Converting an audio file from one format or bitrate to another, typically at the cost of audio quality.
Transcoding is the process of decoding an audio file from its current format and re-encoding it into a different format, codec, or bitrate. When the output format is lossy (such as MP3 or AAC) or has a lower bitrate than the source, the conversion is destructive and permanently discards audio information that cannot be recovered.
Why it matters
A DJ who transcodes a high-quality file to a lower-quality format degrades the audio before it ever reaches the speakers. The most common mistake is converting a lossy file a second time, stacking compression artifacts from two separate encode passes.
In practice
Always transcode from the highest-quality source you have. If you must convert, go WAV or AIFF to MP3/AAC, never MP3 to MP3. Label transcoded files clearly in your library so you know to replace them if a lossless source becomes available.
