
> Up next:
> 
> - move a few fixes that didn't involve 32-bit types back to SDL 1.2.
> - debug all this. I still have to fix several converters. If you wrote 
> any of these audio backends, I'd appreciate you looking at my changes 
> and not making too much fun of me.  :)
> - longer term: multiple devices up next, which leads to capture support.
> 
> --ryan.
> 
> 
> 
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