vf_lavfi: copy AVFrame metadata into vf_lavfi priv

store it as mp_tas and add VFCTRL_GET_METADATA to access it from elsewhere

Signed-off-by: wm4 <wm4@nowhere>

old-configure test by wm4.

old-configure

@@ -2744,6 +2744,17 @@ fi
 echores "$_avcodec_has_replaygain_side_data"
 
 
+echocheck "libavutil AVFrame metadata"
+_avutil_has_avframe_metadata=no
+statement_check libavutil/frame.h 'av_frame_get_metadata(NULL)' && _avutil_has_avframe_metadata=yes
+if test "$_avutil_has_avframe_metadata" = yes ; then
+  def_avutil_has_avframe_metadata='#define HAVE_AVFRAME_METADATA 1'
+else
+  def_avutil_has_avframe_metadata='#define HAVE_AVFRAME_METADATA 0'
+fi
+echores "$_avutil_has_avframe_metadata"
+
+
 echocheck "libavutil QP API"
 _avutil_has_qp_api=no
 statement_check libavutil/frame.h 'av_frame_get_qp_table(NULL, NULL, NULL)' && _avutil_has_qp_api=yes
@@ -3373,6 +3384,7 @@ $def_avutil_has_qp_api
 $def_avcodec_has_chroma_pos_api
 $def_avcodec_has_metadata_update_side_data
 $def_avcodec_has_replaygain_side_data
+$def_avutil_has_avframe_metadata
 $def_libpostproc
 $def_libavdevice
 $def_libavfilter

video/filter/vf.h

@@ -120,6 +120,7 @@ enum vf_ctrl {
     VFCTRL_INIT_OSD,         // Filter OSD renderer present?
     VFCTRL_SET_DEINTERLACE,  // Set deinterlacing status
     VFCTRL_GET_DEINTERLACE,  // Get deinterlacing status
+    VFCTRL_GET_METADATA,     // Get frame metadata from lavfi filters (e.g., cropdetect)
     /* Hack to make the OSD state object available to vf_sub which
      * access OSD/subtitle state outside of normal OSD draw time. */
     VFCTRL_SET_OSD_OBJ,

video/filter/vf_lavfi.c

@@ -39,6 +39,7 @@
 #include "common/msg.h"
 #include "options/m_option.h"
 #include "common/av_opts.h"
+#include "common/tags.h"
 
 #include "video/img_format.h"
 #include "video/mp_image.h"
@@ -66,6 +67,8 @@ struct vf_priv_s {
     AVRational timebase_out;
     AVRational par_in;
 
+    struct mp_tags* metadata;
+
     // for the lw wrapper
     void *old_priv;
     void (*lw_recreate_cb)(struct vf_instance *vf);
@@ -266,6 +269,17 @@ static struct mp_image *av_to_mp(struct vf_instance *vf, AVFrame *av_frame)
     return img;
 }
 
+static void get_metadata_from_av_frame(struct vf_instance *vf, AVFrame *frame)
+{
+#if HAVE_AVFRAME_METADATA
+  struct vf_priv_s *p = vf->priv;
+  if (!p->metadata)
+      p->metadata = talloc_zero(p, struct mp_tags);
+
+  mp_tags_copy_from_av_dictionary(p->metadata, av_frame_get_metadata(frame));
+#endif
+}
+
 static int filter_ext(struct vf_instance *vf, struct mp_image *mpi)
 {
     struct vf_priv_s *p = vf->priv;
@@ -287,6 +301,8 @@ static int filter_ext(struct vf_instance *vf, struct mp_image *mpi)
             av_frame_free(&frame);
             break;
         }
+        get_metadata_from_av_frame(vf,frame);
+
         vf_add_output_frame(vf, av_to_mp(vf, frame));
     }
 
@@ -307,6 +323,10 @@ static int control(vf_instance_t *vf, int request, void *data)
     case VFCTRL_SEEK_RESET:
         reset(vf);
         return CONTROL_OK;
+    case VFCTRL_GET_METADATA:{
+        *(struct mp_tags*) data = *vf->priv->metadata;
+        return CONTROL_OK;
+    }
     }
     return CONTROL_UNKNOWN;
 }

wscript

@@ -396,6 +396,12 @@ Libav libraries ({0}). Aborting.".format(" ".join(libav_pkg_config_checks))
         'func': check_statement('libavcodec/avcodec.h',
                                 'enum AVPacketSideDataType type = AV_PKT_DATA_REPLAYGAIN',
                                 use='libav')
+    },{
+        'name': 'avframe-metadata',
+        'desc': 'libavutil AVFrame metadata',
+        'func': check_statement('libavutil/frame.h',
+                                'av_frame_get_metadata(NULL)',
+                                use='libav')
     }
 ]