[PATCH wayland-protocols 1/4] stable: add presentation-time draft
ppaalanen at gmail.com
Tue Feb 23 09:50:52 UTC 2016
On Mon, 22 Feb 2016 11:45:44 -0800
Bill Spitzak <spitzak at gmail.com> wrote:
> On Mon, Feb 22, 2016 at 5:34 AM, Pekka Paalanen <ppaalanen at gmail.com> wrote:
> > + Argument 'refresh' gives the compositor's prediction of how
> > + many nanoseconds after tv_sec, tv_nsec the very next output
> > + refresh may occur. This is to further aid clients in
> > + predicting future refreshes, i.e., estimating the timestamps
> > + targeting the next few vblanks. If such prediction cannot
> > + usefully be done, the argument is zero.
> > +
> > + The 64-bit value combined from seq_hi and seq_lo is the value
> > + of the output's vertical retrace counter when the content
> > + update was first scanned out to the display. This value must
> > + be compatible with the definition of MSC in
> > + GLX_OML_sync_control specification. Note, that if the display
> > + path has a non-zero latency, the time instant specified by
> > + this counter may differ from the timestamp's.
> > +
> > + If the output does not have a constant refresh rate, explicit
> > + video mode switches excluded, then the refresh argument must
> > + be zero.
> > +
> > + If the output does not have a concept of vertical retrace or a
> > + refresh cycle, or the output device is self-refreshing without
> > + a way to query the refresh count, then the arguments seq_hi
> > + and seq_lo must be zero.
> I think the two middle paragraphs above need to be swapped. Number 1 and 3
> are talking about the refresh nanoseconds, number 2 and 4 are talking about
> the sequence counter.
sure, makes sense.
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