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· by OpenIPC team

An open decoder for China's video standard, and an open ISP for Xiongmai

Cameras encode SVAC 3.0 now and we wrote the decoder for it, faster than the vendor's; the XM510 got an open image pipeline whose white balance beats the factory one; and five more chip makers arrived in the emulator.

A camera can now record in SVAC 3.0, and we wrote the decoder

SVAC is China's national video standard for security systems, and its third edition is not even ratified yet — it is a public-comment draft. Cameras on the Hi3516CV6xx encode it now and serve it over RTSP, and libsvac3d takes that stream apart. It plugs into FFmpeg, so anything can play it.

The decoder is written from the draft's text. Where that text disagrees with what real streams need, docs/errata.md records what the decoder does instead and why. Every picture of the test corpus decodes bit for bit as the reference decoder does.

It is also faster than the vendor's decoder. On one thread it is ahead on every clip, and on four the gap opens up: ours takes 0.95 s on the heaviest clip against the vendor's 1.40, and 1.59 s against 1.76 on a 2560x1440 one. Inside are hand-written SIMD kernels for x86 and ARM, an entropy decoder of our own, and several pictures decoded at once — and whatever the thread count, the bits that come out are identical.

We also measured what SVAC3 buys in compression, on one chip and the same clips. The answer is sobering: against H.265 it saves between 0 and 6%, which puts it in the same class. Choose it to comply with Chinese requirements, not to save bandwidth. For comparison, H.264 asks for 10-21% more than H.265 on those clips.

An open ISP for the XM510, and its white balance is better than the factory one

The ISP is the part which turns the raw numbers off the sensor into a picture, and on Xiongmai it was closed. There is a daemon of our own now: auto-exposure, auto white balance, noise reduction and sharpening by gain, suppression of the banding mains lamps leave, calibrated colour matrices, and a framework for sensors with six already in it. Verified on two live boards: the lab XM510 with a JX-H62, and a 53X13 board with an AR0130.

The white balance turned out more accurate than the factory one. In an ordinary room in daylight the vendor's drifts cyan: it takes dim wood, a beige and orange chair for grey, sets its gains by them, and the real grey patches of a colour chart end up at R/G 0.35. We raised the brightness above which a pixel counts as grey at all and now count only the bright ones; the whole-frame result then lands within 5% of the chart's grey. And when there are fewer than three hundred bright grey pixels the ISP holds the gains it has rather than hunting — otherwise, in the first frames before exposure has brought the picture up, it would fall into the same cyan trap itself.

How it was done is the interesting part: the factory ISP's behaviour was traced in our own emulator. The digital twin has stopped being a demonstration and become the tool you reverse-engineer with. It is all in openxiongmai.

Five new makers in the emulator

Allwinner, Fullhan, Grainmedia, more Xiongmai and SigmaStar all arrived in qemu-bench at once. Not merely "the kernel boots", either: a YI camera dump on an Allwinner V831 comes up off its own flash with networking, an SD card and a coded picture; a retail camera dump on a SigmaStar MSC313E serves H.264 over RTSP; and Sofia on the XM530V200, XM533 and XM535 serves H.265 to the same place.

The unified bootloader repository took in Ingenic

That is a different architecture, MIPS, and the T40 and T41 are the first to build, NAND images included. Images for the XM V200 series landed in OpenIPC/u-boot too.

The line drawn over the video became programmable

It used to take the time and a name. It now takes any value the camera knows about itself — the die temperature, the shutter, its name, its address, its uptime, a meter reading. Your own value goes in a file and the camera draws whatever is in it, so anything a script on the camera can write can go on the picture. The web interface lays all of it out as buttons, and the camera itself supplies the list of what is available.

Also

  • A pan/tilt head has presets. Store a position, go back to it, delete it — from the pad in the browser, over ONVIF and over DVRIP.
  • Meter reading reached a working state. The reading can be drawn straight onto the video as a line of its own. The camera waits out a drum mid-carry instead of writing nonsense at that moment, the count survives a restart, the window adjusts itself if the camera is turned a little, and what the meter is busy with shows up on /metrics.
  • Image stabilisation works on SigmaStar now, and its effect is measured off the video rather than asserted.
  • The board catalogue grew by several hundred entries: Anjoy Vision's own archive and 59 more modules, Haixin Weishi's modules, the CamHi catalogue. Plus detailed notes from the community — Tino Darkness worked through 46 Anjoy boards, with photographs and pin-1 markings.
  • You can merge two of your own Club accounts into one if you signed in through Telegram one day and GitHub the next.
  • The GK7201V200 is brought up to where the GK7205V200 is, and openingenic fixed the ISP accessors on the T30.
  • OpenIPC has been an Associate Member of the Linux Foundation since August last year, which the footer of every page now says.