Api

[pierre31]

Hi, I would like to write real time audio app.
Using directx I can't go under ~25 ms..Or maybe I didn't suceed... who knows.
So I'd like to know if it can be quicker using api or any other things I could be able to use...?
And some links please...
Thanks a lot
Pierre

[RockNix]

imo there is no way to decrease latency between i/o much smaller than the values you mentioned.

it is in the nature of windows - no rtos at all !

rocknix ///

[pierre31]

I've made an apply wich has full duplex (in->out) .
Using the mixer I can ear the microphone directly or / and with my app.
An audible delay appear...
So they might be a way ...?

Thx for your reply
Pierre

[RockNix]

things you should keep in mind:

digital audio processing always has a latency between i/o due to A/D D/A convertion, interrupt handlings, register readouts and so on ...

not the very big latency if we are talking about a hw-dsp system

within windows things are different - as i said before, no rtos at all - you should never forget waveApi is buffer based and so is DX but with smaller ones. a hw-system in best case is sample based ( normally as pass-through) and this brings up the short times from input to output - times you will NEVER reach within windows.

than dont forget - windows is multitasking. your application is interrupted again and again and there is no way to break this chain.

some soundcards allow to route the input directly to the output and the windows mixer does nothing more than scalling the analog(!)-amplifiers from the soundcard. this is NOT signal-processing on the digital side like you do when reading buffers from input and send them back to output ...

hope it makes things a little clearer ...

[pierre31]

Hey Thanx A Lot,
I will sure be back with some more questions soon :D
Tchao
Pierre