mpv/video/out/present_sync.c

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/*
* This file is part of mpv.
*
* mpv is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* mpv is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with mpv. If not, see <http://www.gnu.org/licenses/>.
*/
#include <time.h>
#include "mpv_talloc.h"
#include "osdep/timer.h"
#include "present_sync.h"
/* General nonsense about this mechanism.
*
* This requires that that caller has access to two, related values:
* (ust, msc): clock time and incrementing counter of last vsync (this is
* increased continuously, even if we don't swap)
*
* Note that this concept originates from the GLX_OML_sync_control extension
* which includes another parameter: sbc (swap counter of frame that was
* last displayed). Both the xorg present extension and wayland's
* presentation-time protocol do not include sbc values so they are omitted
* from this mechanism. mpv does not need to keep track of sbc calls and can
* have reliable presentation without it.
*/
void present_sync_get_info(struct mp_present *present, struct vo_vsync_info *info)
{
info->vsync_duration = present->vsync_duration;
info->skipped_vsyncs = present->last_skipped_vsyncs;
info->last_queue_display_time = present->last_queue_display_time;
}
void present_sync_swap(struct mp_present *present)
{
int64_t ust = present->current_ust;
int64_t msc = present->current_msc;
// Avoid attempting to use any presentation statistics if the ust is 0 or has
// not actually updated (i.e. the last_ust is equal to current_ust).
if (!ust || ust == present->last_ust) {
present->last_skipped_vsyncs = -1;
present->vsync_duration = -1;
present->last_queue_display_time = -1;
return;
}
present->last_skipped_vsyncs = 0;
int64_t ust_passed = ust ? ust - present->last_ust: 0;
present->last_ust = ust;
int64_t msc_passed = msc ? msc - present->last_msc: 0;
present->last_msc = msc;
if (msc_passed && ust_passed)
present->vsync_duration = ust_passed / msc_passed;
struct timespec ts;
if (clock_gettime(CLOCK_MONOTONIC, &ts))
return;
int64_t now_monotonic = ts.tv_sec * UINT64_C(1000000000) + ts.tv_nsec;
int64_t ust_mp_time = mp_time_ns() - (now_monotonic - ust);
present->last_queue_display_time = ust_mp_time;
}
void present_update_sync_values(struct mp_present *present, int64_t ust,
int64_t msc)
{
present->current_ust = ust;
present->current_msc = msc;
}