ViewCast Osprey PCI, User Manual

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AVStream Driver Reference Information
72 ViewCast
AVStream driver reference information
In DirectShow, the words “filter” and “pin,” as well as “driver” and “device,” are frequently used.
Figure 51 illustrates their relationship as they apply to Osprey hardware and drivers.
Figure 51. Filters, pins, and properties
At the bottom of this diagram are one or more physical Osprey hardware devices. All Osprey devices
of a given type (such as Osprey 230 or Osprey 560) are controlled by a single Osprey binary, the
Osprey AVStream Driver. 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 SimulStream is enabled, 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 only one input to be selected at a time, and one set of hardware
control settings to be applied. 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