Reencode

Reencode, in digital media processing, refers to decoding a data stream or file and then encoding it again into a possibly different format, codec, or set of parameters. This differs from remultiplexing or remuxing, which changes containers but not the encoded data, and from simple repackaging.

The typical workflow involves decoding to an uncompressed or intermediate representation, optionally applying processing such as resampling or color space conversion, and then encoding with a chosen encoder. Each re-encode can introduce generation loss if a lossy codec is used. Even lossless re-encodes can affect metadata or timing. Quality is influenced by bitrate, resolution, frame rate, and audio sample rate, as well as chroma subsampling and other codec settings. Re-encoding can produce artifacts such as blockiness or blurring, particularly when reducing bitrate.

Applications of reencoding include format migration for compatibility, optimizing content for streaming bandwidth, preparing footage for editing, or applying processing steps (deinterlacing, color correction) before final export. It is commonly performed with tools such as FFmpeg, HandBrake, or GStreamer, which support converting between codecs and containers and adjusting encoding parameters. After re-encoding, verifying metadata and synchronization is advisable to ensure the output remains usable in downstream workflows.

Legal and ethical considerations may apply, as re-encoding copyrighted material can be restricted by licensing terms or anti-circumvention rules. When distributing re-encoded content, it is important to respect rights and licenses associated with the source material.