+unsigned long ffio_get_checksum(AVIOContext *s);
+unsigned long ff_crc04C11DB7_update(unsigned long checksum, const uint8_t *buf,
+ unsigned int len);
+
+/**
+ * Open a write only packetized memory stream with a maximum packet
+ * size of 'max_packet_size'. The stream is stored in a memory buffer
+ * with a big endian 4 byte header giving the packet size in bytes.
+ *
+ * @param s new IO context
+ * @param max_packet_size maximum packet size (must be > 0)
+ * @return zero if no error.
+ */
+int ffio_open_dyn_packet_buf(AVIOContext **s, int max_packet_size);
+
+/**
+ * Create and initialize a AVIOContext for accessing the
+ * resource referenced by the URLContext h.
+ * @note When the URLContext h has been opened in read+write mode, the
+ * AVIOContext can be used only for writing.
+ *
+ * @param s Used to return the pointer to the created AVIOContext.
+ * In case of failure the pointed to value is set to NULL.
+ * @return 0 in case of success, a negative value corresponding to an
+ * AVERROR code in case of failure
+ */
+int ffio_fdopen(AVIOContext **s, URLContext *h);