Quality control for OTT


Adrian Pennington , September 30th, 2017

As video viewers continue to shift towards OTT video consumption on smart TVs and mobile devices, they expect broadcast-level quality, and with the advent of 4K/UHD and HDR streaming, expectations are even exceeding broadcast quality.

At the same time, many OTT video providers do not own or operate the infrastructure they rely on for the quality that will attract and retain viewers, and secure revenue. This shift has created an increasing need for flexible, scalable measurement tools that can address the new reality of video delivery both from a business and a technical perspective.

“There’s never been a time like this in the broadcast industry, with so many fundamental changes in technology and workflows coming together at the same time,” says Charlie Dunn, general manager, video product line, Tektronix. “An industry driven by rapid change requires more than technical evolution. It requires what we call ‘revolutioneering’. This means we’re doing more than just accommodating change and new technologies – we’re helping to lead the charge.”

IP introduces new technical and skills challenges. These include jitter, latency and the risk of dropped packets, and network asymmetry that results in different path delays upstream and downstream.

“Deploying IP for video production applications is effectively the collision of the two worlds of video and network engineering,” says Mike Waidson, application engineer for Tektronix’s video business division. “Video engineers are comfortable with the use of SDI, coax cable, patch panels, black burst, and tri-level sync for timing and, above all, monitoring signal quality. The challenge for the video engineer is to understand IT technologies and the impact of an IT infrastructure on the video.”

On the other hand, network engineers are familiar and comfortable with IP flows, protocols, network traffic, router configuration, precision time protocol (PTP), and network time protocol (NTP) for timing.

“The biggest difference is that in most data centre applications, lost data can be re-sent. This is not the case with high bitrate video,” says Waidson. “The challenge for the network engineer lies in understanding video technology and its impact on the IT infrastructure.”

Tektronix offers PRISM for broadcast engineers and IT professionals to monitor and analyse IP streams and the associated content in real time. This enables early identification and diagnosis of network or content issues such as intermittent loss of video, audio, or data content.

The latest capabilities in this area include analysis of PTP synchronisation timing, support for SMPTE ST 2022-7 redundancy, IGMP V3 and new API support for system integration into network management systems, and IP stream capture for even deeper analysis.

“An ‘all IP’ infrastructure is the vision for most broadcasters, and is already starting to happen in many facilities,” says Waidson. “The reality is, however, that the transition won’t happen overnight, leading to the need to manage hybrid SDI and IP infrastructures, and thus a need for IP and video engineers to work closely together to ensure seamless operation and quickly track down faults.”

Adding UHD to the mix

Added to this complexity is the increasing amount of 4K UHD content being put through the chain, with requirements to ensure compliance with enhanced colour and dynamic range attributes.

New software for Leader Instruments’ LV5490 waveform monitor is claimed to be the world’s first “direct-digital 4K noise measurement processor”. The LV5490 module measures noise in luminance or RGB component chroma channels.

“Camera noise measurement is a complicated and long-winded operation requiring digital to analogue conversion of signals that could also introduce noise to the signal,” explains Leader’s European regional development manager, Kevin Salvidge. “Now, camera owners can simply connect the SDI output of their camera directly into the LV5490 and measure the noise levels.”

The LV5490 4K is the company’s flagship waveform monitor, which can be twinned with the LV7390 4K rasteriser to reap the full benefits of cameras operating in UHD and HDR. The LV7390 can be used to measure up to four 3G-SDI, HD-SDI, or SD-SDI sources simultaneously. An HDR option for the LV5490 also enables this instrument to measure both 4K and HD HDR in ITU.BT.2100 Hybrid Log Gamma, Dolby PQ, and Sony SLOG-3 protocols.

The Ultra XR is Omnitek’s UHD waveform rasterizer that addresses HDR and wide colour gamut compliance requirements at frame rates up to 60Hz in an SDI data stream. In addition to the high resolution waveform monitor, traditional instruments such as vectorscope are included. Although this tool provides a level of usefulness in 4K UHD applications, additional instruments (such as a BT.2020 colour space waveform display, histogram, and CIE gamut charts) are provided to ensure that the image meets the UHD BT.2020 colour requirements.

Blackmagic Design’s SmartScope Duo 4K model features displays for waveform, vectorscope, RGB and YUV, histogram, audio phase, and level scopes. It is possible to monitor video on one LCD while running a scope such as waveform, histogram, or audio on the other screen – a userful combination that enables the video being monitored to be viewed alongside a real-time scope measurement, all on the same device.

Phabrix is also majoring in 4K/UHD and HDR in its most recent tools. Its Qx 12G is offered as a single device for “essential product development, infrastructure compliance testing, and 4K/UHD content monitoring”, using a hybrid of IP and SDI video formats.

