Difference between Chunk Message Header and Message Header in RTMP

Question

Reading the RTMP Specification. I see there are two headers:

1. Chunk Message Header - Type 0 (pg. 14 of the spec)
2. Message Header (pg. 22 of the spec)

What is the difference between these headers? When is one used over the other?

Answer 1

I watched this video, and the Message Header shown in pg. 22 of the spec is something that you COULD send/implement in your own RTMP client/server, but it is not mandatory. This would make things like sending an flv over RTMP easier. This Message Header would be part of the chunk payload, to give additional information about what you're sending.

So, this is not related at all to the Chunk Message Header, which simply depends on the format specified by the Chunk Basic Header.