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Pa5X Preload buffer fundamentals

Posted: Sat Oct 07, 2023 1:09 am
by AntonySharmman
Preload buffer is the amount of real ECL Ram (not Pa5X declared Ram that is actually Nand on board memory ) where portion of samples
is loaded when OS boots in order CPU to catch real time reproduction of sample in streaming from disk mode with no latency.
This is the well known DFD (direct from disk) method that is used in VST players since 25 years in PC/Mac and software samplers.

In Pa5X , the size of this sample portion is 8ΚΒ and same for any size of imported sample.
The devoted area of ECL Ram for user samples in Pa5X is 260 Mb and can handle up to 30.000 samples and 4GB (8GB compressed) of overall
size of samples will define of how many will fit in custom user area.
In the following picture you can see the size of Preload buffer size of 10 imported samples https://i.imgur.com/AwHhVMy.jpg

Kronos works in the same way but preloaded portion is twice larger and preload buffer is over 1 GB but samples are read directly from SSD
unlike Pa5X where samples are read from on board Nand memory where they are stored after importing/loading.

What will consume and waste Pa5X preloading buffer size ?
- Hundreds of stereo time sliced imported loops/Rex samples that can consume over 170 samples positions per stereo MultiSample.
- Hundreds of Drum samples of very short duration that will waste the fixed preloading buffer size.


Hope this helps

Posted: Sat Oct 07, 2023 10:03 am
by mstodola
Thank you Antony. I don't use sliced rhythmic loops so I didn't know anything about them. So DAW's and other software on computers create these, and special software players within the DAW's or other software play these back.

Again, thank you.

Posted: Sat Oct 07, 2023 11:00 am
by AntonySharmman
Normally in a computer , a saved sample in order to be reproduced in real time with no latency , must be loaded in real ECL Ram since
required speed is 100 times faster than a fast SSD.
Around 2000 , where VST started to have huge size , Ram was not enough to load many VST simultaneously so DFD method started
to work with only portion of samples to be loaded in Ram and reproduce samples in real time while the rest portion of sample was loaded
in temporary CPU buffer Ram from SSD/HD since speed is too slow to actually read the whole sample from it.

That's why , when you open a VST in your DAW and select a sound , always a loading time will follow and this procedure is the Ram
preloading of samples portion in Ram.

The same method has been applied in PaSeries for over 10 years in factory resources and after Pa4X OS Next , this method also
applied to user samples.
Therefore in fact real Ram was not dramatically increased , only the on board Nand memory where full factory & user samples are saved
together with preloaded samples portions that are loaded in Ram while booting.


Hope this helps