Video Streaming Protocols in Windows Mobile 6.5

Windows Mobile 6.5, released in late 2009, relied primarily on the integrated Windows Media Player Mobile client to handle multimedia playback over cellular and local wireless networks. This article outlines the specific network streaming protocols natively supported by the operating system, detailing how video content was delivered to devices prior to the emergence of modern adaptive bitrate standards.

Microsoft Media Server (MMS)

Windows Mobile 6.5 natively supported Microsoft's proprietary streaming protocol, MMS (mms://). Historically used by Windows Media Services, MMS allowed the operating system to stream Windows Media Video (WMV) and Advanced Systems Format (ASF) files. The platform supported both transport variants:

  • MMST: MMS over TCP, which provided reliable delivery at the cost of potential latency.
  • MMSU: MMS over UDP, which prioritized real-time delivery by accepting packet loss without retransmission.

Real-Time Streaming Protocol (RTSP)

To ensure compatibility with mobile carrier multimedia services and the 3GPP standard, Windows Mobile 6.5 supported RTSP (rtsp://). RTSP served as the control protocol to establish and manage streaming sessions, while the underlying data was transmitted using:

  • RTP (Real-time Transport Protocol): Handled the delivery of audio and video payloads, commonly containing MPEG-4 Part 2 or H.263 video paired with AMR audio.
  • RTCP (RTP Control Protocol): Monitored transmission statistics and quality of service to adjust playback metrics.

HTTP Streaming and Progressive Download

Windows Mobile 6.5 supported video delivery over standard HTTP (http://):

  • HTTP Progressive Download: Allowed video files to begin playback while the remainder of the file was still buffering and downloading to local storage.
  • Windows Media HTTP Streaming (MS-WMSP): When connecting to Windows Media Servers over port 80, the media player utilized an HTTP-based protocol to bypass firewalls that typically blocked MMS or RTSP ports.

Protocol Limitations

Modern adaptive streaming standards such as HTTP Live Streaming (HLS), Dynamic Adaptive Streaming over HTTP (MPEG-DASH), and Microsoft Smooth Streaming were not natively supported out of the box on Windows Mobile 6.5. Accessing streams utilizing newer codecs or protocols required third-party media players or carrier-specific software implementations.