IP has been regarded as the future for broadcasting in both studio distribution and broadcast centre-to-transmitter links for the last 10 years. As the technology starts to become the norm rather than the exception, one of its leading proponents, GatesAir, has shown its continuing commitment to the format in recent months. At NAB, the company introduced a new IP audio transport codec for STLs and contribution and delivery networks, while last week it announced its membership of the RAVENNA partnership.
GatesAir is the former Harris Broadcast division of the Gores Group for network management, digital audio console, studio to transmitter links (STLs) and transmitters for radio and large-scale, single frequency transmission in TV. In March this year, the parent company announced its decision to split Harris into two operations, with GatesAir and Imagine – covering conventional TV and radio, broadband, new media devices, online distribution and 'non-traditional' programming – running as "two focused companies innovating across different ends of the technology spectrum,” in the words of Charlie Vogt, chief executive of both.
At the time of the announcement, Rich Redmond, chief product officer for GatesAir, said the company was in a better position "to build best-of-breed, over-the-air solutions that take advantage of the latest breakthroughs and changes that will occur over the next decade in content delivery and distribution across the globe". While established technologies such as T1 are still important in transmission and LTE broadcast is being positioned as a possible alternative or complementary format in both distribution and contributions, IP appears to be the big priority at the moment as far as studio networking and STLs are concerned.
To reflect this, GatesAir launched the Intraplex IP Link range of audio codecs (pictured) during this year's NAB. These are promoted as "the industry's first end-to-end, interoperable solution for transporting AES (Advanced Encryption Standard)-192 signals over IP”. The aim is to offer broadcasters a reliable, low-cost means to moving programme audio – with its associated data – in the form of a digital composite stereo signal and allow "a seamless migration from legacy analogue connections".
Redmond explained at the launch: "Broadcasters are interested in the higher quality audio signals that AES-192 transport can achieve, as it eliminates analogue conversion processes that can degrade signals as they pass through the air chain." He added that this approach would require less equipment, which would save operators money, and was able to "carry a complete bitstream coming out of the on-air processor and packetise it via IP, all while applying forward error-correction and redundant streams".
On the studio connectivity side of audio broadcasting, the debate over the last few years has been whether to go with Dante or RAVENNA. Both are audio over IP (AoIP) systems but each is seen as having strengths for specific applications. While Dante, developed by Audinate, has been adopted by a number of broadcast equipment manufacturers, it is also a live and installed sound system. RAVENNA, conceived by Philipp Lawo and produced by Lawo associate company ALC NetworX, is promoted as a more dedicated broadcast system.
GatesAir has gone the broadcasting route, announcing on 16 June that it had joined the RAVENNA community of partners. Redmond explains that the decision was influenced by RAVENNA's compliance with the Audio Engineering Society AES67 standard for IP interoperability (although Dante also offers this). "We believe AES67 is an IP standard to be used within facilities, because it offers more error mitigation and other safety/control features for the transport of audio," he says.
Redmond adds that RAVENNA and AES67 will be used to connect its studio products, including the Flexiva range of IT-based networked digital audio consoles, to STLs using the new IPLink range. "This means everything will remain in the IP domain," he says. "The RAVENNA technology will be implemented in a gateway product for IP connectivity within a facility, which will interface with a whole host of studio products, including phone systems and mic processors."
While assured latency, correction of interrupted packets and error correction are necessary in transport streams for STLs, Redmond comments that they are critical in the studio. "Too much delay is disruptive to the talent," he says. "So you especially need a low latency interface in the studio."
In the long-term, Redmond sees the greater implementation of IP as helping to simplify studio installation, much in the same way that the AES/EBU format did 20 years ago by allowing digital audio to be easily connected over standard connectors like XLRs. "RAVENNA – and AES67 – takes it to the next generation by creating an IP backbone within facilities," he concludes.