Roku HD110 User Guide - Page 91

Speed, BrightSign compatibility, readperf

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various strategies. These strategies include wear leveling when writing, automatic error correction when reading, re-writing a block that is becoming susceptible to read errors, and moving blocks around in the NAND chip that are repeatedly read over and over. A typical BrightSign application includes an attract video loop. If this video is fairly short, then a small number of flash blocks are read repeatedly. Over a month or so, the number of times the attract loop plays can be enough to trigger fatigue read errors if the CF card's controller chip is not designed to handle and eliminate these type of errors. Industrial rated CF/SD cards are designed with high levels of repeated use in mind. Whereas consumer CF/SD cards may be designed with lower cost or quality standards that assume a digital camera is the typical usage scenario. Speed All modern CF cards we have tried have sufficient read speed for digital sign and kiosk applications with standard definition video. In general you need a card that can sustain read rates of over 3 megabytes per second for standard video. However for standard video, we recommend CF/SD cards with read rates of 4 megabytes per second, which are easy to find. For Hi-Def video, we recommend a card that can sustain read rates of over 6 megabytes per second. You can test a card's speed with BrightSign by placing a file on it, and using the BrightSign Shell readperf command. BrightSign compatibility BrightSign is compatible with most CF/SD cards, but may not be 100% compatible with every model. Although there are standards for CF/SD card interfaces, most chips are slightly different. We have tested with a large number of chips, and at this point have high compatibility. When deploying a group of BrightSigns into the field, BrightSign strongly recommends that you test the CF/SD card with the BrightSign software version you are using before deployment, and insist that your CF/SD card duplicator uses the same CF/SD brand and model number as the model number you tested. 85 • •

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various strategies. These strategies include
wear leveling
when writing, automatic error
correction when reading, re-writing a block that is becoming susceptible to read errors, and
moving blocks around in the NAND chip that are repeatedly read over and over.
A typical BrightSign application includes an
attract
video loop. If this video is fairly short, then a
small number of flash blocks are read repeatedly. Over a month or so, the number of times the
attract loop plays can be enough to trigger fatigue read errors if the CF card’s controller chip is
not designed to handle and eliminate these type of errors. Industrial rated CF/SD cards are
designed with high levels of repeated use in mind. Whereas consumer CF/SD cards may be
designed with lower cost or quality standards that assume a digital camera is the typical
usage scenario.
Speed
All modern CF cards we have tried have sufficient read speed for digital sign and kiosk
applications with standard definition video. In general you need a card that can sustain read rates
of over 3 megabytes per second for standard video. However for standard video, we recommend
CF/SD cards with read rates of 4 megabytes per second, which are easy to find. For Hi-Def video,
we recommend a card that can sustain read rates of over 6 megabytes per second. You can test
a card’s speed with BrightSign by placing a file on it, and using the BrightSign Shell
readperf
command.
BrightSign compatibility
BrightSign is compatible with most CF/SD cards, but may not be 100% compatible with every
model. Although there are standards for CF/SD card interfaces, most chips are slightly different.
We have tested with a large number of chips, and at this point have high compatibility.
When deploying a group of BrightSigns into the field, BrightSign strongly recommends that you
test the CF/SD card with the BrightSign software version you are using before deployment, and
insist that your CF/SD card duplicator uses the same CF/SD brand and model number as the
model number you tested.