Instruction manual

Using for Capture and Playback

Blackmagic Design Applications

Using Blackmagic Disk Speed Test to check your disk (PC)

If you want to check your disk array speed for uncompressed video, Blackmagic Disk Speed Test

can be run to check the array speed and provide the results in video frame rates. This makes

it much easier to understand how various disk arrays will handle video capture and playback at

various video resolutions and frame rates.

Disk Speed Test provides more accurate results for large disk arrays, as often the manufacturer

provided speed results only check small data blocks; so you only get an indication of the cache

speed of the disk and not the sustained data rate of the disk. Video uses sustained data rates and

only Disk Speed Test provides a long burst of data for more accurate results.

When using Disk Speed Test, you need to account for disk seeking, so it’s best to add a healthy

margin to the results. If a disk array tests at 32 frames per second HD 1080, it doesn’t mean you can

do 29.97 HD capture and playback, as the margin is too tight. When checking the results, look at the

8 bit YUV 4:2:2 video sections, as Intensity Pro uses the 8 bit uncompressed video format.

Disk Management.

Building uncompressed disk arrays (PC)

When you’re working with uncompressed HD video, the internal hard disk will not be fast

enough. You need a high speed disk array. These can be purchased pre-built, or you can build

your own using two hard disks for SD or at least eight hard disks for HD. The ﬁrst step is to install

and connect the hard disks.

If you intend to run your disk array as a software stripe, you will need to make sure that “host RAID”

is disabled. Use the “Disk Management” tool in “Computer Management” within Windows XP

™

to set up your software RAID, or refer to third party instructions when using pre-conﬁgured

hardware RAIDs.

Further information can be obtained via the Windows XP

™

Help and Support. Search and review the

section on “Dynamic Disks”. This section will provide you with information on conﬁguration steps

on striping your disk array. Due to disk seeks, when calculating the data rates required for your disk

system, it is a good idea to add a safety margin due to ﬂuctuations in disk speed. Disk speeds can

be increased by adding more disks. Serial ATA (SATA) disks can reduce to half their speed as they

become full, so in a 2-disk SATA array you should aim for a 100% safety margin. In an 8-disk SATA

array, a 30% safety margin should be adequate. Generally the more disks in the array, the better.

Note: Other vendors and third parties may provide different data rates for uncompressed video, the

above recommendations are tested for use with Intensity Pro.

Disk Speed RAID results after testing a disk array.