I think your entire issue is going to be resolved by simply using a software that is more appropriate to DV capturing.
Like most everything else that comes with Windows, Windows Movie Maker is pretty pathetic. It's a weak little program, a pale shadow of other tools that exist. Just think about how Wordpad is no replacement for Word. Or how Solitaire is no replacement for pretty much any other game.
The WMV format is also what I refer to as an "end product" format, it's meant to never be edited again, due to compression and other tech flaws.
It's very tempting to want to take a shortcut with the computer, encoding a video can often seem long and time-consuming. But what happens is you get in situations like this, where quality is simply not there. The only real way to "cheat" at speed is to use a DVD recorder (which operates like a VCR).
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With what you have right now, all we need to do is transfer the DV from the device to the computer as AVI files.
The "locked audio/video" of the Canopus is kind of misleading. Once the video leaves the box, there's really nothing stopping a/v from losing sync. Then again, Canopus is well known for being a tad misleading and smoke-blowing about it products. A little too much hype and hoopla for my blood.
The speed of saving your audio file is undoubtedly related to some sort of compression being done on the file. I doubt you're saving a WAV (PCM) file, which is the native uncompressed format of digital audio, and processes and saves much faster.
I actually covered WinDV capturing in another post on the support forum, but I've quoted it below for your convenience.
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If this were my project, and were on a budget of cheap or free tools, I'd approach it from this method:
1. Transfer DV to hard drive in an AVI file, using WinDV.
FORK IN THE ROAD......
OPTION #1
2. Encode the entire AVI file over to an MPEG. There are several encoders to choose from, including TMPGEnc Plus, CCE Basic, and Procoder Express.
3. Use an MPEG editor to remove the commercials. TMPGEnc can do it for free, albeit slower and little less accurate that some of the paid options. Womble MPEG-VCR and VideoReDo are two more excellent options.
4. Demux the a/v streams, convert the audio to WAV with the freeware tool Besweet (or FFMPEG, either way) and then restore the audio in
SoundForge. Save the WAV, then use Besweet (or FFMPEG) to convert back to AC3 or MP2 audio.
5. Author your disc in authoring software, something easy like TMPGEnc DVD Author is cheap and not hard at all to use.
OPTION #2
2. Use
VirtualDub to save sections of the video stream without re-encoding. Or frameserve from
VirtualDub into an MPEG encoder. Repeat as needed, re-assemble the MPEG files later, in an MPEG editor.
3. Demux the a/v streams, convert the audio to WAV with the freeware tool Besweet (or FFMPEG, either way) and then restore the audio in
SoundForge. Save the WAV, then use Besweet (or FFMPEG) to convert back to AC3 or MP2 audio.
4. Author your disc in authoring software, something easy like TMPGEnc DVD Author is cheap and not hard at all to use.
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You may want to let me know what software you already own (like SoundForge, Premiere, Procoder, etc).