Audio codec

An audio codec is a method or system for encoding and decoding digital audio. It may compress audio losslessly or discard information to reduce file size or bitrate.

Pulse-code modulation: A method that represents an analog signal as regularly sampled digital amplitude values. Uncompressed digital audio commonly uses PCM as the representation a codec stores or transforms.
Lossy compression: Compression that reduces data by discarding information that cannot be exactly recovered. Lossy codecs trade exact reconstruction for substantially lower audio bitrates.
Streaming media: The continuous delivery and playback of media over a network as data arrives. Streaming services select codecs to balance sound quality, bandwidth use, and device support.
Sampling (signal processing): The process of measuring a continuous signal at discrete points in time. Sampling determines the time resolution of digital audio before codec compression begins.
Data compression: The representation of data using fewer bits than its original form. Audio codecs are specialized compression systems built around the structure and perception of sound.
Perceptual coding: A compression approach that removes or coarsely represents information judged less audible to human listeners. Lossy codecs exploit limits of hearing to reduce bitrate without equally reducing perceived quality.
Lossless compression: Compression that reduces data while allowing exact reconstruction of the original input. Lossless codecs preserve every sample, unlike perceptual codecs that discard information.
Digital audio file: A file that stores audio data in digital form, often alongside metadata. A file container can hold codec-encoded audio together with timing and descriptive information.
Sample rate: The number of samples taken from a signal per second, measured in hertz. Sample rate helps determine the audio bandwidth a codec must represent.
Digital music distribution: The delivery of recorded music as digital files or network streams. Compact codecs made large-scale online music distribution practical under limited storage and bandwidth.

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