vo_gpu_next: add an option to control subtitles peak for HDR

Users may want to have darker subtitle brightness for HDR viewing

Don't apply it for video screenshots

Closed #13680

Author: dyphire

DOCS/interface-changes/subs-hdr-peak.txt

@@ -0,0 +1 @@
+add `--subs-hdr-peak` option

DOCS/man/options.rst

@@ -2779,6 +2779,12 @@ Subtitles
     canvas size. Can be useful to test broken subtitles, which often happen
     when the video was transcoded, while attempting to keep the old subtitles.
 
+``--subs-hdr-peak=<sdr|video|100-10000>``
+    Controls the subtitle peak of hdr videos, sdr means ``PL_COLOR_SDR_WHITE``,
+    video uses video data，you can also specify a value. (``--vo=gpu-next`` only)
+
+    Default: sdr.
+
 ``--sub-ass=<yes|no>``
     Render ASS subtitles natively (default: yes).
 

video/out/vo_gpu_next.c

@@ -165,6 +165,7 @@ static void update_lut(struct priv *p, struct user_lut *lut);
 
 struct gl_next_opts {
     bool delayed_peak;
+    int subs_hdr_peak;
     int border_background;
     float corner_rounding;
     bool inter_preserve;
@@ -186,6 +187,8 @@ const struct m_opt_choice_alternatives lut_types[] = {
 #define OPT_BASE_STRUCT struct gl_next_opts
 const struct m_sub_options gl_next_conf = {
     .opts = (const struct m_option[]) {
+        {"subs-hdr-peak", OPT_CHOICE(subs_hdr_peak, {"sdr", 0}, {"video", -1}),
+            M_RANGE(100, 10000)},
         {"allow-delayed-peak-detect", OPT_BOOL(delayed_peak)},
         {"border-background", OPT_CHOICE(border_background,
             {"none",  BACKGROUND_NONE},
@@ -206,6 +209,7 @@ const struct m_sub_options gl_next_conf = {
     .defaults = &(struct gl_next_opts) {
         .border_background = BACKGROUND_COLOR,
         .inter_preserve = true,
+        .subs_hdr_peak = 0,
     },
     .size = sizeof(struct gl_next_opts),
     .change_flags = UPDATE_VIDEO,
@@ -293,6 +297,7 @@ static void update_overlays(struct vo *vo, struct mp_osd_res res,
     struct priv *p = vo->priv;
     double pts = src ? src->pts : 0;
     struct sub_bitmap_list *subs = osd_render(vo->osd, res, pts, flags, mp_draw_sub_formats);
+    int subs_hdr_peak = p->next_opts->subs_hdr_peak;
 
     frame->overlays = state->overlays;
     frame->num_overlays = 0;
@@ -365,17 +370,21 @@ static void update_overlays(struct vo *vo, struct mp_osd_res res,
             // Infer bitmap colorspace from source
             if (src) {
                 ol->color = src->params.color;
-                // Seems like HDR subtitles are targeting SDR white
-                if (pl_color_transfer_is_hdr(ol->color.transfer)) {
+                if (pl_color_transfer_is_hdr(ol->color.transfer) && subs_hdr_peak != -1) {
                     ol->color.hdr = (struct pl_hdr_metadata) {
-                        .max_luma = PL_COLOR_SDR_WHITE,
+                       .max_luma = (subs_hdr_peak == 0) ? PL_COLOR_SDR_WHITE : subs_hdr_peak,
                     };
                 }
             }
             break;
         case SUBBITMAP_LIBASS:
             if (src && item->video_color_space && !pl_color_space_is_hdr(&src->params.color))
                 ol->color = src->params.color;
+            if (subs_hdr_peak != -1) {
+                ol->color.hdr = (struct pl_hdr_metadata) {
+                   .max_luma = (subs_hdr_peak == 0) ? PL_COLOR_SDR_WHITE : subs_hdr_peak,
+                };
+            }
             ol->mode = PL_OVERLAY_MONOCHROME;
             ol->repr.alpha = PL_ALPHA_INDEPENDENT;
             break;