Game Development Reference
In-Depth Information
Table 9.4
Value assignment for the NALU type
Type
Type description
Reason for type assignment
0
Reserved
-
1
Sequence header
Start code value is B0
2
Video extension
Start code value is B5
3
User data
Start code value is B2
4
Video edit
Start code value is B7
5
Picture header of I frame
Start code value is B3
6
Picture header of P frame Start code value is B6 and the picture coding type of the
picture header is 01
7
Picture header of B frame Start code value is B6 and the picture coding type of the
picture header is 10
8
Slice data of I frame
Start code value is 00 AF and the start code value of the last
picture header before this NALU is B3
9
Slice data of P frame
Start code value is 00 AF and the start code value of the last
picture header before this NALU is B6, and the picture
coding type of the picture is 01
10
Slice data of B frame
Start code value is 00 AF and the start code value of the last
picture header before this NALU is B6, and the picture
coding type of the picture is 10
11-23 Reserved
-
24-31 Unspecified
-
(0x000001) in the same position to transform the NAL unit stream back into an IEEE
1857 video bitstream.
For IEEE 1857.2 audio, similar conversion from the audio bitstream into NAL
unit stream is defined. The difference is that the part after each NALU header is
called RBSP, containing the contents of audio frames. Each NALU should contain
exactly one audio frame.
9.2.1.2 Elementary Streams and Sample Definitions
The elementary streams and sample structures used to store audiovisual content inside
the file format are specified. Since the audiovisual bitstreams have been converted into
NAL unit streams, all NALUs shall be present in these elementary streams. An IEEE
1857 video sample contains an IEEE 1857 video access unit, while an IEEE 1857.2
audio sample contains a NALU converted from one audio frame. The elementary
stream is stored in the ISO base media file format in the following canonical format,
so that systems that need to customize the stream for delivery over different transport
protocols—MPEG-2 system, RTP, and so on.
