Monday, December 11, 2006
and I think my cat killed it. I think she thought it was taking too much of my attention away from the important matter of keeping her petted and clean. I took my gentle revenge later...
I'm doing ok using the alsa 96k plughw on the laptop itself for now, but I'm going to need to do vocals sooner or later, so I bit the bullet and bought myself the pci version of the rme multiface card. It'll go into my dual opteron when it arrives thursday or friday. I should order myself more ram but that involves ripping the machine apart to see what's in it. ESR and Rob Landley have written a nice paper on how application memory pressure on the 4GB barrier will push x86_64 into the mainstream - I don't buy it (reasons too long to go into here) - but it's pretty obvious I need at least 2GB of ram to do what I want to do at this point, and I might as well go to 3GB in case the sticks I buy are incompatible with the 2 500MB sticks in the machine already. Hmm, maybe ESR and Landley have a point...
I've been cataloging what I do differently from most normal audio hackers in Linux. The big item is that I'm running at 96khz throughout, which means I'm pushing 2.18 times more data through the system than a system running at CD speeds - 44.1khz.
There are a lot of places where Linux audio apps make assumptions that you are running at a "normal" sampling rate. Most ladspa plugins for example have a default of 0-70db dynamic range, which is fine at 44.1/16 bit, but way too small for 96k/24, which has roughly double that. It's possible that the default stack size, and other fixed allocations in these apps are mistakenly tuned to 44.1 as well. I've got some tests in the queue for that.
One of the things that irks me right now is that the stereo gate I have doesn't want to compile. The mono gate does, with a 96k range, but that doesn't help lest I split tracks and does weird things to stereo instruments.
A gate is rather important when you are adding effects that may or may not like running at this high a resolution - You really need a gate on devices that can't output across the entire dynamic range (or, worse, leave noise behind at low levels) - you get all sorts of weird side effects from running reverb (as one example) on a bunch of not-quite-silent 96k channels and mixing down to 44.1 - the effects do NOT drop below the noise floor as they should.
Well, I've got enough problems to keep me busy without working audio hardware, time to delve back into it... I really should finish the core posting of this blog... ¶ 9:27 AM
I'm doing ok using the alsa 96k plughw on the laptop itself for now, but I'm going to need to do vocals sooner or later, so I bit the bullet and bought myself the pci version of the rme multiface card. It'll go into my dual opteron when it arrives thursday or friday. I should order myself more ram but that involves ripping the machine apart to see what's in it. ESR and Rob Landley have written a nice paper on how application memory pressure on the 4GB barrier will push x86_64 into the mainstream - I don't buy it (reasons too long to go into here) - but it's pretty obvious I need at least 2GB of ram to do what I want to do at this point, and I might as well go to 3GB in case the sticks I buy are incompatible with the 2 500MB sticks in the machine already. Hmm, maybe ESR and Landley have a point...
I've been cataloging what I do differently from most normal audio hackers in Linux. The big item is that I'm running at 96khz throughout, which means I'm pushing 2.18 times more data through the system than a system running at CD speeds - 44.1khz.
There are a lot of places where Linux audio apps make assumptions that you are running at a "normal" sampling rate. Most ladspa plugins for example have a default of 0-70db dynamic range, which is fine at 44.1/16 bit, but way too small for 96k/24, which has roughly double that. It's possible that the default stack size, and other fixed allocations in these apps are mistakenly tuned to 44.1 as well. I've got some tests in the queue for that.
One of the things that irks me right now is that the stereo gate I have doesn't want to compile. The mono gate does, with a 96k range, but that doesn't help lest I split tracks and does weird things to stereo instruments.
A gate is rather important when you are adding effects that may or may not like running at this high a resolution - You really need a gate on devices that can't output across the entire dynamic range (or, worse, leave noise behind at low levels) - you get all sorts of weird side effects from running reverb (as one example) on a bunch of not-quite-silent 96k channels and mixing down to 44.1 - the effects do NOT drop below the noise floor as they should.
Well, I've got enough problems to keep me busy without working audio hardware, time to delve back into it... I really should finish the core posting of this blog... ¶ 9:27 AM
