The way many TV programmes are made these days is not too different to how it was in the past, but some are taking full advantage of new technologies that combine IT and broadcast engineering skills, writes Kevin Hilton.
There is a hint of chicken and egg about broadcast television production these days. The general opinion is that the process has changed in recent years, but what is not clear is whether that has happened because of the incorporation of emerging technologies or as a response to new programme styles and formats. The certainty is that IT and computer-based working is now a major part of the process and works alongside long-established TV audio and video engineering practices.
The move to file-based operations and transfer of material and programmes is a clear indication of the influence of IT on broadcasting today, as is the growing use of IP (internet protocol) in its various forms to transport audio and video, not just for contribution purposes between locations and studios but on the delivery part of the chain from broadcast centres to transmission.
The Advanced Media Workflow Association (AMWA) has been instrumental in promoting and setting standards for the exchange of digital media and metadata over different platforms. It is a proponent of the Advanced Authoring Format (AAF), but has also worked to maintain compatibility with other formats, including MXF (Material eXchange Format, which the AMWA co-created), SMPTE’s BXF (Broadcast Exchange Format) and XML (Extensible Mark-up Language).
Audio-only material can be carried in various forms, with Broadcast Wav files still the primary format but AAC (Advanced Audio Coding) is also an option. In most TV applications sound is embedded in the video stream.
While IT has made itself felt in this way, more conventional broadcast engineering methods sustain, largely to cope with the high bandwidth necessary to carry good quality audio and video signals. “In many cases today backhaul/contribution – getting material from the field to the TV station – and delivery to the terrestrial or cable distribution network is still quite ‘traditional’,” comments Jan Eveleens, chief executive of Axon Digital Design. “It is mostly microwave or satellite connections using MPEG transport streams, which provide the high-quality/high bit-rate in the case of contribution.”
Axon produces a range of transport stream monitors, routers and interfaces, among other products, that are used widely in broadcasting. Eveleens sees the growing availability – and decreasing cost – of dark-fibre and IP connections as increasingly attractive to broadcasters looking for new contribution and distribution networks. “Especially in metropolitan areas this is happening a lot already,” he says. “SMPTE/VSF created the SMPTE2022 family of standards for this, which is targeted at contribution/backhaul applications and provides options for high-quality compressed MPEG transport streams or uncompressed SDI quality video.”
For audio-only applications Eveleens points to the AES67 standard, which was developed to provide interconnectivity and operability between different audio over IP (AoIP) formats, as “a good candidate for backhaul/contribution and distribution of audio signals over standard/public networks”. Axon is also a proponent of the AVB (Audio Video Bridging) Ethernet-based system, which Eveleens sees as a potential replacement for SDI networks in broadcasting. He says that audio was 75% of the maximum data rate in an AVB network, with the remainder being made up of other information. Eveleens has observed that there is “substantial potential in broadcasting, as the existing SDI-based infrastructure has come to the end of its life cycle and customers are starting to look at (networked) alternatives."
According to Pieter Schillebeeckx (pictured, above), product director at TSL Products, there are now more formats coming into TV master control rooms (MCRs), with a further explosion due: “There will be Ethernet and AoIP solutions, as well as AES and analogue coming into 3G and SDI environments. There are more channels arriving at the MCR that need to be monitored, and Dolby [encoded signals] is a big part of that. The Dolby E transport stream needs to be monitored but there’s also the metadata so the media can be checked to know it is correct.”
TSL Products recently added AVB capability to its PAM Series of monitors. These have units for both Dolby and non-Dolby encoded signals, and can now monitor audio metadata in accordance with the SMPTE 2020 specification, and also have loudness capability.
On the up
The number of audio channels used in broadcasting has risen considerably over the past 10 years, with 16 now the norm to accommodate stereo, surround tracks, any alternative languages or voice description, plus metadata. This proliferation is mirrored by the high number of microphone inputs – most of them wireless – now used on TV productions. Reality shows – live contests such as Big Brother, talent shows like The X Factor and fly-on-the-wall-style documentaries – have not only pushed up the demand for more mics on a production but also stretched the capability of recording systems so that they run constantly.
As Mick Bass, commercial director of location broadcasting specialist Roll to Record (RtR), explains, the requirement is to catch “everything that is said”. RtR works on both Big Brother and the Educating... series of school-based documentaries; the link between these is that they are based on characters and stories, which develop as the programme goes on. “We record as much as is humanly possible,” Bass says. “Embedded audio is part of the production and we try to get as good a mix as we can, even though it is done on the fly.” He adds that both wireless and boom mics, which are used for more peripheral figures who are not miked up, are also recorded as ISO feeds on to JoeCo BlackBox recorders.
JoeCos, along with SADiE workstations and Sound Devices PIX 270s, have been used by sound recordist Simon Bishop for his work on The X Factor and Britain’s Got Talent. Bishop refers to this style of production as “blanket coverage”, which has become part of a “whole fascinating genre that has appeared in the last 10 to 15 years”. In the beginning, he says, it took some doing to get older, existing tape machines to accommodate the new way of working. “Now the kit is becoming more compact and user friendly,” he comments.
