Expensive and error-prone digital tapes has forced the BBC to look at using computers running Linux to help produce its programmes.
Expensive and error-prone digital tapes have forced the BBC to look at using computers running Linux to help produce its programmes.
Speaking at the annual linux.conf.au Linux and open source conference in Melbourne, Australia, Stuart Cunningham from BBC research, said copying digital tapes was a slow process as it must be done in real-time.
"The key to solving digital tape problem is with standards-based files in the MXF (material exchange format) as you can store more in less space," Cunningham said.
To solve this problem, the BBC Research team developed Ingex for tapeless TV production using Linux.
Ingex is used to get the TV footage from the studio into the post-production editing suite by intercepting it via the Serial Digital Interface (SDI), a digital broadcast standard, rather than from tape.
"Ingex is a low-cost, file-base production system where a commodity PC with an SDI capture card that does software encoding with ffmpeg and writes MXF files, which can be stored on a NAS server or a USB drive," Cunningham said, adding a USB drive can be physically transported to post-production.
Once the USB drive arrives at post production, the AAF (Advanced Authoring Format) and MXF files are copied to the Avid editing "bin" for post-production.
The team set up two dual quad-core Intel systems with 4Gb of RAM and 4Tb of disk storage with the XFS file system. OpenSUSE Linux is the operating system.
The XFS file system was found to have the best performance for getting high bit-rate video to disk, and an open source developer was contracted to develop a DVCPRO50 codec for ffmpeg which resulted in a better decoder than many of the hardware based decoders, according to Cunningham.
"The goal of this is to get rid of all tapes [as] we save the time in manually processing tapes," he said.
The new system was first used for the show Dragon's Den and then for a Foo Fighters music video which needed a fast turn-around for digital TV and web TV.
Next was the soap opera EastEnders which has strict storage protocols, mostly done with tapes.
"We provided a NAS server running with 10Tb of storage which is a no-name brand PC running Linux and Samba," Cunningham said. "I couldn't encourage them to drop tape all together and use our system so they are still using tape."
"Now we have proven it works, productions are going to rely on it and the next version will have RAID-5. We've thought about complete redundancy and that would double the cost, but we are already much cheaper than the alternatives."
After the initial prototype in 2005, BBC is now in trial stage so productions "willing to have a few extra bits of kit lying around the studio" are using files instead of tape.
"Tape is still useful for backup so the next stage of production will expect to use our system for online and offline [storage] and only use tape when something goes wrong," Cunningham said.
Ingex is high-definition ready and has been tested and can use the same hardware to do two digital streams which no commercial hardware can do.
All of the source code is available at ingex.sourceforge.net.
Cunningham said BBC has been involved in open source, particularly standardisation, "for a while" and where it benefits the industry "it is quite straightforward to release it".
BBC's next challenge will be to migrate its massive archive of a million tapes to the LTO format and then eventually to disc where appropriate.