EXS 24 Logic Sampler Users Group

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).

I tried loading this large Logic project with this EXS setting to both
normal and 32 bit. With OS X's Activity Monitor showing me my RAM usage, 32
bit float mode scarfed up my physical RAM like crazy and paged to disk. It
seems that Logic would load up samples for instruments being used, but then
if you jump to a different section of your song file where other samples are
being used, or select the track with the EXB3 for instance and started
tickling the ivories, boy would crap start a'crackling! Activity Monitor
showed fervent VM pageins... and CRASH! Logic would go down. Repeatedly.

Then, set the EXS prefs to normal and the physical RAM usage is much better.
 
> If you are using virtual memory and you have this setting on my guess is that
> it would only affect the preloaded buffer section of the sample.

Actually, does Logic in OS X even have its own virtual memory?? In OS 9,
there was that System extension you could use (forget its name -- probably
something obvious). But, in OS X is there anything like that going on with
Logic??

Anyhoo, I stand by my point: OS X's virtual memory is poison to a stable
Logic system. "Original" sample storage and "Normal" sample rate conversion
helps avoid it.