demux: export video rotation parameter

Now the rotation hint is propagated everywhere. It just isn't used
anywhere yet.

demux/demux_lavf.c

@@ -478,6 +478,14 @@ static void handle_stream(demuxer_t *demuxer, int i)
                     / (float)(codec->height * codec->sample_aspect_ratio.den);
         sh_video->i_bps = codec->bit_rate / 8;
 
+        AVDictionaryEntry *rot = av_dict_get(st->metadata, "rotate", NULL, 0);
+        if (rot && rot->value) {
+            char *end = NULL;
+            long int r = strtol(rot->value, &end, 10);
+            if (end && !end[0])
+                sh_video->rotate = ((r % 360) + 360) % 360;
+        }
+
         // This also applies to vfw-muxed mkv, but we can't detect these easily.
         sh_video->avi_dts = matches_avinputformat_name(priv, "avi");
 

demux/stheader.h

@@ -81,6 +81,7 @@ typedef struct sh_video {
     float aspect;         // aspect ratio stored in the file (for prescaling)
     int i_bps;            // == bitrate  (compressed bytes/sec)
     int disp_w, disp_h;   // display size
+    int rotate;           // intended display rotation, in degrees, [0, 359]
     MP_BITMAPINFOHEADER *bih;
 } sh_video_t;
 

video/decode/vd_lavc.c

@@ -444,6 +444,7 @@ static void update_image_params(struct dec_video *vd, AVFrame *frame,
         .colorlevels = avcol_range_to_mp_csp_levels(ctx->avctx->color_range),
         .chroma_location =
             avchroma_location_to_mp(ctx->avctx->chroma_sample_location),
+        .rotate = vd->header->video->rotate,
     };
 }