Signal range checker
Super-black, super-white, reserved codes and gamut in broadcast and IMF masters
A grade can look fine on a monitor and still carry codes a transmission chain won’t: blacks crushed below the legal floor, highlights over the ceiling, colours that turn into R′G′B′ no display can show, or the codes the standards keep for SDI timing. Drop a ProRes, DNxHD/DNxHR, XDCAM (MPEG-2), AVC-Intra, XAVC, HEVC or JPEG 2000 master to see how much of the picture goes out, how far, and in which frames. Every frame is decoded at full precision, without the clamping most decoders apply, and measured in your browser. Nothing is uploaded.
Drop a master: ProRes, DNx, XDCAM, AVC-Intra, XAVC, HEVC or JPEG 2000
MOV or MXF. Every frame is decoded and measured in your browser. Nothing is uploaded.
What’s measured
- Luma and chroma against the nominal range: Y′ 16–235 and Cb/Cr 16–240 at 8 bits (64–940 and 64–960 at 10). Below the floor is super-black, above the ceiling super-white. EBU R 103 tolerates a margin either side (5–246 at 8 bits), and the checker says which side of it the extremes fall. Past that margin, R 103 counts it as out of gamut, flagged over 1% of the picture.
- Reserved codes: 0 and 255 at 8 bits, 0–3 and 1020–1023 at 10. BT.709 and BT.2020 keep them for SDI timing references, so in a picture they get clipped or misread.
- Gamut: each pixel converted to R′G′B′ with the file’s matrix, then checked against −5% to +105%. EBU R 103 says to flag it only when it covers more than 1% of the picture, and that’s the threshold used here.
Every figure is the share of a single frame’s pixels, and the worst frame is the one reported. Colour bars are recognised and left out, because their PLUGE goes below black on purpose. Full-range files use every code, so only gamut applies. Only the standards-based checks are made.
What isn’t checked
- Frames after damage in a long-GOP file. In MPEG-2, H.264 and HEVC most frames are predicted from others, so after a decode error the decoder patches over what’s missing until the next key frame. Those frames are left out and counted. HEVC doesn’t report damage at all, so a damaged HEVC file can’t be told from a clean one here.
- Codecs other than ProRes, DNx, MPEG-2, H.264, HEVC and JPEG 2000, and anything not in MOV or MXF.
- R 103 recommends low-pass filtering before the gamut measurement. This checker doesn’t filter, so a single sharp overshoot counts. That makes it stricter than a filtered gamut monitor, not more lenient.
- No broadcaster or streamer delivery spec. A pass here is against the published standards only.
Sources
- EBU R 103 v3.0 (2020), Video signal tolerance in digital television systems, Table 1 and Annex 1
- ITU-R BT.709-6, Parameter values for the HDTV standards, Part 2, digital representation
- ITU-R BT.2020-2, Parameter values for UHDTV systems, Table 5, quantisation
- ITU-R BT.601-7, Studio encoding parameters of digital television, Table 3
Related: HDR metadata checker (MaxCLL and MaxFALL from the picture) · line-up checker · file header reader.