We can fix it in post
Feb 1, 2005 12:00 PM, David Austerberry, editor
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Every week, I visit several post-production and broadcast facilities. One issue that comes up regularly is the frequent gap between the producers' views of acceptable technical quality and the standards laid down by the program commissioners at the broadcast networks.
The producers are, not unnaturally, worried about cost. Their primary concern is to tell the story. If a few cutaways are needed, or a second camera unit, there is a strong temptation to send out an assistant producer with a consumer camcorder. If there are any issues, “they'll fix it in post.”
The post-production companies edit and finish the material, then deliver to the technical requirements of the broadcaster. The problems start when material turns up on a consumer tape cassette. First, there is no time code. All the shots have to be manually logged.
The real problems occur with compositing. You can't pull a satisfactory matte from sub-sampled color channels. Long ago when the Rec. 601 standard was developed, it was acknowledged that a good chroma key required a minimum of 4:2:2 sampling. Consumer formats use 4:2:0 or 4:1:1 sampling. Not only that, but high levels of compression are used to maximize recording times and minimize data rates. With HD, new issues creep in. What if the cutaways are 720p, and the primary shots are 1080i? That means standards conversion will be needed in post to avoid motion artifacts and to get the same look.
The post house has to deal with these problems: the lack of time code, soft color information and compression artifacts. It may have to intercut film-originated material with progressive and interlace video.
We are entering a new world of consumer high-definition. No doubt there will be the same temptations to shoot with consumer camcorders, and “they'll fix it in post.” The view will be taken that it is high definition, so it must be good quality. Tests undertaken by users on the new HDV cameras have indicated some models capture very good pictures, equal in quality to digital Betacam.
Usually, the use of sub-broadcast quality camcorders is not deliberate; it stems from lack of technical knowledge, plus the attraction of the cost-saving. A professional camera is deemed to need a grip and lighting personnel, in addition to the camera operator. As broadcast engineers, we have to spread the word that just because the specification of the device says 1080 lines, that does not mean it will meet the needs of television program production. It will be just fine for the wedding videographer or the high school video department, but is it good enough for television?
This title aims to spread the word to engineers: It is up to you to help disseminate the message that we must keep up the standards of technical quality. Modern equipment is so easy to use that it can be easy for non-technical people to be unaware of the issues of scan formats and compression. The HD equipment is very affordable, so there is no reason not to deliver high- quality tapes to the post house. So a plea to anyone in production: Fix it before it gets to post.
Send comments to: • dausterberry@primediabusiness.com • www.broadcastengineering.com
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