Almost everything sold as “VR” is sold on a word rather than on a property of the file. This page explains what the property actually is, what the numbers on a product page mean, and why a figure like “8K” means something completely different here than it does on a television box. None of it is complicated. It is just never explained, because explaining it would make a lot of catalogues look thin.
Three things have to be true of the file
A clip is made for a headset when three separate properties hold at the same time. They are independent of each other, and a file can have one or two of them and still be useless in a headset.
- A wrapping projection. Ordinary video is a flat rectangle. A headset file is a piece of a sphere. The picture is stored so that a player can paste it onto the inside of that sphere and let you turn your head inside it. Without this, the video is a rectangle floating in front of you — a cinema screen, not a place.
- Two eye images. Depth is not a filter. It exists because your left eye and your right eye see slightly different pictures, and your brain reads the difference as distance. A file that carries one picture has no depth in it, and no software can invent the missing one convincingly. It will look like a very large photograph wrapped around you.
- Native capture. Both of the above can be faked after the fact by converting flat footage. The result has a wrapping projection and two eye images, and still looks wrong, because the two images were computed from one and the geometry does not match what your eyes expect. Converted material is the single most common thing sold as VR in small niches.
VR180 and 360 — and why 180 is usually the better choice
The two common shapes are 180 degrees and 360 degrees. A 360 file surrounds you completely; a 180 file covers the half-sphere in front of you. It sounds as though 360 is simply more, and for a landscape it is.
For anything with performers in it, 180 is normally the better trade, for two reasons. The first is that the crew, the lights and the rest of the room are behind the camera, and in a 360 shot there is nowhere to hide them. The second is arithmetic: the same pixels stretched over twice the angle are half as dense. A 360 file has to be roughly twice the size of a 180 file just to look equally sharp, and it is spending that budget on a hemisphere you are facing away from.
Side by side, and why one number is really two
The usual way to store two eye images is to put them next to each other in one frame: left eye in the left half, right eye in the right half. That arrangement is called side-by-side, and it has one consequence that explains most of the confusion around VR resolution.
If a file is 7680 by 3840, each eye does not get 7680 pixels across. It gets 3840 — half the width. The advertised number is the number for both eyes together. So a “4K VR” clip delivers about 1920 pixels to each of your eyes, which is a 1080p picture per eye, spread across your whole field of view.
The number that actually decides sharpness
The useful measure is not the pixel count. It is how many pixels land in one degree of what you see. Call it pixels per degree. Your headset has a fixed ability here: a current standalone headset resolves somewhere around 20 to 25 pixels per degree at the centre of view. Feed it fewer and the picture is soft no matter how good the camera was; feed it far more and you are paying for detail the display cannot show.
A VR180 file spreads each eye’s width across 180 degrees. That gives a very unflattering set of numbers, and they are worth stating plainly:
- 8K side-by-side (7680 × 3840, so 3840 per eye) — about 21 pixels per degree.
- 6K side-by-side (5760 × 2880, so 2880 per eye) — about 16 pixels per degree.
- 4K side-by-side (3840 × 1920, so 1920 per eye) — about 11 pixels per degree.
- 2K side-by-side (1920 × 960, so 960 per eye) — about 5 pixels per degree.
Read that against the headset’s 20 to 25 and the picture changes completely. 8K is not excessive here. It is roughly the point at which the file stops being the limiting factor. 4K, which sounds generous, delivers less than half of what the display in front of your face can resolve, which is exactly why so much VR material looks like a soft, slightly smeared version of a scene rather than a scene.
Why the same word means something else on a television
Put a flat 4K video on a virtual cinema screen in the same headset and it looks sharp. Same file size, same word on the box, completely different result. The reason is the denominator.
A virtual screen occupies maybe 60 degrees of your view, not 180. Those 3840 pixels across 60 degrees work out at roughly 64 pixels per degree — two and a half times more than the headset can resolve. The flat file has pixels to spare; the VR file of the same name is starved. It is the same number describing two entirely different densities, and nobody selling VR has any incentive to point that out.
This single fact explains most disappointed first VR purchases. The buyer is not imagining the softness, and the producer did not necessarily lie. The word simply does not carry the meaning the buyer brought to it.
Codecs, and why the player you use changes what you get
A frame that large has to be compressed hard, and not every device can decode every method. Three are in common use.
- H.264 is understood by everything, and that is its only advantage. At these frame sizes it is inefficient, and most headset browsers refuse it above roughly 4K, so it cannot carry the top rungs at all.
- HEVC handles 8K comfortably and is what dedicated VR players decode natively. Ordinary browsers — including the browser built into a headset — frequently will not touch it.
- AV1 is the newer option, decodes 8K in current headset browsers, and needs meaningfully less bandwidth for the same picture. Older hardware cannot decode it in hardware at these sizes.
The practical consequence is that a well-built title carries several versions of itself, and that the version you receive depends on the player you opened it with. Two people can buy the same clip, one watches in a dedicated player and one in a headset browser, and they can legitimately see different quality. That is not a fault. It becomes a fault when only one version exists and the rest of the sales page implies otherwise.
What a serious delivery looks like
A title built properly is not one file. It is a set of steps, and the player picks one based on your connection and your hardware, switching as conditions change. A complete set for VR180 looks roughly like this — the figures are the ones used by the shop this directory points at:
- 8K HEVC, 7680 × 3840, around 55 Mbit/s — for a dedicated player on a fast connection.
- 8K AV1, 7680 × 3840, around 40 Mbit/s — the same picture for a headset browser, which cannot decode the rung above.
- 6K HEVC, 5760 × 2880, around 35 Mbit/s.
- 4K H.264, 3840 × 1920, around 24 Mbit/s — the compatibility rung that any device can play.
- 4K HEVC, 3840 × 1920, around 18 Mbit/s.
- 4K AV1, 3840 × 1920, around 14 Mbit/s.
- 2K, 1920 × 960 — the emergency rung for a bad connection.
- A flat 1080p version — one eye, ordinary rectangle, for watching without a headset at all.
Eight versions of one clip is a lot of encoding, and that is precisely why most small producers ship one file and call it VR. There is nothing dishonest about shipping one file. There is something dishonest about advertising the top rung and shipping the bottom one, which is a different problem and the subject of another page here.
Frame rate, and the part that makes people ill
Judder that would pass unnoticed on a monitor is unpleasant in a headset, because the image is locked to your head and your inner ear has an opinion about it. Sixty frames per second is comfortable. Thirty is watchable when the camera does not move, which in VR180 it usually does not, and is the reason a fixed camera is not merely a production constraint but a kindness.
The related rule is that a VR camera should not move at all unless there is a very good reason. Your body knows it is sitting still. A moving viewpoint contradicts that, and the contradiction is what makes people take the headset off.
The honest summary
VR is not a better picture. It is a different one, with a much harsher pixel budget, and it only pays off when the file is built for it from the camera onward. A converted flat clip, a single 4K file, or a scene shot for editing rather than for presence will all disappoint, and none of those failures are visible on the product page.
Which is why the next question is not what to buy but how to tell what you got. That is on the check your file page, and the practical side of watching — headsets, players, getting a file onto the device — is on how to watch.