Audio Codec
Definition
A standard for encoding and decoding digital audio, determining file format, compression, and quality.
Audio codecs define how audio is stored and transmitted. Lossless codecs (WAV, FLAC) preserve the original signal perfectly but produce larger files. Lossy codecs (MP3, AAC, Opus) reduce file size by discarding inaudible information, which can affect ASR accuracy if compression is too aggressive.
For speech recognition, the audio codec affects both quality and processing overhead. Uncompressed PCM (WAV) is ideal but storage-intensive. Opus at reasonable bitrates provides a good balance. Very low-bitrate codecs can introduce artifacts that degrade transcription accuracy. On-device processing typically works with uncompressed audio from the microphone, avoiding codec artifacts entirely.