AMB to SPX Converter

AMB files contain audio encoded in Ambisonic B-format, a full-sphere surround sound technique conceived by Michael Gerzon during the 1970s. Unlike channel-based systems such as 5.1 or 7.1, Ambisonics captures a complete three-dimensional sound field using spherical harmonics — first-order B-format consists of four channels: W (omnidirectional), X (front-back), Y (left-right), and Z (up-down). This representation is speaker-independent, meaning one recording can be decoded to any loudspeaker arrangement or binaural headphones without remixing. AMB files typically store uncompressed PCM data and are processed by tools like SoX or specialized plugins. A core advantage is spatial flexibility — creators produce one master file that adapts to stereo, surround, or immersive playback. The format also scales elegantly: higher-order Ambisonics adds channels for increased spatial precision upon the same mathematical framework. With the growth of virtual reality, 360-degree video, and spatial audio for gaming, Ambisonics has experienced a resurgence, adopted by platforms like YouTube for immersive media delivery.

Speex is an open-source audio codec purpose-built for speech compression, developed by Jean-Marc Valin under the Xiph.Org Foundation. First released in October 2002, it targets voice-over-IP, conferencing, and any scenario where spoken word needs to travel efficiently over a network. SPX files wrap Speex-encoded audio inside an Ogg container, pairing the codec's speech optimization with Ogg's streaming capabilities. Three sampling rates are supported — narrowband at 8 kHz, wideband at 16 kHz, and ultra-wideband at 32 kHz — along with variable bitrate encoding that adapts in real time to speech complexity. A standout advantage is its patent-free, BSD-licensed nature, which allowed developers to embed it freely in both commercial and open-source products. Speex also bundles acoustic echo cancellation, noise suppression, and automatic gain control, features that rival codecs typically delegate to external libraries. Although its creators officially recommend Opus) as a successor since 2012, Speex remains deployed in legacy VoIP systems, archived recordings, and embedded devices where its lightweight decoder footprint is still valued.