A recent official convert to AIMS, PHABRIX says the unit will support TR03, AES67, and PTP (ST 2059-2), as defined in the draft SMPTE 2110 specification, in upcoming software releases.

“Qx 12G offers the fastest 12G-SDI physical layer testing, with its real-time Eye technology instantly highlighting any SMPTE compliance issues, including eye under/overshoot,” explains Phabrix’s managing director, Phillip Adams. “Advanced 12G/6G-SDI physical layer tools include Jitter waveform, Jitter insertion and FFT analysis, and pathological test patterns. Built-in automation control allows testing to be performed faster, more reliably, and at lower cost.”

For HDR and wide colour gamut applications, Qx 12G provides new generator patterns plus a CIE 1931 X Y chart with Rec.709 and BT.2020 overlays for measuring chromaticity. There’s also a programmable HDR heat-map to highlight luminance zones of a signal, as well as HDR vectorscope and waveform tools. All these HDR instruments support the Dolby PQ standard. Future software releases will support the HLG and SLOG3 HDR standards.

IneoQuest Technologies, which since March has been part of the Telestream stable, has evolved a FoQus Delivery service to help clients migrate to “all-software” system architectures that could be deployed as virtualised solutions in cloud-supporting data centres. Akamai, the world’s largest CDN, is one such customer.

“The FoQus Delivery service provides a pay-as-you-go subscription-based business model that is prevalent in the OTT market, supporting both network-less video providers that are offering pure OTT services, as well as video providers that are extending beyond their on-network offerings with OTT,” explains Calvin Harrison, CEO. “What we can do is test, monitor, and fault-detect OTT data streams right the way through a distribution network, from the broadcast centre to the point of consumption on literally any device or platform.”

Other solutions for monitoring the transport stream include Dektec’s StreamXpert, available in both full and “lite” versions for real-time analysis, monitoring, and recording; and Axon Digital’s Smart 90-series. The latter blends the capabilities of its SMART DVB 10-series/50-series and SMART DVB IP Viewer. Supporting up to 8 MPTS or 40 SPTS, the SMART 90-series also provides black and freeze-frame detection, running continually on all services as a background process.

Sencore offers the CMA 1820 compressed media analyser that allows engineers, system integrators and network operators to verify standards compliance, identify media interoperability issues, develop products around new codecs, and troubleshoot transmission issues. There’s an OTT option that allows direct examination of manifest files and the corresponding media. Other options for this product include closed caption, subtitle, SCTE35-DPI, and PTS/DTS alignment analysis.

Automated and manual QC

Broadcasters and content owners spend a large portion of their revenue on acquiring content, but this content cannot be monetised until it has successfully made it throughout the complete production workflow. Making quality control (QC) part of the ingest and production process ensures that only high-quality content will be delivered on multiple platforms.

Until recently, this was a tedious task during which an operator had to view all the content to detect errors. It resulted in a costly and time-consuming procedure, in which metadata couldn’t even be checked. The explosion in file-based workflow means traditional manual methods are no longer effective. With tens, even hundreds, of deliverables needed for each media asset, human operators using traditional video and audio test equipment struggle to cope without help. Automated QC (AQC) has become a commercial imperative.

“AQC will save a lot of manual effort and actually do a better job in checking all the technical parameters of the different versions,” says Thomas Dove, director of technology, QC products for Telestream. “With the correct workflow, in many cases manual QC need only be done on a master file and output files may not require any manual QC at all.”

“Efficient QC requires consistency,” stresses Ian Valentine, director business development, video test, at Tektronix. “This becomes especially important as the reliance on automation increases. We have found that measurements and checks made during acquisition and post production ultimately propagate throughout the whole workflow.”

Beyond QC, Interra Systems talks about QA (quality assurance). The latest version of its Baton solution enhances AQC by allowing users to add manual (eyeball) checks. With this hybrid approach, operators can detect certain issues, such as lip sync, which AQC solutions cannot.

“While automation has been transformative for the broadcast community in terms of speeding up workflows, AQC tools do not fully implement an organisation’s overall QC policy,” says Ashish Basu, vice president of global sales and business development. “Relying on a combination of AQC and manual intervention is ultimately the best approach to understanding false negatives and positives, detecting critical issues that aren’t yet detected by automation alone, and taking appropriate corrective measures.”

In the next few years, artificial intelligence will make significant inroads into these areas: initially these tools will be limited in functionality and value, but they will gradually replace much of what must now be done manually. Developments in this area are expected to be in the spotlight at this year’s IBC conference, which will be taking place in September.


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