What is transcoding?
Transcoding means decoding existing media and encoding it again, usually to make it smaller, more compatible, or suitable for a different delivery target.
A new encoded version
If HEVC video is changed to H.264 for an older device, the original HEVC stream must normally be decoded and a new H.264 stream created. That is transcoding.
Simple workflow
Why transcode?
- Make a file playable on older hardware.
- Reduce bitrate or resolution for streaming.
- Change an audio codec for compatibility.
- Create proxy or delivery versions.
- Meet platform upload requirements.
Does transcoding lose quality?
If a lossy source is encoded into another lossy stream, usually yes. A high-quality transcode may look or sound very close to the source, but it is still a new compressed generation. Lossless-to-lossless transcoding can preserve the decoded signal exactly.
Common confusion
Conversion might mean remuxing, metadata changes, resampling or other operations. Transcoding specifically involves decoding and encoding media.
Plex-like media systems may create a compatible stream on the fly when the client cannot direct-play the original.