Windows Mobile 6.5 RTSP Streaming Media Formats

Windows Mobile 6.5 included a native edition of Windows Media Player Mobile designed to handle network multimedia streaming over various protocols, including the Real Time Streaming Protocol (RTSP). While RTSP is an open industry standard, Windows Media Player Mobile specifically prioritized RTSP implementations designed for Microsoft streaming ecosystems, alongside limited compatibility for mobile carrier multimedia standards. This article details the specific RTSP streaming link types, transport protocols, codecs, and container formats supported by Windows Media Player in Windows Mobile 6.5.

Windows Media Player Mobile in Windows Mobile 6.5 handled links using the standard rtsp:// uniform resource identifier (URI) scheme. Under the RTSP specification, the player communicated with streaming servers to negotiate sessions and receive media streams via several underlying transport configurations:

  • RTSP over UDP (RTSPU): The default transport mechanism where RTSP handles control commands (such as PLAY, PAUSE, and TEARDOWN) over TCP, while the actual audio and video payload is streamed via Real-time Transport Protocol (RTP) over UDP.
  • RTSP over TCP (RTSPT): Used when firewalls or network address translation (NAT) devices blocked UDP traffic. The RTP media packets were interleaved directly into the existing RTSP TCP connection.
  • Protocol Rollover (MMS to RTSP): When given an mms:// URL, the player utilized protocol rollover logic. If modern Windows Media Services were hosting the stream, the player automatically negotiated down to RTSP over UDP or TCP rather than the legacy MMS protocol.

Media Formats and Containers

Windows Media Player Mobile strictly limited the container formats and payloads it would demux and decode over an RTSP connection. The primary supported formats included:

  • Advanced Systems Format (ASF): The primary streaming container for Windows Media. Over RTSP, ASF packets were encapsulated directly inside RTP payloads.
  • Windows Media Video (WMV): Video content streamed via RTSP was limited primarily to WMV versions 7, 8, and 9 (Simple and Main profiles).
  • Windows Media Audio (WMA): Audio streams delivered over RTSP typically utilized WMA 7, 8, or 9 Standard. WMA Professional and Lossless were not supported over mobile RTSP sessions.

3GPP and Carrier RTSP Streams

Outside of Microsoft’s proprietary Windows Media ecosystem, mobile carriers during the Windows Mobile 6.5 era heavily utilized RTSP for 3GPP streaming services (such as mobile TV or carrier video portals).

Standard Windows Mobile 6.5 builds had limited core support for raw 3GPP/MPEG-4 over RTSP via default DirectShow filters. However, devices shipped with OEM-integrated decoders (such as those from HTC, Samsung, or mobile network operators) could process:

  • 3GP/MP4 Streams: RTSP links pointing to .3gp or .mp4 endpoints with Session Description Protocol (SDP) negotiation.
  • H.263 Video: Baseline Profile video inside 3GP streams.
  • MPEG-4 Part 2 Video: Simple Profile video.
  • AMR-NB Audio: Adaptive Multi-Rate Narrowband audio for voice-centric streaming.
  • AAC Audio: Low Complexity (AAC-LC) audio channels.

Streaming Server Requirements

For an RTSP link to play successfully in Windows Mobile 6.5 without third-party players:

  1. Windows Media Services (WMS): The source was typically hosted on Windows Server 2003 or Windows Server 2008 running Windows Media Services 9 Series or later, configured with RTSP publishing points (e.g., rtsp://media.example.com/live.wmv).
  2. SDP Delivery: The server had to properly supply media metadata using Session Description Protocol (SDP) parameters that matched the processing capabilities and limited screen resolutions (typically QVGA, VGA, or WVGA) of Windows Mobile 6.5 hardware.