[Libav-user] Parsing MPEG4 AVC video, Whats the hex starting bitstream of video NAL units

Amir Rouhi-Rmit amir.rouhi at rmit.edu.au
Fri Apr 8 03:36:42 CEST 2011

Hi to all Encoding and Decoding MPEG4- AVC experts

I am trying to analyse MPEG4-AVC video in compressed domain by opening the
video file in binary mode and read the bits inside. As you know , the
structure of MPEG-4 AVC video format is based on NAL(Network Abstraction
Layer) units stream which can be in form of bytestream or packetized units.
NAL units can be divided to VCL(Video Coding Layer) units and non VCL units.
For a number of VCL NAL units there is a non VCL NAL units which contain
some information of VCL group. Every VCL NAL units start with a byte as
1-whats the bitstream of this one byte header of VCL NAL unit?

We know also every NAL unit start with 3 byte which is named: Start Code
2-Whatd the bitstream of start code prefix?

We also know that a group of VCL NAL units which form a primary coded
picture, are called an Access Unit. The Access Unit start with some bytes as
Access Unit Delimiter.
3-What is the bitstream of Access Unit Delimiter?

 I would be pleased if anybody help me to find the answers.
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