Quicktime next frame without time

Hello,
I’m want to update movie “in update() override” frame by idle !
By default it’s by time !
I want to synchronize perfectly framerate of video and framerate of app.

Into void MovieBase::updateFrame()
There is QTVisualContextCopyImageForTime !

QTVisualContextCopyImageForTime(
QTVisualContextRef visualContext,
CFAllocatorRef allocator, /* can be NULL /
const CVTimeStamp * timeStamp, /
can be NULL */
CVImageBufferRef * newImage);

I have quicktime movie at 60 ips and framerate of app at 60 hz !
For moment I have a gig (lag) while 15s every 5 min !

I search again !

Any idea ?

Thanks

http://discourse.libcinder.org/t/quicktime-timestamp/514