audio mixing??

yokfran · Post by **yokfran** » Sun Jan 31, 2010 8:46 pm

i'm wondering how to mix two or more sound stream.
is there any internal functions to mix the audio(buffer)?

i've searched all the pspsdk "src" dir by word "mix", but only one line found:

Code: Select all

try&#40;"ms0&#58;/PSP/../PSP/"&#41;;   /* mixed                       */

so i really dont know how to do, but i've seen a thread named "SceAudioMixer" from psplink.

If anyone knows, please teach me how to mix audio through internal functions.
thank u very much.

Torch · Post by **Torch** » Mon Feb 01, 2010 2:02 am

No one mixes audio in real time games. That's why you need a sound card with lots of channels. Just play each on a different channel.

yokfran · Post by **yokfran** » Mon Feb 01, 2010 1:11 pm

Torch wrote:No one mixes audio in real time games. That's why you need a sound card with lots of channels. Just play each on a different channel.

thanks for the reply

So, i have to mix audio buffers in another thread.

m0skit0 · Post by **m0skit0** » Mon Feb 01, 2010 8:17 pm

No, I think Torch means play one sound in one channel, the other in other channel, simultaneously, then you get a mixed result.

yokfran · Post by **yokfran** » Tue Feb 02, 2010 1:31 am

m0skit0 wrote:No, I think Torch means play one sound in one channel, the other in other channel, simultaneously, then you get a mixed result.

I think he said "sound card" that means he was saying the situation on PC.
(Does psp have hardware sound card? I dont know...)

The psp has only 8 audio channels, but I want 2 channels for each music/sound, so i must create 4 threads for audio output.
I dont know each size of each audio stream, one maybe 1 sec(short sound), or maybe 2 min(long music), so I cannot just play them directly, thay must be mixed before output function called.

So I want to know, is there an internal functions to mix audio, better via psp hardware. Like decode atrac3/mp3...

Torch · Post by **Torch** » Tue Feb 02, 2010 2:24 am

You have to manage with 8 channels.

crazyc · Post by **crazyc** » Tue Feb 02, 2010 2:31 am

Torch wrote:You have to manage with 8 channels.

The PSP (at least 1000 and 2000) has only 1 hardware stereo channel. The mixing of the 8 "channels" occurs in a kernel thread. If you mix yourself use sceAudioSRCOutputBlocking for a nice performance boost due to the skipping of the software mixer and get hardware sample rate conversion as a bonus.

yokfran · Post by **yokfran** » Tue Feb 02, 2010 2:32 am

Torch wrote:You have to manage with 8 channels.

Right,

but one thing i cared about is, sometimes there may be lot of audio streams playing at the same time, so mixing is necessary.

Thanks for the advice.