Bandwidth Throttling

The user-mode screen capture technology has the ability to "throttle" itself to a restricted amount of bandwidth. This may be preferable when responsiveness and throughput are more important than screen quality, particularly over low-bandwidth connections. The amount of throttling is controlled by parameters set in a "user-mode screen capture profile". The “Configure…” button on the Screen tab brings up a dialog that allows the end-user to select a hard-coded, predefined configuration, or to specify a custom configuration.

Each profile consists of the following information:

u Description string

u Image type (two choices -- Hextile (default), or JPEG). The Host will automatically use JPEG compression if the connected Master doesn’t support Hextile. For Hextile encoding, the ‘image compression quality’ value is not used because Hextile is a lossless compression.

u Image compression quality (numeric value 1-100, with 100 being best quality)

u Polling frequencies (three values -- Capture Rate, Foreground, and Background, in milliseconds). Note however that the UI will display these values on a scale of 1 to 10, with 1 being the least aggressive (longest time), and 10 being the most aggressive (shortest time). The underlying API and settings storage will have the raw millisecond values.

u Bandwidth limit (numeric value 5-200 kilobytes/sec, for -1 for unlimited)

The Host settings are preconfigured with the following four profiles:

Profile Settings	High	Medium	Medium Low	Low
Description	High Quality	Medium	Medium-Low (recording)	Low (recording)
Image Type	Hextile	Hextile	Hextile	Hextile
Compression Quality	100	100	100	100
Polling Frequency	9/8/6	7/6/4	4/5/4	2/2/2
Bandwidth Limit	Unlimited	100 Kbyte/sec	60 Kbyte/sec	30 Kbyte/sec

The Medium-Low and Low profiles are appropriate for high volume screen recording environments, when screen quality can be traded off for lower screen capture rates, smaller screen recording file sizes and restricted bandwidth usage. You can create your own custom profile by selecting [Custom] from the drop-down list and specifying your desired parameters.