do not read probe data if format is specified - match_ext() must be exported

git-svn-id: file:///var/local/repositories/ffmpeg/trunk@1222 9553f0bf-9b14-0410-a0b8-cfaf0461ba5b

libav/utils.c

@@ -54,7 +54,7 @@ void av_register_output_format(AVOutputFormat *format)
     format->next = NULL;
 }
 
-static int match_ext(const char *filename, const char *extensions)
+int match_ext(const char *filename, const char *extensions)
 {
     const char *ext, *p;
     char ext1[32], *q;
@@ -335,10 +335,12 @@ int av_open_input_file(AVFormatContext **ic_ptr, const char *filename,
         if (buf_size > 0) {
             url_setbufsize(&ic->pb, buf_size);
         }
+        if (!fmt) {
             /* read probe data */
             pd->buf_size = get_buffer(&ic->pb, buf, PROBE_BUF_SIZE);
             url_fseek(&ic->pb, 0, SEEK_SET);
         }
+    }
     
     /* guess file format */
     if (!fmt) {