ffmpeg: Deprecate display rotation override with a metadata key

Now that we have proper options for defining display matrix
overrides, this should no longer be required.

fftools does not have its own versioning, so for now the define is
just set to 1 and disables the functionality if set to zero.

fftools/ffmpeg.c

@@ -2713,12 +2713,14 @@ static int init_output_stream_streamcopy(OutputStream *ost)
         }
     }
 
+#if FFMPEG_ROTATION_METADATA
     if (ost->rotate_overridden) {
         uint8_t *sd = av_stream_new_side_data(ost->st, AV_PKT_DATA_DISPLAYMATRIX,
                                               sizeof(int32_t) * 9);
         if (sd)
             av_display_rotation_set((int32_t *)sd, -ost->rotate_override_value);
     }
+#endif
 
     switch (par->codec_type) {
     case AVMEDIA_TYPE_AUDIO:

fftools/ffmpeg.h

@@ -53,6 +53,7 @@
 #define FFMPEG_OPT_PSNR 1
 #define FFMPEG_OPT_MAP_CHANNEL 1
 #define FFMPEG_OPT_MAP_SYNC 1
+#define FFMPEG_ROTATION_METADATA 1
 
 enum VideoSyncMethod {
     VSYNC_AUTO = -1,
@@ -532,11 +533,15 @@ typedef struct OutputStream {
     int is_cfr;
     int force_fps;
     int top_field_first;
+#if FFMPEG_ROTATION_METADATA
     int rotate_overridden;
+#endif
     int autoscale;
     int bitexact;
     int bits_per_raw_sample;
+#if FFMPEG_ROTATION_METADATA
     double rotate_override_value;
+#endif
 
     AVRational frame_aspect_ratio;
 

fftools/ffmpeg_mux_init.c

@@ -1321,6 +1321,7 @@ static void of_add_metadata(OutputFile *of, AVFormatContext *oc,
             for (int j = 0; j < oc->nb_streams; j++) {
                 OutputStream *ost = of->streams[j];
                 if ((ret = check_stream_specifier(oc, oc->streams[j], stream_spec)) > 0) {
+#if FFMPEG_ROTATION_METADATA
                     if (!strcmp(o->metadata[i].u.str, "rotate")) {
                         char *tail;
                         double theta = av_strtod(val, &tail);
@@ -1328,9 +1329,18 @@ static void of_add_metadata(OutputFile *of, AVFormatContext *oc,
                             ost->rotate_overridden = 1;
                             ost->rotate_override_value = theta;
                         }
+
+                        av_log(NULL, AV_LOG_WARNING,
+                               "Conversion of a 'rotate' metadata key to a "
+                               "proper display matrix rotation is deprecated. "
+                               "See -display_rotation for setting rotation "
+                               "instead.");
                     } else {
+#endif
                         av_dict_set(&oc->streams[j]->metadata, o->metadata[i].u.str, *val ? val : NULL, 0);
+#if FFMPEG_ROTATION_METADATA
                     }
+#endif
                 } else if (ret < 0)
                     exit_program(1);
             }