Use a suitable timebase in VQF demuxer

Originally committed as revision 22868 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavformat/vqf.c

@@ -189,6 +189,7 @@ static int vqf_read_header(AVFormatContext *s, AVFormatParameters *ap)
         return -1;
     }
     c->frame_bit_len = st->codec->bit_rate*size/st->codec->sample_rate;
+    av_set_pts_info(st, 64, 1, st->codec->sample_rate);
 
     return 0;
 }