From 493f54ada083b4d6c8f14f02607224fe258c211c Mon Sep 17 00:00:00 2001
From: Michael Niedermayer <michaelni@gmx.at>
Date: Mon, 15 Mar 2010 22:54:22 +0000
Subject: [PATCH] Add AVSEEK_FORCE flag to indicate that the code should
 attempt to seek by any means.

Originally committed as revision 22557 to svn://svn.ffmpeg.org/ffmpeg/trunk
---
 libavformat/avio.c    | 2 +-
 libavformat/avio.h    | 8 ++++++++
 libavformat/aviobuf.c | 5 +++--
 3 files changed, 12 insertions(+), 3 deletions(-)

diff --git a/libavformat/avio.c b/libavformat/avio.c
index 1371722cfc..af9e049142 100644
--- a/libavformat/avio.c
+++ b/libavformat/avio.c
@@ -202,7 +202,7 @@ int64_t url_seek(URLContext *h, int64_t pos, int whence)
 
     if (!h->prot->url_seek)
         return AVERROR(EPIPE);
-    ret = h->prot->url_seek(h, pos, whence);
+    ret = h->prot->url_seek(h, pos, whence & ~AVSEEK_FORCE);
     return ret;
 }
 
diff --git a/libavformat/avio.h b/libavformat/avio.h
index 80ec48f725..8145f92861 100644
--- a/libavformat/avio.h
+++ b/libavformat/avio.h
@@ -192,6 +192,14 @@ int64_t av_url_read_seek(URLContext *h, int stream_index,
  */
 #define AVSEEK_SIZE 0x10000
 
+/**
+ * Oring this flag as into the "whence" parameter to a seek function causes it to
+ * seek by any means (like reopening and linear reading) or other normally unreasonble
+ * means that can be extreemly slow.
+ * This may be ignored by the seek code.
+ */
+#define AVSEEK_FORCE 0x20000
+
 typedef struct URLProtocol {
     const char *name;
     int (*url_open)(URLContext *h, const char *url, int flags);
diff --git a/libavformat/aviobuf.c b/libavformat/aviobuf.c
index 1cbed1d5e7..29d0715357 100644
--- a/libavformat/aviobuf.c
+++ b/libavformat/aviobuf.c
@@ -150,8 +150,9 @@ int64_t url_fseek(ByteIOContext *s, int64_t offset, int whence)
         offset1 >= 0 && offset1 <= (s->buf_end - s->buffer)) {
         /* can do the seek inside the buffer */
         s->buf_ptr = s->buffer + offset1;
-    } else if(s->is_streamed && !s->write_flag &&
-              offset1 >= 0 && offset1 < (s->buf_end - s->buffer) + (1<<16)){
+    } else if(s->is_streamed && !s->write_flag && offset1 >= 0 &&
+              (   offset1 < (s->buf_end - s->buffer) + (1<<16)
+               || (whence & AVSEEK_FORCE))){
         while(s->pos < offset && !s->eof_reached)
             fill_buffer(s);
         if (s->eof_reached)