Add an OpenH264 decoder wrapper

While it is less featureful (and slower) than the built-in H264
decoder, one could potentially want to use it to take advantage
of the cisco patent license offer.

Signed-off-by: Martin Storsjö <martin@martin.st>

libavcodec/libopenh264.h

@@ -0,0 +1,39 @@
+/*
+ * OpenH264 shared utils
+ * Copyright (C) 2014 Martin Storsjo
+ *
+ * This file is part of Libav.
+ *
+ * Libav is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * Libav is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with Libav; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#ifndef AVCODEC_LIBOPENH264_H
+#define AVCODEC_LIBOPENH264_H
+
+#define OPENH264_VER_AT_LEAST(maj, min) \
+    ((OPENH264_MAJOR  > (maj)) || \
+     (OPENH264_MAJOR == (maj) && OPENH264_MINOR >= (min)))
+
+// This function will be provided to the libopenh264 library.  The function will be called
+// when libopenh264 wants to log a message (error, warning, info, etc.).  The signature for
+// this function (defined in .../codec/api/svc/codec_api.h) is:
+//
+//        typedef void (*WelsTraceCallback) (void* ctx, int level, const char* string);
+
+void ff_libopenh264_trace_callback(void *ctx, int level, const char *msg);
+
+int ff_libopenh264_check_version(void *logctx);
+
+#endif /* AVCODEC_LIBOPENH264_H */