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%% Video Capture                              by Douglas J. Nakakihara %%
%%                                                 dnakakihara@bix.com %%
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NOTICE: This is the originally submitted text for an article that
appeared in the September 6, 1993 issue (#113) of MICROTIMES magazine. 
(There are some slight edited differences between the published
version and this one.)

This article is freely-distributable as long as it remains unchanged
and this notice and the copyright remain included.

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or similar media, including those electronically distributed,
without obtaining prior approval from the author.  This provision
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Specific permission has been granted to Amiga Report.

Copyright(C)1993 Douglas J. Nakakihara.

The author can be reached thru Internet at dnakakihara@bix.com.

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30fps Video Capture and Non-linear Digital Editing 
By Douglas J. Nakakihara 

	There are a lot of people who believe that capturing moving video 
on a desktop PC is a fairly easy thing to do.  Just install a video 
capturing board in your PC, connect the thing to your video source, and 
click the record button.  Just like a VCR, right?  Well, not quite. 

	The problem lies in data transfer rates.  Depending on file 
format, a single full-frame of video is at least one-half megabyte in 
size.  So one second of video is about 15MB of data.  A PC normally 
can't transfer that much data to a hard drive that quickly.  Saving the 
data to RAM is an alternative, but cost prohibitive for anything more 
than a few seconds.  To compensate, most boards capture less than a 
full-frame of video.  Until some sort of hardware compression like JPEG 
becomes affordable, for the average desktop videographer, capturing 
full-frame video at 30fps may seem to be just a dream. 

The VLab 

	Well Toto, we're not in Kansas anymore.  MacroSystemUS's VLab card 
for the Commodore Amiga can do 30fps full-frame video capture.  Perhaps 
even more astonishing is that fact that you can even use a cheap 
consumer grade VCR as your video source.  Have I piqued your interest 
yet? 

	VLab accomplishes this amazing feat using their innovative 
Interleaved Frame Recording (IFR) technique.  Basically the VLab 
captures frames as fast as your Amiga can do it.  By making multiple 
passes at the video source, VLab automatically captures more and more 
frames.  For example, on the first pass it might capture frames 1, 16, 
31,...  The second time around, it might pick up frames 2, 17, 32,...  
As you can see, ultimately, all 30 frames for each second can be 
captured!  In this example, it would take 15 passes to capture all of 
the frames.  Obviously, this will only work for video on tape or 
laserdisc.  (Be kinda hard to rewind live video!) 

	The secret to IFR is the selection of a Keyframe, which provides 
VLab with a point of reference on your video source.  Once the Keyframe 
has been identified, VLab only needs to know how many seconds after the 
Keyframe it should wait before capturing frames.  When VLab is capturing 
frames, it knows based on time which frames it needs to capture--
accuracy to a thirtieth of a second is child's play for a computer.  A 
Keyframe seems to occur whenever there is an abrupt change in the video 
signal, like when the camera cuts to a different location or to a close 
up of an actor. 

	The IFR process basically works like this.  First you put your VCR 
in play mode and click on VLab's Find Keyframe button.  VLab will let 
you know when a Keyframe is found, which must precede the start of your 
scene.  (If it isn't simply start a little farther back on the tape and 
try again.)  As soon as your scene comes up, click on the Start Scene 
button.  Now all you need to do is click the Start button, rewind the 
tape past the Keyframe, and play the tape again.  Each time VLab 
finishes a pass of capturing frames, you must rewind and play the tape 
again. 
	 
	The total number of captured frames is selectable by the user.  If 
you're capturing at 30fps, just multiply the length of your scene in 
seconds by 30.  To improve capturing speed and decrease storage 
requirements, you can reduce the capture resolution or capture in black-
and-white.  When doing IFR, make sure you disable your screen saver as 
it may throw VLab's timing off and cause the wrong frames to be 
captured. 

