[linux-audio-dev] LADSPA needs & wishes

Steve Harris steve at plugin.org.uk
Tue Jan 30 08:53:07 UTC 2007

On 30 Jan 2007, at 01:25, Fraser wrote:

> Hi Steve,
>> Ah, well the host is not supposed to change port values during run()
>> anyway, the idea in LADSPA (and LV2) is that the host should chop the
>> run() block where port values change. In practice not all hosts do
>> that, some just pick a suitably small block size, eg. 32 frames and
>> quantise the changes to that rate.
> I didn't realise that - perhaps I glossed over that bit of the spec.
> A block size of 32 frames would really exagerate unnecessary paramter
> conversion...

Sure, which is why people do tend to do the if (oldval != newval)  
thing on expensive parameter calculations. 32 is really the extreme  
end, I would think that typically its higher than that.

JACK systems do run down to the 32 frame buffer level, so you have to  
be able to handle it anyway. It's quite inefficient as the cost of  
calling the run() function of every plugin for every block is  

- Steve

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