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mpv/video/out/opengl/context_x11egl.c
Sultan Alsawaf 0d44ae319d x11: remove PresentNotifyMSC from egl/glx/vulkan to fix xpresent timing
PresentNotifyMSC turns out to be not only redundant, but also harmful with
mesa-backed egl/glx/vulkan VOs because for all of them, mesa uses
PresentPixmap behind the scenes when DRI3 is available, which already
spawns a PresentCompleteNotify event when the buffer swap actually
finishes. This is important because without using the timing information
from these PresentCompleteKindPixmap events, there's no way for mpv to know
exactly when a frame becomes visible on the display.

By using PresentNotifyMSC in conjunction with DRI3-enabled mesa, two
problems are created:
1. mpv assumes that a vblank won't elapse (i.e., it assumes the current MSC
   won't change) between the time when mesa enqueues the buffer swap and
   the time when mpv calls PresentNotifyMSC to ask xorg for a notification
   at the next MSC, relative to the current MSC at the time that xorg reads
   it for the PresentNotifyMSC call. This means that mpv could get a
   notification one or more vblanks later than it expects, since the
   intention here is for mpv to get a notification at the MSC that the
   buffer swap completes.
2. mpv assumes that a buffer swap always takes one vblank to complete,
   which isn't always true. A buffer swap (i.e., a page flip) could take
   longer than that depending on hardware conditions (if the GPU is running
   slowly or needs to exit a low-power state), scheduling delays (under
   heavy system or GPU load), or unfortunate timing (if the raster scan
   line happens to be at one of the last few rows of pixels and a vblank
   elapses just before the buffer swap is enqueued).

This causes mpv to have a faulty assumption of when frames become visible.

Since mpv already receives the PresentCompleteNotify events generated by
mesa's buffer swaps under the hood, the PresentNotifyMSC usage is unneeded
and just throws a wrench in mpv's vsync timing when xpresent is enabled.

Simply removing the PresentNotifyMSC usage from the egl, glx, and vulkan
VOs fixes the xpresent vsync timing.
2023-01-25 03:13:23 +00:00

