hari@hpsgl1.sgp.HP.COM (Hariram RAMACHANDRAN) (03/15/91)
Low Cost MultiMedia Solution
----------------------------
I've been hacking away at a pet interest of mine which may be of some interest
to educators interested in providing low-cost educational multimedia solutions.
I'm not sure if the technique is already in use, so I'd appreciate any
feedback/opinions.
Design Philosophy
-----------------
Current IVD applications require expensive Laserdisc players and the application
isn't 'configurable' in the sense that the video material can't be changed
without the considerable expense of pressing a new Laserdisc.
The obvious solution would be to use a generic VCR, if there was some way of
determining the absolute play location of the video and to control the video
so that it can be cue-ed to the right location. This technique would be
appropriate for low-cost educational applications, where cue time is not of
overriding importance.
The following hardware setup, using a generic VCR and IBM PC, with some
additional hardware, allows you to accomplish this.
Hardware Setup
--------------
PC VCR
--------------------- -------- ------------------
| | |CORE |**** | |
| DVA TCR RS232 | ------- (IR)| (1) |
| | | | | ^ ------------------
| | | | | | | |
| | | | | | Audio Video
--------------------- | (4) | |
| ^ ^ ^ | | |(3) | (2)
| | | | --------- | |
| | |____|_________AUDIO_________________| |
| |________________VIDEO__________________________|
|
| -------------
| | |
------------------>|VGA MONITOR|
-------------
The setup I'm working with includes a VCR hooked up to an SMPTE Time Code
Reader card and a VideoLogic DVA-4000 video genlock card. The VCR is controlled
by a CORE unit (I can't for the life of me remember what the acronym stands
for) which is a universal programmable IR controller which can be controlled
by a serial interface.
Control Structure
-----------------
The structure I've highlighted above allows a PC to control a generic VCR
(with IR remote capabilities) and determine the absolute play location
of a video tape and map that video anywhere on a VGA monitor. I'll outline
control flow below (follow the legend in the diagram above):
1) Firstly, an existing video is dubbed with SMPTE standard Time Code
on audio channel 1 (at 0dB). The dubbing is done using a Time Code
Generator (which is a standard feature of the Time Code Card).
2) The video output of the VCR is hooked directly to the genlock card.
3) The audio output of the VCR (which contains the time code stream) is
fed to the Time Code Reader card (TCR). In this way, the controlling
program can detect the exact video play location, frame by frame.
4) To close the loop, the controlling program must have some means of
controlling the VCR. That's where the CORE unit comes in. The CORE
can be programmed to control any IR remote VCR and the control
program talks to the CORE via an RS232 interface.
Example
-------
I've written an application (which I call the Video Notebook), which implements
the control structure above. I chose David Attenborough's 'Life on Earth'
series, dubbed the SMPTE time code on the audio channel. Using Video Notebook
a student can select various topics in a point and click environment. For
instance, if he/she selects 'reptiles', then a series of options will be
displayed - "Bearded Dragon", "Australian Frilled Lizard", "Fijian Green
Iguana" .....
If the student selects the "Fijian Green Iguana" option, he'll be presented
with a multimedia screen, with a text window describing features of the
Fijian Green Iguana, a still window displaying a still of the iguana and a
video window. If the student wants to watch the video, he moves the
mouse cursor over a video icon and selects it. The control program then takes
over, sends a command to the CORE unit which starts cueing the VCR to the
appropriate location on the tape and then sends the play command to start
playing. When the segment has ended, the control program detects the end
time code and stops the VCR. The student is then free to browse through
other entries or create new entries (pages) in the Notebook.
To add a new page to the Notebook, the student selects
the appropriate icon, and is presented with a blank Notebook page. The student
can then watch the video in this environment, add text, capture a still and
define a video segement to be associated with the page. When the page is saved,
it becomes one of the available options in the main menu.
The code is still in its prototype stage, but I've found it a very useful
educational tool, but being a myopic techie with no concept of
educational requirements, I'd like to get opinions about the usefulness of
such a package, from an educator's perspective, as well as from anyone
else with opinions about other application areas that might take advantage
of such a set up.
Before I forget, I estimate the cost of such a setup to be about $1000,
using the lower cost genlock cards that have come on the market, and assuming
that an existing PC and VCR are used.
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Hari Ramachandran Internet: hari@hpsgl1.hp.com
APD R&D Fax : (65) 2743431
Hewlett Packard Singapore
1150 Depot Road
Singapore 1129
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