In this instance the style of production does seem to be informing the design of new products. Sound Devices’ latest mixer-recorder is the 688, which follows on from the three-year-old analogue 12-input/16-track 664 (a cycle that perhaps illustrates the pace of change in broadcasting and the ability of manufacturers to react to it). The 688 is fully digital and has 16-track recording, with polyphonic or monophonic Broadcast Wav files saved to SD and Compact Flash cards. It includes six high-bandwidth mic/line inputs on XLRs with a further six line-level inputs using TA3 connectors, which are said to be for “more complex productions”. New features include 12-channels of MixAssist auto-mixing and the optional SL-6 power distribution and six-channel wireless system.
Paul Isaacs, vice president of marketing and product design at Sound Devices, says the radio mic feature and number of tracks on the recorder are aimed at both reality shows and episodic drama production. “Production is heavily wireless-based today,” he comments. “With reality shows it’s unscripted and there is a lot of talent to mic up. They’re being shot by multiple cameras, not just in close-up but wide shots as well, so boom mics can’t be used.”
Booms are still used in drama production but wireless mics are there for ISOs and situations like long shots. “People are looking to deliver a mix from two booms on two channels, either in mono or two-channel stereo, and then up to 12 ISOs for each wireless,” Isaacs says.
The MixAssist feature on the portable 688 parallels automatic mixing functions that have been appearing on digital consoles for OB trucks and studios over the last few years; the Studer Vista 9 now features its own version, as does Lawo’s mc² range, while Calrec has put Automixer on the Bluefin2 signal processor used for both the Apollo and Artemis desks. Like those manufacturers, Sound Devices emphasises that this technology is not designed to do away with sound recordists or operators. “It’s for when people are dealing with more and more sources, as on reality shows and round-table discussions,” says Isaacs. “The idea is for it to assist with the mixing, not take over. MixAssist has an advanced algorithm and is based on ambient noise, so if there is more than one mic open, the system will determine which is the stronger signal.”
Above: Sound recordist Simon Bishop
Sound Devices recorders are also used for drama production, as are those produced by Nagra, Zaxcom, Aaton Digital and Sonosax. Before extending his activities into reality ‘blanket coverage’, Bishop concentrated on location recording for TV. He still works in this field, most consistently on the BBC light crime drama New Tricks. For this work he uses either the Zaxcom Deva 16-track recorder or the company’s compact Nomad.
The new generation of digital recorders and now the shift to file-based operations means that recordists like Bishop have to deal with getting files on to the appropriate media that can then be sent to the post-production facility. While handling the audio in this way continues to be in the domain of the production mixer, Bishop says that a newish addition to the camera-vision crew can prove useful in also making copies of sound files.
“I’m finding now that if there is a DIT [digital image technician, whose principle job it is to take care of picture files from the digital camera and get them to the post house] on set, he or she will have copied my stuff and already walked away with it to send off,” he says. “I still put my tracks on Compact Flash and approximately six to ten cards are rotated between the location and the facility. Occasionally I use a spinning hard drive but I haven’t had to hand in a DVD-RAM for over three years. Machines like the PIX are very clever because you can network all the drives. We’re not using WiFi yet but it can’t be far away.”
Networking is a well-established part of broadcast production today but it is not as all-encompassing as the overall concept would suggest. The current situation, and the way both studio and location installations might continue to be arranged in the future, tends more towards self-contained systems. This applies to one or more OB trucks on site, as well as studios within a complex. MADI has made a comeback in this respect and there are possibilities for the Ravenna AoIP format in broadcast environments.
While Dolby E is still used to get multiple channels of audio from OB trucks and other locations, it is now almost never used in studio centres, where uncompressed, discrete sound is the norm. Although 5.1 surround is still not used routinely for every programme by all broadcasters, the methodology being used at BSkyB’s Sky Studios (previously known as Harlequin 1) could point the way ahead.
Speaking at last year’s Audio Networking Forum in London, Martin Black, senior sound supervisor and technical consultant at BSkyB, explained that the Calrec consoles installed in the sound galleries are connected to two bays of Hydra2 router cores, which enables any control area to be used with any studio.
Speaking at the same conference, Patrick Warrington, technical director of Calrec Audio, commented that as time moves on such installations could be based on the principle of a hybrid network. This would use Hydra2 in the studio centre or OB vehicle but be connected to an AoIP distribution network, with AES67 as the interface.
Broadcast audio production involves a great many elements – acquisition, distribution, production, monitoring and post-production equipment, audio formats, file standards and networking protocols – and the growing complexity of both how programmes are made and the power of the technologies being used may not simplify matters. But if all that can be kept in the background then the goal of making interesting – or at least ratings grabbing – programmes can be achieved.