It so happened that I got involved in video digitization project. Here is a quick description of my setup and workflow.
Key points
Video capture of DV video streams using QuickTime is not effective, as QT will try to encapsulate DV stream, resulting in both high cpu usage/dropped frames. Capture can be performed either using iMovie or using digital VCR application in FireWire SDK 22. This normally results in less then 50% CPU usage on a 1.2 Ghz iBook, and generates a proper DV stream.
In order to speed up exporting and importing data when working with iMovie, one can select “show package contents” in finder, and look inside the iMovie project. Capture.iMovieProject/Media/ contains the video streams, which can be moved out and edited in stand-alone applications, or moved in to speed up import procedure a great deal (it helps if streams that are being imported are of the same format as the project, although in iMovie 6 anything that QT supported seemed to work, I just pay for it in terms of conversion time at the final export).
Setup
Currently my tools are a Sony Hi8 video camera, essentially a consumer model, two different VCRs (A Mitsubishi and a Hitachi), and a Canopus ADVC-110 analog to digital adapter.
Canopus box emulates a DV camera, and speaks a subset of DV protocol, so as far as host system is concerned, it is a somewhat dumb DV camera. Somewhat dumb because it silently ignores any of the DV commands that have to do with reading the tape markers or rewinding the tape. Some of the commands tend to confuse it, and it in turn changes from “analog to digital” to “digital to analog” conversion. But in 99 out of a 100 cases it works really well.
Not all VCRs are born equal. My Hitachi generates grainier image using the same footage, however it is more resilient to video tape damage, and doesn’t loose tracking as easily as Mitsubishi does.
Usual way of performing digitization consists of plugging a video camera or VCR into Camopus box, which in turn gets plugged over firewire into an external hard drive, which in turn gets plugged in over firewire into an iBook, that runs iMovie.
iBook runs either iMovie HD 5 or 6 (depending on which iBook). iMovie project is set to “DV” quality, and saved on the the external drive (or wherever there is plenty of storage space). My rule of thumb is 12.5 gigs of disk space per 1 hour of DV video.
Difference between iMovie HD 5 and iMovie HD 6 that I’ve noticed is in the resilience to interference. iMovie 6 seems better at dealing with damaged tapes with dropping video frames. What iMovie HD 5 would show as a full frame dropout, iMovie 6 will only show as a horizontal black line across the image. No differences if source material is of reasonable quality.
Most problems I’ve had were primarily caused by length and quality of firewire cables. Short, well shielded cables and only a couple of devices on firewire bus work best in my experience.
Workflow
In iMovie I enable the video camera capture mode (should be automatic the moment it detects a video camera plugged in), and hit play. iMovie sends a “play” command to Canopus box, which Canopus box happily ignores.
Then I manually cue up the video tape to about where I want to start capturing from, keeping in mind that capturing more is better then capturing less, I can then cue and splice things up in software.
Once I am happy, I click “import” in iMovie, and “press play on tape” (str) , and watch for a while that things are happy.
iMovie imports video in 1 hour chunks, so 12 gig files are about the largest size I deal with.
Once I am done digitizing, I quit iMovie, and look inside the .iMovieProject/Media/ folder, that by now contains Capture nn.dv files. I move .dv files out of the iMovie project, and open these in QuickTime. If video was filmed with a mono audio track, before further editing, I adjust the audio signal to be center-center instead of left-right in the dv stream (Apple-J in QT Pro, followed by clicking on audio, and adjusting the position of the audio channels)
I do rough cuts of the stream in QuickTime as well.
Main .dv file is opened, and scenes out of it that are of interest are copied and pasted into new QT windows, and trimmed as needed.
At this point my usual procedure is to create a folder, and export scenes that are worth preserving out of QT in DV fromat into this folder, using xx0-filename.dv naming scheme. This naming convention is similar to naming lines in BASIC, and allowes me to roughly adjust the scene sequence before importing these back into iMovie.
Once captured streams are edited, I open iMovie again, and create a new project, again in DV format. I save the empty project and again quit iMovie. In my experience iMovie takes forever to import things as it both converts the stream that it imports to the project format, and copies it into project’s Media sub-folder, so it is alot faster to just drop .dv files into Media subfolder of the iMovie project, and re-start iMovie. On a re-start iMovie will complain that there are new tracks in the project, and asks if I want to delete them, or just move them to trash. I select to move them to trash, and once iMovie starts, move them out of the trash into the timeline.
It takes me about an hour and a half to cut and export a moderately representative sample of what I capture, and I discard on average between 40 and 60% of source material.