linuxaudio.org

On Sun, Sep 25, 2011 at 10:01 PM, David Robillard  wrote:

quoted text
> On Sun, 2011-09-25 at 14:28 +0100, Aurélien Leblond wrote:

>> >1. Audio in/out ports. These are just blocks of samples, same

>> >   as e.g. Jack buffers. Some call this 'PCM' but that is a

>> >   misnomer.

>> >

>> >2. Control in/out ports. These are technically identical to

>> >   audio ports (full sample rate), but the signals carried

>> >   on them are normally not meant to be audio. How they are

>> >   interpreted depends on the module and the particular port.

>> >   Frequency control inputs can be linear or log, in the latter

>> >   case that means 1/octave. Gain controls can be linear or log,

>> >   there is AFAIK no fixed conversion factor for the latter. For

>> >   example the VCA module uses 80dB/1 in exponential mode, but

>> >   other gain controls may be different.

>> >

>> >   Control ports are audio rate, but most modules/plugins subsample

>> >   some or most of them. They either just use the first value in a

>> >   block, or recompute internal paramters based on the last value

>> >   in a block and then interpolate them linearly.

>> >

>> >   Since control signals are (at least officially) at audio rate,

>> >   LADPSPA plugins designed to be used in AMS (e.g. mine) will

>> >   declare their control inputs as audio inputs.

>>

>> Thanks, I think it makes things way clearer!

>> What's confusing me so far is that I ported the VCO2 module, but with

>> exactly the same setup, the VCO2 LV2 in Ingen sounds out of tune

>> compared to the one in AMS. I thought it was due to some kind of

>> needed convertion, but maybe I'll go back to my code to double check I

>> didn't make any mistakes!

>

> The note builtin in Ingen uses Hz for frequency. Anything else is

> completely insane :)

>

> There is a converter plugin in 'omins' which I need to port to LV2 as

> well one of these days...

Hi David,

Could you let me know where in Omins it is?

I can port this for you... One plugin to create won't kill me (and I

start to enjoy it anyway!)
Aurélien

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