Long GOP

What it means

A Long GOP stream groups frames into a GOP. Each group starts with a full keyframe, and the frames after it store only what changed, predicted from earlier or later frames. Because most of a scene stays similar from one frame to the next, this saves an enormous amount of space.

Almost all action cameras, drones and phones record Long GOP H.264 or HEVC. It is the reason a camera can record 4K at 60 frames per second onto a small card for an hour.

The trade-off is that a frame in the middle of a group depends on the frames around it to be rebuilt.

How it works in practice

Editing software has to decode a chain of frames to show any single one, which makes scrubbing, reverse playback and frame-accurate cuts heavier work for the computer. On a strong machine with hardware decoding, it feels fine. On an older laptop, Long GOP 4K HEVC can stutter.

Common fixes are using proxies or transcoding to an intra-frame codec for editing, then finishing from the originals. For quick edits and uploads, working directly with the camera files is usually enough.

Long GOP also handles most action well, but extreme changes, such as fireworks or confetti, can briefly overwhelm it.

What to watch out for

Very fast, chaotic motion like water spray, snow, foliage in wind or rapid panning changes almost every pixel, so the predicted frames need far more data. At a fixed Bitrate, the encoder runs short and produces smearing or blocky artifacts. A higher bitrate setting helps on such scenes.

Re-encoding Long GOP footage several times compounds the losses. Each export throws away more detail. Edit from the originals and export once, rather than chaining exports through several apps. If a phone app trims a clip, it may re-encode it without telling you, so trim on the computer instead when quality matters.