+/** @param temporal_reference A string to which we should add two characters per frame;
+ * the first is T or B depending on whether it's top- or bottom-field first,
+ * the second is 3 or 2 depending on whether "repeat_pict" is true or not.
+ * @return true if some video was decoded, otherwise false.
+ */
+bool
+FFmpegExaminer::video_packet (AVCodecContext* context, string& temporal_reference, AVPacket* packet)