Look Ma, No Hands 

	There are also provisions for automating the rewinding process.  I 
highly recommend a terrific product called AirLink by Geodesic Designs.  
This is an inexpensive infrared (IR) universal remote control for the 
Amiga.  Example ARexx scripts to control AirLink are already included 
with the VLab software.  AirLink can automatically rewind your tape past 
the Keyframe and then put your VCR back into the play mode, at the end 
of each IFR pass!  Essentially, once you've set up the IFR parameters, 
you can click a button and walk away.  AirLink will also work with 
camcorders, laserdiscs, etc., as long as they can be controlled with an 
IR remote. 

Storage Requirements 

	You're going to need a large hard disk to store all of the frames 
you capture.  Although IFR initially saves frames in a compact YUV 
format, at 30fps, the storage requirements can really add up.  I am 
hoping that a provision to convert the captured images to a smaller file 
format after each IFR pass, thus reducing overall storage requirements, 
will be added in the future. 

	For the average user, 30fps may be overkill.  The storage 
requirements alone may discourage its use.  A more manageable frame rate 
is 15fps.  Obviously, motion will not be as smooth as it is at 30fps, 
but it's not annoying. 

Other Features 

	In addition to IFR, VLab will also capture a sequence of frames at 
up to 6fps.  This is sort of like making a single IFR pass at a video 
source.  However, the sequence-capture has a little more control over 
what is captured.  A nice feature is that you have the option of using a 
resolution of one-half, a third, or a quarter of the screen.  This can 
significantly reduce storage requirements.  Obviously, VLab won't even 
break a sweat capturing a single frame of video.  Individual frames can 
be saved in any Amiga format including 24-bit IFF and AGA. 

	VLab has loads of other features including extensive ARexx 
support.  You can also monitor the incoming video source in greyscale in 
a movable window.  Video played fairly smoothly in this window on my 
A3000.  You can't see much detail, so depending on your needs you might 
want to use a signal splitter and watch the video source on a separate 
monitor.  Real time color, contrast, luminance, and gamma controls as 
well as luminance, chromanance, and noise filters. 

	VLab fits into any Zorro II/III slot and does not require the 
video slot.  The VLab Y/C version includes two RCA video inputs plus a 
Y/C connector for Hi-8 and SVHS video sources.  Inputs are software 
selectable.  An external version is available for the A500, A600, and 
A1200. 

Now What Do I Do? 

	Applications for the VLab are only limited by your imagination.  
For example, most desktop video users are limited to morphing--the 
current "hot" video effect--one static image to another.  With VLab you 
can now generate the images needed for moving morphs (i.e., the source 
and target images are moving).  Examples of moving morphs can be seen in 
the movie Terminator 2 and Michael Jackson's Black or White music video.  
For the 3D rendering people, how about the ability to wrap moving video 
onto your objects!  Computer-aided presentations could include video 
segments without the need for VCRs or laserdiscs.  Vlab could provide 
source images for rotoscoping (painting on frames by hand).  A non-
linear digital editing system could also be designed around VLab.  
Bottom line: the ability to affordably capture video at 30fps is going 
to open whole new worlds to desktop video. 

The VLab-Retina Team 

	When the VLab is teamed with MacroSystemUS's Retina display card, 
VLab's features are enhanced.  The video source can be monitored on a 
Retina display in 16-bit color.  There is a noticeable delay in the 
display update, but it does give you a better idea of what will 
ultimately be captured.  Also, Retina comes with a program called 
Makerace that will compile the captured images with sound into an 
animation playable on the Retina.  With a VGA video encoder, it should 
be a fairly simple operation to get the Retina output to videotape.  On 
my Amiga 3000, I was able to play a 320 x 200 animation with sound using 
a 16-bit display at about 15fps.  For even faster playback, read on! 

