Remote Color Grading and Editorial Review

When you are shooting a movie at tight schedule and need to accelerate your post production, then remote collaborative approach is a good choice. You don't need to have all professionals on-site because via remote approach you can collaborate with your teammates wherever they are located. Industry trend to remote solutions is quite clear and it happens not just due to the coronavirus. The idea to accelerate post production via remote operation is viable and companies tend to remove various limitations of conventional workflow - now the professionals could choose a place and a time to work remotely.

 

remote color grading

 

Nowadays, there are quite a lot of software solutions which could offer reliable remote access via local networks or via public internet. Most of them are built without an idea about professional usage at post production. Nevertheless, in color grading and editorial reviewing we need to utilize professional hardware which can visualize 10-bit and 12-bit frames. Most of existing video conference solutions (Skype, ZOOM, OBS) are not capable of doing that, so we've implemented a software to solve that task.

Remote color grading with existing hardware appliances

There are quite a lot of hardware units (encoding-decoding and IP streaming solutions) which together with software could offer high performance and low latency workflow to solve the task of remote color grading. These are fully-managed remote collaboration solutions for high-quality, realtime color grading, editing, digital intermediates and approvals:

  • Sohonet ClearView
  • Nevion Virtuoso
  • Streambox Chroma HD HDR, 4K HDR and DCI
  • Nimbra Media Gateway
  • VF-REC (Village Island)

These fast and quite expensive hardware appliances are not always available, especially if you are working from home. Below we present a software solution which is capable of running on conventional PC and be able to meet all requirements for remote color grading in terms of image quality, performance and latency.

How we do Remote Color Grading?

User has two screens: for the shared content and for video conferencing. The first screen is able to visualize 10/12-bit images to see the result of color grading, the other is necessary for access to remote PC, where color grading software is running.

We offer cost-effective software solution which is able to record, encode, transmit, receive, decode and visualize various transport streams and SDI signals. To ensure 24/7 operation with an ability to create and to process 2K live SDI streams with visually lossless encoding, we've applied the JPEG2000 (J2K) compression algorithm, which could be very fast on NVIDIA GPUs.

 

live remote colour grading workflow

 

This is our basic workflow for remote color grading: Video Source (Baseband Video) -> Capture device (Blackmagic DeckLink or AJA Kona) -> SDI unpacking on GPU -> J2K Encoder on GPU -> Facility Firewall -> Public Internet -> Remote Firewall -> J2K Decoder on GPU -> SDI packing on GPU -> Output device (Blackmagic DeckLink or AJA Kona) -> Video Display (Baseband Video).

Here you can see more info for live workflow

  • Capture baseband video streams via HD-SDI or 3G-SDI frame grabber (Blackmagic DeckLink 8K Pro, AJA Kona 4 or Kona 5)
  • Live encoding with J2K codec that supports 10-bit YUV 4:2:2 and 8/10/12-bit 4:4:4 RGB
  • Send the encoded material to the receiver/decoder - point-to-point transmission over ethernet or public internet
  • Stream decoding - Rec.709/Rec.2020, 10-bit 4:2:2 YUV or 10/12-bit 4:4:4 RGB
  • Send stream to baseband video playout device (Blackmagic or AJA frame grabber) to display 10-bit YUV 4:2:2 or 8/10/12-bit 4:4:4 RGB material on external professional display

That basic workflow covers just the task of precise color visualization. Color grading is actually done via remote access to a PC with installed grading software. This is not difficult to do, though we need to be able to check image quality at remote professional monitor with high bit depth.

Values for Remote Color Grading

  • Reduce the cost of remote production
  • Cut down of travel and rent costs for the team
  • Low cost and high quality solution on conventional PC to work from home for videographers and editors
  • Your team will work on multiple projects (time saving and multi-tasking)
  • Remote work will allow to choose the best professionals to work with

Technical requirements

  • High speed acquisition and realtime processing of SD, HD and 3G-SDI streams
  • Input and output SDI formats: RGB, RGBA, v210, R10B, R10L, R12L
  • Fast JPEG2000 encoding and decoding (lossy or lossless) on NVIDIA GPU
  • High image quality
  • Color control and preview on professional monitor
  • Maximum possible bit depth (10-bit or 12-bit per channel)
  • Fast and reliable data transmission over internal or public network
  • Low latency
  • OS Linux Ubuntu/Debian/CentOS (Windows version is coming soon)
  • Recommended grabbers:
    • Blackmagic 6G SDI: DeckLink Studio 4K, DeckLink SDI 4K
    • Blackmagic 12G SDI: DeckLink 4K Extreme 12G, DeckLink 8K Pro
  • Recommended GPU: NVIDIA Quadro RTX 4000 / 5000 / 6000

J2K Streamer: j2k encoder - transmitter - receiver - j2k decoder

  • High performance implementation of lossless or lossy J2K algorithm
  • 8-bit, 10-bit and 12-bit color depth
  • 4:2:2 and 4:4:4 color subsampling
  • Color spaces Rec.709, DCI P3, Rec.2020
  • SD, HD, 3G 2K resolutions and frame rates (support for UHD and 4K is also available)

Security and content protection

  • AES 128-bit encryption with symmetric key both for video and audio

It's possible to encrypt both video and audio with 128-bit AES encryption with symmetric key without any increase in a stream latency. Please note that the encryption currently ensures only confidentiality. As a hash, CRC-32 is used, so it doesn't guarantee cryptographical integrity.

Low latency transport for realtime streaming

  • From 300 ms to 1 sec end-to-end latency
  • Public internet and/or fiber networking for remote sessions
  • 10 to 250 Mbps bit rates

Maximum performance for JPEG2000 compression and decompression features could be achieved with multithreading at batch mode. This should be done to implement massive parallel processing according to J2K algorithm. At batch processing mode we need to collect several images, which is not good for end-to-end latency. Here we have a trade-off between performance and latency for the task of JPEG2000 encoding and decoding. For example, at remote color grading application we would be interested to have minimum latency, so we need to process each J2K frame separately, without batch. Though in most cases it's better to choose acceptable latency and get the best performance with batch and multithreading.

Performance measurements

Currently, our J2K encoder is faster than J2K decoder, so total performance is limited by J2K decoding. On NVIDIA Quadro RTX 6000 the software can offer 24 fps and more for 4K resolution at 12-bit with 4:4:4 subsampling. In the case with 2K resolution, the software could achieve more than 60 fps. The performance depends on GPU model and on parameters of J2K encoding, etc. We suggest to test network bandwidth and software latency to choose the best parameters.

Competitors

Our software is offering an approach for low-latency remote color grading. Please note that this is not actually the software for color grading. This is the solution to work remotely with conventional grading, VFX and post production software like Blackmagic Davinci Resolve, Adobe Premiere Pro, AVID Media Composer, Baselight, etc. We don't compete with these color grading applications at all.

We would recommend to utilize TeamViewer, AnyDesk, Google Remote Desktop, Ammyy Admin, Mikogo, ThinVNC, UltraVNC, WebEx Meetings, LogMeIn Pro, which could offer remote access to color grading software, but they are able to work with just 8-bit color frames instead of 12-bit color. This is the key difference. As soon as for high quality post production we need to work with 12-bit color, that requirement is essential and the task or low latency solution with acceptable compression ratio is very important. Still, any software from the above list is useful to ensure an access to remote PC.

Hardware-based solutions like Nevion, Streambox, Sohonet are our competitors as well. These are reliable and very expensive solutions. Our approach needs less hardware and could offer high quality, low latency and cheaper solution for remote color grading and post production.

Other info from Fastvideo about J2K and digital cinema applications

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