The screenshot command normally converts the currently displayed video
frame to an image. Add support for an alternative screenshot mode
that is supposed to capture the real window contents. Such a
screenshot contains a possibly scaled version of the frame, the OSD,
and subtitles.
Add a default key binding Alt+s for taking screenshots in this mode.
This needs special VO support, and might not work with all VOs (this
commit does not yet contain an implementation for any VO, only the
infrastructure).
Add a VO command (VOCTRL_SCREENSHOT) which requests a screenshot
directly from the VO. If VO support is available, screenshots will be
taken instantly (no more 1 or 2 frames delay). Taking screenshots when
hardware decoding is in use will also work (vdpau). Additionally, the
screenshots will now use the same colorspace as the video display.
Change the central MPContext to be allocated with talloc so that it
can be used as a talloc parent context.
This commit does not yet implement the functionality for any VO (added
in subsequent commits).
The old screenshot video filter is not needed anymore if VO support is
present, and in that case will not be used even if it is present in
the filter chain. If VO support is not available then the filter is
used like before. Note that the filter still has some of the old
problems, such as delaying the screenshot by at least 1 frame.
