h264 Raw Video Stream Format

Question

I am now working on decoding an h264 byte stream on Android. The stream is sent from a third party product and I am not so sure about its video format. The document says the stream consists of PPS and SPS NAL units. But the h264 byte stream I received includes sequences starting with 0x00 0x00 0x00 0x01 and the 5th byte could be 0x09, 0x21 or 0x06 in the sample I received. This has triggered me up for a while because it seems to be different from the usual indicator of 0x67 or 0x68. Does anyone know what 0x09/0x21/0x06 mean in NAL unit headers?

Answer 1

0x09 is an access unit delimiter. 0x21 is a non IDR frame or slice. 0x06 is an SEI message. See my answer here for more info. Possible Locations for Sequence/Picture Parameter Set(s) for H.264 Stream