[ubuntu-studio-devel] ubuntustudio controls

Len Ovens len at ovenwerks.net
Sun Jun 15 14:30:50 UTC 2014

On Sun, 15 Jun 2014, Ralf Mardorf wrote:

> On Sat, 2014-06-14 at 13:43 -0700, Len Ovens wrote:
>> The user will have to learn what the lowest latency is that they
>> can use for a certain task without xruns. We can't do that. I would
>> like to have an "About Latency" button for this reason.
> That's a good idea. Btw. it might be important not only to educate
> people how to use -p and -n options and that the lowest latency depends
> to the load, but also to mention that it's possible to change the
> latency during production, likely not on the fly, but it anyway is
> possible and could be helpful, but that this could cause issues when
> using some apps. At least last time I used Qtractor, the anyway not good

Yes latency can be changed on the fly... that is jack does not have to be 
restarted. However there are audio artifacts at the switch even in 
applications that deal correctly with it. For example both ardour and 
guitarix will keep working (adour even in the middle of playback) but 
there will be a glitch. However, other programs will have to be restarted 
such as rakarrack in order to work right on the new latency.

The only plus for changing latency on the fly is that Jack always owns the 
audio device. Changing -p is easy. changing -n can not be done on the fly 
for jackd only for jackdbus and it still requires a full reload... though 
the reload doesn't seem to affect connections (I should check that more 

> latency compensation for audio tracks did only fit to the latency, that
> was used for recording and got out of sync, when I changed the latency
> during production. Theoretical it would be nice to do some recordings
> with low latencies, while many tracks are muted during such a recording,
> to produce less load and then when e.g. mixing with a high load, to
> increase the latency.

I do this all the time. I record at low latency with effects, eq, etc. 
turned off. Then mixdown at higher latency so my computer has the CPU 
headroom for effects. This was more of an issue with my old machine (some 
12 years old now) than with my newer one, but it still gives me more room 
for creativity. This is quite common from what I have heard from other 
people. It is one of the things I suggest to people who are asking about 
such things.

Len Ovens

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