[LAU] Plugin confused

Chris Cannam cannam at all-day-breakfast.com
Tue Nov 16 09:40:44 UTC 2010

On Mon, Nov 15, 2010 at 10:11 PM, Paul Davis <paul at linuxaudiosystems.com> wrote:
> On Mon, Nov 15, 2010 at 4:55 PM, Julien Claassen <julien at c-lab.de> wrote:
>> Hello Chip!
>>  I think there is the Vamps system. I don't know, what these plugins were
>> developed for. I know, that there are problems for finer speech processing.
> VAMP is not a realtime plugin API. Its designed for things that need
> to do at least 1 pass over the data before deciding what to do.

Not necessarily.  Vamp plugins can be causal, i.e. returning values as
they receive the input -- though at the moment there's no standard way
for hosts to find out whether a plugin is causal or not.  However,
it's true that they are never "real-time safe".

The real difference between Vamp plugins and the others mentioned here
is to do with their purpose.  Vamp plugins are intended for analysis
-- they receive audio as input, but output structured data and get to
define their own structure to an extent.

You can in principle do some of the same stuff with LADSPA or LV2; for
example LADSPA plugins can have output control ports (returning
analytical results, though only very simple ones) and you can define
LV2 extensions to describe more sophisticated data.  But Vamp is
actually designed for the purpose and has quite a distinctive API, and
different semantics in areas like plugin instantiation and
configuration order, in order to make it appropriate for this use.


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