09 Dec 2013

How to Rejuvenate an old HD Camera Featured

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How to Rejuvenate an old HD Camera How to Rejuvenate an old HD Camera Peter Davies

Index

Did you know you can convert older tape-based HD cameras to a file-based recording system, very easily?

 It's tempting to generalise and say that the quality of video cameras just gets better and better. It's true, of course: we have 4K cameras, large sensors and raw video. But in another way, that's not completely fair to the marvellous cameras that have been around for the best part of a decade.

Tape Recording on the HDW-750P

Take the HDW-750P for example. Introduced around ten years ago, it shot progressive or interlaced 1080 video at 25 frames per second (in Europe). And it recorded directly to... tape.

To anyone that remembers the 1960s the idea that you can record video without tape still seems amazing. That you can record it now to solid state memory just seems incredible. It's very easy to loose perspective when you look at recent developments. Just twelve years ago, it was hard enough to store more than a few tracks of mp3 audio onto a flash memory, never mind a whole feature film recorded in uncompressed 4K (well, actually, that would still be difficult, but, nevertheless, 4K uncompressed recording is a workflow that's in use on film sets today).

When it came out, the HDW-750P seemed pretty state of the art. The pictures were very good. And the technology was pretty familiar. People were used to working with tape, and HDCAM was similar enough to Digital Betacam that there were few issues with handling it.

The data rate wasn't all that high either, by today's standards, and although the compression could be a bit noisy, it was robust. What it didn't do was record at the full resolution of the sensor. Video recorded to HDCAM cape is down sampled to 1440 x 1080 resulting in rectangular pixels. The final bitrate is 144 Mbit/s, although most people using tape at the time weren't concerned with data rates at all: tape is tape!

So these very well made HD cameras never had a chance to display the full quality of their output. Despite having great sensors and usually being fitted with very good glass, they weren't able to display their true greatness.

Times Have Changed

But now, all that's changed. With exactly the same camera, but with a much simpler workflow, and with very much cheaper ancillary equipment, you can get significantly higher quality from these cameras that might otherwise have been consigned to oblivion.

When external recorders came out, they had a very different target audience than owners of expensive but old broadcast cameras. The first recorders were designed to work with file-based cameras whose bitrates were restricted by the Long GOP compression they were forced to use so that they could cram HD material into the tiny and expensive flash storage that was available then. Let's be clear about this: what they achieved with bitrates of between 25 and 35 Mbit/s was actually very good. It's just that it wasn't perceived as being as good as it could be, especially by broadcasters, who fairly quickly declared that they wanted to see at least 50 Mbit/s for Long GOP recordings.

The other focus for early external recorders was HDSLR cameras. These quickly because the "go-to" device for Pro-level shooting once film makers realised that you could get cinematic-looking footage from them, albeit with all sorts of ergonomic and technical disadvantages, not least, again, low bitrates.

But the field recorder manufacturers were frustrated by HDSLRs because they would not give up their video to external devices easily. Annoyingly, the camera makers always seemed to superimpose the information normally restricted to the viewfinder on the HDMI output feed. You'd get your recording modes, autofocus points and ASA numbers splattered all over your images, and there was nothing you could do about it. In addition, many of the cameras outputted slightly non-standard video, including, but not limited to, strange pulldown cadences, non-standard aspect ratios, and desaturated video.

The situation with HDSLRs has improved a lot, and, meanwhile, professional video cameras have upped their recording bitrates, but most still benefit from external recording, not least for the increase in recording time, and, still, from a somewhat more marginal gain in quality.



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RedShark News Staff

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