Make it possible for a log context to keep track of its parent context.

This is usefull to keep track and display relations where things are a
bit more complex (like AVProtocols or demuxers used by demuxers and such)

Originally committed as revision 23199 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavutil/avutil.h

@@ -41,7 +41,7 @@
 
 #define LIBAVUTIL_VERSION_MAJOR 50
 #define LIBAVUTIL_VERSION_MINOR 15
-#define LIBAVUTIL_VERSION_MICRO  2
+#define LIBAVUTIL_VERSION_MICRO  3
 
 #define LIBAVUTIL_VERSION_INT   AV_VERSION_INT(LIBAVUTIL_VERSION_MAJOR, \
                                                LIBAVUTIL_VERSION_MINOR, \

libavutil/log.h

@@ -62,6 +62,14 @@ typedef struct {
      * 0 means there is no such variable
      */
     int log_level_offset_offset;
+
+    /**
+     * Offset in the structure where a pointer to the parent context for loging is stored.
+     * for example a decoder that uses eval.c could pass its AVCodecContext to eval as such
+     * parent context. And a av_log() implementation could then display the parent context
+     * can be NULL of course
+     */
+    int parent_log_context_offset;
 } AVClass;
 
 /* av_log API */