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From: Murray McDowall <murraymc@...>
Date: Fri, 30 Jul 2004 at 1:41:11 PM
Subject: Re: [EXS] CPU overloads
Message #12494
This is a reply to #12489.
At 02:05 PM 7/29/04 -0400, you wrote: > > On 7/29/04 1:45 PM, "Murray McDowall" <murraymc@...> wrote: > > >> "Sample Storage: "Original". "Yes, 32 Bit Float" does load more of the > >> samples into RAM, effectively not using Logic's virtual memory. > > > > > > Actually, this parameter does not affect virtual memory - it determines > > whether > > or not samples are converted to 32 bit float when loading them into RAM. > This > > is the format the audio engine uses so it saves the CPU load of converting > the > > formats at the time the sample is triggered but at the cost of increased > RAM > > footprint. > > But it does effect OS X's virtual memory. As you say there's "a cost of AN > INCREASED RAM FOOTPRINT". And, if you have ten tons of samples loaded and > that footprint gets too big, you run out of physical RAM.. And then, OS X's > virtual memory kicks in -- and that's when I experienced significant > crackling and Logic crashing. We're talking well over a gig of samples on a > 2GB system across about sixty instruments, including one EVB3, one EVP88 and > one Space Designer instance with dual 1.3GHz G4 (an upgraded Sawtooth). (puts on mirrored shades and suth'n accent) What we have here is a communication problem. In an effort to avoid patent infringement problems Emagic's sample streaming was termed "Virtual Memory." This system of buffering sample starts in RAM and spooling the rest up from disk is internal to Logic and is like the system in other streaming samplers -- or DAWs which playback audio tracks for that matter. In OSX (or WinXP ) Virtual Memory is the name given for memory paging to disk and is another matter altogether. The use of the same name for OS paging and sample streaming has led to our misunderstanding. You are correct that as soon as you run out of physical ram the buffering of samples fails and you get crackles on playback of EXS24 streaming samples. It is also correct that 32 bit Sample loading is nothing to do with Emagics "Virtual Memory" - ie sample streaming. Regards, M
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