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mhely46
02-25-2006, 03:12 PM
Dear all,

Please find below a very belated compilation of replies to my query re “3
video files” (preceded by the original query). Very many thanks again to all
who replied – a veritable mine of valuable info. I’ve abbreviated the
replies below (leaving out the niceties to keep it brief...).

Original query:
I've acquired some digital video files taken simultaneously from 3
orthogonally mounted webcams (front, overhead, side views). The video was
taken in very close confines and is of a worker’s upper body/head activity.
The system which controls the videos and creates the files is called
"Tracer" and, I think, was designed for surveillance purposes.
Unfortunately, it produces a separate video file (the file extension is
".smf") for each of the 3 cameras; and the playback software (called "Media
Player" Ver.2.1.2, 2003, by Giantec Inc) only allows one file to be loaded
at a time for viewing.

So far, the only way I've found to see all three views at once is to open
the playback program 3 times, load one file into each, then try to manually
synchronise the 3 using the on-screen time-stamp and the play/pause buttons
- extremely cumbersome; must be re-done every time the video is paused
(because pressing 3 pause buttons one after the other throws the sync out
again!!).

Has anyone experience with either combining such video files and/or with
alternative software that can cope with 3 files and allow (and maintain)
their synchronisation (and, possibly, whether they need to be converted to
some other file type)???


Replies:
1. From: David Brown [davidbrown@bigpond.com]
Use a video editing program to combine the three. Then you'll have just 1
file. The tool you need is "picture in picture". I attach a tiny bit of
video to show it.


2. From: Todd Bentley [T.Bentley@latrobe.edu.au]
One simple option would be for you to sync the video files in the manner you
describe, and then to use screen capture software to capture a single video
file of the screen while these are playing. One such tool is hypercam (see
http://www.hypercam.com/ - free to download and try, it will put a small
watermark on the resulting video unless you pay for it). Read this first
though - http://www.hypercam.com/hc/faqs.asp#PlayOverlay . The main problem
with this option is quality of video will be deteriorated.

The best solution would be to find someplace that has a video mixer capable
of mixing at least 3 channels (a quad-video mixer). You would input each
video file into a single channel (the fourth channel would need to remain
blank), and you could combine these three channels into a single one. You
would still need to sync the file initially. This could be output onto a
dvr, vcr, or back onto the computer in a single media file (any format
really).

These two solutions are ones that are often used in the usability area where
we want to see the screen, the fingers / hands on the keyboard and mouse,
and the person's face.


3. From: B W Heller [B.Heller@sheffield.ac.uk]
I wrote a utility that can do this for up to 4 images, it is just for our
internal use, so has lots of rough edges, but we find it useful. I can send
you the executable or the Visual Basic source code. The video must be
playable in Windows Media Player for it to work, so you will probably need
to convert to an avi file first. Also, I doubt if it will work with the
latest media player release, as Microsoft seem to have changed the
interface, it does work with version 9. If you can convert the files and
want to try the program please let me know.


4. From: Marc Portus [mportus@ozemail.com.au]
I think you'll find there are a number of software packages that will do
what you want, though I think it will be most likely you'll need to convert
the files to .avi files (I find using an Indeo Codec 5.1 best for this, but
there are many other codecs which I haven't used) first.

My experience is with Silicon Coach, which allows you to synchronise and
view up to 4 video files simultaneously. There are many other products that
do similar things such as Dartfish and Swinger. They all have websites. You
may find something that comes a bit cheaper than these products but I don't
know of any off the top.


5. From: Wendy Gilleard [wgillear@scu.edu.au]
Peak vicon systems allow for separate loading of different tapes and then
you can trim them to the same time stamp which means they all start at the
same time. Try contacting John Corcoran (Oz peak agent) who might be able
to let you know if this would work and who has system close to you.

6. From: Niall Colgan [niall.colgan@ucd.ie]
Correct me if I am wrong you want to load the 3 video file simultaneously.
If that is correct you could use matlab. Either break the video file into
its individual frames and you can play each individual frame from each
camera something like:

mri = uint8(zeros(128,128,1,27));
for frame=1:27
[mri(:,:,:,frame),map] = imread('mri.tif',frame);
end

mov = immovie(mri,map);
movie(mov);

or I am nearly sure there is a command to read in the video file and play it
as is.


7. From: Wagner de Godoy [wagner.godoy@bol.com.br]
Perhaps "Dartfish Connect" can be useful in your research.
Try: http://www.dartfish.com/en/products/products.jsp


8. From: Patrick Drechsler [patrick@pdrechsler.de]
1) Redlake's MotionScope can play many videos simultaneously. I'm
not sure if it's for free since you have to fill in a request
form.

