[linux-audio-user] terrible soundwith jackd/pro audio apps

Hi folks, all this is on a laptop running ubuntu feisty with latest updates and a few packages from offsite (e.g. ardour2, traverso). I want to use my laptop to edit and produce rough cuts of audio documentaries. This whole project takes place in the digital domain -- clips are recorded to high-bitrate mp3 and dumped to my hd over usb, and the final product is always either an mp3 or a wav file. I only use my sound card to listen to the piece as I'm working on it, so I'd hoped that the fact that it's a cheap intel_hda sound card wouldn't matter that much. Up to now I've been using audacity 1.3b, and it works ok but I find the interface somewhat clumsy and inflexible. ardour2 and traverso both have much more powerful interfaces, in my opinion. Unfortunately neither of these apps seems to work right for me. In particular, both of them produce very choppy and static-ridden audio, especially ardour2. traverso is also somewhat unstable -- too bad, since it's very fast and I love the interface. traverso works somewhat better with the alsa driver than it does with the jack driver, so naturally my suspicions turn to jackd, with which I have little experience. Here's my setup: -normally run with a lightly-modified ubuntu 2.6.19 kernel, which uses the 'voluntary preemption' switch and hz_250; I've also installed and been trying out the stock 'lowlatency' kernel which enables full preemption and hz_1000. fyi, here's what grep says about the configs: matt@gont:~$ grep -i hz /boot/config-2.6.19-7-ref-generic # CONFIG_HZ_100 is not set CONFIG_HZ_250=y # CONFIG_HZ_1000 is not set CONFIG_HZ=250 CONFIG_MACHZ_WDT=m matt@gont:~$ grep -i hz /boot/config-2.6.20 config-2.6.20-5-generic config-2.6.20-6-lowlatency config-2.6.20-6-generic matt@gont:~$ grep -i hz /boot/config-2.6.20-6-lowlatency # CONFIG_HZ_100 is not set # CONFIG_HZ_250 is not set # CONFIG_HZ_300 is not set CONFIG_HZ_1000=y CONFIG_HZ=1000 CONFIG_MACHZ_WDT=m CONFIG_NO_IDLE_HZ=y matt@gont:~$ grep -i preem /boot/config-2.6.20-6-lowlatency # CONFIG_PREEMPT_NONE is not set # CONFIG_PREEMPT_VOLUNTARY is not set CONFIG_PREEMPT=y CONFIG_PREEMPT_BKL=y CONFIG_DEBUG_PREEMPT=y I usually run jackd from the commandline thus: /usr/bin/jackd -R -dalsa -dhw:0 this is with the realtime-lsm module installed and loaded, running as gid 29, so the user has access to the lowlatency stuff. I have definitely noticed some improvements usintg the lowlatency kernel, but it's all still not very good. This really does surprise, me, so I'm wondering what adjustments I might try to make to my setup to improve jack's performance, and with it, the performance of either traverso or ardour2. I've been messing around with jack options, esp. the --period option (made it as high as I could, 4096) and the -s option (without it I get lots and lots and LOTS of xruns). I think that both of these help a little, but in the end I still have audio which is at the very least clipped and unclear. the same clips sound way way better in audacity running aoss -- so my hardware is clearly capable of handling the audio itself, evne while processing multiple other signals from e.g. amarok or aplay. but with jack it's a no-go, and unfortunately iwth traverso as well. nor do I think my cpu is the issue here -- I have a dell latitude d820, with a core-duo running at 1.83gHz. I really don't need very low latency since I'm not working with music, but with fairly rough vocal tracks and ambient sounds. But I do want a well-funcitoning editor/mixer. I hope this is the right place to ask for help! thanks, matt -- Matt Price History Dept University of Toronto matt.price(a)utoronto.ca