From d9dec6893a0c66870d08bdfbee5b0ad9fcb66674 Mon Sep 17 00:00:00 2001
From: "Reynaldo H. Verdejo Pinochet" <reynaldo@osg.samsung.com>
Date: Mon, 23 Nov 2015 23:45:38 -0800
Subject: [PATCH] Require libav provided by FFmpeg at build-time

Libav-incompatible changes were introduced to support
FFmpeg and we can no longer properly support Libav.

FFmpeg micro versions for libav* start at 100 (this was
done to differentiate from Libav builds). We use this
to bail at configure time if the system libav* libraries
are not provided by FFmpeg.

https://bugzilla.gnome.org/show_bug.cgi?id=758183
---
 configure.ac | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/configure.ac b/configure.ac
index 89a3318..84cf31a 100644
--- a/configure.ac
+++ b/configure.ac
@@ -271,6 +271,20 @@ if test "x$with_system_libav" = "xyes"; then
   AC_DEFINE([LIBAV_SOURCE], ["system install"], [Describes where the Libav libraries come from.])
   HAVE_LIBAV_UNINSTALLED=0
   AC_MSG_NOTICE([Using system-installed libav code])
+  AC_MSG_CHECKING([whether libav is provided by FFmpeg])
+  AC_LINK_IFELSE([AC_LANG_PROGRAM([[
+    #include <libavcodec/avcodec.h>
+    ]],[[
+        #if LIBAVCODEC_VERSION_MICRO >= 100
+        /* FFmpeg uses 100+ as its micro version */
+        #else
+        #error libav provider should be FFmpeg
+        #endif
+    ]])], [is_ffmpeg=yes], [is_ffmpeg=no])
+  AC_MSG_RESULT([$is_ffmpeg])
+  if test "$is_ffmpeg" = no; then
+    AC_MSG_ERROR([Uncompatible libavcodec found])
+  fi
 else
   AC_MSG_NOTICE([Using local Libav snapshot])
   
-- 
2.7.4