[MacDV] Re: DV->JPEGs?

Mon Dec 23 18:57:32 PST 2002

one more thought...  if you go the digital still camera route, I 
believe you can get a slide-transfer adapter that just clips onto the 
front of the lens (of course the camera would need good macro 
abilities).  You'd just need a good light source to illuminate it.

On Monday, December 23, 2002, at 08:52 PM, Mark M. Florida wrote:

> 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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