ustreamer: add janus-gateway webrtc support

Co-authored-by: Nick Cao <nickcao@nichi.co>

pkgs/applications/video/ustreamer/default.nix

@@ -1,5 +1,19 @@
-{ lib, stdenv, fetchFromGitHub, libbsd, libevent, libjpeg, libdrm, pkg-config }:
-
+{ lib
+, stdenv
+, fetchFromGitHub
+, libbsd
+, libevent
+, libjpeg
+, libdrm
+, pkg-config
+, janus-gateway
+, glib
+, alsa-lib
+, speex
+, jansson
+, libopus
+, withJanus ? true
+}:
 stdenv.mkDerivation rec {
   pname = "ustreamer";
   version = "6.12";
@@ -11,13 +25,30 @@ stdenv.mkDerivation rec {
     hash = "sha256-iaCgPHgklk7tbhJhQmyjKggb1bMWBD+Zurgfk9sCQ3E=";
   };
 
-  buildInputs = [ libbsd libevent libjpeg libdrm ];
+  buildInputs = [
+    libbsd
+    libevent
+    libjpeg
+    libdrm
+  ] ++ lib.optionals withJanus [
+    janus-gateway
+    glib
+    alsa-lib
+    jansson
+    speex
+    libopus
+  ];
 
   nativeBuildInputs = [ pkg-config ];
 
   makeFlags = [
     "PREFIX=${placeholder "out"}"
     "WITH_V4P=1"
+  ] ++ lib.optionals withJanus [
+    "WITH_JANUS=1"
+    # Workaround issues with Janus C Headers
+    # https://github.com/pikvm/ustreamer/blob/793f24c4/docs/h264.md#fixing-janus-c-headers
+    "CFLAGS=-I${lib.getDev janus-gateway}/include/janus"
   ];
 
   enableParallelBuilding = true;