[MacDV] DV->JPEGs?

[Mark M. Florida]

I would suggest (and yes, it involves a possible equipment purchase) to 
just use a digital still camera.  If you  only need enough res for 
video, then shoot at a lower resolution (give yourself a little extra 
room, though -- don't go under 800x600 for video use).  The color range 
of most digital cameras is close to the "legal" video color/contrast 
range, so that shouldn't be a problem -- if anything, just create a 
Photoshop action to batch process your images to squeeze the colors 
into the "legal" video spectrum.  Another possible advantage of using a 
digital still camera is: if you shoot at a higher resolution, then you 
will have a better looking copy in case you want to use these images 
for something else in the future.  Oh... one more thing... if you use 
iPhoto to import from the still camera, then you have a visual 
reference for selecting the slides, and you can (fairly) easily export 
to video by just making a new "Photo Album" of the pictures you want to 
use, and then exporting to video from there.

(I guess you left out what system you have, what kind of camera you 
have, etc. -- important info for figuring out the best way to do 
something with what you already have)

Also, you might want to look into getting an old A/V Mac -- like a 7100 
or 8100 with an A/V card (or even a 7500, 7600 or 8500).  You could 
connect your camera's analog outputs to the analog inputs on the A/V 
card and use the built-in "Video Player" app to capture still frames -- 
it automatically saves them in a sequentially numbered sequence -- 
super convenient!

The last option involves a possible software purchase.  Premiere has a 
"Time Tapse" function that you can use either automatically or 
manually.  So you could record your slideshow to video as you 
described, then use the "Time Lapse" feature to manually capture the 
clip every time it changes (click a button with your mouse).  You could 
use this feature with any version of Premiere from 4.0 on up to 6.0 
(don't know about 6.5 though), and you could use it with an old A/V Mac 
(Premiere 4-5), or any FireWire Mac (Premiere 6)...  So maybe just a 
couple hundred dollars (at the absolute most) to set up an old A/V Mac 
with an old version of Premiere.

I wouldn't sweat it trying to come up with some crazy software to 
visually analyze the video (unless you do this kind of programming 
already).  And if you do create something like this, I'm sure you'll 
have a decent market with some folks on this here e-mail list.

So... to sum up your choices:

1. Use a digital camera (or even something like Sony's video cameras 
with the Memory Stick slot -- I have one and it works fine for 
capturing video stills)

2. Get an old A/V Mac and use the built-in (clunky) capture software to 
grab stills from your existing video camera.

3. Get Adobe Premiere 6.x and use the "Time Lapse" feature on any 
FireWire Mac

4. Get Adobe Premiere 4.x (or 5.x) and use the "Time Lapse" feature on 
any older A/V Mac (with analog video inputs)

5. Write a video analyzer app that will extract stills when a scene 
changes? (and sell as shareware maybe?)

Just some thoughts.

Hope that helps.

- Mark


On Monday, December 23, 2002, at 05:28 PM, Randy Wilson wrote:

> 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.
>
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