NAME¶
r.out.mpeg - Raster File Series to MPEG Conversion.
KEYWORDS¶
raster, export
SYNOPSIS¶
r.out.mpeg
r.out.mpeg help
r.out.mpeg [-
qc]
view1=
string[,
string,...]
[
view2=
string[,
string,...]]
[
view3=
string[,
string,...]]
[
view4=
string[,
string,...]] [
output=
string]
[
qual=
integer] [--
verbose] [--
quiet]
Flags:¶
- -q
-
Quiet - suppress progress report
- -c
-
Convert on the fly, use less disk space (requires r.out.ppm with stdout
option)
- --verbose
-
Verbose module output
- --quiet
-
Quiet module output
Parameters:¶
- view1=string[,string,...]
-
Raster file(s) for View1
- view2=string[,string,...]
-
Raster file(s) for View2
- view3=string[,string,...]
-
Raster file(s) for View3
- view4=string[,string,...]
-
Raster file(s) for View4
- output=string
-
Name for output file
Default: gmovie.mpg
- qual=integer
-
Quality factor (1 = highest quality, lowest compression)
Options: 1-5
Default: 3
DESCRIPTION¶
r.out.mpeg is a tool for combining a series of GRASS raster maps 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 map 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.
With
-c flag the module converts "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.
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 requires the
r.out.ppm GRASS module with the
stdout option.
SEE ALSO¶
r.out.ppm
AUTHOR¶
Bill Brown, U.S. Army Construction Engineering Research Laboratories
Last changed: $Date: 2008-05-16 21:09:06 +0200 (Fri, 16 May 2008) $
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