DV->JPEGs?

[Randy Wilson]

I'm wondering if anyone knows how to take a DV stream and automatically
extract the individual frames out of it as JPEGs?

Better yet, are there any libraries out there that give you access to
the actual frames in a DV stream?

What I want to do is organize a large (>20,000) set of slides.  I
thought I could run a DV camcorder while I rifle through the slides
(about 2 seconds per slide).  Then I could write a little bit of code to
examine each frame of the DV stream (either directly, or look at the
pictures extracted from it) in order to determine how bright it is.  By
looking at the brightness level as the frames move along, there will be
an area of relative darkness, followed by a transition to lightness
(with perhaps some adjustment going on as the auto exposure does its
thing), then sudden darkness again.  This would appear, if plotted out,
as a series of flat plateous and flat valleys with some overcorrective
transitions between them, along with a bit of noise, of course.  With a
few constraints on how fast/slow the slides are allowed to be pushed
through, it should be possible to find the point a few frames before
each transition begins.  Then that frame could be snipped out as its own
.jpeg file and eventually labeled in such a way as to make it possible
to find the original slide again (or at least know that it's "about
slide 25" in a particular row in a particular box) when a high-quality
scan is needed of it.

What I'd REALLY like, of course, is a slide scanner that was actually
fast [like 3 seconds per slide] with a large slide feeder (like 150+
slides at once), but alas, no such luck.

In the short term, I want to make a nice 1-hour video featuring a lot
of slides from this collection (maybe 1000).  But I'd like to have a
quick scan available to select which ones I want to use.  But the
quality of the quick scans--while if displayed on a video
directly--would be too blocky for any sort of smooth zooming/panning
shots.

Also, is there a format for saving individual miniDV frames in that
would avoid further compression? The frames are already pretty heavily
compressed.  They could be saved as TIFF, of course, but if I wanted to
save individual frames out and then use them later as still clips in
iMovie, for example, is there a particular format that would avoid
decompression/recompression?  Just wondering.

Wow.  That's a lot of questions.