4k 10bit Line Test

This is a companion article in which we explore the viability of creating 10bit content. We researched and devised test content to determine which codec will bring us the best visual result, at the fastest render time, allow for server side compositing, and not instantly fill up very valuable media server storage space.

In this summary piece we document the test itself listing out the intention, the workshop parameters and the hardware used to conduct the test.

For the main article see the original entry here: https://dandelion-burdock.com/articles/10bit-workflow-viability

Proof of technical delivery and ensuring signal integrity from the playback device, through a signal router, fibre transmission/reception, to the projector at 4096x2160 (4k DCI), 10bit, 4.2.2, 60Hz.

The full line test was conducted at Christie Europe, April 2019. Video playback (disguise), signaling (Lightware), projection(Christie Digital) and workflow professionals (dandelion+burdock) were present at this test.

All media displayed was created by dandelion+burdock LLC, to comply with DPX 10bit 4096x2160 pixel image sequence played back at 60 frames per second. The media reel only contains generic material. This reel was made for the purpose of 10bit signal testing.

The projector was set to about 35% output, at a throw distance of about 4m, onto a white projection canvas. We measured a consistent 4637K color temperature, 3380 Lux (direct illumination).

• Media Server
  • disguise VX4, 4x HDMI 2.0 VFC output card, Windows 10 Enterprise 64bit (17763)
  • Disk image: OS image version: 91 / Windows-8-6.2.9200
  • D3 build: r15.2.2, rev 55428
• Output 10bit proofing monitor
  • BenQ SW320 (4k UHD, 10bit, HDMI 2.0, 60Hz)
• Media Server GUI monitor
  • ASUS PB27U (4k UHD, 10bit, HDMI 2.0, 60Hz)
• 4K Switching Router
  • Lightware MX2 24x24 HDMI 2.0 Matrix router
  • Firmware version: 1.3.5b2
• Projector
  • Christie d4k40rgb projector
  • Firmware version: d4k40-RGB 1.1.0
  • Projector settings: DCI 4069x2160@60 10-bit | bt709 | HDR-PG smpte 2084
• Fibre Transmitter/Receiver
  • Lightware HDMI 2.0-OPTJ-TX-90/ HDMI 2.0-OPTJ-RX-90
• HDMI 2.0 cable
  • Club 3d / 17.8Gbps compliant / 1 + 2 meter variant
• HDMI 2.1 cable
  • Club 3d / 48 Gbps compliant / 1 meter
• Fibre
  • FS Aqua OM3 Multimode SC/UPC (Square Connector)
• Camera
  • Canon EOS 600D at 35mm f2.1-11 (56mm full chip equivalent)
• Radiometer
  • Konica Minolta CL200A
• Miscellaneous Items
  • USB peripherals, Control Laptop for Christie Software Tools

For all 10bit verification steps, a high bit depth, high resolution version of the below image, excluding the overlaid key, was employed.

For each step up the possible steps of grey increase by a power of 2. If there is banding in the top two steps, which is similar to the 8Bit row, only 8bit signal depth has been achieved. If the two top steps become finer progressively, the signal is transferred and displayed at 10Bit.

The following tests were conducted in the order presented. The intention was to verify the signal flow and performance with each more complex step. We outline the flow and involved hardware, followed by any issues and the appropriate resolutions.

10bit signal proof and DPX sequence playback from media server to 4k UHD monitor, via direct HDMI cable (2m maximum cable length)

• Result: Positive
• Requirements: EDID and 3D-Caps management in ATI/Windows

10bit signal proof and DPX sequence playback from media server to 4k UHD monitor and 4k DCI projector, via 2 discreet direct HDMI cables (2m maximum cable length)

• Result: Positive
• Requirements: EDID and 3D-Caps management in ATI/Windows
• Issue: Initial connection of projector defaulted to UHD resolution (3840x2160@60 10-bit)
  • Solution: Release and re-engage EDIDs on the Media Server/ATI/Windows to establish full DCI 4096x2160@60 10-bit, reported in disguise and on the Projector Input Card.
• Issue: Projection color display too vibrant compared to the reference monitor.
  • Solution: Projector color space set to Rec.2020 full range. Gamma: PG (HDR 10) smpte 2084.
• Issue: Projector colors at Rec.2020, required color management in disguise. Interpreting DPX in the media server as Rec.2020 dropped the overall image intensity and saturation.
  • Solution: Setting Christie D4K40 and disguise to Rec709 to look consistent throughout.
  • Explanation: While all source media was managed at Rec.2020 color space, DPX images contain a half float representation of RGB, without embedded color profiles. The color space for playback was choses in the Media server and tested at Rec.709 and Rec.2020. Color management is therefore possible.

