A SDI router can be used for remote monitoring, troubleshooting, and remotely switching in external processing elements when necessary.
Broadcasters and local newscasts using the internet for physical distancing are the TV engineering topic of the moment.
Cobalt Digital recently produced a webinar focused on the latest in HDR technologies, transport streams and remote monitoring and management. Much of the information was presented by Dr. Ciro Noronha, executive vice president of engineering at Cobalt Digital. His presentation has been edited to bring the newest internet contribution and monitoring information to the top of the story.
In terms of digital video encoding, consumer-grade is 4:2:0, 8-bit. Contribution-grade is 4:2:2, 10-bit. HDR is 4:2:0, 10-bit. Most professional encoders and decoders support 4:2:2/4:2:0, 8-bit/10-bit. Full ancillary data support is also necessary for professional use for closed captioning, active format description (AFD), SCTE-104, SMPTE ST-2108 for HDR and ST-2038 for other ancillary data.
People outside the studio can send contribution-grade A/V to a professional receiver and use the internet as a low-latency, cost-effective contribution link. Stations can send a consumer-grade version of the content with higher latency for remote monitoring purposes, easily seen on tablets, computers, smart TVs and phones. Doing so requires encoders and decoders with the right feature sets.
Some people want to generate multiple versions of the same input using a built in down-scaler to generate one version for production and another at lower resolution for remote monitoring. Most professional encoders and decoders support everything from SD to UHD HDR. Professional codec systems must support HLS and RTMP to generate streams that are CDN-compatible, receivable on multiple consumer-grade devices, and they must support secure communications.
Professional encoders and decoders must use RIST or a similar protocol to make the internet a reliable, low-latency contribution link. RIST is the interoperable, multi-vendor, open protocol developed by the Video Services Forum (VSF) for video transport over unmanaged networks. The VSF also published the TR-03 and TR-04 recommendations which later became part of ST-2110.
In a RIST enabled system, if a packet is lost the decoder asks the encoder to send it again. The buffer adds no latency to the transmission, but it manages compensating for the round-trip delay if packets are retransmitted. RIST is an industry specification. It is not a standard, but Dr. Noronha said it will be eventually.
The RIST Main Profile adds tunneling that allows the use of a single UDP port for all communication and opens the firewall at either the encoder or decoder side. RIST encryption is at the same level as bank transactions on the web. Authentication controls who can connect to the equipment.
Remote Monitoring and Management
Virtually every device today is managed and controlled through a network connection. The key is to design your infrastructure with the flexibility to switch in/out processing resources as necessary, and to be able to monitor signals at different stages in their paths.
An easy way to accomplish this is with a SDI router. The multiviewer can be encoded for a consumer-grade remote monitoring connection. By wiring processing devices into the system using device inputs as router destinations and device outputs as source inputs on the router, processing such as up/down/cross and frame rate conversion, audio processing and HDR can be switched in and out remotely.
Similarly, test equipment with a rasterizer SDI output can be similarly wired into the SDI router for remote observation and troubleshooting. Two Cobalt Digital products are specifically designed for remote test and measurement. One is the 9978-ANC-MON ancillary data monitoring probe. Through DashBoard, it shows not only the picture with VU meters, but also other critical data such as captioning and loudness, and it provides full status forwarding using IP/SNMP.
The other T&M device is the 9960-TG2-REF1 dual test signal generator, featuring two independent channels with moving box, CC and SCTE-104. It too provides full status forwarding using IP/SNMP.
HDR production begins by converting SDR sources to HDR and ends with 10-bit HEVC encoding for broadcast and 8-bit AVC for legacy SDR devices.
HDR Production Tools
How do productions mix HDR and SDR sources to produce in HDR? SDR sources can use Inverse Tone Mapping (ITM) to create a HDR signal. Cobalt uses licensed Technicolor SL-HDR1 Processing to create SDI with ST2108 metadata to recreate HDR, much as color was added as a subcarrier to the black and white baseband video signal.
Technicolor’s suite of HDR conversion tools for this task is informed by deep learning from Technicolor’s years of Hollywood colorimetry experience. Video is analyzed frame-by-frame in real time to make adjustments more quickly than a human operator could. As lighting conditions change over the course of a broadcast, the human operator can focus on other parts of the production.
In manual mode, the Technicolor ITM SDR to HDR controls give the user the ability to adjust the ranges between shadows, midtones, and highlights in the content. A preset mode provides 28 preconfigured settings differentiated by brightness and contrast. In auto mode, the Technicolor algorithm will adjust settings frame-by-frame in real time according to the incoming content. Fine-tuning adjustments can be made to the unit at the beginning of an event, but after that the ITM process will make any adjustments due to changing lighting conditions during the event.
The 9904-UDX-4K 12G/6G/3G/HD/SD UHD Up/Down/Cross Converter/Frame Sync/Embed/De-Embed Audio Processor is Cobalt Digital’s next generation of advanced scaler/frame synchronizers for the openGear platform. It is used to process the HDR sources, SDR sources, and to process the line output to the 9992-ENC for 10-bit SDR with HDR metadata for HEVC encoding. A 9223 is used to encode the legacy 8-bit SDR MPEG-4 AVC stream. The TV set uses the SL-HDR metadata to reconstruct the HDR signal for display.
Static conversion from SDR to HDR or HDR to SDR can be done via a 3D-LUT file. The 3D-LUT file maps the color space and applies the appropriate EOTF transfer curve. This mapping is applied to all the frames of video regardless of the signal. The Cobalt 9904-UDX-4K is able to insert static LUTS with the +3DLUT-PRO and +3DLUT-4K options. Adding the +3DLUT-BBC option allows the card to come preconfigured with standard LUTs suggested by the BBC for professional broadcast.
Dynamic conversion takes a static LUT as a base and it allows the user to customize the look and feel of the content in real time. Dynamic Intelligent Conversion by Technicolor uses an algorithm to automatically compensate for changing lighting conditions during a broadcast.
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