Re: [Jack-Devel] Mixing inside process callback

Patrick Robin <[hidden]> writes:
> I am writing a Jack client ( a drum instrument using the NDK samples
> library )

Is this some Google/Andoid thing? Can you link please?

> The client is polyphonic, 42-60 voices since many drum hits need to
> play at the same time.
>
> It is my understanding that all audio samples we write to the jack
> audio buffers must be in the -1.0 1.0 range?
>
> How does jack deal with values outside of this range , clipping?
> normalize?

Samples are clipped when they reach the audio hardware. Between JACK
apps, samples can exceed the -1.0 1.0 range.

> To stay within the -1.0 1.0 range, I need to mix all active voices. I
> tried multiplying all active voices by 1/n (where n is the number of
> voices) but it is not realistic sounding since very quiet drums will
> bring down the volume of louder cymbals for examples. Also if n= the
> total number of possible voices (active or not) a single playing voice
> gets way too quiet. If I use n= active voices only, the volume will
> shift during playback as voices become active or dead.
>
> Is there a more realistic way to mix various voices?

Just mix them. You may want to provide a master level control for
adjusting the total level. If the result must be suitable for DAC,
consider using a some dynamics effect like limiter or compressor.

-- 
Nedko Arnaudov <GnuPG KeyID: 5D1B58ED>

1362341790.31210_0.ltw:2, <87ppzgz1bq.fsf at arnaudov dot name>