Video file recorded by Windows Media Center, a program used to play multimedia content and record TV shows; encodes video using MPEG-2 compression and audio using MPEG-1 Layer II or Dolby Digital AC-3 compression; may also include descriptive metadata and digital rights management (DRM) information. The WTV Windows Media Center video format is successor of the DVR-MS Windows Media Center video format and was introduced in Windows 7
An SPX file is a Speex audio file saved within an Ogg Vorbis container. Speex is an open source patent-free audio format designed for speech compression. It supports variable bitrate (VBR) encoding and several features not found in other audio codecs. Some examples include embedded encoding, intensity stereo encoding, and voice activity detection.