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

libavutil/frame.c

@@ -98,6 +98,23 @@ static void remove_side_data(AVFrameSideData ***sd, int *nb_side_data,
     }
 }
 
+static void remove_side_data_by_entry(AVFrameSideData ***sd, int *nb_sd,
+                                      const AVFrameSideData *target)
+{
+    for (int i = *nb_sd - 1; i >= 0; i--) {
+        AVFrameSideData *entry = ((*sd)[i]);
+        if (entry != target)
+            continue;
+
+        free_side_data(&entry);
+
+        ((*sd)[i]) = ((*sd)[*nb_sd - 1]);
+        (*nb_sd)--;
+
+        return;
+    }
+}
+
 AVFrame *av_frame_alloc(void)
 {
     AVFrame *frame = av_malloc(sizeof(*frame));
@@ -764,6 +781,38 @@ AVFrameSideData *av_frame_side_data_new(AVFrameSideData ***sd, int *nb_sd,
     return ret;
 }
 
+int av_frame_side_data_clone(AVFrameSideData ***sd, int *nb_sd,
+                             const AVFrameSideData *src, unsigned int flags)
+{
+    AVBufferRef     *buf    = NULL;
+    AVFrameSideData *sd_dst = NULL;
+    int              ret    = AVERROR_BUG;
+
+    if (!sd || !src || !nb_sd || (*nb_sd && !*sd))
+        return AVERROR(EINVAL);
+
+    buf = av_buffer_ref(src->buf);
+    if (!buf)
+        return AVERROR(ENOMEM);
+
+    if (flags & AV_FRAME_SIDE_DATA_FLAG_UNIQUE)
+        remove_side_data(sd, nb_sd, src->type);
+
+    sd_dst = add_side_data_from_buf(sd, nb_sd, src->type, buf);
+    if (!sd_dst) {
+        av_buffer_unref(&buf);
+        return AVERROR(ENOMEM);
+    }
+
+    ret = av_dict_copy(&sd_dst->metadata, src->metadata, 0);
+    if (ret < 0) {
+        remove_side_data_by_entry(sd, nb_sd, sd_dst);
+        return ret;
+    }
+
+    return 0;
+}
+
 AVFrameSideData *av_frame_get_side_data(const AVFrame *frame,
                                         enum AVFrameSideDataType type)
 {

libavutil/frame.h

@@ -1021,6 +1021,26 @@ AVFrameSideData *av_frame_side_data_new(AVFrameSideData ***sd, int *nb_sd,
                                         enum AVFrameSideDataType type,
                                         size_t size, unsigned int flags);
 
+/**
+ * Add a new side data entry to an array based on existing side data, taking
+ * a reference towards the contained AVBufferRef.
+ *
+ * @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 src   side data to be cloned, with a new reference utilized
+ *              for the buffer.
+ * @param flags Some combination of AV_FRAME_SIDE_DATA_FLAG_* flags, or 0.
+ *
+ * @return negative error code on failure, >=0 on success. In case of
+ *         AV_FRAME_SIDE_DATA_FLAG_UNIQUE being set, entries of matching
+ *         AVFrameSideDataType will be removed before the addition is
+ *         attempted.
+ */
+int av_frame_side_data_clone(AVFrameSideData ***sd, int *nb_sd,
+                             const AVFrameSideData *src, unsigned int flags);
+
 /**
  * @}
  */