onsdag 23 december 2009

Success with new Jack settings

No wonder there are problems when you are stupid! I was using the obsolete "freebob" driver instead of the newer FFADO "firewire" driver in Jack. Once this was corrected, even Bristol seemed relatively stable. (I'm on Ubuntu Studio (Karmic) using an Edirol FA-66, FYI)

Now I can achieve lower latency, too. With a sample rate of 44.1 kHz and a buffer size of 64 frames/period (latency according to Qjackctl: 4.35 msec) things seem to work well. With a buffer size of 32 (latency: 2.18 msec) Adour disconnects from Jack, and with an even lower setting, my whole system gets very slow. But I've worked with higher latencies than 4.35 msec without being dissatisfied, so this is a win.

At maximum sample rate (192 kHz) I can get down to 4 msec (with 256 frames/period). I can go even lower but then my system gradually gets a bit slow. Somehow Hydrogen doesn't recognize the higher sample rate, or maybe all the samples in the drum kits are recorded with a lower sample rate, because everything gets more high-pitched when Jack is set to a higher rate.

I guess I could tweak the settings more to achieve optimal performance. I don't know what "No memory lock" or "Unlock memory is", and I know even less what the difference between these two is, so I will need to read up on it. Maybe "Periods/buffer" is something to get acquanted with as well. Checking the memory lock boxes has had no apparent effect, though.

Ardour still throws a segmentation fault once in a while, particularly when normalizing a region or when trying to reconnect to Jack once connection was lost (Ardour always dies when I try that at 192 kHz). This is quite annoying, and I hope I can fix it. Hydrogen has also died once for no apparent reason.

In short: I'm back on track. My goal is to have a stable environment for composing, recording and mixing. There are still some things to work out but I'm getting closer!

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