avutil/frame: add helper for adding side data to array

Additionally, add an API test to check that the no-duplicates
addition works after duplicates have been inserted.

libavutil/Makefile

@@ -271,6 +271,7 @@ TESTPROGS = adler32                                                     \
             ripemd                                                      \
             sha                                                         \
             sha512                                                      \
+            side_data_array                                             \
             softfloat                                                   \
             tree                                                        \
             twofish                                                     \

libavutil/frame.c

@@ -747,6 +747,23 @@ AVFrameSideData *av_frame_new_side_data(AVFrame *frame,
     return ret;
 }
 
+AVFrameSideData *av_frame_side_data_new(AVFrameSideData ***sd, int *nb_sd,
+                                        enum AVFrameSideDataType type,
+                                        size_t size, unsigned int flags)
+{
+    AVBufferRef     *buf = av_buffer_alloc(size);
+    AVFrameSideData *ret = NULL;
+
+    if (flags & AV_FRAME_SIDE_DATA_FLAG_UNIQUE)
+        remove_side_data(sd, nb_sd, type);
+
+    ret = add_side_data_from_buf(sd, nb_sd, type, buf);
+    if (!ret)
+        av_buffer_unref(&buf);
+
+    return ret;
+}
+
 AVFrameSideData *av_frame_get_side_data(const AVFrame *frame,
                                         enum AVFrameSideDataType type)
 {

libavutil/frame.h

@@ -999,6 +999,28 @@ const char *av_frame_side_data_name(enum AVFrameSideDataType type);
  */
 void av_frame_side_data_free(AVFrameSideData ***sd, int *nb_sd);
 
+#define AV_FRAME_SIDE_DATA_FLAG_UNIQUE (1 << 0)
+
+/**
+ * Add new side data entry to an array.
+ *
+ * @param sd    pointer to array of side data to which to add another entry,
+ *              or to NULL in order to start a new array.
+ * @param nb_sd pointer to an integer containing the number of entries in
+ *              the array.
+ * @param type  type of the added side data
+ * @param size  size of the side data
+ * @param flags Some combination of AV_FRAME_SIDE_DATA_FLAG_* flags, or 0.
+ *
+ * @return newly added side data on success, NULL on error. In case of
+ *         AV_FRAME_SIDE_DATA_FLAG_UNIQUE being set, entries of matching
+ *         AVFrameSideDataType will be removed before the addition is
+ *         attempted.
+ */
+AVFrameSideData *av_frame_side_data_new(AVFrameSideData ***sd, int *nb_sd,
+                                        enum AVFrameSideDataType type,
+                                        size_t size, unsigned int flags);
+
 /**
  * @}
  */

libavutil/tests/side_data_array.c

@@ -0,0 +1,103 @@
+/*
+ * Copyright (c) 2023 Jan Ekström <jeebjp@gmail.com>
+ *
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include <stdio.h>
+#include "libavutil/frame.c"
+#include "libavutil/mastering_display_metadata.h"
+
+static void print_clls(const AVFrameSideData **sd, const int nb_sd)
+{
+    for (int i = 0; i < nb_sd; i++) {
+        const AVFrameSideData *entry = sd[i];
+
+        printf("sd %d, %s",
+               i, av_frame_side_data_name(entry->type));
+
+        if (entry->type != AV_FRAME_DATA_CONTENT_LIGHT_LEVEL) {
+            putchar('\n');
+            continue;
+        }
+
+        printf(": MaxCLL: %u\n",
+               ((AVContentLightMetadata *)entry->data)->MaxCLL);
+    }
+}
+
+typedef struct FrameSideDataSet {
+    AVFrameSideData **sd;
+    int            nb_sd;
+} FrameSideDataSet;
+
+int main(void)
+{
+    FrameSideDataSet set = { 0 };
+
+    av_assert0(
+        av_frame_side_data_new(&set.sd, &set.nb_sd,
+                               AV_FRAME_DATA_AMBIENT_VIEWING_ENVIRONMENT,
+                               0, 0));
+
+    // test entries in the middle
+    for (int value = 1; value < 4; value++) {
+        AVFrameSideData *sd = av_frame_side_data_new(
+            &set.sd, &set.nb_sd, AV_FRAME_DATA_CONTENT_LIGHT_LEVEL,
+            sizeof(AVContentLightMetadata), 0);
+
+        av_assert0(sd);
+
+        ((AVContentLightMetadata *)sd->data)->MaxCLL = value;
+    }
+
+    av_assert0(
+        av_frame_side_data_new(
+            &set.sd, &set.nb_sd, AV_FRAME_DATA_SPHERICAL, 0, 0));
+
+    // test entries at the end
+    for (int value = 1; value < 4; value++) {
+        AVFrameSideData *sd = av_frame_side_data_new(
+            &set.sd, &set.nb_sd, AV_FRAME_DATA_CONTENT_LIGHT_LEVEL,
+            sizeof(AVContentLightMetadata), 0);
+
+        av_assert0(sd);
+
+        ((AVContentLightMetadata *)sd->data)->MaxCLL = value + 3;
+    }
+
+    puts("Initial addition results with duplicates:");
+    print_clls((const AVFrameSideData **)set.sd, set.nb_sd);
+
+    {
+        AVFrameSideData *sd = av_frame_side_data_new(
+            &set.sd, &set.nb_sd, AV_FRAME_DATA_CONTENT_LIGHT_LEVEL,
+            sizeof(AVContentLightMetadata),
+            AV_FRAME_SIDE_DATA_FLAG_UNIQUE);
+
+        av_assert0(sd);
+
+        ((AVContentLightMetadata *)sd->data)->MaxCLL = 1337;
+    }
+
+    puts("\nFinal state after a single 'no-duplicates' addition:");
+    print_clls((const AVFrameSideData **)set.sd, set.nb_sd);
+
+    av_frame_side_data_free(&set.sd, &set.nb_sd);
+
+    return 0;
+}

tests/fate/libavutil.mak

@@ -148,6 +148,10 @@ FATE_LIBAVUTIL += fate-sha512
 fate-sha512: libavutil/tests/sha512$(EXESUF)
 fate-sha512: CMD = run libavutil/tests/sha512$(EXESUF)
 
+FATE_LIBAVUTIL += fate-side_data_array
+fate-side_data_array: libavutil/tests/side_data_array$(EXESUF)
+fate-side_data_array: CMD = run libavutil/tests/side_data_array$(EXESUF)
+
 FATE_LIBAVUTIL += fate-tree
 fate-tree: libavutil/tests/tree$(EXESUF)
 fate-tree: CMD = run libavutil/tests/tree$(EXESUF)

tests/ref/fate/side_data_array

@@ -0,0 +1,14 @@
+Initial addition results with duplicates:
+sd 0, Ambient viewing environment
+sd 1, Content light level metadata: MaxCLL: 1
+sd 2, Content light level metadata: MaxCLL: 2
+sd 3, Content light level metadata: MaxCLL: 3
+sd 4, Spherical Mapping
+sd 5, Content light level metadata: MaxCLL: 4
+sd 6, Content light level metadata: MaxCLL: 5
+sd 7, Content light level metadata: MaxCLL: 6
+
+Final state after a single 'no-duplicates' addition:
+sd 0, Ambient viewing environment
+sd 1, Spherical Mapping
+sd 2, Content light level metadata: MaxCLL: 1337