A MP3/RTP input plugin for Winamp

(Built from "LIVE555 Streaming Media")

AOL/Nullsoft's "Winamp" audio player (for Windows) can receive and play multicast (RTP) MP3 audio sessions, using a special input plugin: in_rtp.dll. This plugin allows Winamp to receive RTP-based MP3 streams directly, without the need for a separate multicast receiver 'helper application' (such as "playRTPMPEG").

Important Note: This plugin works for Winamp version 2 or 5. It will not work for the ill-fated "Winamp3".

Downloading and installing the "in_rtp.dll" plugin

Download the binary file in_rtp.dll, and copy it to your Winamp "Plugins" folder - usually "C:\Program Files\Winamp\Plugins".

Receiving MP3/RTP streams using the plugin

With the "in_rtp.dll" plugin installed, you can receive a MP3/RTP stream from Winamp by giving it the "Open Location" command (<control>-l ('ell')), and entering the 'pseudo-URL' rtp://<multicast-address>:<port> e.g.,
You can also use this pseudo-URL if you start Winamp from a command shell, e.g.,
winamp rtp://


Additional options

Reading ".sdp" files

With this plugin, Winamp can also read a SDP (Session Description Protocol) file that describes a MP3 session (as an alternative to entering the session's parameters in a "rtp://" 'pseudo-URL'). The name of this file must end in ".sdp". A ".sdp" file can either be a local file (which you can simply 'drop' on Winamp), or a file on a remote HTTP server (which Winamp can open using a "http://" URL).

Opening RTSP URLs

This plugin also has a built-in RTSP client. This allows you to open URLs that begin:
if this URL refers to a session that contains a MP3 stream.

If Winamp exits unexpectedly

If this plugin encounters an error (such as being given a malformed URL), it outputs an error message to 'stderr' and exits.

You can see this error message by running Winamp from the Windows 'Command Prompt' (shell), as follows:

winamp 2> err.txt
After Winamp exits, the file "err.txt" (in this case) should contain an error message.

About the plugin's implementation

The plugin was implemented using the (open source) "LIVE555 Streaming Media" source-code libraries, with high-level scripting in Tcl.