NAME
r.out.mpeg - Raster File Series to MPEG Conversion Program
SYNOPSIS
r.out.mpeg
r.out.mpeg help
r.out.mpeg [-qc] view1=name[,name,...]
[view2=name[,name,...]]
[view3=name[,name,...]]
[view4=name[,name,...]]
[output=name]
[qual=value]
DESCRIPTION
r.out.mpeg is a tool for combining a series of GRASS raster files
into a single MPEG-1 (Motion Pictures Expert Group) format file. MPEG-1
is a "lossy" video compression format, so the quality of each resulting
frame of the animation will be much diminished from the original raster
image. The resulting output file may then be viewed using your favorite
mpeg-format viewing program.
MPEG-2 and MPEG-4 provide much better quality animations.
The user may define up to four "views", or sub-windows, to animate
simultaneously. e.g., View 1 could be rainfall, View 2 flooded areas,
View 3 damage to bridges or levees, View 4 other economic damage, all
animated as a time series. A black border 2 pixels wide is drawn around
each view. There is an arbitrary limit of 400 files per view (400
animation frames). Temporary files are created in the conversion
process, so lack of adequate tmp space could also limit the number of
frames you are able to convert.
The environment variable GMPEG_SIZE is checked for a value to use as the
dimension, in pixels, of the longest dimension of the animation image.
If GMPEG_SIZE is not set, the animation size defaults to the rows &
columns in the current GRASS region, scaling if necessary to a default
minimum size of 200 and maximum of 500. These size defaults are overridden
when using the -c flag (see below). The resolution of the current GRASS
region is maintained, independent of image size. Playback programs have
to decode the compressed data "on-the-fly", therefore smaller dimensioned
animations will provide higher frame rates and smoother animations.
UNIX - style wild cards may be used with the command line version in place
of a raster file name, but wild cards must be quoted.
Example:
r.out.mpeg view1="rain[1-9]","rain1[0-2]" view2="temp*"
If the number of files differs for each view, the view with the fewest files
will determine the number of frames in the animation.
OPTIONS
Flags:
- -q
- Quiet - suppress progress report.
- -c
- Convert "on the fly", uses less disk space by using r.out.ppm
with stdout option to convert frames as needed instead of converting all
frames to ppm before encoding. Only use when encoding a single view.
Use of this option also overrides any size defaults, using the CURRENTLY
DEFINED GRASS REGION for the output size. So be careful to set region to
a reasonable size prior to encoding.
Parameters:
- view1
- Raster file(s) for View1.
- view2
- Raster file(s) for View2.
- view3
- Raster file(s) for View3.
- view4
- Raster file(s) for View4.
- output
- Name for MPEG output file.
- Default: gmovie.mpg
- qual
- Quality factor (1-5).
- Default: 3
A quality value of qual=1 will yield higher quality images, but
with less compression (larger MPEG file size). Compression ratios will
vary depending on the number of frames in the animation, but an MPEG
produced using qual=5 will usually be about 60% the size of
the MPEG produced using qual=1.
BUGS
MPEG images must be 16-pixel aligned for successful compression, so if
the rows & columns of the calculated image size (scaled, with borders
added) are not evenly divisible by 16, a few rows/columns will be cut off
the bottom & right sides of the image. The MPEG format is optimized to
recognize image MOTION, so abrupt changes from one frame to another will
cause a "noisy" encoding.
NOTES
This program requires the program mpeg_encode (aka ppmtompeg):
MPEG-1 Video Software Encoder
(Version 1.3; March 14, 1994)
Lawrence A. Rowe, Kevin Gong, Ketan Patel, and Dan Wallach Computer Science
Division-EECS,
Univ. of Calif. at Berkeley
Available from Berkeley:
http://bmrc.berkeley.edu/frame/research/mpeg/mpeg_encode.html
or as part of the netpbm package (ppmtompeg):
http://netpbm.sourceforge.net
Playback may be done with many viewers; mpeg_encode's official companion
is mpeg_play available from Berkeley at
ftp://mm-ftp.cs.berkeley.edu/pub/multimedia/mpeg/play/
or a precompiled Debian package from
http://packages.debian.org/ucbmpeg-play
(includes maintained source code).
Use of the -c flag also requires the program r.out.ppm
with the stdout option.
AUTHOR
Bill Brown, U.S. Army Construction Engineering Research Laboratories
Last changed: $Date: 2004/10/20 09:53:39 $