[linux-audio-dev] Todays changes to "LADSPA2" strawman

Ralf Beck musical_snake at gmx.de
Sun Apr 30 16:25:51 UTC 2006


Chris Cannam schrieb:

>On Sunday 30 Apr 2006 00:01, Dave Robillard wrote:
>  
>
>>We need a better API with which to build good, useful things.
>>    
>>
Use LACPA instead of LADSPA ;-)

It has
* audio i/o support
* sample accurate midi i/o support
* controls with midi mapping
* timeinfo support: tempo/beat/bar + samplenumber
* automatic plugin gui builder support through simple ascii file
* network capable (gui can run on different machine than plugin engine)
* return to host the real value as a string instead of some fancy hints 
(=> good for displaying automation data)
* has named audio and control i/os
* fixed 2^x length buffersize when processing

The default configuration is in a simple ascii file with some even 
simpler format:
First line contains the field delimiter used for this file, rest is in 
the following format:
type:name:displaytype:[num:[values]]:midi controller type:midi 
controller number
 
:   <- delimiter to use in this file
audio:left in
audio:right in
audio:sidechain
control:Gain left:slider:cc:1
control:Gain right:slider:cc:2
control:Link:pushbutton:cc:3  <- 7bit resolution with single CC
control:Frequency:slider:cc:msb:4:lsb:5    <- 14bit resolution using 2 CCs
control:Type:radiobutton:2:Mono:Stereo:nrpn:7  <- 14bit resolution 
through NRPN

and so on.

All audio data is -1.0 .. 1.0, all control data is 0.0 .. 1.0.
There are no min/max values needed, because the plugin knows itself what 
the value is and
the host can request a string representing the actual value + unit for 
display purposes as needed (same for plugin gui)

example: host requests control 1, value 0.5    plugin returns "0.5 dB"

For timeinfo i dropped smpte because its is trivial to calculate a smpte 
frame from the samplenumber and
can thus be calculated by the plugin needing smpte synchronisation itself.

Ralf

PS: the lacpa.h i sent earlier to the list is outdated (and wouldn't 
even compile)









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