ViewCast Osprey PCI, Руководство пользователя

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Osprey PCI User Guide
ViewCast 77
Preview Pin to Video Renderer
Figure 54. Preview pin to video renderer
Video renderer is the oldest and simplest DirectShow renderer. It does not use DirectDraw in the
rendering process, which makes it substantially slower than VMR7 described below. It is the default
rendering pathway that will be chosen when an application says “Render” without specifying a
preferred pathway. For this reason, many applications deliver unnecessarily slow rendering
performance.
Video renderer works best when your output format is RGB rather than YUV, with the RGB format
matched to your screen depth. On most modern systems, that means RGB32 is the preferred
format. If a YUV format is used, an extra filter, AVI Decompressor will be inserted into the graph to
convert the YUV to RGB. The driver can do this conversion faster internally.
Preview Pin to Overlay Mixer to Video Renderer
Figure 55. Preview pin to overlay mixer to video renderer
Compared to a direct connection of Preview Pin to Video Renderer, the combination of Overlay
Mixer plus Video Renderer provides performance that is …different. It is hard to be more specific
than that without reference to specific machines; refer to the data tables below.
This pathway is the only one that renders closed captioning correctly when a DShow CC or VBI pin is
used rather than the driver’s internal rendering. For CC rendering, the output of the Line 21 filter
connects to an input of the Overlay Mixer.
The best video format to use with Overlay Mixer is YUY2.