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