vo_opengl: add check-pattern suboption for testing

This uses glXGetVideoSyncSGI() to check how many vsyncs happened since
the last flip_page() call. It allows checking a pattern of vsync
increments of at most 2 elements. For example, to check ~24 fps playback
on a ~60 Hz monitor, this can be used:

--vo=opengl:check-pattern=[3-2]:waitvsync

Whether the reported results are accurate or just plain wrong may depend
on the driver and if the waitvsync sub-option is used. There are no
guarantees.

This option is undocumented, and may be removed again in the near or
distant future.

0 files changed, 0 insertions, 0 deletions