MPEG(1) MPEG(1)
14 June 1993
NAME
mpeg - MPEG compression and decompression
SYNOPSIS
mpeg [-d] [-NTSC] [-CIF] [-QCIF] [-PF] [-NPS] [-MBPS mbps] [-UTC]
[-XING] [-DMVB] [-MVNT]
[-a StartNumber] [-b EndNumber]
[-h HorizontalSize] [-v VerticalSize]
[-f FrameInterval] [-g GroupInterval]
[-4] [-c] [-i MCSearchLimit] [-o] [-p PictureRate]
[-q Quantization] [-r Target Rate]
[-s StreamFile] [-x Target Filesize] [-y]
[-z ComponentFileSuffix i]
ComponentFilePrefix1 [ComponentFilePrefix2 ComponentFilePrefix3]
DESCRIPTION
mpeg is a multimedia image sequence compression/decompression program
that performs MPEG encoding and decoding.
OPTIONS
-NTSC
indicates that the source frame size for the Luminance component
is 352x240 and for the Chrominance components is 176x120. This is
the default size.
-CIF indicates that the source frame size for the Luminance component
is 352x288 and for the Chrominance components is 176x144.
-QCIF
indicates that the source frame size for the Luminance component
is 176x144 and for the Chrominance components is 88x72.
-PF indicates that the component sizes specified by -h and -v are not
multiples of 16 and furthermore that the input files (or output
files) should be exactly that specified by the component size -h
and -v (or as read from the compressed stream). Otherwise the
input and output files will be the component size rounded up to a
multiple of 16 in each dimension.
-NPS The NPS option allows the encoder to encode without having the
restriction that the last macroblock in a slice cannot be
skipped. For coding purposes, the first macroblock in a slice
must be coded, although the decoder will probably handle that
case as well.
-MBPS
This specifies the macroblocks per slice. If left unspecified
then the number of macroblocks per slice is the number of
macroblocks on one row of the image.
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MPEG(1) MPEG(1)
14 June 1993
-UTC Forces the frame number of the image to match the Group-of-
Pictures time code. Only useful for the decoder.
-XING
enables XING compatible encoding for intra-frame only files for
the XING decoders. May not be robust, but eventually XING
encoders and decoders will become more MPEG compatible. This
specifies 160x120 encoding (apparently the defacto) for XING
decoders. If you wish to overide the 160x120 encoding for XING
image format, use the -h and -v options after the -XING option.
By default -PF is always selected with -XING option.
-DMVB
denotes Dynamic Motion Vector Bounding. Should reduce the
overall bits spent in the motion vectors if set. Generally
doesn't do that much for the default settings, but changing the
search limit will automatically enable the dynamic motion vector
bounding feature.
-MVNT
disables the motion vector telescoping. Generally telescoping is
a big gain when the search window is small, though if the search
window grows large, telescoping may not be beneficial.
-a denotes the following value to be the start of the filename index
[inclusive]. Defaults to 0.
-b denotes the following value to be the end of the filename index
[inclusive]. Defaults to 0.
-d enables the decoder. The only options useful for the decoder are
the filename specifications and the -NPS, -UTC commmands; the
rest of the command-line information is used for encoding.
-h is the horizontal size of the picture in terms of the luminance
component, used for a non -NTSC, -CIF, -QCIF filesize. See the
preceding note about -PF about the dimensions of the file
relative to that of the component.
-v is the vertical size of the picture in terms of the luminance
component, used for a non -NTSC, -CIF, -QCIF filesize. See the
preceding note about -PF about the dimensions of the file
relative to that of the component.
-f is the number of interpolated frames between each intra/predicted
frame. FrameInterval-1 is the number of interpolated frames
within each frame interval.
-g is the number of frame intervals per group-of-pictures. With a
group interval of 1 then there are no predicted frames. The
value GroupInterval-1 is the number of predicted frames in each
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14 June 1993
group of pictures.
-4 is used to DC Intraframe mode where only the DC components of
each picture block is coded.
-i is the diameter of the motion estimation search. The diameter
must be be positive. The default value is 15 for a search window
of approx (+- 7.5, +- 7.5). The motion estimation is telescopic
for frame distances greater than 1 (thus having a greater
effective range). The telescopic motion estimation can be turned
off by the -MVNT flag. This option can now have a value greater
than 15 but less than approximately 960. For large values the
estimation becomes very slow.
-o signals that the program interpreter will read the control
algorithms from the standard input.
-p specifies the picture rate by a code directly placed into the
stream. It must be a number between 0 and 8. (default 5=30Hz).
-q gives a value for the quantization not in the presence of rate
control (rate control automatically changes the quantization
values). If rate control is specified, this parameter gives a
value for the initial quantization of the first frame (which the
program usually takes an educated guess at).
-r specified a rate for the coded stream. If this is enabled, a
buffer model is used to limit the size of the coding stream. Note
this is given in bits per second.
-s specifies the filename to store the coded image. If unspecified
it defaults to ComponentFilePrefix0.mpg.
-v designates that quantization decisions are to be written to
standard output. This is the verbose mode.
-x gives a target filesize for the compressed stream. This overrides
the rate option -r, if specified. This is specified in bits. The
actual implementation of this technique is through calculating
the equivalent bit-rate. Since the buffer usually has some
contents at the end of coding, the final filesize is larger than
actually designated.
-y enables the double-precision floating point Reference DCT. The
default is the Chen DCT.
-z denotes the component file suffixes in sequential order. For
example
-z .y.clr -z .u.clr -z .v.clr indicates that the luminance and
the two chrominance files end with a suffix of .y.clr, .u.clr,
and .v.clr, in that order. If unspecified, the suffixes default
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MPEG(1) MPEG(1)
14 June 1993
to .Y, U, and .V.
ComponentFilePrefixn
must be specified. In general, the other component files share
the same prefix and will default to ComponentFilePrefix1 if not
explicitly specified. However, in some cases the prefix is what
changes in the file and we can specify this individually.
EXAMPLES
To encode a set of raw raster scan YCbCr (also known as digital YUV)
files with dimension 352x240 Y, 176x120 U,V, with labels, hello0.Y
hello0.U hello0.V, hello1.Y hello1.U hello1.V, ..., hello12.Y
hello12.U hello12.V through the mpeg encoder, type
mpeg -a 0 -b 12 hello -s hello.mpg
This creates the output file hello.mpg. In order to decode such a file
into a sequence of image files with prefix goodbye, type
mpeg -d -s hello.mpg goodbye
The output will be placed in the files goodbye0.Y goodbye0.U
goodbye0.V, goodbye1.Y goodbye1.U goodbye1.V, ..., goodbye12.Y
goodbye12.U goodbye12.V. These image sequences can be displayed by
the cv program. The image sequences can also be converted to ppm and
back through the programs cyuv2ppm and ppm2cyuv Those utility programs
available by anonymous ftp from
havefun.stanford.edu:pub/cv/CVv1.2.1.tar.Z. There are more options
within an internal program interpreter. Please see the accompanying
documentation in doc.ps for more details.
FTP
mpeg is available by anonymous ftp from
havefun.stanford.edu:pub/mpeg/MPEGv1.2.tar.Z.
BUGS
Somewhat slower than many commercial implementations. Please inform
the author at achung@cs.stanford.edu if any bugs are found.
AUTHOR
Andy Hung
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