Glossary
Creator media glossary A to Z
The terms that come up once you start converting, compressing or cropping video for a specific platform, defined plainly, with the tool or spec page each one actually affects.
A
- AACAdvanced Audio Coding: the lossy audio codec inside most MP4 videos, and the audio format YouTube and Instagram ask for in uploads.
- Alpha channelThe transparency information stored in an image or video, alongside its red, green and blue color data.
- Aspect ratioThe proportional relationship between a video or image's width and height, written as two numbers like 9:16 or 16:9.
- Audio sample rateHow many times per second audio is measured when it is recorded digitally, in kilohertz: 44.1 kHz for music and CDs, 48 kHz for video.
- AV1A royalty-free codec built for streaming efficiency, offering meaningfully smaller files than H.264 or even VP9 at the same quality.
B
C
- Caption limitThe maximum number of characters a platform allows in a post's caption - it varies enormously, from 280 on X to over 60,000 on Facebook.
- Chroma subsamplingStoring color at a lower resolution than brightness to save space, written as a ratio: 4:4:4 (full color), 4:2:2 or 4:2:0 (color at a quarter of the pixels).
- CodecThe algorithm that compresses video or audio data - H.264 and AAC are the two you'll run into most, packed inside a container like MP4.
- Container formatA file format like MP4, MOV or WebM that wraps a video stream, an audio stream and metadata together - it's the packaging, not the compression.
F
H
- H.264 (AVC)The most widely supported video codec, decoded natively by essentially every phone, browser and TV made in the last fifteen years.
- H.265 (HEVC)A newer codec that roughly halves file size versus H.264 at similar quality, at the cost of narrower playback support.
- HDR videoHigh dynamic range video: brighter highlights, deeper shadows and more colors than standard (SDR) video, recorded and graded with a wider color standard and HDR metadata.
- HEICApple's photo format: HEIF images (.heic) that store the same visual quality as JPEG in less space. iPhones save photos this way by default.
I
J
K
L
- Lossless vs. lossy compressionLossless compression shrinks a file without discarding any data; lossy compression discards data a viewer is unlikely to notice, for a much smaller file.
- LUFSLoudness Units relative to Full Scale: a measure of how loud audio sounds over time, used by streaming and podcast platforms to set every track to a similar volume.
M
P
- PNGA lossless image format that preserves transparency - the standard choice for logos, screenshots and graphics with text.
- ProResApple's family of high-quality video codecs built for editing rather than delivery: large files, easy playback and little visible loss, from ProRes 422 Proxy to ProRes 4444 XQ.
- Proxy editingEditing with lightweight copies (proxies) of your footage that stay linked to the originals, so playback is smooth, while the final export still uses full-quality media.