What does this H264 NAL Header Mean?

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0000 0109 1000 0001 6742 0020 e900 800c
3200 0001 68ce 3c80 0000 0001 6588 801a

As far as I know, 0000 01 is the start prefix code to identify a NAL Unit. What does "09 .... " mean? Is it the header type byte?

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    0000 0109 1000 0001 6742 0020 e900 800c
    3200 0001 68ce 3c80 0000 0001 6588 801a

-> 000001| 09 (AUD)| 10 | 000001 | 67(SPS) | xxxx (SPS data)
   xx | 000001 | 68 (PPS)| xxxx (PPS data)

AUD, SPS, PPS is type of NALU (Network Abstraction Layer Units) NALU have about 31 types.

09 AUD mean Access Unit Delimiter.

Access Unit Delimiter (AUD). An AUD is an optional NALU that can be use to delimit frames in an elementary stream. It is not required (unless otherwise stated by the container/protocol, like TS), and is often not included in order to save space, but it can be useful to finds the start of a frame without having to fully parse each NALU.

Check this answer for more information.

I also have a question about how to decode h264 stream (in iOS).

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