Video Compression (Part 3 of 4)
Using Final Cut Pro and the Sorenson Video Codec
to Prepare QuickTime Video for Web Distribution

By Richard Lainhart


In retrospect, I did make a couple of mistakes that should have been corrected. First, Jordan's Mac monitor is on and flickering visibly in the shots, which is not only distracting but just adds unnecessary moving pixels to the frame. Second, there were a lot of miscellaneous hard drives and other gear with fans on and running, adding a lot of ambient noise to audio. The QDesign Music codec, like the Sorenson Video codec, works better with cleaner input material, and whining fans and other noise sources just cause greater degradation in the final output. Any extraneous hardware should be turned off in a QuickTime video shoot.

Once I had the footage I needed, I took it back to my studio and transferred it via FireWire (through a Ratoc CBFW2 FireWire PC Card interface) into Final Cut Pro running on my PowerBook, a G3 400. A DV camcorder with a FireWire interface is ideal for shooting video that will end up on the Web, not only because the video is inherently high quality, but also because you can transfer that video as digital data into a computer-based editing system without any loss. Converting analog video to digital always adds some noise to the picture, and noise is the hardest image of all to compress.

In Final Cut Pro, I edited the shots I wanted to use for the final movie, and assembled them with straight cuts to black between shots, rather than dissolves. I also added head and tail titles, also without fades. As mentioned above, working with straight cuts helps reduce image degradation in the final compressed clip by reducing the number of changing pixels in the frame. Because the audio was fairly noisy, due to the all the fans in the room, I applied some EQ to the audio to clean it up a bit and faded the beginning and end of each audio cut to help soften the abruptness of the video cuts. Then I rendered the titles and exported the entire project as a full-res DV movie, making sure not to recompress the frames on export. The final clip, 4 minutes and 18 seconds long, weighed in at 935 MB.

The final step was to import the clip into Media Cleaner Pro 4.0 for Sorenson compression. It would have been possible to do basic Sorenson compression directly from Final Cut Pro, but Media Cleaner is built around Sorenson and lets you tweak the deeper levels of the codec for better quality video. You can also add copyright and other information to the clip in Media Cleaner, something that's not possible in Final Cut Pro. Once in Media Cleaner, I set up a custom compression template for Jordan's video. This template set the video data rate to 30 KB/sec, the frame size to 320 by 240 pixels with high-quality deinterlacing and scaling, and the frame rate to 29.97, the same frame rate the video was shot in. Using QDesign, I set the audio track data rate to 5 KB/sec, 44 KHz, 16 bit, mono. I also typed in copyright, movie name, and production information to burn these into the final movie.

Read Part [1] [2] [3] [4]