allow enable_file_write_buffering to alternatively allow you to set the exact…

allow enable_file_write_buffering to alternatively allow you to set the exact size of the pre buffer

src/switch_ivr_async.c

@@ -1639,10 +1639,19 @@ SWITCH_DECLARE(switch_status_t) switch_ivr_record_session(switch_core_session_t
 
 	fh->channels = channels;
 
-	vval = switch_channel_get_variable(channel, "enable_file_write_buffering");
-	if (!vval || switch_true(vval)) {
+	if ((vval = switch_channel_get_variable(channel, "enable_file_write_buffering"))) {
+		int tmp = atoi(vval);
+		
+		if (tmp > 0) {
+			fh->pre_buffer_datalen = tmp;
+		} else if (switch_true(vval)) {
+			fh->pre_buffer_datalen = SWITCH_DEFAULT_FILE_BUFFER_LEN;
+		}
+
+	} else {
 		fh->pre_buffer_datalen = SWITCH_DEFAULT_FILE_BUFFER_LEN;
 	}
+
 	
 	if (!switch_is_file_path(file)) {
 		char *tfile = NULL;