For years Long GOP encoding has been dismissed by many as difficult to edit, all too ready to fall apart over multiple generations of processing and ill-suited to pictures with fast movement. Kieron Seth explains why Panasonic now embraces Long GOP with AVC Ultra.
Organizations such as Panasonic have eschewed Long GOP formats for broadcast applications because of their difficult-to manage frame sequence: HDV, Mpeg-2 for DVD and XDCAM all use a structure of 15 frames in each GOP and are only 8-bit. Only by increasing the bitrate to 50Mb/s have manufacturers been able to develop a Long GOP codec that meets broadcast requirements for HD. However, says a Panasonic's spokesman rather enigmatically: “We've always avoided Long GOP. We just didn't think existing codecs stand up to the rigours of post production.”
It came as a surprise then, that the company launched a broadcast Long GOP codec as part of its AVC-Ultra range. The spokesman continues: “Technology, processing power and codec development has moved on considerably. What we have been able to achieve is amazing: a full raster 1920 x 1080, 4:2:2 10-bit codec at 25Mb/s.”
Why, when storage capacities are rising fast and prices are falling consistently, has the manufacturer chosen to launch such a codec now, at the same time as announcing the 12-bit 4K ready AVC Intra444, a codec that seems far more in keeping with the future of the industry.
Perhaps the answer comes in the form of its latest camcorder, the HPX600. Intriguingly, it features IT connections such as USB, Ethernet and WiFi, while demonstrations at IBC showed it linking with cloud solutions. So while its 100Mb/s will be suited to TV documentaries and the like, a 25Mb/s option may well suit news camera crews on location overseas under pressure to upload content over IP to the broadcaster.
While the Epic, Alexa and Cinema Camera offer uncompressed or recording to intermediate codecs, these systems are in truth used largely for specialist, more 'artistic' productions. Speed of workflow is an advantage, not a necessity. In the world of shoot and broadcast TV production, Long GOP's Internet-friendly low bitrates may mean that it's time is not yet up.