[FFmpeg-devel] [PATCH 2/2] avutil: add HDR10+ dynamic metadata serialization function

["Raphaël Zumer" <raphael.zumer@vimeo.com>]

Resent due to my mail client incorrectly re-wrapping lines in the version I sent earlier.
See the previous patch for context.

Signed-off-by: Raphaël Zumer <rzumer@tebako.net>
---
 libavutil/hdr_dynamic_metadata.c | 147 +++++++++++++++++++++++++++++++
 libavutil/hdr_dynamic_metadata.h |  10 +++
 libavutil/version.h              |   2 +-
 3 files changed, 158 insertions(+), 1 deletion(-)

diff --git a/libavutil/hdr_dynamic_metadata.c b/libavutil/hdr_dynamic_metadata.c
index 98f399b032..72d310e633 100644
--- a/libavutil/hdr_dynamic_metadata.c
+++ b/libavutil/hdr_dynamic_metadata.c
@@ -225,3 +225,150 @@ int av_dynamic_hdr_plus_from_t35(AVDynamicHDRPlus *s, const uint8_t *data,
 
     return 0;
 }
+
+AVBufferRef *av_dynamic_hdr_plus_to_t35(AVDynamicHDRPlus *s)
+{
+    AVBufferRef *buf;
+    size_t size_bits, size_bytes;
+    PutBitContext pbc, *pb = &pbc;
+
+    if (!s)
+        return NULL;
+
+    // Buffer size per CTA-861-H p.253-254:
+    size_bits =
+    // 56 bits for the header
+    58 +
+    // 2 bits for num_windows
+    2 +
+    // 937 bits for window geometry for each window above 1
+    FFMAX((s->num_windows - 1), 0) * 937 +
+    // 27 bits for targeted_system_display_maximum_luminance
+    27 +
+    // 1-3855 bits for targeted system display peak luminance information
+    1 + (s->targeted_system_display_actual_peak_luminance_flag ? 10 +
+        s->num_rows_targeted_system_display_actual_peak_luminance *
+        s->num_cols_targeted_system_display_actual_peak_luminance * 4 : 0) +
+    // 0-442 bits for intra-window pixel distribution information
+    s->num_windows * 82;
+    for (int w = 0; w < s->num_windows; w++) {
+        size_bits += s->params[w].num_distribution_maxrgb_percentiles * 24;
+    }
+    // 1-3855 bits for mastering display peak luminance information
+    size_bits += 1 + (s->mastering_display_actual_peak_luminance_flag ? 10 +
+        s->num_rows_mastering_display_actual_peak_luminance *
+        s->num_cols_mastering_display_actual_peak_luminance * 4 : 0) +
+    // 0-537 bits for per-window tonemapping information
+    s->num_windows * 1;
+    for (int w = 0; w < s->num_windows; w++) {
+        if (s->params[w].tone_mapping_flag) {
+            size_bits += 28 + s->params[w].num_bezier_curve_anchors * 10;
+        }
+    }
+    // 0-21 bits for per-window color saturation mapping information
+    size_bits += s->num_windows * 1;
+    for (int w = 0; w < s->num_windows; w++) {
+        if (s->params[w].color_saturation_mapping_flag) {
+            size_bits += 6;
+        }
+    }
+
+    size_bytes = (size_bits + 7) / 8;
+
+    buf = av_buffer_alloc(size_bytes);
+    if (!buf) {
+        return NULL;
+    }
+
+    init_put_bits(pb, buf->data, size_bytes);
+
+    // itu_t_t35_country_code shall be 0xB5 (USA)
+    put_bits(pb, 8, 0xB5);
+    // itu_t_t35_terminal_provider_code shall be 0x003C
+    put_bits(pb, 16, 0x003C);
+    // itu_t_t35_terminal_provider_oriented_code is set to ST 2094-40
+    put_bits(pb, 16, 0x0001);
+    // application_identifier shall be set to 4
+    put_bits(pb, 8, 4);
+    // application_mode is set to Application Version 1
+    put_bits(pb, 8, 1);
+
+    // Payload as per CTA-861-H p.253-254
+    put_bits(pb, 2, s->num_windows);
+
+    for (int w = 1; w < s->num_windows; w++) {
+        put_bits(pb, 16, s->params[w].window_upper_left_corner_x.num / s->params[w].window_upper_left_corner_x.den);
+        put_bits(pb, 16, s->params[w].window_upper_left_corner_y.num / s->params[w].window_upper_left_corner_y.den);
+        put_bits(pb, 16, s->params[w].window_lower_right_corner_x.num / s->params[w].window_lower_right_corner_x.den);
+        put_bits(pb, 16, s->params[w].window_lower_right_corner_y.num / s->params[w].window_lower_right_corner_y.den);
+        put_bits(pb, 16, s->params[w].center_of_ellipse_x);
+        put_bits(pb, 16, s->params[w].center_of_ellipse_y);
+        put_bits(pb, 8, s->params[w].rotation_angle);
+        put_bits(pb, 16, s->params[w].semimajor_axis_internal_ellipse);
+        put_bits(pb, 16, s->params[w].semimajor_axis_external_ellipse);
+        put_bits(pb, 16, s->params[w].semiminor_axis_external_ellipse);
+        put_bits(pb, 1, s->params[w].overlap_process_option);
+    }
+
+    put_bits(pb, 27, s->targeted_system_display_maximum_luminance.num * luminance_den /
+        s->targeted_system_display_maximum_luminance.den);
+    put_bits(pb, 1, s->targeted_system_display_actual_peak_luminance_flag);
+    if (s->targeted_system_display_actual_peak_luminance_flag) {
+        put_bits(pb, 5, s->num_rows_targeted_system_display_actual_peak_luminance);
+        put_bits(pb, 5, s->num_cols_targeted_system_display_actual_peak_luminance);
+        for (int i = 0; i < s->num_rows_targeted_system_display_actual_peak_luminance; i++) {
+            for (int j = 0; j < s->num_cols_targeted_system_display_actual_peak_luminance; j++) {
+                put_bits(pb, 4, s->targeted_system_display_actual_peak_luminance[i][j].num * peak_luminance_den /
+                    s->targeted_system_display_actual_peak_luminance[i][j].den);
+            }
+        }
+    }
+
+    for (int w = 0; w < s->num_windows; w++) {
+        for (int i = 0; i < 3; i++) {
+            put_bits(pb, 17, s->params[w].maxscl[i].num * rgb_den / s->params[w].maxscl[i].den);
+        }
+        put_bits(pb, 17, s->params[w].average_maxrgb.num * rgb_den / s->params[w].average_maxrgb.den);
+        put_bits(pb, 4, s->params[w].num_distribution_maxrgb_percentiles);
+        for (int i = 0; i < s->params[w].num_distribution_maxrgb_percentiles; i++) {
+            put_bits(pb, 7, s->params[w].distribution_maxrgb[i].percentage);
+            put_bits(pb, 17, s->params[w].distribution_maxrgb[i].percentile.num * rgb_den /
+                s->params[w].distribution_maxrgb[i].percentile.den);
+        }
+        put_bits(pb, 10, s->params[w].fraction_bright_pixels.num * fraction_pixel_den /
+            s->params[w].fraction_bright_pixels.den);
+    }
+
+    put_bits(pb, 1, s->mastering_display_actual_peak_luminance_flag);
+    if (s->mastering_display_actual_peak_luminance_flag) {
+        put_bits(pb, 5, s->num_rows_mastering_display_actual_peak_luminance);
+        put_bits(pb, 5, s->num_cols_mastering_display_actual_peak_luminance);
+        for (int i = 0; i < s->num_rows_mastering_display_actual_peak_luminance; i++) {
+            for (int j = 0; j < s->num_cols_mastering_display_actual_peak_luminance; j++) {
+                put_bits(pb, 4, s->mastering_display_actual_peak_luminance[i][j].num * peak_luminance_den /
+                    s->mastering_display_actual_peak_luminance[i][j].den);
+            }
+        }
+    }
+
+    for (int w = 0; w < s->num_windows; w++) {
+        put_bits(pb, 1, s->params[w].tone_mapping_flag);
+        if (s->params[w].tone_mapping_flag) {
+            put_bits(pb, 12, s->params[w].knee_point_x.num * knee_point_den / s->params[w].knee_point_x.den);
+            put_bits(pb, 12, s->params[w].knee_point_y.num * knee_point_den / s->params[w].knee_point_y.den);
+            put_bits(pb, 4, s->params[w].num_bezier_curve_anchors);
+            for (int i = 0; i < s->params[w].num_bezier_curve_anchors; i++) {
+                put_bits(pb, 10, s->params[w].bezier_curve_anchors[i].num * bezier_anchor_den /
+                    s->params[w].bezier_curve_anchors[i].den);
+            }
+            put_bits(pb, 1, s->params[w].color_saturation_mapping_flag);
+            if (s->params[w].color_saturation_mapping_flag) {
+                put_bits(pb, 6, s->params[w].color_saturation_weight.num * saturation_weight_den /
+                    s->params[w].color_saturation_weight.den);
+            }
+        }
+    }
+
+    flush_put_bits(pb);
+    return buf;
+}
diff --git a/libavutil/hdr_dynamic_metadata.h b/libavutil/hdr_dynamic_metadata.h
index 1f953ef1f5..f75d3e0739 100644
--- a/libavutil/hdr_dynamic_metadata.h
+++ b/libavutil/hdr_dynamic_metadata.h
@@ -21,6 +21,7 @@
 #ifndef AVUTIL_HDR_DYNAMIC_METADATA_H
 #define AVUTIL_HDR_DYNAMIC_METADATA_H
 
