[LAU] Voice-to-drums in general and the Trigger LADSPA in particular

Fons Adriaensen fons at linuxaudio.org
Thu Sep 22 21:38:51 UTC 2011

On Thu, Sep 22, 2011 at 11:42:05PM +0400, Artem Vakhitov wrote:
> On 22.09.2011 23:16, Fons Adriaensen wrote:
>> If you need not only the timing but also to control volume
>> then it's unlikely this can be done without delay. The part
>> of the input that would contain usable information to control
>> volume would very probably come after the trigger, but to
>> play the sample you need both. The only solution then is to
>> delay the trigger. That means that simple solutions such as
>> the ladspa plugin can't do what you want.
> The thing is, I do not need to do that in any kind of real time. It  
> would be sufficient to feed a "beat box" .wav file at the input and get  
> the corresponding .wav or .mid file at the output. All digital  
> processing can be done fully off-line, so all timing and amplitude info  
> is there in advance.

Even if it hasn't to work in real time Pd is probably the
ideal tool to prototype such a system. The alternative
would be to write some ad-hoc C/C++ code, possibly using
existing 'feature extraction' libraries or plugin code.

As a first guess, what you need would be:

- (optional) some pre-filtering to make the trigger
  more reliable,
- the trigger itself,
- a delay on the trigger,

and in parallel

- (optional) some pre-filtering for the envelope
- an envelope follower,
- when the delayed trigger arrives, read the envelope
  follower and start the sample playback.



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