lavc: add width and height fields to AVFrame

width and height are per-frame properties, setting these values in
AVFrame simplify the operation of extraction of that information,
since avoids the need to check the codec/stream context.

libavcodec/avcodec.h

@@ -1265,6 +1265,13 @@ typedef struct AVFrame {
      * - decoding: Read by user.
      */
     AVRational sample_aspect_ratio;
+
+    /**
+     * width and height of the video frame
+     * - encoding: unused
+     * - decoding: Read by user.
+     */
+    int width, height;
 } AVFrame;
 
 struct AVCodecInternal;

libavcodec/pthread.c

@@ -600,6 +600,8 @@ int ff_thread_decode_frame(AVCodecContext *avctx,
         *got_picture_ptr = p->got_frame;
         picture->pkt_dts = p->avpkt.dts;
         picture->sample_aspect_ratio = avctx->sample_aspect_ratio;
+        picture->width  = avctx->width;
+        picture->height = avctx->height;
 
         /*
          * A later call with avkpt->size == 0 may loop over all threads,

libavcodec/utils.c

@@ -860,6 +860,8 @@ int attribute_align_arg avcodec_decode_video2(AVCodecContext *avctx, AVFrame *pi
                               avpkt);
             picture->pkt_dts= avpkt->dts;
             picture->sample_aspect_ratio = avctx->sample_aspect_ratio;
+            picture->width  = avctx->width;
+            picture->height = avctx->height;
         }
 
         emms_c(); //needed to avoid an emms_c() call before every return;