I have uploaded a NMU to fix this. debdiff attached.
diff -Nru flvstreamer-2.1c1/debian/changelog flvstreamer-2.1c1/debian/changelog
--- flvstreamer-2.1c1/debian/changelog 2022-11-29 02:15:49.000000000 +0100
+++ flvstreamer-2.1c1/debian/changelog 2022-11-29 02:11:49.000000000 +0100
@@ -1,3 +1,13 @@
+flvstreamer (2.1c1-1.1) unstable; urgency=medium
+
+ * Non-maintainer upload
+ * Convert to 3.0 source format (Closes: #1007545)
+
+ [ Helmut Grohne ]
+ * Fix FTCBFS: Let dh_auto_build pass cross compilers (Closes: #850934)
+
+ -- Bastian Germann <b...@debian.org> Tue, 29 Nov 2022 02:11:49 +0100
+
flvstreamer (2.1c1-1) unstable; urgency=low
* New upstream release
diff -Nru flvstreamer-2.1c1/debian/rules flvstreamer-2.1c1/debian/rules
--- flvstreamer-2.1c1/debian/rules 2022-11-29 02:15:49.000000000 +0100
+++ flvstreamer-2.1c1/debian/rules 2022-11-29 02:11:49.000000000 +0100
@@ -4,7 +4,7 @@
dh $@
override_dh_auto_build:
- $(MAKE) flvstreamer streams
+ dh_auto_build -- flvstreamer streams
override_dh_installdocs:
dh_installdocs README
diff -Nru flvstreamer-2.1c1/debian/source/format
flvstreamer-2.1c1/debian/source/format
--- flvstreamer-2.1c1/debian/source/format 1970-01-01 01:00:00.000000000
+0100
+++ flvstreamer-2.1c1/debian/source/format 2022-11-29 02:11:36.000000000
+0100
@@ -0,0 +1 @@
+3.0 (quilt)
