By Tom Coughlin
Indian Wells, California — Although current content distribution is at HD, it is clear that 4K distribution will be commonplace in just a few years. As a result, many content producers are capturing content in both HD formats and 4K formats.
As might be expected, this increases the total data rate needed to capture this dual format content as well as the resulting storage capacity requirements. The actual size of the total content package depends upon the 4K content format.
During an HPA Tech Retreat session moderated by Hollywood Post Alliance’s president, Leon Silverman, there was an interesting presentation on 4K and HD dual production. The particular examples were TV content shot on a Sony F55 camera, which supports this dual recording mode. The objective was that this footage (shot in New York City) would be available the following day in the Los Angeles production facility. The HD proxies were pushed to the LA lab using Aspera for dailies creation.
The 4K formats considered included 4K Raw. This format captures RGB data directly from the image sensors plus camera metadata. This format is the closest digital equipment to film negatives and offers the greatest flexibility for post. This is very important for content shot in challenging lighting environments where the additional post production possible with 4K Raw content can be used to advantage. However it also requires high bandwidth and storage capacity to support, particularly when paired with simultaneous HD capture. Some of the resulting 4K Raw files were 15X larger than the HD files from dual 4K/HD recording.
The content creators decided that since they were shooting a comedy pilot program in a studio they could get by without the additional post capability that 4K Raw could provide. As a consequence they decided to shoot HD and 4K XAVC. This is an encoded and compressed format resulting in 10 bit, (4,2,2), 80 mb/s. Using the 4K XAVC format they were able to record HD and 4K content on the same SxS card in the Sony F55 cameras. Note that 45 minutes of HD and 4K XAVC could fit on a 128GB SxS card.
The plan was to do the initial pilot work on the HD content and then if the show was picked up, re-do the master using the 4K XAVC content. Four F55 cameras were used for the production shoot. The producers planned future content capture would continue with this dual-format capability. Note that in the LA facility, the 4K footage was kept on LTO tape as well as local SAN storage. Using compressed 4K content (XAVC) allowed faster transfer of content between NYC and LA, reducing the time for content ready for viewing.
Tom Coughlin, the founder of Coughlin Associates (www.tomcoughlin.com) has over 30 years of magnetic recording engineering and engineering management experience at companies developing flexible tapes and floppy disc storage as well as rigid disks at such companies as Polaroid, Seagate Technology, Maxtor, Micropolis, Nashua Computer Products, Ampex and SyQuest. He can be reached at email@example.com.