Media Players

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Media Players are tools like Real Player and Windows Media player which play the streaming/non streaming media to the end user. As already mentioned

• Real Media Server uses its proprietary codec called RM(Real Media), RV(Real Video) and (RA)Real Audio based on H264 standard and these media files can be played only by Real Player
• Windows Media Server uses its proprietary WMV(Windows Media Video). These media files can be played by Windows media player

There are other mime types which can be encoded and the above mentioned are default ones.

Streaming Protocols - internals

Streaming protocols consists of two parts

• Control protocol
• Data protocol

Control protocol

Control protocol is responsible for actions like

• Stop
• Pause
• Rewind(RW)
• Fast-Forward(FF)

The media server and media player can communicate in two way communication model to do the above operations.

Example: MMS, RTSP, RTMP

Data only protocol

Data only protocol is the protocol can also be used to stream media packets. Here the server just pushes data and the media player cannot control the streams.

Example: RTP(Real-time Transport Protocol)

Real Time Streaming Protocol (RTSP)

RTSP is the most popular streaming protocol supported by popular media servers like Helix, WMS etc. RTSP is a control protocol which works in collaboration with data protocol called Real Time Protocol (RTP).

• RTSP usually works on port Number 554
• The RTSP URL usually looks like - RTSP://server:554/publishing_point/media_file.rm

MMS

Microsoft Media Server protocol was the proprietary protocol of Microsoft for media streaming. This protocols were supported by earlier versions of Windows Media Services(WMS). I.e. versions before WMS series 9. Though series 9 is backward compatible with MMS, RTSP is the preferred protocol. This protocol can run over both UDP, TCP

• MMSU – Runs over UDP, Preferred and default protocol
• MMST - Runs over TCP, Roll over happens to this protocol if the network is TCP based.

If UDP and TCP is not available. The roll over takes place to HTTP transport layer.

• MMS usually works on port Number 1175
• The MMS URL usually looks like - mms://server:1175/publishing_point/media_file.asf

HTTP

HTTP can also be used for media stream delivery. This option is especially useful to bypass corporate fire walls were all port numbers except 80 are accessible which is the default web server port number.

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