Transcoding
Also known as: re-encode video, transcode meaning, video conversion, recompress video
Transcoding is decoding a video and re-encoding it into a different codec, bitrate, resolution, or container. It is how a compressor shrinks a file or makes it playable on another device — and because re-encoding is lossy, each pass can lower quality slightly.
- Decodes then re-encodes to new settings
- Lossy: each pass can reduce quality
- Lowering bitrate or resolution shrinks the file
What transcoding actually does
A transcoder first decodes the source video back into raw frames, then re-encodes those frames with new settings — a different codec, a lower bitrate, a smaller resolution, or a new container. Changing only the wrapper without touching the video stream is called remuxing, which is faster and lossless; true transcoding rebuilds the compressed data.
This is the work behind most video compressors and converters. Lowering the bitrate or scaling down the resolution is what makes the output file smaller, so a long clip that fills gigabytes can drop substantially after a transcode.
Quality and generation loss
Because common video codecs are lossy, every transcode discards some detail. Re-encoding the same clip over and over — known as generation loss — compounds that softening, so it is best to transcode once from the highest-quality source you have rather than repeatedly from already-compressed copies.
Switching to a more efficient codec lets you keep similar visual quality at a lower bitrate, which is the main lever for shrinking video without an obvious drop in sharpness.