Glossary
What is H.264?
MarkdownWhat H.264 is
H.264 compresses video by storing only what changes between frames. It is usually found in MP4 and MOV files and is the default safe choice for sharing.
Why it matters on a Mac
Every Mac, iPhone, browser and most TVs can play H.264. If a video will not play for someone you sent it to, re-encoding it as H.264 in an MP4 is the usual fix.
How to check it on macOS
Open the video in QuickTime Player and choose Window > Show Movie Inspector to see the format. Media Info in Toolbox lists the codec of each video and audio track.
How Toolbox handles it
Compress Video and Convert Video can encode with H.264 or HEVC. Convert Video can copy streams without re-encoding when the codecs already fit the new container, which is fast and loses no quality.
Frequently asked questions
Is H.264 the same as MP4?
No. MP4 is a container. H.264 is one codec that can be stored inside it.
Is H.264 or HEVC smaller?
HEVC is about half the size at similar quality.
Is H.264 lossy?
Yes. Higher quality settings keep more detail but the file is larger.
