On Tue, 2003-01-14 at 23:05, Tan Wei Chong wrote:
> Dear all,
> 
> I am trying to implement an Xv driver.
> I came across this one function call StopVideo() and DESIGN doc says it is to 
>indicate that the driver should stop displaying the video.
> I would like to know if the interface will only be trigger by an event like window 
>manager's moving window or can a client invoke it like how PutImage() is invoked thru 
>XvShmPutImage()? 
> I am also curious about whether there is any corresponding function that indicate 
>when the driver should continue displaying the video again after a StopVideo().

Let dd = device dependent
Let di = device independent

StopVideo is implemented the dd part of the video driver, the di
portions of Xv will call it for a number of reasons, for instance the
user may have invoked the XvStopVideo API call or the window is in the
process of moving or being iconified. As a implementor of the dd
functions you don't care why its called, you only need to respond to the
call. The call includes a flag indicating if you should start or stop
video. You job is to test the flag and communicate with the device
(probably via mmio register access) to start or stop decoding video into
the frame buffer. Note that some devices decode directly in the frame
buffer while others use a separate buffer and blend (i.e. merge) the
video and graphics together, in the later case you can just
enable/disable the blending.

John


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