The VideoLAN Forums

http://wiki.videolan.org/Modules_source_tree

Based on the article above, what is difference between "access" and "access-output" module?

An access module is to handle in input (reading from file, rtsp, udp, http, ftp etc), whereas an access-output is to handle an output. ( writing to file, udp, rtsp etc)

Thanks for your response, but one more question. How about "stream_out" module? Is this for the RTP output?

Also, I've been looking at the code for the streaming part (server). Based on my observation it seems the VLC breaks down each streaming step by reading the file, putting into a buffer (FIFO), make it into packet, and send depending on the protocol used. Am I understanding this correctly?

So if I want to implement new type of protocol (instead of UDP/HTTP/etc) I should be able to write a code to use different protocol for server/client, right?

stream_out is a module manipulating all elementary streams of a stream. They can do a wide range of different things. duplicate, standard, rtp, transcode and display are the most commonly used stream_out modules, but there are a few others.