Create MPEG - Creates MPEG movies of AVS images.
Name
Create MPEG - Creates MPEG movies of AVS images.
Summary
Name Create MPEG
Type
Inputs input - field 2D 4-vector uniform byte REQUIRED
Parameters
Name Type Default Choices
Filename browser File Type Filename
Pause toggle
Forget it oneshot
Make it oneshot
Repeat frame oneshot
size string Width : 000 Height : 000
Frame string Frame : 000
Description
Create MPEG is a subroutine module which will create MPEG movies from
a series of AVS images. It uses Andy Hung's 'MPEG' which is available
by anonymous ftp from:
havefun.stanford.edu:pub/mpeg/old/MPEGv1.2.tar.Z (the latest version
is MPEGv1.2.1 but this module has not been tested with it)
Because of the way MPEG movies are encoded by 'MPEG', many temporary
Files
need to be stored, bear this in mind when choosing which
directory to make your movie in.
To make a movie simply create an animation with the animator and then
bring Create MPEG onto the network area and connect it to the device
which is displaying the image (e.g. geometry viewer, image viewer) and
connect it up via a gamma correction module (see NOTE below). Select
the directory you want to create the movie in, select the file you
want the movie to be saved as, turn off pause and play the sequence
via the animator. When the sequence has finished press the 'Make it'
button this will execute 'MPEG' and will take quite a while to
execute. After 'MPEG' has finished all the temporary files are
removed.
Movies don't necessarily need to be made with the animator they can be
made with animate integers. There is however a problem if using the
image viewer's flipbook and spinning objects in the geometry
viewer. These modules don't wait for the image they output to be
processed before going onto the next and thus images are lost.
Inputs
input - field 2D 4-vector uniform byte
An AVS image.
Parameters
filename (browser)
The file name of the MPEG movie to create. Whilst the movie is being
created temporary files called 'filename'_tempxxx where xxx is a
number followed by either Y,U or V. After the movie has been made two
files will be left 'filename' which is the movie and
'filename'_messages which contains the messages returned by 'MPEG'
whilst making the movie.
The filename cannot be changed whilst a movie is being made you must
first 'Make' or 'Forget' the current movie to change the name of the
movie file.
pause (oneshot)
This determines whether new images are to be added to the movie.
Forget it (oneshot)
Forgets the movie currently being made. This causes all the temporary
files to be erased and the next image received will start a new movie.
Make it (oneshot)
This causes the movie to be created and the temporary files to be
created. It is as this stage that the message file is created. The
time this takes to execute is dependent on the number of frames and
the size of them.
Repeat Frame (oneshot)
This adds a frame to the sequence which is the same as the last frame
added.
Width : 000 Height : 000
This text window shows the width and height of the MPEG movie which
would be produced by the input image.
Frame : 000 (string)
This text window shows the current frame count to give you an idea of
how long and big your movies will be.
Example networks
Example
ONE: using the animator.
Stage: one : making the animation.
read geom AVS ANIMATOR
|
geometry viewer
Use this network to create the animation.
Stage: one : making the movie of the animation.
read geom AVS ANIMATOR
|
geometry viewer
|
Create MPEG
EXAMPLE TWO: using animate floats.
animate float generate colourmap read volue
\___________ | __________________|
\ | / |
arbitrary slicer volume bounds
|_____________________/
|
geometry viewer
|
Create MPEG
create_mpeg.net:
To run the sample network in create_mpeg.net
1. Compile and link the create_mpeg module
2. Read the create_mpeg module into AVS
3. Load the network file ``test.net''. This network
will create a movie of an isosurface with an increasing
value in the file /tmp/hy-iso.mpeg
4. Toggle the ``sleep'' parameter on the animated_float module
5. When the sequence has finished click the ``Make it'' button
on the create_mpeg module to create the sequence in the file
/tmp/hy-iso.mpeg
NOTES:
AVS automatically gamma corrects images as it displays them. The
internal representation of them is not gamma corrected. And so before
an image is sent to 'Create MPEG' it must be gamma corrected either
with 'Prepare Video', otherwise movies will appear dark.
MPEG movies must be the same size throughout the movie and so changing
the size of the input image will cause that image to be ignored.
It is best to create the Animation without 'Create MPEG' in the
Network
editor because if you change the name of the MPEG file to
create The animator will try and change it back. This causes a warning
message to come up telling you not to change the filename whilst
creating a movie. If this happens click on 'O.K.' and there will be no
adverse effects and the filename should be restored to what it was
originally.
MPEG movies of large images will take a long time to decompress and
display (not to mention the huge disk space required) and so a slow
refresh rate might occur. Also MPEG requires images with an even width
and height and so the MPEG movie might be a cropped by a pixel
horizontally and vertically.
ACKNOWLEDGEMENTS
Thanks go to Andy C Hung who wrote 'mpeg' which is at the heart of
this module.
See also
prepare_video
Animator
Author
For further information please contact:
The Computer Graphics Unit
Manchester Computing Centre
The University of Manchester
Manchester M13 9PL
United Kingdom
tel: +44 61 275 6095
fax: +44 61 275 6040
email: cgu-info@mcc.ac.uk
/*__________________________________________________________________________
Alex Knowles
Manchester Computing Centre, Computer Graphics Unit Tel. 061 275 6095
E-Mail
alex@ed.ac.uk
ark@hpa.cgu.mcc.ac.uk
--------------------------------------------------------------------------*/