Add AVOption support for muxers.

Patch by Anssi Hannula, anssi d hannula a iki d fi

Originally committed as revision 26195 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavformat/avformat.h

@@ -22,7 +22,7 @@
 #define AVFORMAT_AVFORMAT_H
 
 #define LIBAVFORMAT_VERSION_MAJOR 52
-#define LIBAVFORMAT_VERSION_MINOR 91
+#define LIBAVFORMAT_VERSION_MINOR 92
 #define LIBAVFORMAT_VERSION_MICRO  0
 
 #define LIBAVFORMAT_VERSION_INT AV_VERSION_INT(LIBAVFORMAT_VERSION_MAJOR, \
@@ -368,6 +368,8 @@ typedef struct AVOutputFormat {
     const AVMetadataConv *metadata_conv;
 #endif
 
+    const AVClass *priv_class; ///< AVClass for the private context
+
     /* private fields */
     struct AVOutputFormat *next;
 } AVOutputFormat;

libavformat/utils.c

@@ -2720,6 +2720,10 @@ int av_set_parameters(AVFormatContext *s, AVFormatParameters *ap)
         s->priv_data = av_mallocz(s->oformat->priv_data_size);
         if (!s->priv_data)
             return AVERROR(ENOMEM);
+        if (s->oformat->priv_class) {
+            *(const AVClass**)s->priv_data= s->oformat->priv_class;
+            av_opt_set_defaults(s->priv_data);
+        }
     } else
         s->priv_data = NULL;