POE::Filter::Audio::Mad - Simple filter support POE::Component::Audio::Mad::Handle
## could be any wheel, really.. my $wheel = POE::Wheel::ReadWrite->new( Filter => POE::Filter::Audio::Mad->new(), ## other options.. );
POE::Filter::Audio::Mad is a simple filter designed to translate streams of characters into structured command packets. This is a fairly simple filter, as such, it places certain restrictions on the format of the data passed through it. However, the input and output of this filter are very similar and have the same restrictions. Input is achived by translating textual input into command packets; command packets are hashrefs with two fields: 'id' and 'data'. The 'id' field is interpreted as a string, and contains the name of the command to execute. The 'data' field is interpreted as a list of named options, similar to a hash, but you are not allowed to use any whitespace characters in your keys. To start a command, you send the command name followed by a newline. If you wish to include any named paramaters, include them each on their own line. place the name of the parmater first on the line, followed by whitespace and then the value of that paramater followed by a newline. To finish the command, send a blank line follwed by a newline. For example, to create a command packet with an id of 'open' and two named parmaters: 'filename' that contains a path to a file, and 'play' which is a boolean you would send:
open filename /path/to/some/stream.mp3 play 1
Output is achived almost through exactly the same rules, except of course, reversed. Status packets are sent to the filter as hashrefs with two fields 'id' and 'data', id is the name of the status message and data is a hashref possibly containing key/value pairs for named values. The filter will then translate the status packet into a text string for output to wherever. The string starts with the 'id' field of the status packet followed by a newline. Then each key/value pair in the 'data' field is sent. The key is sent first and is guaranteed not to contain any whitespace, then a single space and the value is sent followed by a newline. The entire packet is followed by a blank line and a newline. For example, a status packet packet with an id field containing 'DECODER_STATUS_DATA' and the data field containing the named paramaters: 'played' containing the value 50, and 'progress' containing the value 10 would be translated to:
DECODER_STATUS_DATA played 50 progress 10
This filter is a bit simplistic, but intentionally so. It's meant to provide an incredibly simple interface to the POE::Wheel::Audio::Mad decoder core. You could just as well use the POE::Filter::Reference filter to communicate more easily with another perl process. This is meant to be used with thin clients.
Mark McConnell, <firstname.lastname@example.org>
Copyright 2003 by Mark McConnell
This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself with the exception that you must also feel bad if you don't email me with your opinions of this module.