Addaly is in open beta. Things will change, and AI answers can be wrong — check anything that matters.

Editing Video

Cuts, sound, colour and export — taught on DaVinci Resolve, which costs nothing.

Lesson 2 of 7710 min

What the camera actually wrote to the card

Four decisions the camera made without asking you

A video file is not a stack of photographs. It is the result of four separate compromises, made at the moment of recording, that you inherit for the rest of the project. You cannot undo any of them in the edit. Knowing what they were tells you, before you start, which shots will hold up and which will fall apart the moment you touch them.

One: which frames are whole

Intra-frame codecs store every frame complete. ProRes, DNxHR and most camera RAW work this way. Files are large and scrubbing is instant, because frame 4,312 is simply there.

Long-GOP codecs — the H.264 and H.265 that phones and consumer cameras write — store an occasional complete frame and describe everything in between as differences. GOP means group of pictures; a typical consumer camera uses a keyframe every 30 to 60 frames, so one to two seconds apart.

The consequence bites in three places. Playback is heavy, which the proxy lesson solved. Cutting is imprecise in some tools, because a cut in the middle of a GOP has to be reconstructed. And each re-encode compounds: every generation of H.264 throws away detail the previous one kept.

Two: how much colour was kept

Cameras record more brightness detail than colour detail, because the eye notices luminance far more than chroma. The notation is three numbers.

  • 4:4:4 — full colour for every pixel. Rare outside cinema cameras and graphics.
  • 4:2:2 — colour sampled at half horizontal resolution. Most professional cameras, and many mirrorless cameras when recording externally.
  • 4:2:0 — colour sampled at half horizontal and half vertical resolution. Every phone, every consumer camera, every streaming delivery file.

In 4:2:0 one colour sample covers a 2×2 block of pixels. For watching, this is invisible. For working, it is not. A green-screen key builds its matte from colour, so at 4:2:0 the matte has a quarter of the resolution of the picture and every edge comes back blocky. Fine detail against a strongly coloured background — hair, a chain, text — smears. Heavy saturation changes in a grade expose the blocks.

This is the single most common reason a key that looked achievable on set is impossible in the edit.

Three: how many steps there are between black and white

8-bit gives 256 levels per channel. 10-bit gives 1,024. That sounds like a small difference and it is not, because the levels are not spread evenly across what you see — they are spread across what the camera captured.

If the camera recorded a normal, contrasty picture, 8-bit is usually enough. If it recorded a log profile — flat and grey, holding a wide brightness range so you can redistribute it later — then you are stretching 256 levels across a much bigger range. Add the contrast back in the grade and the gaps between levels become visible as banding: stepped rings in a sky, a wall, a gradient behind a face.

The practical rule: log is a 10-bit feature. On an 8-bit phone or entry-level camera, a well-exposed standard profile beats log almost every time.

Four: how many bits per second

The capture bitrate is the budget the encoder had. A phone at 1080p might write 20 Mbps; the same phone at 4K writes 50 to 100; a mirrorless camera at 4:2:2 10-bit might write 400. Content matters more than resolution here — rain, foliage, confetti and fast camera moves exhaust a low bitrate long before a talking head does.

The tell for a starved bitrate is macroblocking: 16×16 squares appearing in the darkest and busiest parts of the frame. No amount of grading recovers it, and sharpening makes it worse.

Four decisions the camera made before you saw the fileWhole frames, or differencesIntra-frame scrubs instantly and is huge; long-GOPis small and expensive to decodeHow much colour was kept4:2:0 gives one colour sample per 2 by 2 block,which is what breaks a keyHow many levels between black and white256 per channel at 8-bit, 1,024 at 10-bit. Logstretches them thinHow many bits per secondAbout 20 Mbps on a phone at 1080p, 400 on a camerarecording 4:2:2 10-bitNone of the four can be undone in the edit. One ffprobe command answers all four, once per camerarather than once per clip.
Four decisions the camera made before yousaw the fileWhole frames, or differencesIntra-frame scrubs instantly and is huge;long-GOP is small and expensive to decodeHow much colour was kept4:2:0 gives one colour sample per 2 by 2 block,which is what breaks a keyHow many levels between black and white256 per channel at 8-bit, 1,024 at 10-bit. Logstretches them thinHow many bits per secondAbout 20 Mbps on a phone at 1080p, 400 on acamera recording 4:2:2 10-bitNone of the four can be undone in the edit. Oneffprobe command answers all four, once per camerarather than once per clip.

Read the file rather than guessing

FFmpeg is free, installs on every platform, and answers all four questions in one command:

bash
ffprobe -v error -select_streams v:0 \
  -show_entries stream=codec_name,pix_fmt,bit_rate,r_frame_rate,width,height \
  -of default=noprint_wrappers=1 clip.mp4

A typical phone answers codec_name=hevc, pix_fmt=yuv420p, bit_rate=48000000, r_frame_rate=30/1. The p in yuv420p means progressive; yuv422p10le would mean 4:2:2, 10-bit, little-endian. MediaInfo is a free graphical alternative if you would rather click.

Do this once per camera, not once per clip. The answer is a property of how the camera was set, and it will be the same for the whole shoot.

What this changes about your decisions

  • Planning a key: check chroma subsampling before the shoot, not after.
  • Planning a heavy grade: check bit depth, and turn log off if the camera is 8-bit.
  • Planning archival: your master should be intra-frame, even though the camera original was not.
  • Handed someone else's footage: run ffprobe first. It takes ten seconds and it tells you what the day is going to be like.

Today

Run the command above on the newest clip on your phone and the oldest clip you still have. Write down the four answers for each. The difference between them is usually the difference between two afternoons of work.

The one thing to keep

A camera file carries four fixed decisions — whole frames or differences, how much colour was kept, how many brightness levels, and how many bits per second — and each one sets a hard limit on what the edit can do later.

Before you move on

An editor is handed 4K phone footage of a presenter in front of a green sheet. The lighting was even and the sheet is clean, but every attempt at a key produces blocky, stepped edges around the hair. What is the mechanism?

Pick the one you would defend. Nobody sees your answer.

No ads. No data sale. No public scores on people. Ever.

© 2026 Addaly