A Match Made in Heaven 

	MovieMaker ($895 list) from Interactive Video Systems is a non-
linear digital video and audio editing system that comes with its own 
16-bit stereo sound card.  MovieMaker provides a way to arrange and play 
VLab-captured frames full-screen at 30fps, with 16-bit sound to boot!  
MovieMaker works very nicely in an Amiga 3000 and should work better in 
an Amiga 4000, if it has a Zorro III SCSI controller (currently a rare 
species).  MovieMaker operates best with certain hard drive models so 
IVS also offers it bundled with an approved hard drive. 

	Using VLab's IFR, I captured several seconds of video.  I also 
digitized the audio using AES, the audio software that comes with 
MovieMaker.  Then using ADPro, I converted the captured YUV images to 
DCTV format.  Incidentally, ASDG's product ProControl, a front-end for 
ADPro, made this a very easy task and saved me the trouble of writing my 
own ARexx script.  Next I imported the DCTV files into the MovieMaker 
hard disk partition.  (MovieMaker requires its own partition.)  It took 
a couple of tries to get the audio synced properly, but the resulting 
playback was incredible! 

	Using MovieMaker's wordprocessor-like editing functions, I was 
able to manipulate my captured video in nearly unlimited fashion.  Max 
Headroom stutter effects were easy as pie to do.  This VLab-MovieMaker-
DCTV setup seems like a natural for doing MTV-style music videos. 

	Although MovieMaker's output is not broadcast-quality, it is more 
than adequate for home and industrial use.  MovieMaker would also be 
valuable in a professional pre-production environment.  Quick rendered 
3-D animations could be edited and tested with an audio track before 
being rendered in broadcast-quality form.  Also, storyboarding would be 
a breeze with MovieMaker using either static or animated sequences. 

	MovieMaker needs about 100MB per minute of playback.  I would 
estimate that for serious work, you'll need at least a 1GB hard drive.  
Remember, the original source files have to also exist before they are 
transferred to the MovieMaker partition.  Fortunately, 1GB drives have 
becoming somewhat affordable lately.  Note that MovieMaker does not 
require you to dedicate the entire drive, it only needs a partition. 

That's A Wrap 

	At current street prices, a VLab-AirLink-MovieMaker-DCTV package 
will cost you around $1,500.  If you need a hard drive, you'll have to 
add that into the cost too.  This may sound expensive, but I am not 
aware of anything on any computer platform that will match the 
performance and flexibility of this set up--at least in this price 
range. 

AirLink 

	I just couldn't end this article without mentioning a little bit 
more about AirLink.  By itself, this is an awesome device.  It acts as a 
programmable universal IR remote.  All you do is draw a picture of your 
remote using any paint program (you only need to include the functions 
you will use).  Then you point your remote at the AirLink device, which 
plugs into the joystick port, and record the IR signals one at a time.  
Each recorded signal can be associated with any button in your picture.  
The AirLink's IR LED can be triggered by your mouse,  ARexx, user-
defined hot keys, serial and parallel port data, and MIDI events.  With 
AirLink, all IR-remote-controlled devices, like laserdiscs, TVs, VCRs, 
Stereos, CD players, etc. can be at your beckoned call.  You will no 
longer be limited to controlling only those devices that have serial 
port access.  AirLink is perfect for multimedia presentations. 

	You can even trigger other events beside IR, including sending 
data out the MIDI, serial and parallel ports, executing ARexx commands, 
emulating keystrokes and mouse clicks, and executing programs.  It is 
also possible to add eight additional IR LEDs using an adapter connected 
to the parallel port!  An upcoming version of the software will allow 
you to open an AirLink control window on any public screen.  With this, 
you can control your VCR and be doing VLab operations, all from the same 
screen! 

VLab Y/C 
$599.95 
VLab 
$499.95 
VLab External 
$549.95 
MacroSystemUS 
17019 Smugglers Cove 
Mt. Clemens, MI 48038 
(313)263-0095 

AirLink 
$50 
Geodesic Designs 
P.O. Box 956068 
Duluth, GA 30136 
(404)822-0566 

MovieMaker
$895
Interactive Video Systems 
14804 Beach Blvd. 
La Mirada, CA 90638 
(714)228-2040