diff --git a/libavformat/avio_internal.h b/libavformat/avio_internal.h
index f140897c5df1b..df614b22d9d31 100644
--- a/libavformat/avio_internal.h
+++ b/libavformat/avio_internal.h
@@ -71,6 +71,8 @@ uint64_t ffio_read_varlen(AVIOContext *bc);
 /** @warning must be called before any I/O */
 int ffio_set_buf_size(AVIOContext *s, int buf_size);
 
+int ffio_limit(AVIOContext *s, int size);
+
 void ffio_init_checksum(AVIOContext *s,
                         unsigned long (*update_checksum)(unsigned long c, const uint8_t *p, unsigned int len),
                         unsigned long checksum);
diff --git a/libavformat/utils.c b/libavformat/utils.c
index f0df759bf56f5..edcae2fe376e9 100644
--- a/libavformat/utils.c
+++ b/libavformat/utils.c
@@ -264,11 +264,8 @@ AVInputFormat *av_find_input_format(const char *short_name)
     return NULL;
 }
 
-
-int av_get_packet(AVIOContext *s, AVPacket *pkt, int size)
+int ffio_limit(AVIOContext *s, int size)
 {
-    int ret;
-
     if(s->maxsize>=0){
         int64_t remaining= s->maxsize - avio_tell(s);
         if(remaining < size){
@@ -283,6 +280,13 @@ int av_get_packet(AVIOContext *s, AVPacket *pkt, int size)
             size= remaining+1;
         }
     }
+    return size;
+}
+
+int av_get_packet(AVIOContext *s, AVPacket *pkt, int size)
+{
+    int ret;
+    size= ffio_limit(s, size);
 
     ret= av_new_packet(pkt, size);