avconv: reset input_ts_offset between files.

Signed-off-by: Alex Converse <alex.converse@gmail.com>

avconv.c

@@ -3065,6 +3065,7 @@ static int opt_input_file(const char *opt, const char *filename)
     audio_channels    = 0;
     audio_sample_fmt  = AV_SAMPLE_FMT_NONE;
     av_dict_free(&ts_scale);
+    input_ts_offset = 0;
 
     for (i = 0; i < orig_nb_streams; i++)
         av_dict_free(&opts[i]);

doc/avconv.texi

@@ -144,7 +144,6 @@ slower, but more accurate.
 @item -itsoffset @var{offset}
 Set the input time offset in seconds.
 @code{[-]hh:mm:ss[.xxx]} syntax is also supported.
-This option affects all the input files that follow it.
 The offset is added to the timestamps of the input files.
 Specifying a positive offset means that the corresponding
 streams are delayed by 'offset' seconds.