WIRELESS TRANSMITTERS GE AR .
phones have the processing power to implement test and measurement display – histogram, waveform and so on – as well as computationally tougher things like 3D LUTs. There are issues of battery life for all-day monitoring, and the required network layer inevitably adds delay, but it’s a handy option. Radio communications become more robust if we dedicate more bandwidth to error correction. The Vaxis Atom 500 (the range is the model number) lets us trade-off image quality against reliability, and react to congested airwaves; ideally, range is up to 500ft. The basic version handles HDMI with loop-through at £399, while the £460 version adds SDI. Both transmitter and receiver are set up to mount Sony NP-F batteries. The Atom 500 SDI is one of the least expensive ways to send SDI pictures. It’s also the only option to offer printed case designs. Never has democratisation of film and TV gear been so artistically expressed. DEEPER POCKETS For those who can afford it, the Vaxis Storm series goes further and faster, competing more directly with the likes of Teradek. The Storm 3000 (£5243) comes in versions latching directly onto a V-mount or Anton/Bauer battery plate. The price bump buys us under-a-millisecond latency and 3000ft of range, as well as such niceties as timecode and support for Arri-specific playback features. The less expensive Storm 2000 is slightly shorter-ranged, and there
simultaneously – and there are wired options to take received data into a laptop as part of a live streaming set-up. The company promotes 80ms latency on both its Mars 400 and 300 options, which probably represents a realistic estimation of what they’ll achieve with 24fps material. The less-expensive Mars 300 is an HDMI-only option, that’s so lightweight it’s shown riding on a gimbal-mounted camera. It retains compatibility with the company’s mobile phone
are compatible monitors with built-in receivers. Hollyland offers a huge range of production technology, from streaming and intercom systems to radio mics, though with an identifiable focus on wireless communications. Its Mars series includes the 400S Pro (£616), which packs both a direct point-to-point video link and streaming option into one box, handling SDI or HDMI. Various combinations of four Android or iOS devices, or two dedicated receivers, can listen
TWO IN ONE The Accsoon CineEye 2S Pro (above) transmits SDI and HDMI – as does the Hollyland Mars 400S Pro (below)
Many wireless devices separate the tasks of compressing the data to fit the available bandwidth, and sending that data over by radio, called source encoding and channel encoding, respectively. That separation means all the bits and bytes end up being treated as equally important, which isn’t ideal; the least-valuable bit in any digital number only alters that number by one, and in 8-bit video, that’s only 1/256th of the total value, equivalent to a scattering of noise. Combining the jobs – encoding the video then transmitting it – is called joint source-channel encoding, and to skim the subject unforgivably, it allows the system to prioritise critical information and avoid conventional compression. The result is near-zero latency and more graceful degradation at the edges of performance.
49. SEPTEMBER 2021
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