if (snapshot_prefix) {
if (snapshot_prefix[0] == '-' && snapshot_prefix[1] == 0) {
- src->writePNM(std::cout);
+ char comment[21];
+ snprintf(comment, sizeof comment, "%u", call_no);
+ src->writePNM(std::cout, comment);
} else {
char filename[PATH_MAX];
snprintf(filename, sizeof filename, "%s%010u.png", snapshot_prefix, call_no);