avcodec/avcodec: add helpers to convert between packet and frame side data

They will be used in following commits.

Signed-off-by: James Almer <jamrial@gmail.com>

doc/APIchanges

@@ -2,6 +2,9 @@ The last version increases of all libraries were on 2025-03-28
 
 API changes, most recent first:
 
+2025-10-30 - xxxxxxxxxx - lavc 62.17.100 - packet.h
+  Add av_packet_side_data_from_frame() and av_packet_side_data_to_frame().
+
 2025-10-xx - xxxxxxxxxx - lavu 60.16.100 - pixfmt.h
   Add AVCOL_TRC_EXT_BASE, AVCOL_TRC_V_LOG,
   AVCOL_PRI_EXT_BASE and AVCOL_PRI_V_GAMUT.

libavcodec/avcodec.c

@@ -815,3 +815,53 @@ int avcodec_get_supported_config(const AVCodecContext *avctx, const AVCodec *cod
         return ff_default_get_supported_config(avctx, codec, config, flags, out, out_num);
     }
 }
+
+int av_packet_side_data_from_frame(AVPacketSideData **psd, int *pnb_sd,
+                                   const AVFrameSideData *src, unsigned int flags)
+{
+    AVPacketSideData *sd = NULL;
+
+    for (unsigned j = 0; ff_sd_global_map[j].packet < AV_PKT_DATA_NB; j++) {
+        if (ff_sd_global_map[j].frame != src->type)
+            continue;
+
+        sd = av_packet_side_data_new(psd, pnb_sd, ff_sd_global_map[j].packet,
+                                     src->size, 0);
+
+        if (!sd)
+            return AVERROR(ENOMEM);
+
+        memcpy(sd->data, src->data, src->size);
+        break;
+    }
+
+    if (!sd)
+        return AVERROR(EINVAL);
+
+    return 0;
+}
+
+int av_packet_side_data_to_frame(AVFrameSideData ***psd, int *pnb_sd,
+                                 const AVPacketSideData *src, unsigned int flags)
+{
+    AVFrameSideData *sd = NULL;
+
+    for (unsigned j = 0; ff_sd_global_map[j].packet < AV_PKT_DATA_NB; j++) {
+        if (ff_sd_global_map[j].packet != src->type)
+            continue;
+
+        sd = av_frame_side_data_new(psd, pnb_sd, ff_sd_global_map[j].frame,
+                                    src->size, flags);
+
+        if (!sd)
+            return AVERROR(ENOMEM);
+
+        memcpy(sd->data, src->data, src->size);
+        break;
+    }
+
+    if (!sd)
+        return AVERROR(EINVAL);
+
+    return 0;
+}

libavcodec/packet.h

@@ -489,6 +489,36 @@ void av_packet_side_data_remove(AVPacketSideData *sd, int *nb_sd,
  */
 void av_packet_side_data_free(AVPacketSideData **sd, int *nb_sd);
 
+struct AVFrameSideData;
+
+/**
+ * Add a new packet side data entry to an array based on existing frame
+ * side data, if a matching type exists for packet side data.
+ *
+ * @param flags              Currently unused. Must be 0.
+ * @retval >= 0              Success
+ * @retval AVERROR(EINVAL)   The frame side data type does not have a matching
+ *                           packet side data type.
+ * @retval AVERROR(ENOMEM)   Failed to add a side data entry to the array, or
+ *                           similar.
+ */
+int av_packet_side_data_from_frame(AVPacketSideData **sd, int *nb_sd,
+                                   const struct AVFrameSideData *src, unsigned int flags);
+/**
+ * Add a new frame side data entry to an array based on existing packet
+ * side data, if a matching type exists for frame side data.
+ *
+ * @param flags              Some combination of AV_FRAME_SIDE_DATA_FLAG_* flags,
+ *                           or 0.
+ * @retval >= 0              Success
+ * @retval AVERROR(EINVAL)   The packet side data type does not have a matching
+ *                           frame side data type.
+ * @retval AVERROR(ENOMEM)   Failed to add a side data entry to the array, or
+ *                           similar.
+ */
+int av_packet_side_data_to_frame(struct AVFrameSideData ***sd, int *nb_sd,
+                                 const AVPacketSideData *src, unsigned int flags);
+
 const char *av_packet_side_data_name(enum AVPacketSideDataType type);
 
 /**

libavcodec/version.h

@@ -29,7 +29,7 @@
 
 #include "version_major.h"
 
-#define LIBAVCODEC_VERSION_MINOR  16
+#define LIBAVCODEC_VERSION_MINOR  17
 #define LIBAVCODEC_VERSION_MICRO 100
 
 #define LIBAVCODEC_VERSION_INT  AV_VERSION_INT(LIBAVCODEC_VERSION_MAJOR, \