[linux-audio-dev] Additional LADSPA hints

[Paul Davis]

>On Wed, 15 Jan 2003 18:13:35 +0000
>Steve Harris <S.W.Harris at ecs.soton.ac.uk> wrote:
>
>> AUDIO_RATE_CONTROL. Hints than an audio control should/could be controlled
>> by a high time res. slider or control data, but shouldn't be connected to
>> the next audio signal by default. I can't think of any simple examples off
>> hand, but combined with MOMENTARY it could be used for sample accurate
>> tempo tapping.
>> 
>> My comments: I really like MOMENTARY and RANDOMISABLE. AUDIO_RATE_CONTROL
>> could be useful, but might be painful for hosts to implement. I dont have
>> any particular use for it right now.
>
>Not to mention that AUDIO_RATE_CONTROL would completely useless in JACK?  
>You'd have a buffer-full of samples and apply frequency shift to them, which w
>ould change the length of that buffer, which you couldn't give to JACK unless 
>you do some rebuffering.

this is true of *any* output paradigm. the audio interface only
accepts N frames per second. if you had N frames to deliver in one
second, then stretched them to N*2 frames, it will necessarily take
you twice as long to deliver them - the interface isn't going to speed
up for you.

>Correct me if I'm wrong.  We have similar issue with ecasound's Pitch Shifter 
>operator in connection with JACK.

steve has written LADSPA pitch shifters and they work just fine with
the fixed-sized buffer paradigm.

--p