HDR video basics
High dynamic range stores brighter highlights, deeper shadows and more colours than standard video. It only looks that way when every link in the chain agrees.
HDR video stores a wider range of brightness and colour than standard video (SDR). It uses the PQ or HLG curves from ITU-R BT.2100, 10-bit samples and the wider BT.2020 colours. It needs an HDR screen, an HDR-ready codec and correct metadata from end to end. If any link is missing, the picture is converted to SDR or looks washed out.
Standard video has described light the same way since the days of tube televisions. It has a narrow range of brightness, a modest set of colours, and eight bits per sample. Cameras and screens moved on long ago. High dynamic range, or HDR, is the set of standards that lets video carry what they can now capture and show. A candle flame and a sunlit window can sit in the same frame, with colours that standard video had to clip.
HDR is also the quality feature most likely to go wrong. It works only when the file, the codec, the player, the operating system and the display all agree on what the numbers mean. This guide explains the pieces in plain terms and names the formats you will meet. It shows why HDR so often looks grey and flat on the wrong screen. It also gives practical advice for uploading HDR footage to a platform whose ladder, like VideoBB's, is H.264. The other quality settings are covered in the video quality hub.
SDR, and what it left out
Standard dynamic range video follows ITU-R BT.709. Its colour gamut, or range of colours, was chosen to match the phosphors of broadcast monitors. Its transfer curve was designed around a reference display. In practice it uses eight bits per sample, giving 256 steps from black to white. Reference SDR displays are conventionally graded around 100 candelas per square metre. Real scenes span far more. A bright sky is thousands of times brighter than a shadow, and a modern phone screen can already exceed 1,000 cd/m² in a highlight. SDR handles the gap by squeezing highlights and clipping the brightest values. Colours outside the gamut collapse to its edge. That is why sunsets in SDR turn to bands of orange and neon signs lose their glow.
SDR versus HDR at a glance
| SDR | HDR | |
|---|---|---|
| Standard | ITU-R BT.709 | ITU-R BT.2100 |
| Colour gamut | BT.709 | BT.2020 |
| Transfer function | BT.709 camera curve, BT.1886 display | PQ (SMPTE ST 2084) or HLG |
| Bit depth | 8 bits per sample in delivery | 10 bits minimum |
| Peak brightness | Graded around 100 cd/m² | PQ signals up to 10,000 cd/m²; displays vary |
| Delivery codecs | H.264, H.265, VP9, AV1 | H.265 Main 10, VP9 profile 2, AV1 10-bit |
PQ and HLG: two ways of describing light
BT.2100 defines two transfer functions, and every HDR format uses one of them. A transfer function maps stored numbers to real brightness. Perceptual Quantizer (PQ), standardised as SMPTE ST 2084, is absolute. Each code value stands for a specific brightness, up to a nominal 10,000 cd/m². The display is expected to reproduce it or map it down. That precision is why PQ formats carry metadata about the mastering display and the content's brightest values. A less capable screen then knows how far it must compress.
Hybrid Log-Gamma (HLG), developed by the BBC and NHK for broadcast, is relative. It describes brightness as a share of the display's own peak and needs no metadata. It also degrades gently on SDR screens, because its lower half resembles a normal gamma curve. Phones commonly record HLG-based HDR; streaming services and discs mostly deliver PQ.
HDR formats you will meet
All four sit on top of BT.2100. The differences are metadata and licensing.
PQ with static metadata (mastering display and MaxCLL/MaxFALL). Open, and the baseline that every HDR display supports.
HDR10 plus dynamic metadata that can change scene by scene, so tone mapping adapts. Royalty-free; support varies by display.
PQ with proprietary dynamic metadata and several profiles. Widely supported on televisions and Apple devices; licensed.
No metadata, broadcast-friendly, and what many phones record. Looks acceptable on SDR displays that ignore the HDR signalling.
Why HDR looks grey on the wrong screen
An HDR file stores brightness on a different scale from SDR. Show it on a display or through a pipeline that does not know this, and the values are read as if they were SDR. The middle of the PQ curve, where most of the picture lives, lands as a dull mid-grey. Highlights look flat and colours look faded. That washed-out look is the mark of missing or ignored metadata. Viewers see it when a browser or an embed decodes an HDR file without tone mapping. The opposite failure, oversaturated and crushed, happens when SDR content is wrongly flagged as HDR. Neither is a fault in the footage; both are a mismatch in signalling somewhere along the chain.
Codecs, containers and browsers
HDR needs ten bits per sample. H.264 has a 10-bit High profile, but it is almost never used for HDR delivery, because hardware decoders and players do not expect it. In practice HDR travels as H.265 Main 10, VP9 profile 2 or 10-bit AV1. The colour primaries, transfer characteristics and matrix coefficients are signalled in the stream. The static or dynamic metadata travels alongside. Browser and device support is uneven. Safari on Apple hardware plays HDR HLS. Chrome and Edge play HDR VP9 and AV1 on displays and operating systems that support it. Many other combinations silently fall back to SDR. The codec comparison covers what each codec supports, and the container guide explains where the signalling lives.