226 lines
6.2 KiB
C

/*
* 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 <assert.h>
#include <X11/Xlib.h>
#include <X11/extensions/Xpresent.h>
#include <EGL/egl.h>
#include <EGL/eglext.h>
#include "common/common.h"
#include "video/out/present_sync.h"
#include "video/out/x11_common.h"
#include "context.h"
#include "egl_helpers.h"
#include "utils.h"
#define EGL_PLATFORM_X11_EXT 0x31D5
struct priv {
GL gl;
EGLDisplay egl_display;
EGLContext egl_context;
EGLSurface egl_surface;
};
static void mpegl_uninit(struct ra_ctx *ctx)
{
struct priv *p = ctx->priv;
ra_gl_ctx_uninit(ctx);
eglMakeCurrent(p->egl_display, EGL_NO_SURFACE, EGL_NO_SURFACE,
EGL_NO_CONTEXT);
eglTerminate(p->egl_display);
vo_x11_uninit(ctx->vo);
}
static int pick_xrgba_config(void *user_data, EGLConfig *configs, int num_configs)
{
struct ra_ctx *ctx = user_data;
struct priv *p = ctx->priv;
struct vo *vo = ctx->vo;
for (int n = 0; n < num_configs; n++) {
int vID = 0, num;
eglGetConfigAttrib(p->egl_display, configs[n], EGL_NATIVE_VISUAL_ID, &vID);
XVisualInfo template = {.visualid = vID};
XVisualInfo *vi = XGetVisualInfo(vo->x11->display, VisualIDMask,
&template, &num);
if (vi) {
bool is_rgba = vo_x11_is_rgba_visual(vi);
XFree(vi);
if (is_rgba)
return n;
}
}
return 0;
}
static bool mpegl_check_visible(struct ra_ctx *ctx)
{
return vo_x11_check_visible(ctx->vo);
}
static void mpegl_swap_buffers(struct ra_ctx *ctx)
{
struct priv *p = ctx->priv;
eglSwapBuffers(p->egl_display, p->egl_surface);
if (ctx->vo->x11->use_present)
present_sync_swap(ctx->vo->x11->present);
}
static void mpegl_get_vsync(struct ra_ctx *ctx, struct vo_vsync_info *info)
{
struct vo_x11_state *x11 = ctx->vo->x11;
if (ctx->vo->x11->use_present)
present_sync_get_info(x11->present, info);
}
static bool mpegl_init(struct ra_ctx *ctx)
{
struct priv *p = ctx->priv = talloc_zero(ctx, struct priv);
struct vo *vo = ctx->vo;
int msgl = ctx->opts.probing ? MSGL_V : MSGL_FATAL;
if (!vo_x11_init(vo))
goto uninit;
p->egl_display = mpegl_get_display(EGL_PLATFORM_X11_EXT,
"EGL_EXT_platform_x11",
vo->x11->display);
if (!eglInitialize(p->egl_display, NULL, NULL)) {
MP_MSG(ctx, msgl, "Could not initialize EGL.\n");
goto uninit;
}
struct mpegl_cb cb = {
.user_data = ctx,
.refine_config = ctx->opts.want_alpha ? pick_xrgba_config : NULL,
};
EGLConfig config;
if (!mpegl_create_context_cb(ctx, p->egl_display, cb, &p->egl_context, &config))
goto uninit;
int cid, vID, n;
if (!eglGetConfigAttrib(p->egl_display, config, EGL_CONFIG_ID, &cid)) {
MP_FATAL(ctx, "Getting EGL_CONFIG_ID failed!\n");
goto uninit;
}
if (!eglGetConfigAttrib(p->egl_display, config, EGL_NATIVE_VISUAL_ID, &vID)) {
MP_FATAL(ctx, "Getting X visual ID failed!\n");
goto uninit;
}
MP_VERBOSE(ctx, "Choosing visual EGL config 0x%x, visual ID 0x%x\n", cid, vID);
XVisualInfo template = {.visualid = vID};
XVisualInfo *vi = XGetVisualInfo(vo->x11->display, VisualIDMask, &template, &n);
if (!vi) {
MP_FATAL(ctx, "Getting X visual failed!\n");
goto uninit;
}
if (!vo_x11_create_vo_window(vo, vi, "gl")) {
XFree(vi);
goto uninit;
}
XFree(vi);
p->egl_surface = mpegl_create_window_surface(
p->egl_display, config, &vo->x11->window);
if (p->egl_surface == EGL_NO_SURFACE) {
p->egl_surface = eglCreateWindowSurface(
p->egl_display, config, (EGLNativeWindowType)vo->x11->window, NULL);
}
if (p->egl_surface == EGL_NO_SURFACE) {
MP_FATAL(ctx, "Could not create EGL surface!\n");
goto uninit;
}
if (!eglMakeCurrent(p->egl_display, p->egl_surface, p->egl_surface,
p->egl_context))
{
MP_FATAL(ctx, "Could not make context current!\n");
goto uninit;
}
mpegl_load_functions(&p->gl, ctx->log);
struct ra_gl_ctx_params params = {
.check_visible = mpegl_check_visible,
.swap_buffers = mpegl_swap_buffers,
.get_vsync = mpegl_get_vsync,
};
if (!ra_gl_ctx_init(ctx, &p->gl, params))
goto uninit;
ra_add_native_resource(ctx->ra, "x11", vo->x11->display);
return true;
uninit:
mpegl_uninit(ctx);
return false;
}
static void resize(struct ra_ctx *ctx)
{
ra_gl_ctx_resize(ctx->swapchain, ctx->vo->dwidth, ctx->vo->dheight, 0);
}
static bool mpegl_reconfig(struct ra_ctx *ctx)
{
vo_x11_config_vo_window(ctx->vo);
resize(ctx);
return true;
}
static int mpegl_control(struct ra_ctx *ctx, int *events, int request,
void *arg)
{
int ret = vo_x11_control(ctx->vo, events, request, arg);
if (*events & VO_EVENT_RESIZE)
resize(ctx);
return ret;
}
static void mpegl_wakeup(struct ra_ctx *ctx)
{
vo_x11_wakeup(ctx->vo);
}
static void mpegl_wait_events(struct ra_ctx *ctx, int64_t until_time_us)
{
vo_x11_wait_events(ctx->vo, until_time_us);
}
const struct ra_ctx_fns ra_ctx_x11_egl = {
.type = "opengl",
.name = "x11egl",
.reconfig = mpegl_reconfig,
.control = mpegl_control,
.wakeup = mpegl_wakeup,
.wait_events = mpegl_wait_events,
.init = mpegl_init,
.uninit = mpegl_uninit,
};