The Insider’s Guide to Live 4K
4K Production Over the Internet
LIVE PRODUCTION OVER IP – 4K READY SET GO!
Whether they’ve planned for it or not, broadcast engineers, OB van operators, and all types of television producers must now
contend with an increasing demand for 4K UHD content. Although the majority of live television broadcasts remain in HD or
even SD, 4K UHD screens are beginning to outsell HD displays. The increasing pressure to differentiate and deliver premium
service quality for UHD screens is resulting in a growing concern among broadcast professionals that they will fall short once
a call comes in to deliver 4K content.
While some broadcast engineers may decide to make a complete switchover to 4K UHD workflows or to add a separate 4K
UHD video production unit, the majority will need to continue delivering HD services while also producing more 4K content. As
they have already invested a significant sum in their HD broadcast gear, they will therefore also need to consider how to deliver
4K UHD broadcast content through their existing infrastructure including contribution over IP, originally sized for HD content.
MORE THAN ONE WAY TO CAPTURE 4K
As every broadcast engineer knows, SDI cables do not come cheap. A 100 foot or 30 meter cable can cost anywhere from
between $50 to $300. Multiply this by all the cameras and production equipment needed for a production studio or remote
OB kit and the total amount of investment in cable can run to thousands of dollars.
Although newer 4K cameras will feature 6G or 12G SDI outputs, it may make sense to continue using 3G SDI cables, especially
in workflows designed to support HD with occasional 4K production. In this case, a 4K video encoder, such as the Haivision
Makito X4, can ingest 4K content over 3G SDI.
There are two methods for capturing 4K video over 4 3G SDI inputs: SQD and 2SI. SQD divides the 4K source image into
four separate quadrants which are then stitched together. Each quadrant is essentially a separate encode. 2SI simultaneously
encodes 4 pixels, one from each quadrant, at a time. This approach, although somewhat more complex, is better suited for
digital video effects (DVE) as it can handle the entire 4K image at once, versus having 4 separate effect engines per quadrant.
MORE PIXELS, MORE BANDWIDTH, MORE CABLES
4K UHD content has a resolution of 3840 x 2160 pixels, which is four times the resolution of HD video. In addition, content for
live sports is typically captured at twice the frame-rate of standard HD, that’s 60 frames per second in North America and
Japan, and 50 frames per second in Europe and most of the rest of the world. By doubling the frame-rate, the size of raw video
streams also doubles so that 4K UHD p50 or p60 requires up to eight times the bandwidth as standard HD at 25 or 30 frames per second.
The wide color gamuts (WCG) supported by UHD (SMPTE ST 2036-1) and needed for HDR requires that video is captured in
10-bit pixel depths which can increase content size by about 25% compared to 8-bit video. Add all of these considerations up and it is clear that 4K UHD requires significantly more throughput than HD.
For new studio builds or refurbishment projects, 12G SDI cables will be best suited for 4K workflows. Single mode fiber might
also be considered for longer distances.
Taking a leap of faith to all IP with SMPTE-2110 might also be an option. For everyone
else with existing infrastructure designed for HD workflows, options for catering to 4K UHD content without immediately
replacing every piece of equipment should be considered.
- 8-bit HD video (1920 x 1080p) at 30 frames per second
- 0-bit 4K (3840 x 2160p) at 60 frames per second
- G (3 gigabits per second) SDI
- 2G (12 gigabits per second) SDI
- 2G SDI
- G SDI
- HD 2160p60 (11.14 Gbps)
- HD 2160p30 (8.91 Gbps)
- D 1080p60 (2.97 Gbps)
- D 1080p30 (1.49 Gbps)
- x 3G SDI