2) If you have access to MATLAB you can use this little script to
stick 3 videos side by side (files have to be in AVI format):

--88---
% works with linux & windows
% select 3 files:
[filename1,pathname1] = uigetfile('.avi','pick first AVI file');
[filename2,pathname2] = uigetfile('.avi','pick second AVI file');
[filename3,pathname3] = uigetfile('.avi','pick third AVI file');
file1 = fullfile(pathname1,filename1);
file2 = fullfile(pathname2,filename2);
file3 = fullfile(pathname3,filename3);
pdMovie1 = aviread(file1);
pdMovie2 = aviread(file2);
pdMovie3 = aviread(file3);
fileinfo1 = aviinfo(file1);
fileinfo2 = aviinfo(file2);
fileinfo3 = aviinfo(file3);

% create the movie (might take some time...)
% avis have to have same height and length!
for i=1:size(pdMovie1,2)
output(i).cdata = [pdMovie1(i).cdata, pdMovie2(i).cdata, ...
pdMovie3(i).cdata];
output(i).colormap = pdMovie1(i).colormap;
end;

% name of the new avi file:
[pathstr,name,ext,versn] = fileparts(filename1);
newmoviename = [pathname1,name,'_combined', ...
num2str(fileinfo1.FramesPerSecond),ext];

% create the avi file:
movie2avi(output, newmoviename, ...
'fps', fileinfo1.FramesPerSecond, ...
'compression', 'none');
close
--88---
HTH


9. From: Andrew Abercromby [AAbercromby@pioneer.coe.uh.edu]
A low-tech option might be to manually synchronize them once by hand and use
either a screen video capture program (don't know if such a thing exists;
I'm thinking about a program that would essentially do multiple 'print
screen' functions) or simply use a digital video camera and optically record
the synchronous images from each webcam while they are playing on the same
monitor (or different monitors in the field of view. You'd lose resolution
but it would be a quick and dirty solution.


10. From: Pavel Sholukha [sholukha@acrosport.ru]
In terms of video synchronization i would like to recommend you specially
designed programs: http://www.siliconcoach.com/products/pro.php
http://www.siliconcoach.com/products/student.php
They both support up to 4 simultaneous video playback on your screen and
digitizing features for video analysis. From my experience it's easy and
comfortable in use. It may became a little problem that they works only with
avi files, but I'm sure some smf->avi converters may be easily found.


11. From: Alfred Finch [Pmfinch@isugw.indstate.edu]
To view 2 or more (8 is the most I have used) camera view movies
simultaneously, the Ariel APAS APASview module permits the synchronized
viewing of avi video files. It has a VCR control that will advance the movie
frame by frame or run in a continous loop. I use this module and software
regularly in sport performance analyses with Elite athletes and then I can
take a snap shot of any time / position and this will provide a printable
pcx file for analysis The Ariel APAS can be downloaded for a free month
trial from the Arielnet.com web site. Avi movies of the 3 synchronized
views can be made from automatically recorded sequential screen shot with
another software product called Hypercam. The avi movie of the combined
views then can be played with any media player software on a pc. Also these
avi files can be used to create a rendered movie on a DVD that will play on
portable DVD player or on the TV. Please contact me if you have any further
questions.


12. From: DEWITT, JOHN K. [john.k.dewitt1@jsc.nasa.gov]
Try Dartfish.com. They allow up to 4 video files to be synchronized and
viewed simultaneously

13. From: Richard Sesek [r.sesek@utah.edu]
We used a security camera "splitter" to shoot 4 views at once for an
ergonomics study. The cameras used were wireless. The quality is not great
(probably would be much better if directly wired). Our study is
observational (does not require tracking with software etc.). For our
needs, it was a quick and inexpensive solution to "moving/turning workers".


14. From: Jeremy Suggs [suggs@MIT.EDU]
Here is some info from a friend of mine. He made a "home" movie that
synchronized multiple views, so his thoughts may be of use to you:

I used Apple's Final Cut Pro, which is only available for Macs and
sells for about $500 academic. There is a "light" version of the
software called Final Cut Express that costs $150 academic, and it
has all the main features of the Pro version, plus a few nice
features for less experienced users.

For Windows, there is a program very very similar to Final Cut called
Premiere, by Adobe, which costs about $700 academic.

There are free video editing applications that come built-in to most
new computers (iMovie for mac, Windows Movie Maker for windows) but
trying to do a multiple-camera-angle video on one of these would be
nigh impossible.


15. From: Mohammad Reza Fotoohabadi [m.fotoohabadi@pgrad.unimelb.edu.au]
Dr. Barry Stillman (School of Physiotherapy, Melbourne Uni. Victoria, Aust.)
told me that you can use "Silicon Coach", a device to synchronize up to 4
images on the screen simultaneously. This instrument has to be in every
school of physio. around the world. However,if you do not have access to
that you can purchase it from a
company in NEW ZEALAND for about $2000, or contact one of Australian
Football (Footy) Clubs for further information.


16. From: Alan Duffett (Vic. W/Cover – by telephone)
Suggested using Adobe Premier or similar video editing software. Also
suggested taking video files to a company that specialises in video editing
– they may be able to combine into a single, synchronised video.


Apologies if I've missed anyone....a few replies came in very much later
than the rest.

Thanks again to all,

Max.

__________________________________

Max Hely
Safety Science Associates Pty Ltd
PO Box 2444
Bowral NSW 2576
Phone: 02-4862-1129
Fax: 02-4862-1149
Mobile: 0412-920-300
Email: max.hely@safetyscience.com

__________________________________


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