Fix colour range property for subsampled sources (#2357).

[dcpomatic.git] / src / lib / ffmpeg_content.cc

diff --git a/src/lib/ffmpeg_content.cc b/src/lib/ffmpeg_content.cc
index 4bc88e1e4937ca2e896101ae8903c0539893cd7e..496ad5f1a2772574c1681becbe7e158d74151d8d 100644 (file)
--- a/src/lib/ffmpeg_content.cc
+++ b/src/lib/ffmpeg_content.cc
@@ -538,10 +538,12 @@ FFmpegContent::add_properties (shared_ptr<const Film> film, list<UserProperty>&
                video->add_properties (p);
 
                if (_bits_per_pixel) {
-                       /* Assuming there's three components, so bits per pixel component is _bits_per_pixel / 3 */
-                       int const lim_start = pow(2, _bits_per_pixel.get() / 3 - 4);
-                       int const lim_end = 235 * pow(2, _bits_per_pixel.get() / 3 - 8);
-                       int const total = pow(2, _bits_per_pixel.get() / 3);
+                       auto pixel_quanta_product = video->pixel_quanta().x * video->pixel_quanta().y;
+                       auto bits_per_main_pixel = pixel_quanta_product * _bits_per_pixel.get() / (pixel_quanta_product + 2);
+
+                       int const lim_start = pow(2, bits_per_main_pixel - 4);
+                       int const lim_end = 235 * pow(2, bits_per_main_pixel - 8);
+                       int const total = pow(2, bits_per_main_pixel);
 
                        switch (_color_range.get_value_or(AVCOL_RANGE_UNSPECIFIED)) {
                        case AVCOL_RANGE_UNSPECIFIED:
@@ -554,14 +556,14 @@ FFmpegContent::add_properties (shared_ptr<const Film> film, list<UserProperty>&
                                /// file is limited, so that not all possible values are valid.
                                p.push_back (
                                        UserProperty (
-                                               UserProperty::VIDEO, _("Colour range"), String::compose(_("Limited (%1-%2)"), lim_start, lim_end)
+                                               UserProperty::VIDEO, _("Colour range"), String::compose(_("Limited / video (%1-%2)"), lim_start, lim_end)
                                                )
                                        );
                                break;
                        case AVCOL_RANGE_JPEG:
                                /// TRANSLATORS: this means that the range of pixel values used in this
                                /// file is full, so that all possible pixel values are valid.
-                               p.push_back (UserProperty (UserProperty::VIDEO, _("Colour range"), String::compose (_("Full (0-%1)"), total)));
+                               p.push_back(UserProperty(UserProperty::VIDEO, _("Colour range"), String::compose(_("Full (0-%1)"), total - 1)));
                                break;
                        default:
                                DCPOMATIC_ASSERT (false);