ffplay: support rotated video.

with -f lavfi -i testsrc=s=hd1080 as source:
  rotate=90*PI/180  vs transpose=clock:   42fps -> 64fps
  rotate=180*PI/180 vs vflip,hflip:       75fps -> 77fps
  rotate=270*PI/180 vs transpose=cclock:  43fps -> 63fps

configure

@@ -2565,7 +2565,7 @@ ffmpeg_select="aformat_filter anull_filter atrim_filter format_filter
                setpts_filter trim_filter"
 ffplay_deps="avcodec avformat swscale swresample sdl"
 ffplay_libs='$sdl_libs'
-ffplay_select="rdft crop_filter"
+ffplay_select="rdft crop_filter transpose_filter hflip_filter vflip_filter rotate_filter"
 ffprobe_deps="avcodec avformat"
 ffserver_deps="avformat fork sarestart"
 ffserver_select="ffm_muxer rtp_protocol rtsp_demuxer"

doc/ffplay.texi

@@ -162,6 +162,10 @@ Force a specific video decoder.
 
 @item -scodec @var{codec_name}
 Force a specific subtitle decoder.
+
+@item -autorotate
+Automatically rotate the video according to presentation metadata. Set by
+default, use -noautorotate to disable.
 @end table
 
 @section While playing

ffplay.c

@@ -329,6 +329,7 @@ static const char **vfilters_list = NULL;
 static int nb_vfilters = 0;
 static char *afilters = NULL;
 #endif
+static int autorotate = 1;
 
 /* current context */
 static int is_full_screen;
@@ -1784,7 +1785,7 @@ static int configure_video_filters(AVFilterGraph *graph, VideoState *is, const c
     char sws_flags_str[128];
     char buffersrc_args[256];
     int ret;
-    AVFilterContext *filt_src = NULL, *filt_out = NULL, *filt_crop;
+    AVFilterContext *filt_src = NULL, *filt_out = NULL, *last_filter = NULL;
     AVCodecContext *codec = is->video_st->codec;
     AVRational fr = av_guess_frame_rate(is->ic, is->video_st, NULL);
 
@@ -1815,16 +1816,49 @@ static int configure_video_filters(AVFilterGraph *graph, VideoState *is, const c
     if ((ret = av_opt_set_int_list(filt_out, "pix_fmts", pix_fmts,  AV_PIX_FMT_NONE, AV_OPT_SEARCH_CHILDREN)) < 0)
         goto fail;
 
+    last_filter = filt_out;
+
+/* Note: this macro adds a filter before the lastly added filter, so the
+ * processing order of the filters is in reverse */
+#define INSERT_FILT(name, arg) do {                                         \
+    AVFilterContext *filt_ctx;                                              \
+                                                                            \
+    ret = avfilter_graph_create_filter(&filt_ctx,                           \
+                                       avfilter_get_by_name(name),          \
+                                       "ffplay_" name, arg, NULL, graph);   \
+    if (ret < 0)                                                            \
+        goto fail;                                                          \
+                                                                            \
+    ret = avfilter_link(filt_ctx, 0, last_filter, 0);                       \
+    if (ret < 0)                                                            \
+        goto fail;                                                          \
+                                                                            \
+    last_filter = filt_ctx;                                                 \
+} while (0)
+
     /* SDL YUV code is not handling odd width/height for some driver
      * combinations, therefore we crop the picture to an even width/height. */
-    if ((ret = avfilter_graph_create_filter(&filt_crop,
-                                            avfilter_get_by_name("crop"),
-                                            "ffplay_crop", "floor(in_w/2)*2:floor(in_h/2)*2", NULL, graph)) < 0)
-        goto fail;
-    if ((ret = avfilter_link(filt_crop, 0, filt_out, 0)) < 0)
-        goto fail;
+    INSERT_FILT("crop", "floor(in_w/2)*2:floor(in_h/2)*2");
+
+    if (autorotate) {
+        AVDictionaryEntry *rotate_tag = av_dict_get(is->video_st->metadata, "rotate", NULL, 0);
+        if (rotate_tag && *rotate_tag->value && strcmp(rotate_tag->value, "0")) {
+            if (!strcmp(rotate_tag->value, "90")) {
+                INSERT_FILT("transpose", "clock");
+            } else if (!strcmp(rotate_tag->value, "180")) {
+                INSERT_FILT("hflip", NULL);
+                INSERT_FILT("vflip", NULL);
+            } else if (!strcmp(rotate_tag->value, "270")) {
+                INSERT_FILT("transpose", "cclock");
+            } else {
+                char rotate_buf[64];
+                snprintf(rotate_buf, sizeof(rotate_buf), "%s*PI/180", rotate_tag->value);
+                INSERT_FILT("rotate", rotate_buf);
+            }
+        }
+    }
 
-    if ((ret = configure_filtergraph(graph, vfilters, filt_src, filt_crop)) < 0)
+    if ((ret = configure_filtergraph(graph, vfilters, filt_src, last_filter)) < 0)
         goto fail;
 
     is->in_video_filter  = filt_src;
@@ -3564,6 +3598,7 @@ static const OptionDef options[] = {
     { "acodec", HAS_ARG | OPT_STRING | OPT_EXPERT, {    &audio_codec_name }, "force audio decoder",    "decoder_name" },
     { "scodec", HAS_ARG | OPT_STRING | OPT_EXPERT, { &subtitle_codec_name }, "force subtitle decoder", "decoder_name" },
     { "vcodec", HAS_ARG | OPT_STRING | OPT_EXPERT, {    &video_codec_name }, "force video decoder",    "decoder_name" },
+    { "autorotate", OPT_BOOL, { &autorotate }, "automatically rotate video", "" },
     { NULL, },
 };