multiple displays with different refresh rates

Loïc Le Loarer loic.le-loarer at
Wed Feb 8 04:50:23 PST 2012

2012/2/7 Adam Jackson <ajax at>:
> On 2/7/12 5:10 PM, Loďc Le Loarer wrote:
>> I'm trying to play two videos on one X server with two screens with
>> different refresh rates (120Hz and 60Hz) without tearing.
>> Currently I'm using XvShmPutImage with the send_event argument set to
>> true on Xv ports with the XV_SYNC_TO_VBLANK attribute set.
>> The problem is that I'm receiving completion events for both screen at
>> the rhythm of the slowest screen, as if one on two event of the
>> fastest screen were dropped.
>> Do you have an idea of where I should look ?
> You have found one of the fundamental shortcomings of Xv.

Ok, nice to know. Any luck that this is fixed one day or what should
be done to fix this?

> VDPAU might fix this, I've not checked.

I haven't look at VDPAU but I at OpenGL and it seems there are also
some issues to display at two different frames with OpenGL two, is it
also a known shortcoming or is it worth to look deeper at OpenGL ?

Best regards

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