Is a new media container format from Google. Based on video codecs line VP8(9). Its main task is a replacing the old standard MPEG-4. The format is supported by all browsers and is integrated in Adobe Flash technology. For audio codec Vorbis is used; for subtitles and metadata is a the Matroska container.
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.