player: make effective image_display_duration playback_speed aware

Signed-off-by: Mohammad AlSaleh <CE.Mohammad.AlSaleh@gmail.com>

DOCS/interface-changes/speed-aware-image-display-duration.txt

@@ -0,0 +1 @@
+effective `--image-display-duration` takes `--speed` into consideration now

DOCS/man/options.rst

@@ -3409,6 +3409,9 @@ Window
     example if ``--length`` is used to reduce the length to 1 frame, or if
     you seek to the last frame.
 
+    The effective duration is now `--speed` aware, which was not the case in
+    older mpv versions before v0.41.0.
+
     This option does not affect the framerate used for ``mf://`` or
     ``--merge-files``. For that, use ``--mf-fps`` instead.
 

player/command.c

@@ -8148,7 +8148,7 @@ void mp_option_run_callback(struct MPContext *mpctx, struct mp_option_callback *
     if (opt_ptr == &opts->image_display_duration && mpctx->vo_chain
         && mpctx->vo_chain->is_sparse && !mpctx->ao_chain
         && mpctx->video_status == STATUS_DRAINING)
-        mpctx->time_frame = opts->image_display_duration;
+        mpctx->time_frame = opts->image_display_duration / opts->playback_speed;
 }
 
 void mp_notify_property(struct MPContext *mpctx, const char *property)

player/video.c

@@ -1108,7 +1108,7 @@ void write_video(struct MPContext *mpctx)
             get_relative_time(mpctx);
             if (vo_c->is_sparse && !mpctx->ao_chain) {
                 MP_VERBOSE(mpctx, "assuming this is an image\n");
-                mpctx->time_frame += opts->image_display_duration;
+                mpctx->time_frame += opts->image_display_duration / opts->playback_speed;
             } else if (mpctx->last_frame_duration > 0) {
                 MP_VERBOSE(mpctx, "using demuxer frame duration for last frame\n");
                 mpctx->time_frame += mpctx->last_frame_duration;