[ardour-dev] latency compensation questions

[gerard van dongen]

On Thu, 31 Mar 2005 21:00:26 -0800, Mark Knecht <markknecht at gmail.com>  
wrote:

> In the case of the bus nothing 'rolls' so nothing can be 'delayed',  
> correct?
>
> It's an interesting problem.
>
>

It is interesting, although in the case of a reverb-on-a-bus, it is a  
little different.
The reverb in the bus has latency, so ardour compensates by adding a delay  
to the other tracks.
But those tracks are feeding the reverb. So you don't wan't to delay the  
audio file reading at all, you want to add a delay _after_ the sends:

|trackA              |bus1
|                    |
|fader               |reverb causing extra latency
|post-send-to bus1-> |
|                    |
|delay               |
|                    |
|output              |output

Given ardours almost infinite routing possibilities, this is a difficult  
problem to solve in a general way.
I suspect that the latency should always be added at the end of a route's  
signal processing chain, not at the beginning. The place would be between  
the route outputs and the master-bus inputs.
But it there are probably common situations were this is the wrong thing :)

Gerard



> Thanks,
> Mark
>
> On Mar 31, 2005 8:46 PM, Paul Davis <paul at linuxaudiosystems.com> wrote:
>> ... following on, i am not entirely sure it will work correctly
>> for the reverb-in-bus situation. i haven't tried it, or don't remember
>> trying it. the difference is that when a track obeys the delay at
>> "roll time", it just means that its actual pointer into its audio
>> files will be offset. when a bus obeys the delay, it means it hasn't
>> been feeding its plugins for the length of the delay, which may result
>> in an odd result. if this mental model is correct, i can probably fix
>> it. someone should try it out and let me know.
>>
>> --p
>>
>>
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