Isadora Manual v1.3 - TroikaTronix

The standard drives included with most laptops are usually 5400 RPM which will
give less efficient performance, but are still workable depending on the resolution
of your video.
Tip 2: Add as much RAM (Random Access Memory) to your computer
as you can afford.
Modern operating systems rely on a feature called “virtual memory.” When the
computer senses that some data that resides in your computers RAM (i.e. the
extremely fast internal memory linked to your main processor) has not been used
for a while, it will write it out to disk to make more RAM available to other
applications. This is called “page swapping” and can adversely affect performance.
The best way to solve this problem is to add more RAM to your computer. As a
general rule, 2 Gigabytes is a good base line. 4 Gigabytes is even better. Page
swapping will often take place on machines with less memory than 2 Gigabytes of
memory.
Tip 3: Donʼt run other applications at the same time as Isadora
Every running application consumes system resources. So, especially when using
Isadora for a live performance, don’t run any other applications at the same time.
Even if they aren’t “doing anything” they get some of the processor’s time, and thus
slow down Isadora.
Tip 4: Keep your video resolution as low as you can.
The biggest burden any real-time video software faces is the size of the image it has
to process. This data has to be brought in from the hard drive or from a live camera
input, moved through any effects, and sent to the graphics card for output. It’s a
simple relationship: as resolution increases, the speed at which those frames can be
processed decreases.
In addition, there is the CPU overhead necessitated by decoding the video from it’s
compressed format to the uncompressed format that can be processed by the video
effects and/or graphics card.
So, while Isadora has no limitation on the resolution of the video it can play, if you
want good frame rates, it is best to keep the resolution as low as you possible so as
to get the best frame rates.
To give you a sense of the amount of data being processed, take a look at this table:
Isadora Manual
Resolution Megabytes / Frame Megabytes / Sec. @
30FPS
320x240 QVGA 0.3 Mb 9.2 Mb/S
720x480 DV Video 1.3 Mb 41 Mb/S
1920x1080 HD 8.2 Mb 248 Mb/S
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