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authorStefano Pigozzi <stefano.pigozzi@gmail.com>2015-02-07 13:54:18 +0100
committerStefano Pigozzi <stefano.pigozzi@gmail.com>2015-03-04 10:06:08 +0100
commitc028d782c1eec46e2416da483881f1d0b27c2be8 (patch)
treedeb55f566d265b7facb3975b76441eae4d5c72e0 /video/out
parent89306818bb3d2f6942e3cb6bb6c0ce01e7f7f65c (diff)
downloadmpv-c028d782c1eec46e2416da483881f1d0b27c2be8.tar.bz2
mpv-c028d782c1eec46e2416da483881f1d0b27c2be8.tar.xz
vo_opengl: add gamma-auto option
This automatically sets the gamma option depending on lighting conditions measured from the computer's ambient light sensor. sRGB – arguably the “sibling” to BT.709 for still images – has a reference viewing environment defined in its specification (IEC 61966-2-1:1999, see http://www.color.org/chardata/rgb/srgb.xalter). According to this data, the assumed ambient illuminance is 64 lux. This is the illuminance where the gamma that results from ICC color management is correct. On the other hand, BT.1886 formalizes that the gamma level for dim environments to be 2.40, and Apple resources (WWDC12: 2012 Session 523: Best practices for color management) define the BT.1886 dim at 16 lux. So the logic we apply is: * >= 64lux -> 1.961 gamma * =< 16lux -> 2.400 gamma * 16lux < x < 64lux -> logaritmic rescale of lux to gamma. The human perception of illuminance roughly follows a logaritmic scale of lux [1]. [1]: https://msdn.microsoft.com/en-us/library/windows/desktop/dd319008%28v=vs.85%29.aspx
Diffstat (limited to 'video/out')
-rw-r--r--video/out/gl_video.c26
-rw-r--r--video/out/gl_video.h5
-rw-r--r--video/out/vo_opengl.c17
3 files changed, 48 insertions, 0 deletions
diff --git a/video/out/gl_video.c b/video/out/gl_video.c
index f1ea03ed80..7420d9d4d1 100644
--- a/video/out/gl_video.c
+++ b/video/out/gl_video.c
@@ -355,6 +355,7 @@ static int validate_scaler_opt(struct mp_log *log, const m_option_t *opt,
const struct m_sub_options gl_video_conf = {
.opts = (const m_option_t[]) {
OPT_FLOATRANGE("gamma", gamma, 0, 0.1, 2.0),
+ OPT_FLAG("gamma-auto", gamma_auto, 0),
OPT_FLAG("srgb", srgb, 0),
OPT_FLAG("npot", npot, 0),
OPT_FLAG("pbo", pbo, 0),
@@ -2564,6 +2565,31 @@ void gl_video_resize_redraw(struct gl_video *p, int w, int h)
gl_video_render_frame(p, 0, NULL);
}
+float gl_video_scale_ambient_lux(float lmin, float lmax,
+ float rmin, float rmax, float lux)
+{
+ assert(lmax > lmin);
+
+ float num = (rmax - rmin) * (log10(lux) - log10(lmin));
+ float den = log10(lmax) - log10(lmin);
+ float result = num / den + rmin;
+
+ // clamp the result
+ float max = MPMAX(rmax, rmin);
+ float min = MPMIN(rmax, rmin);
+ return MPMAX(MPMIN(result, max), min);
+}
+
+void gl_video_set_ambient_lux(struct gl_video *p, int lux)
+{
+ if (p->opts.gamma_auto) {
+ float gamma = gl_video_scale_ambient_lux(16.0, 64.0, 2.40, 1.961, lux);
+ MP_INFO(p, "ambient light changed: %dlux (gamma: %f)\n", lux, gamma);
+ p->opts.gamma = MPMIN(1.0, 1.961 / gamma);
+ gl_video_eq_update(p);
+ }
+}
+
void gl_video_set_hwdec(struct gl_video *p, struct gl_hwdec *hwdec)
{
p->hwdec = hwdec;
diff --git a/video/out/gl_video.h b/video/out/gl_video.h
index 74a8b7fd93..8c273faa9e 100644
--- a/video/out/gl_video.h
+++ b/video/out/gl_video.h
@@ -35,6 +35,7 @@ struct gl_video_opts {
float scaler_radius[2];
float scaler_antiring[2];
float gamma;
+ int gamma_auto;
int srgb;
int linear_scaling;
int fancy_downscaling;
@@ -83,6 +84,10 @@ void gl_video_eq_update(struct gl_video *p);
void gl_video_set_debug(struct gl_video *p, bool enable);
void gl_video_resize_redraw(struct gl_video *p, int w, int h);
+float gl_video_scale_ambient_lux(float lmin, float lmax,
+ float rmin, float rmax, float lux);
+void gl_video_set_ambient_lux(struct gl_video *p, int lux);
+
void gl_video_set_gl_state(struct gl_video *p);
void gl_video_unset_gl_state(struct gl_video *p);
void gl_video_reset(struct gl_video *p);
diff --git a/video/out/vo_opengl.c b/video/out/vo_opengl.c
index a9435eeac2..9318914dbd 100644
--- a/video/out/vo_opengl.c
+++ b/video/out/vo_opengl.c
@@ -276,6 +276,19 @@ static bool get_and_update_icc_profile(struct gl_priv *p, int *events)
return true;
}
+static void get_and_update_ambient_lighting(struct gl_priv *p, int *events)
+{
+ int lux;
+ int r = p->glctx->vo_control(p->vo, events, VOCTRL_GET_AMBIENT_LUX, &lux);
+ if (r == VO_TRUE) {
+ gl_video_set_ambient_lux(p->renderer, lux);
+ }
+ if (r != VO_TRUE && p->renderer_opts->gamma_auto) {
+ MP_ERR(p, "gamma_auto option provided, but querying for ambient"
+ " lighting is not supported on this platform\n");
+ }
+}
+
static bool reparse_cmdline(struct gl_priv *p, char *args)
{
struct m_config *cfg = NULL;
@@ -390,6 +403,10 @@ static int control(struct vo *vo, uint32_t request, void *data)
get_and_update_icc_profile(p, &events);
vo->want_redraw = true;
}
+ if (events & VO_EVENT_AMBIENT_LIGHTING_CHANGED) {
+ get_and_update_ambient_lighting(p, &events);
+ vo->want_redraw = true;
+ }
if (events & VO_EVENT_RESIZE)
resize(p);
if (events & VO_EVENT_EXPOSE)