asfdec: do not fall back to binary/generic search

asf_read_seek() inside the asf demuxer already does the
right thing, it tries the index and if that fails it uses
binary search. If binary search is called from outside of asfdec.c
it will fail because the asf code cannot clean up after itself.
Therefore introduce AVFMT_NOBINSEARCH that prevents the seek
code to fallback to binary search and AVFMT_NOGENSEARCH that
prevents the seek code to fallback to generic search.

libavformat/asfdec.c

@@ -1299,4 +1299,5 @@ AVInputFormat ff_asf_demuxer = {
     asf_read_close,
     asf_read_seek,
     asf_read_pts,
+    .flags = AVFMT_NOBINSEARCH | AVFMT_NOGENSEARCH,
 };

libavformat/avformat.h

@@ -258,6 +258,8 @@ typedef struct AVFormatParameters {
 #define AVFMT_VARIABLE_FPS  0x0400 /**< Format allows variable fps. */
 #define AVFMT_NODIMENSIONS  0x0800 /**< Format does not need width/height */
 #define AVFMT_NOSTREAMS     0x1000 /**< Format does not require any streams */
+#define AVFMT_NOBINSEARCH   0x2000 /**< Format does not allow to fallback to binary search via read_timestamp */
+#define AVFMT_NOGENSEARCH   0x4000 /**< Format does not allow to fallback to generic search */
 
 typedef struct AVOutputFormat {
     const char *name;

libavformat/utils.c

@@ -1713,10 +1713,12 @@ int av_seek_frame(AVFormatContext *s, int stream_index, int64_t timestamp, int f
         return 0;
     }
 
-    if(s->iformat->read_timestamp)
+    if(s->iformat->read_timestamp && !(s->iformat->flags & AVFMT_NOBINSEARCH))
         return av_seek_frame_binary(s, stream_index, timestamp, flags);
-    else
+    else if (!(s->iformat->flags & AVFMT_NOGENSEARCH))
         return av_seek_frame_generic(s, stream_index, timestamp, flags);
+    else
+        return -1;
 }
 
 int avformat_seek_file(AVFormatContext *s, int stream_index, int64_t min_ts, int64_t ts, int64_t max_ts, int flags)