diff --git a/libavformat/avio.h b/libavformat/avio.h
index 75912ce..56f0a4d 100644
--- a/libavformat/avio.h
+++ b/libavformat/avio.h
@@ -290,12 +290,6 @@ typedef struct AVIOContext {
      */
     int writeout_count;
 
-    /**
-     * Original buffer size
-     * used internally after probing and ensure seekback to reset the buffer size
-     * This field is internal to libavformat and access from outside is not allowed.
-     */
-    int orig_buffer_size;
 
     /**
      * Threshold to favor readahead over seek.
diff --git a/libavformat/aviobuf.c b/libavformat/aviobuf.c
index e752d0e..108f089 100644
--- a/libavformat/aviobuf.c
+++ b/libavformat/aviobuf.c
@@ -33,7 +33,7 @@
 #include "url.h"
 #include <stdarg.h>
 
-#define IO_BUFFER_SIZE 32768
+#define IO_BUFFER_SIZE 262144
 
 /**
  * Do seeks within this distance ahead of the current buffer by skipping
@@ -90,7 +90,6 @@ int ffio_init_context(AVIOContext *s,
     memset(s, 0, sizeof(AVIOContext));
 
     s->buffer      = buffer;
-    s->orig_buffer_size =
     s->buffer_size = buffer_size;
     s->buf_ptr     = buffer;
     s->buf_ptr_max = buffer;
@@ -570,16 +569,16 @@ static void fill_buffer(AVIOContext *s)
     }
 
     /* make buffer smaller in case it ended up large after probing */
-    if (s->read_packet && s->orig_buffer_size && s->buffer_size > s->orig_buffer_size) {
+    if (s->read_packet && s->buffer_size > max_buffer_size) {
         if (dst == s->buffer && s->buf_ptr != dst) {
-            int ret = ffio_set_buf_size(s, s->orig_buffer_size);
+            int ret = ffio_set_buf_size(s, max_buffer_size);
             if (ret < 0)
                 av_log(s, AV_LOG_WARNING, "Failed to decrease buffer size\n");
 
             s->checksum_ptr = dst = s->buffer;
         }
-        av_assert0(len >= s->orig_buffer_size);
-        len = s->orig_buffer_size;
+        av_assert0(len >= max_buffer_size);
+        len = max_buffer_size;
     }
 
     len = read_packet_wrapper(s, dst, len);
@@ -1087,7 +1086,6 @@ int ffio_set_buf_size(AVIOContext *s, int buf_size)
 
     av_free(s->buffer);
     s->buffer = buffer;
-    s->orig_buffer_size =
     s->buffer_size = buf_size;
     s->buf_ptr = s->buf_ptr_max = buffer;
     url_resetbuf(s, s->write_flag ? AVIO_FLAG_WRITE : AVIO_FLAG_READ);
diff --git a/libavformat/utils.c b/libavformat/utils.c
index c25eab4..02ce5e2 100644
--- a/libavformat/utils.c
+++ b/libavformat/utils.c
@@ -138,6 +138,25 @@ FF_ENABLE_DEPRECATION_WARNINGS
 #endif
 #endif
 
+void *av_fast_realloc(void *ptr, unsigned int *size, size_t min_size)
+{
+    if (min_size < *size)
+        return ptr;
+
+    min_size = FFMAX(17 * min_size / 16 + 32, min_size);
+
+    ptr = av_realloc(ptr, min_size);
+    /* we could set this to the unmodified min_size but this is safer
+     * if the user lost the ptr and uses NULL now
+     */
+    if (!ptr)
+        min_size = 0;
+
+    *size = min_size;
+
+    return ptr;
+}
+
 int64_t av_stream_get_end_pts(const AVStream *st)
 {
     if (st->internal->priv_pts) {