diff --git a/readme/apv_isobmff.md b/readme/apv_isobmff.md
index 3bc169f..6b246c3 100644
--- a/readme/apv_isobmff.md
+++ b/readme/apv_isobmff.md
@@ -159,20 +159,7 @@ the full_range_flag field in the frame header of the frames whose value of the p
 ## APV Sample Description
 
 ###	Format of sample
-When APV coded bitstream is encapsulated in a track with APVSampleEntry, each sample shall contain a size of access unit and an access unit of APV coded data.
-
-~~~~
-aligned(8) class APVSample{
-    unsigned int(32) au_length;
-    bit(au_length * 8) access_unit;
-}
-~~~~
-
-+ au_length
-> indicates the size of an access unit measured in bytes. The size does not include the length field itself.
-
-+ access_unit
-> contains a single access unit. It includes both the 4-characters signature and the variable length encapsulated PBU streams.
+When APV coded bitstream is encapsulated in a track with APVSampleEntry, each sample shall contain one and only one access unit of APV coded data. The format of sample shall be same as the raw bitstream access unit, the length field of four bytes preceeding the access unit data, as defined in the section 12.1 of the Internet-Draft of APV [https://datatracker.ietf.org/doc/html/draft-lim-apv].
 
 ###	Sync sample
 Every samples of APV bitstream shall be sync samples.