- av_log(NULL, AV_LOG_FATAL, "Stream map '%s' matches no streams.\n", arg);
- exit_program(1);
+ if (allow_unused) {
+ av_log(NULL, AV_LOG_VERBOSE, "Stream map '%s' matches no streams; ignoring.\n", arg);
+ } else {
+ av_log(NULL, AV_LOG_FATAL, "Stream map '%s' matches no streams.\n"
+ "To ignore this, add a trailing '?' to the map.\n", arg);
+ exit_program(1);
+ }