Glossary
Codec
The method used to compress video into a file and decompress it for playback. H.264 and HEVC are the two you meet when recording a screen.
Raw video is enormous. A single 1080p frame is six megabytes uncompressed, and there are thirty or sixty of them a second. A codec is the method for squeezing that down to something a file can hold and a network can carry, and for unpacking it again on playback. The word is a contraction of coder-decoder.
The two you meet
H.264, also called AVC, is the one everything plays. Every browser, every phone, every version of Windows, every video player. It is twenty years old and it is the safe choice for any file that is going somewhere you do not control.
HEVC, also called H.265, is its successor. At the same picture quality the file is smaller, roughly a third to a half. The catch is playback: Apple devices handle it everywhere, but some Windows editions need a paid extension, and some older browsers and players do not read it at all.
Both are what an MP4 usually holds. AV1 is newer and smaller again, and is what the big platforms re-encode to on their side; almost no screen recorder writes it yet.
Containers
The codec is not the file format. An MP4 or a MOV is a container, a wrapper
that holds a video stream, one or more audio streams and sometimes subtitles,
and says which codec each one uses. An MP4 can hold H.264 or HEVC. A file
ending in .mp4 tells you the container and nothing about what is inside.
What to pick
H.264 in an MP4 for anything shared. HEVC if the file is yours to keep, or you know it is going to a Mac or an iPhone, and the size matters. Prequel's export dialog offers both under those names.
Related terms
- BitrateHow much data a video spends per second of playback, measured in megabits per second. It is the main control over file size and picture quality.
- Frame rateThe number of still pictures a video shows each second, written as fps. Screen recordings are usually made at 30 or 60.
- ResolutionThe size of a video's picture in pixels, width by height. 1080p is 1920 by 1080; 4K is 3840 by 2160.
Questions people ask
- Should I export as H.264 or HEVC?
- H.264 if the file is going to somebody else or somewhere you do not control, because everything plays it. HEVC if you are keeping the file or know where it will play, because it is smaller at the same quality.
- Is MP4 a codec?
- No. MP4 is a container, the file format that holds the video and audio streams. The codec is what those streams are encoded with. An MP4 usually holds H.264 video, and can hold HEVC.
- Why will my HEVC file not play on Windows?
- Windows does not ship an HEVC decoder in every edition; it is a paid extension in the Microsoft Store on some. If a recording is going to Windows users, export it as MP4 with H.264.