ReEncoding

Reencoding refers to the process of converting data that is already encoded in one format into a different encoding or codec. In digital media workflows it is typically achieved by decoding the source content to a raw intermediate representation and then encoding it again into the target format. Reencoding is used to adapt content for different devices, platforms, or bandwidth conditions.

In video and audio contexts, reencoding is often called transcoding or encoding conversion. It may involve changing the codec (for example, from H.264 to H.265), the container, the bitrate, resolution, frame rate, or color space. Reencoding can also apply to image sequences and other streams, and it can include metadata and time-base changes.

Process: the usual pipeline is decode to a raw, uncompressed internal representation, optional signal processing, then encode to the target specifications. For lossy codecs this can introduce quality loss, and repeated cycles can compound artifacts. Lossless reencoding is possible but may still change metadata or broader container structure.

Considerations include device compatibility, licensing and patent constraints for codecs, file size, encoding speed, and the intended use. Two-pass or variable-rate encoding techniques are often employed to balance quality and file size. Hardware accelerators and software encoders provide different trade-offs.

Tools commonly used for reencoding include FFmpeg, HandBrake, and media software suites. In text processing, a related concept is changing character encodings (for example, UTF-8 to ISO-8859-1), which is technically a different domain but shares the idea of converting between representations.