View source for Hacker Guide/Access Demux

{{Back to|Hacker Guide}}
== Description  ==

The modules of ''''access_demux'''' capability are designed to handle the [[{{#rel2abs:../Access}}|access]] and part of the [[{{#rel2abs:../Demux}}|demux]] stage in the same module.

Therefore, you are '''required''' to read [[{{#rel2abs:../Access}}|access]] and [[{{#rel2abs:../Demux}}|demux]] pages before going on.

An access-demuxer could be seen as a demuxer that handles the access at the same time. 

In an access-demuxer, the stream s is null.

Examples of access-demuxer are DVD, Bluray, v4l2 modules.

== Write an access-demux module  ==

To write an access_demuxer module, start by reading the [[{{#rel2abs:../How To Write a Module}}|introduction to module writing]]. 

Then, you should specify your module of being of access_demux type: 

 set_capability( "access_demux", 60 )
 set_category( CAT_INPUT )
 set_subcategory( SUBCAT_INPUT_ACCESS )

== Functions to implement  ==

After implementing Open() and Close() functions, you will need to implement a few majors features that will be implemented by your functions. 

As you can see in [[{{#rel2abs:../Demux}}|demux]], you should define: 

*Demux, as in pf_demux 
*Control, as in pf_control ''' NB:''' please refer to [[{{#rel2abs:../Demux#Control}}|demux Control documentation]]

After implementing those functions, you should assign them to the corresponding pf_ function.

See {{VLCSourceFile|include/vlc_demux.h}} and {{VLCSourceFile|include/vlc_access.h}}

== Demux  ==

Demux in access_demux is a bit different than in a demux module, because all the seeking and access of the stream is internal to the module.

''Prototype'': 

  int (*pf_demux)  ( demux_t * ); 


''Return'': 

It should return 0 for EOF, something positive when success and something negative when fail to demux.

{{Hacker_Guide}}