use context in av_log

Originally committed as revision 11668 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavformat/movenc.c

@@ -1465,7 +1465,7 @@ static int mov_write_header(AVFormatContext *s)
             track->timescale = st->codec->time_base.den;
             av_set_pts_info(st, 64, 1, st->codec->time_base.den);
             if (track->mode == MODE_MOV && track->timescale > 100000)
-                av_log(NULL, AV_LOG_WARNING,
+                av_log(s, AV_LOG_WARNING,
                        "WARNING codec timebase is very high. If duration is too long,\n"
                        "file may not be playable by quicktime. Specify a shorter timebase\n"
                        "or choose different container.\n");