Video codec
Also known as: codec, video compression format
The method used to compress video so it fits on a memory card and to decompress it for playback. H.264, H.265 (HEVC), AV1 and ProRes are common examples.
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What it means
A codec, short for coder-decoder, is the algorithm that squeezes raw camera images into a manageable file and rebuilds them on playback. Uncompressed 4K at 60 fps runs to several gigabits per second; a modern codec brings that down to around 100 Mbps by discarding detail your eyes are unlikely to miss and by storing only what changes between frames.
The codec is separate from the container. MP4 and MOV are boxes; H.264, H.265, AV1 and ProRes are the compression inside them. Two files with the same extension can need completely different decoding power.
How it works in practice
Action cameras use long-GOP codecs: a full keyframe every so often, with the frames in between stored as small differences. That keeps files compact but makes scrubbing heavier, because the computer has to rebuild each frame from its neighbors. Intra-frame codecs such as ProRes compress every frame on its own, which edits smoothly but produces files many times larger.
In camera menus the choice is often disguised. GoPro and iPhone have used labels like Most Compatible and High Efficiency, while DJI simply lists H.264 and H.265. Some modes lock the codec: the highest resolutions, 10-bit recording and top frame rates usually force HEVC, because H.264 cannot keep up at a reasonable bitrate.
What to watch out for
If footage stutters in an editor while the same clip plays fine on the camera, the codec is usually the reason. The camera has a hardware decoder built for exactly that format; an older laptop may not. Check whether your machine decodes HEVC in hardware before shooting a whole trip in it, or plan on proxy editing.
Avoid needless re-encoding too. Each time a long-GOP file is decoded and compressed again, some quality is lost, and running clips through a converter before editing, then exporting again, stacks two generations of loss on top of the camera's own. Convert only when a tool genuinely cannot read the original, and use a high Bitrate when you do.
How RawClip handles it
RawClip reads the two codecs that action cameras, drones and phones actually record: H.264 and H.265/HEVC, in MP4 or MOV, and also AVI or MKV. In the usual case that means no conversion step before upload. The final render is delivered as MP4 in 4K and 1080p.