[SDL] SDL useful for sound synthesis?

Waltzer George george.waltzer at gmail.com
Thu Sep 21 11:20:59 PDT 2006


yep, my mistake. I just confused MIDI with digital (wav format), I thought
he is doing some calculation and in the end snends the wav to the port.

For threads, yes, I forgot that the audio part has already one (using the
callback)
Well, to have such latencies controled, perhaps he should try then an OS
like RTOS or the like among with a good card driver :)

long live SDL...


On 9/21/06, David Olofson <david at olofson.net> wrote:
>
> On Thursday 21 September 2006 19:12, Waltzer George wrote:
> [...]
> > I think that's the clasic problem trying to stream anything,
> > regardless if audio or video.
>
> Real time sound synthesis is quite different from streaming, in that
> you essentially want zero latency. That is, you can't use any
> buffering beyond what the audio subsystem needs to avoid glitches, or
> you lose the whole point of trying to keep the audio output latency
> low in the first place.
>
>
> [...]
> > How to do this without clicks and ugly stuff? Use the treading
> > posibility of SDL,
> > create a thread(there are tutorials about this). You should play
> > from within that tread.
>
> I would strongly recommend *not* using any extra threads for low
> latency audio on most platforms. It increases the risk of operating
> system "coffee breaks" interfering with your audio, and you need
> additional buffering between each pair of threads in the chain,
> adding to the total latency.
>
> SDL already provides an audio thread on platforms that need it, and
> your best bet is to do all audio processing in that thread, that is,
> in the context of the callback from SDL audio.
>
>
> That said, there *are* low latency audio subsystems that use multiple
> threads or even processes to great effect (http://jackaudio.org/),
> but getting that to work reliably can be hard, if at all possible, on
> some platforms. "Don't try this at home!" ;-)
>
>
> //David Olofson - Programmer, Composer, Open Source Advocate
>
> .-------  http://olofson.net - Games, SDL examples  -------.
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> |       http://audiality.org - Music/audio engine          |
> |     http://eel.olofson.net - Real time scripting         |
> '--  http://www.reologica.se - Rheology instrumentation  --'
>
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-- 
george
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