saner default value for convergence_duration

Originally committed as revision 24002 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/parser.c

@@ -74,7 +74,7 @@ AVCodecParserContext *av_parser_init(int codec_id)
     s->fetch_timestamp=1;
     s->pict_type = FF_I_TYPE;
     s->key_frame = -1;
-    s->convergence_duration = AV_NOPTS_VALUE;
+    s->convergence_duration = 0;
     s->dts_sync_point       = INT_MIN;
     s->dts_ref_dts_delta    = INT_MIN;
     s->pts_dts_delta        = INT_MIN;