MPEG-1

MPEG-1 is the designation for a group of audio and video coding standards agreed upon by MPEG (Motion Pictures Coding Experts Group). MPEG-1 Layer 3 is the full name for the popular audio format MP3.

MPEG-1 consists of several standards (termed "Layers"), as follows:

Layer 1: Describes synchronization and multiplexing of video and audio.
Layer 2: Compression codec for non-interlaced video signals.
Layer 3: Compression codec for perceptual coding of audio signals. Also known as MP3.
Layer 4: Describes procedures for testing compliance.

Reference: [ISO/IEC JTC1/SC29/WG11] (June 1996)