Uploading HDR footage to VideoBB
VideoBB's public encoding ladder is H.264, so plan for SDR delivery. The best result comes from doing the conversion yourself before upload, where you can see it, rather than leaving an HDR file to be interpreted by an SDR pipeline. Grade an SDR version in your editor from the HDR timeline, or tone-map with FFmpeg: ffmpeg -i hdr.mov -vf "zscale=t=linear:npl=100,format=gbrpf32le,zscale=p=bt709,tonemap=tonemap=hable:desat=0,zscale=t=bt709:m=bt709:r=tv,format=yuv420p" -c:v libx264 -crf 18 -c:a copy sdr.mp4. The filter chain converts to linear light, maps the highlights down with the Hable curve, and re-encodes as BT.709 8-bit 4:2:0. Check the result on an ordinary screen: skin tones and skies are where tone mapping goes wrong first.
Keep the HDR master. Delivery standards move, and a graded HDR original is the version you will want when they do. The preparation guide covers the rest of the export, and upload accepts the resulting file at up to 4 GB.
HDR checklist before you commit
- Every viewer's display, operating system and browser must support the HDR format; assume many will not.
- The player and host must preserve 10-bit samples and the transfer signalling; an H.264 ladder will not.
- The grade must be checked on both an HDR and an SDR display, because most viewers will see the SDR version.
- Metadata must survive the export; a PQ file without its static metadata is what causes the grey look.
- For web delivery today, an SDR master graded from the HDR original is the safe deliverable.
Where HDR is going on the web
Support is improving from the display side upward. Most new televisions, phones and laptops can show HDR, and codecs with 10-bit profiles are now decodable in hardware on most of them. What lags is the delivery chain: hosting ladders that keep two versions of everything, players that detect capability and switch, and browsers that agree on how to signal it. Until that settles, the practical plan for anyone publishing on the web has three parts. Shoot and master in HDR if the camera allows. Deliver SDR that you have checked yourself. And keep the master. The resolution comparison and the bitrate guide cover the other two quality decisions that, unlike HDR, pay off for every viewer today.
Frequently asked questions
Can I upload an HDR file to VideoBB?
You can upload any file in the accepted containers, HDR included. The public encoding ladder is H.264, so viewers receive an SDR stream. For the best-looking result, do the tone mapping yourself in your editor or with FFmpeg before uploading. Then you can check skin tones and highlights on an ordinary display rather than trusting an automatic conversion.
What is the difference between HDR10 and Dolby Vision?
Both use the PQ transfer function and 10-bit or higher samples. HDR10 carries static metadata that describes the whole programme once. Dolby Vision carries dynamic metadata that can change per scene or per frame, so the display can tone-map more precisely. Dolby Vision is a licensed format with several profiles. HDR10+ is an open alternative with dynamic metadata.
Why does my iPhone video look washed out on my computer?
iPhones have recorded HDR video by default for several generations, using an HLG-based Dolby Vision profile. Played on a display or in software that does not interpret the HDR signalling, the footage appears flat and grey. Convert the clips to SDR before editing for SDR delivery, or set the camera to record SDR when you know the destination.
Is 10-bit the same as HDR?
No. Bit depth is the number of steps between black and white; HDR is the range those steps cover and the transfer function that maps them to light. Ten-bit SDR exists and is useful for grading because it reduces banding in gradients. HDR requires ten bits because its wider range would band badly at eight, but ten bits alone does not make a file HDR.
Sources
- ITU-R BT.2100: Image parameter values for HDR television — Defines PQ, HLG, and the HDR colour and bit-depth parameters.
- ITU-R BT.2020: Parameter values for UHDTV — The wide colour gamut used by HDR video.
- ITU-R BT.709: Parameter values for the HDTV standards — The SDR gamut and transfer characteristics.
- FFmpeg filters documentation: tonemap — The tone-mapping filter used to convert HDR to SDR.
- MDN: Web video codec guide — Codec profiles and HDR support notes for browsers.
Related guides
H.264 vs H.265 vs AV1
One codec plays on everything, one halves the bitrate but carries licensing baggage, and one is royalty-free and gaining ground. How to choose between them for encoding, upload and delivery.
Container vs codec
A file extension names the wrapper. The codec is the compression inside it. Confusing the two is the root of most playback failures, and telling them apart takes one command.
Prepare video for upload
The right export is smaller, uploads faster, is accepted without complaint and transcodes cleanly. It is not the highest possible quality and it is not the smallest file. Here is the middle.
4K vs 1440p vs 1080p
Four times the pixels is not four times the sharpness. What each resolution costs to upload, encode and stream, and when a viewer can tell the difference.