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Osprey 240e/450e User Guide
ViewCast 67
AV Stream driver reference information
DirectShow technology uses terms with specific meanings, for example, filter, pin, driver, and device.
Figure 61 depicts the relationship of DirectShow terms as they apply to Osprey hardware and drivers.
Figure 61. DirectShow
At the bottom of this diagram are one or more physical Osprey hardware devices. For each physical
device the AVStream driver creates one logical Video Device and one logical Audio Device.
On top of each Osprey logical Video Device, one or more Video Filters is created. If the SimulStream
option is not installed, there is a single Video Filter for each Video Device. If SimulStream is installed,
there can be multiple Video Filters for each Video Device.
The distinction between Device and Filter is important mainly to SimulStream users. For non-
SimulStream users, Device and Filter effectively mean about the same thing. For SimulStream users,
each SimulStream Filter acts as a virtual device that can be accessed by name and can deliver a separate
video stream with its own independent control settings.
When you enable SimulStream, some functions and capabilities are device-level, and others are filter-
level. Examples of device-level functions are input select, and the controls for brightness, contrast, hue,
saturation, and sharpness. These are closely tied to the underlying hardware of the device, which
inherently allows you to select only one input at a time, and to apply one set of hardware control
settings. Examples of filter-level functions are crop, logo, and caption settings, which can be different for
each video filter, and in fact for each pin of each filter. Some other capabilities such as deinterlace and
software gamma correction could logically be either device-level or filter-level, but are treated as
device-level for practical reasons.
On top of each Osprey logical Audio Device, one Audio Filter is created, with one or more pins capable of
sourcing one or more audio streams. There is not much practical distinction between an Audio Device
and an Audio Filter in either the SimulStream or non-SimulStream cases.