Glossary
Codecs: how video gets small enough to share
Raw video is enormous — minutes of footage can fill a hard drive — so codecs compress it into files you can edit, stream, and share. Different codecs make different trade-offs between size, quality, and editing smoothness. This guide explains the ones beginners meet and which to pick.
From the Mellius product team · Updated September 28, 2026
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The short answer
A video codec is the method used to compress footage into a file and decompress it on playback — H.264, HEVC (H.265), ProRes, and AV1 are the ones. Efficient codecs like HEVC make smaller files but need more processing; editing codecs like ProRes make files that scrub smoothly. Pick the codec for the job: light for sharing, robust for editing.
It fits the delivery
The right codec meets the destination's spec — H.264 for universal compatibility, HEVC for efficient 4K streaming, AV1 where platforms support it.
It preserves visible quality
A good choice shows no blocking, banding, or mushy detail at the intended screen size and bitrate.
It plays back smoothly
Editing codecs prioritize decode speed for scrubbing and effects, while delivery codecs prioritize small files over editing comfort.
Codec vs. container: what beginners mix up
A codec is the compression method; a container is the file wrapper that holds video, audio, and metadata together. H.264 video typically ships inside an MP4 or MOV container, which is why two .mp4 files can look wildly different — the extension names the box, not the compression inside. When someone says export an MP4, they usually mean H.264 video in an MP4 container.
The main codecs beginners meet are H.264 (the universal workhorse every device plays), HEVC or H.265 (roughly double the efficiency, ideal for 4K, heavier to encode), AV1 (the open, increasingly supported efficiency leader), and ProRes or DNx (professional editing codecs with large files and butter-smooth scrubbing). Each exists because no single trade-off serves archiving, editing, and streaming simultaneously.
Which codec to use, and when
For sharing and uploading, H.264 remains the safest default: every platform accepts it and every device plays it. Choose HEVC when file size matters — 4K uploads, limited storage, faster transfers — and your audience's devices are modern enough to decode it. Use ProRes or DNx as intermediate masters and editing proxies, never as final delivery, since their huge files waste bandwidth without visible benefit.
Bitrate matters as much as codec: a starved H.264 at low bitrate looks worse than a generous one, with blocky gradients and smeared motion. Export at your platform's recommended bitrate for the resolution, use two-pass or quality-based encoding when time allows, and keep a high-quality master so future re-exports never compound compression damage.
Codec mistakes that ruin exports
Re-compressing compressed footage repeatedly is the silent killer: every upload-download cycle or re-export at low bitrate adds artifacts that stack. Edit from the best-quality source available, export delivery copies from a master, and avoid screen-recording an already-compressed stream as source material when the original file exists.
The other classic error is mismatching codec to task — editing native HEVC phone footage on a weak machine and blaming the editor for stutter, or uploading ProRes masters that take hours and get recompressed anyway. Transcode heavy camera files to editing-friendly proxies for the cut, then export delivery codecs from the full-quality originals.
A practical sequence
Put it into practice
- 01
Identify the destination first
Check where the file goes: platform upload, client review, or archive master. The destination dictates the codec shortlist before you touch any settings.
- 02
Pick codec plus sensible bitrate
Choose H.264 for universal delivery or HEVC for efficient 4K, at the platform's recommended bitrate for your resolution. Keep a ProRes or high-bitrate master for future re-exports.
- 03
Test playback before publishing
Watch the export on the target device and scan gradients, motion, and text for artifacts. If it breaks up, raise the bitrate rather than switching codecs blindly.
Frequently asked questions
What is the difference between H.264 and H.265?
H.265 (HEVC) compresses roughly twice as efficiently as H.264, producing similar quality at noticeably smaller sizes — great for 4K. The cost is heavier encoding and decoding, so older devices may stutter. Use H.264 for maximum compatibility and HEVC when size matters and playback hardware is modern.
What codec should beginners export with?
H.264 in an MP4 container is the beginner-safe answer for nearly every platform. It uploads anywhere, plays everywhere, and looks excellent at recommended bitrates. Graduate to HEVC or AV1 when you specifically need smaller 4K files and have confirmed your audience can play them.
Why is my exported video suddenly huge or tiny?
File size comes from codec times bitrate times duration, so check all three. A ProRes export dwarfs an H.264 of the same timeline; a low-bitrate H.264 shrinks it with visible damage. Match the codec to the job and set bitrate deliberately instead of accepting defaults blindly.
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Primary sources
Product capabilities change. These official references support the comparisons above.
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