Please note that the final projection will hit colored and textured surfaces. Therefore the projected image’s color changes, and will not comply with colorimetry as per official standards (see section 5.1/ Material Testing).

10bit signal proof and DPX sequence playback from media server to 4k UHD monitor directly, and 4k DCI projector, via 4k HDMI Video Matrix, with input and output HDMI cables (2m maximum cable length), 2x DCI 4k output from disguise Server to the Matrix, 1x DCI 4k to the projector, 1x UHD 4k to the reference monitor

• Result: Positive
• Requirements: EDID and 3D-Caps management in ATI/Windows, Lightware EDID Emulation
• Issue: Connecting the reference monitor via Lightware MX2 HDMI matrix resulted in a down converted 8-bit UHD signal.
  • Solution: updating DCI 8-bit EDID on the Lightware matrix to DCI 10-bit. The EDID information display in the matrix software is based on info frames and therefore did not conclusively quote a 10bit header. The signal was proven via the greyscale 10bit test pattern.

• Issue: Second disguise HDMI output connection to matrix reported the correct EDID, DCI 4k 10-bit when connected, but showed up in the disguise Server ATI/Windows as 8-bit.
  • Solution: Changing AMD settings, to high bandwidth and no 3D-Caps for each output individually.

• Issue: First time connecting Lightware HDMI DCI 4k to Christie D4K40, the projector displays a black HD frame,while the signal reports correctly in the matrix and on the reference monitor. In some cases the projector input card locks to older or incorrect settings and freezes the output and menu for the respective input.
  • Solution: Reseating the input card reboots the input card and the projector locks to the correct signal. A full power cycle of the projector has the same effect.

D

10bit signal proof and DPX sequence playback from media server to 4k UHD monitor directly, and 4k DCI projector, via 4k HDMI video matrix switcher, with input HDMI cable (2m maximum cable length), output via HDMI>Fibre transmitter, via OM3 fibre, to Fibre>HDMI receiver.

• Result: Positive
• Requirements: EDID and 3D-Caps management in ATI/Windows, Lightware EDID Emulation, Fibre Connection, USB power for the Fibre receiver.
• Observation: Replacing HDMI cable with OPTJ-RX/TX and OM3-SC fibre works instantly.
• Observation: The HDMI Fibre receiver OPTJ-RX can be mounted to an empty input card slot on the D projector safely and receive USB power from the unit.

E

10bit signal proof and simultaneous DPX sequence/10bit VideoCodec/8 bit VideoCodec playback from media server to 4k UHD monitor directly, and 4k DCI projector, via 4k HDMI video matrix switcher, with input HDMI cable (2m maximum cable length), output via HDMI>Fibre transmitter, via OM3 fibre, to Fibre>HDMI receiver.

• Requirements: EDID and 3D-Caps management in ATI/Windows, Lightware EDID Emulation, Fibre Connection, USB power for the Fibre receiver. Content in 10/8bit.
• Method: playback of the same media in the disguise server to the same outputs. While cropping HAP (8bit video) to the left-hand third, NLC (10bit video) to the centre third, and DPX image sequence to the right-hand third of the canvas.
• Results:
  • Playback speed continues at 60Fps on the media server at 3x 4k DCI media.
  • All sources display a good color rendering in Rec.709
  • HAP (8bit) video exposes banding throughout and slight gamma drift in dark sections
  • NLC (10bit/SSIM error around 0.0002) video displays perceptively alike to DPX.

Conclusion

The proposed projection solution, with playback and switching hardware fulfills the video specification, for 60Hz/60Fps 4k DCI playback at 10bit, 4.2.2.

Delivering 10Bit is a working reality, but it does currently require some ATI setup, and images on the projectors look stunning in higher bit depth. Lightware is providing a solid 4K switching and transmission solution.

The disguise VX4 playback load on DPX is fairly high - while playing 2 layers (4096x2160, 60fps) of DPX was successful, further compositing dropped frames. Testing 10bit NotchLC however suggests a lot more throughput at 20% of the DPX size. The team present at our test was not able to pick out the difference between NotchLC and DPX in moving video.

Thank You

Felix, Malis, Joe, Pal, Joao, Peter, Richard, Thomas