Hacker Guide/How To Write a Module
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- This guide is being written by a VLC media player novice. Please check all statements below.
- Using dvdread.c as the template.
Module Descriptor
A VLC media player Module must include a description of itself, and the parameters it accepts.
The module descriptor begins with:
vlc_module_being();
You should set some category information on your module:
set_shortname( _("DVD without menus") ); set_description( _("DVDRead Input (DVD without menu support)") ); set_category( CAT_INPUT );
Note the use of _("") to create a string that needs to be translated.
Predefined Categories include:
- CAT_INTERFACE
- CAT_AUDIO
- CAT_VIDEO
- CAT_INPUT
- CAT_SOUT
- CAT_ADVANCED
- CAT_PLAYLIST
set_subcategory( SUBCAT_INPUT_ACCESS );
See include/configuration.h for definition of all categories and sub-categories.
Adding Parameters
All macros take the following argument list:
add_integer(name, value, p_callback, text, longtext, advc)
- name is the string that identifies this parameter in the configuration. This name may be used at the command prompt to set the configuration value.
- value is the default value for this parameter,
- p_callback is a function pointer that will be called when the value of this parameter is changed.
- p_callback is called with the following arguments:
( p_this, psz_name, oldval, val, p_config->p_callback_data )
- p_this is a pointer to a vlc_object_t struct,
- psz_name is the name of your parameter that is being changed,
- oldval is the old value of the parameter,
- val is the new value of the parameter,
- p_call_back_data is void* data that you can assign for each parameter. Usually NULL.
- p_callback is called with the following arguments:
- text A short description of the parameter,
- longtext A complete description of the parameter,
- advc Boolean, ADVanced Configuration. If TRUE, this parameter will only be displayed when using the --advanced flag. e.g.
vlc -p dvdread --advanced
e.g.
add_integer("dvdread-angle", 1, NULL, "DVD Angle", "Default DVD Angle", NULL")
You may add the following parameters to your module:
- add_integer,
- add_string,
- add_float,
- add_bool,
- add_key,
- add_file,
- add_directory,
For complete definitions, see include/configuration.h