+#include "buffer.h"
 #include "frame.h"
 #include "rational.h"
 
@@ -351,4 +352,13 @@ AVDynamicHDRPlus *av_dynamic_hdr_plus_create_side_data(AVFrame *frame);
 int av_dynamic_hdr_plus_from_t35(AVDynamicHDRPlus *s, const uint8_t *data,
                                  int size);
 
+/**
+ * Serialize dynamic HDR10+ metadata to a user data registered ITU-T T.35 buffer.
+ * @param s A pointer containing the decoded AVDynamicHDRPlus structure.
+ *
+ * @return Pointer to an AVBufferRef containing the raw ITU-T T.35 representation
+ *         of the HDR10+ metadata if succeed, or NULL if buffer allocation fails.
+ */
+AVBufferRef *av_dynamic_hdr_plus_to_t35(AVDynamicHDRPlus *s);
+
 #endif /* AVUTIL_HDR_DYNAMIC_METADATA_H */
diff --git a/libavutil/version.h b/libavutil/version.h
index 900b798971..7635672985 100644
--- a/libavutil/version.h
+++ b/libavutil/version.h
@@ -79,7 +79,7 @@
  */
 
 #define LIBAVUTIL_VERSION_MAJOR  58
-#define LIBAVUTIL_VERSION_MINOR   3
+#define LIBAVUTIL_VERSION_MINOR   4
 #define LIBAVUTIL_VERSION_MICRO 100
 
 #define LIBAVUTIL_VERSION_INT   AV_VERSION_INT(LIBAVUTIL_VERSION_MAJOR, \
-- 
2.39.1

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