avformat: add AVInputFormat flag AVFMT_NO_BYTE_SEEK.

This will prevent seeking by bytes for formats that cannot handle this.

doc/APIchanges

@@ -13,6 +13,9 @@ libavutil:   2011-04-18
 
 API changes, most recent first:
 
+2011-xx-xx - xxxxxxx - lavf 53.9.0
+  Add AVFMT_NO_BYTE_SEEK AVInputFormat flag.
+
 2011-10-12 - lavu 51.12.0
   AVOptions API rewrite.
 

libavformat/avformat.h

@@ -274,6 +274,7 @@ typedef struct AVFormatParameters {
 #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 */
+#define AVFMT_NO_BYTE_SEEK  0x8000 /**< Format does not allow seeking by bytes */
 
 typedef struct AVOutputFormat {
     const char *name;
@@ -408,7 +409,7 @@ typedef struct AVInputFormat {
     /**
      * Can use flags: AVFMT_NOFILE, AVFMT_NEEDNUMBER, AVFMT_SHOW_IDS,
      * AVFMT_GENERIC_INDEX, AVFMT_TS_DISCONT, AVFMT_NOBINSEARCH,
-     * AVFMT_NOGENSEARCH.
+     * AVFMT_NOGENSEARCH, AVFMT_NO_BYTE_SEEK.
      */
     int flags;
 

libavformat/utils.c

@@ -1750,6 +1750,8 @@ int av_seek_frame(AVFormatContext *s, int stream_index, int64_t timestamp, int f
     AVStream *st;
 
     if (flags & AVSEEK_FLAG_BYTE) {
+        if (s->iformat->flags & AVFMT_NO_BYTE_SEEK)
+            return -1;
         ff_read_frame_flush(s);
         return seek_frame_byte(s, stream_index, timestamp, flags);
     }

libavformat/version.h

@@ -24,7 +24,7 @@
 #include "libavutil/avutil.h"
 
 #define LIBAVFORMAT_VERSION_MAJOR 53
-#define LIBAVFORMAT_VERSION_MINOR  8
+#define LIBAVFORMAT_VERSION_MINOR  9
 #define LIBAVFORMAT_VERSION_MICRO  0
 
 #define LIBAVFORMAT_VERSION_INT AV_VERSION_INT(LIBAVFORMAT_VERSION_MAJOR, \