Bits and Bytes
by Todd Yates on Feb.07, 2009, under Post-Production Tips
Today’s entry will focus on a very “techie” topic; codecs, compression and frame rate. At Post Factory we do a large amount of layoffs from client’s hard drives to broadcast tape formats like Digital Betacam, HDCAM and HDCAM-SR. One of the ongoing discussions that we tend to have with clients is the compression/codec settings of their edited sequences and the frame rate of their project. With the advent of the Internet and the proliferation of video on the Internet, there has been a lot of confusion about what settings are best. I would like to address a couple of flawed arguments that I have dealt with over the recent years regarding this topic.
1. Ideally, try to keep the setting of your sequence the same as that of your original footage. More specifically, pick the best codec to digitize in and don’t change it throughout the production process. This can be (and might be someday) the subject of an entire blog entry. I have talked to more than a few people that edit their entire program in the DVCAM codec, then copy that sequence into a new one that is set for Uncompressed 10-bit and bring it to us – unrendered – to be laid off. They are convinced that somehow this will improve the quality of their show. Let me lay this to bed once and for all – it won’t. But it will take a whole bunch of time to render and likely look worse due to increased compression artifacts.
There aren’t that many of us left that can remember the days of good old composite A/B roll editing where you were very concerned about “generation loss”, the degradation of the signal that occurs when you make successive copies of a shot in order to achieve a dissolve or more complicated effect. Back then everyone understood that the first generation is always the best. It didn’t get any better during the process, only worse. The 21st century version of generational loss occurs every time you change compression settings and re-render and just like “back in the day” it doesn’t get any better than the original.
2. There is a big difference between what you can do on a computer and what you can do on broadcast television. The primary lesson here is don’t bring me a 525/23.98fps sequence and ask to have it laid off. There is no tape format that will accept those settings. Before you start editing your project, think about how it will be distributed and plan accordingly. You can play a 525/23.98fps QuickTime movie on a computer, just not on broadcast TV. If you are sending your final show or spot to a station or network to be broadcast, then choose from one of the following formats:
525/29.97fps (Digital Betcam, Betacam SP, DVCAM, DVCPRO etc.)
720/59.94fps (DVCPROHD or HDCAM-SR)
1080/29.97fps – aka 59.94i (HDCAM or HDCAM-SR)
1080/23.98fps (HDCAM or HDCAM-SR)
Stay with one of these setups and you will stay out of trouble. You can always give us a call at Post Factory before you get started with a project. We will be glad to talk to you about the best plan for your particular situation and distribution. Happy editing.
