ppmtompeg Man page

PPMTOMPEG(1) General Commands Manual PPMTOMPEG(1)

NAME

ppmtompeg – encodes MPEG-1 bitstreams

SYNOPSIS

ppmtompeg [ options ] parameter-file

DESCRIPTION

ppmtompeg produces an MPEG-1 video stream. param_file is a parameter
file which includes a list of input files and other parameters. The
file is described in detail below. The -gop, -combine_gops, -frames,
and -combine_frames options are all exclusive. This man page is proba‐
bly incomplete. For complete usage, see the User’s Guide.

OPTIONS

-stat stat_file : causes the encoder to append the statistics to the
file stat_file. In any case, the statistics are output to std‐
out. The statistics use the following abbreviations: bits per
block (bpb), bits per frame (bpf), seconds per frame (spf), and
bits per second (bps).

-quiet num_seconds : causes the program to not report remaining time
for at least num_seconds seconds. A negative values tells the
program not to report at all. 0 is the default (reports once
after each frame). Note that the time remaining is an estimate
and does not take into account time to read in frames.

-realquiet : causes the encoder to run silently, with the only screen
output being errors. Particularly useful when reading input
from stdin.

-no_frame_summary : prevents the program from printing a summary line
for each frame

-float_dct : forces the encoder to use a more accurate, yet more compu‐
tationally expensive version of the DCT.

-gop gop_num : causes the encoder to only encode the numbered GOP
(first GOP is 0). The parameter file is the same as for normal
usage. The output file will be the normal output file with the
suffix “.gop.” No sequence info is output.

-combine_gops : causes the encoder to simply combine some GOP files
into a single MPEG stream. A sequence header/ender are
inserted. In this case, the parameter file need only contain
the YUV_SIZE value, an output file, and perhaps a list of input
GOP files (see below).

-frames first_frame last_frame : causes the encoder to only encode the
frames from first_frame to last_frame, inclusive. The parameter
file is the same as for normal usage. The output will be placed
in separate files, one per frame, with the file names being the
normal output file with the suffix “.frame.” No GOP
header information is output. (Thus, the parameter file need
not include the GOP_SIZE value)

-combine_frames : causes the encoder to simply combine some frames into
a single MPEG stream. Sequence and GOP headers are inserted
appropriately. In this case, the parameter file need only con‐
tain the YUV_SIZE value, the GOP_SIZE value, an output file, and
perhaps a list of frame files (see below).

-nice : causes the program to run any remote processes ‘nicely.’ This
is only relevant if the program is using parallel encoding.
(see ‘man nice.’)

-max_machines num_machines : causes the program to use no more than
num_machines machines as slaves for use in parallel encoding.

-snr : print the signal-to-noise ratio. Prints SNR (Y U V) and peak
SNR (Y U V) for each frame. In summary, prints averages of
luminance only (Y). SNR is defined as 10*log(variance of origi‐
nal/variance of error). Peak SNR is defined as
20*log(255/RMSE). Note that the encoder will run a little
slower if you want it to print the SNR.

-mse : computes the mean squared error per block. Also automatically
computes the quality of the images when set, so there is no need
to specify -snr then.

-bit_rate_info rate_file : prints bit rate information into the file
rate_file. Bit rate info is bits per frame, and also bits per
I-frame-to-I-frame.

-mv-histogram : prints histogram of motion vectors as part of statis‐
tics. There are three histograms — one for P, forward B, and
backward B vectors. Each histogram is a 2-dimensional array,
and there is one entry for each vector in the search window.

PARAMETER FILE
The parameter file MUST contain the following lines (except when using
the -combine_gops or -combine_frames options):

PATTERN

OUTPUT

INPUT_DIR
all input files must reside in this directory. If you
want to refer to the current directory, use ‘.’ (an empty
INPUT_DIR value would refer to the root directory). If
input files will be coming in from standard input, use
‘stdin’.

INPUT
This line must be followed by a list of the input files
(in display order) and then the line
END_INPUT
There are three types of lines between INPUT and
END_INPUT. First, a line may simply be the name of an
input file. Secondly, the line may be of the form
[x-y] single_star_expr can have a single ‘*’ in it. It is
replaced by all the numbers between x and y inclusive.
So, for example, the line
tennis*.ppm [12-15] is replaced by tennis12.ppm, tennis13.ppm, tennis14.ppm,
tennis15.ppm. Uniform zero-padding occurs, as well. For
example, the line
football.*.ppm [001-130] is replaced by football.001.ppm, football.002.ppm, …,
football.009.ppm, football.010.ppm, …, foot‐
ball.130.ppm. The third type of line is:
[x-y+s] Where the line is treated exactly as above, except that
we skip by s. Thus, the line
football.*.ppm [001-130+4] is replaced by football.001.ppm, football.005.ppm, foot‐
ball.009.ppm, football.013.ppm, etc.

BASE_FILE_FORMAT
All the input files must be converted to YUV, JPEG(v4),
JMOVIE, PNM, or PPM format. This line specifies which of
the three formats (actually PPM is a subset of PNM). The
reason for having a separate PPM option is for simplic‐
ity. If your files are RAWBITS ppm files, then use the
PPM option rather than the PNM. Also, depending on the
system, file reads will go much faster with the PPM
option (as opposed to PNM).

INPUT_CONVERT
You must specify how to convert a file to the base file
format. In the conversion command, each ‘*’ is replaced
by the filename (the items listed between INPUT and
END_INPUT). If no conversion is necessary, then you
would just say:
INPUT_CONVERT *
If you had a bunch of gif files, you might say:
INPUT_CONVERT giftoppm *
If you have a bunch of separate a.Y, a.U, and a.V files,
then you might say:
INPUT_CONVERT cat *.Y *.U *.V
Input conversion is not allowed with input from
stdin.

GOP_SIZE
n is roughly the number of frames in a Group of
Pictures (roughly because a GOP must begin with an
I-frame)

SLICES_PER_FRAME
n is roughly the number of slices per frame.
Note, at least one MPEG player may complain if
slices do not start at the left side of an image.
To ensure this does not happen, make sure the num‐
ber of rows is divisible by SLICES_PER_FRAME.

PIXEL
use half-pixel motion vectors, or only full-pixel
ones

RANGE
use a search range of +/- n pixels

PSEARCH_ALG
algorithm must be one of {EXHAUSTIVE, TWOLEVEL,
SUBSAMPLE, LOGARITHMIC}. Tells what kind of
search procedure should be used for P-frames.
Exhaustive gives the best compression, but loga‐
rithmic is the fastest. You select the desired
combination of speed and compression. TWOLEVEL is
an exhaustive full-pixel search, followed by a
local half- pixel search around the best full-
pixel vector (the PIXEL option is ignored for this
search algorithm).

BSEARCH_ALG
algorithm must be one of {SIMPLE, CROSS2, EXHAUS‐
TIVE}. Tells what kind of search procedure should
be used for B-frames. Simple means find best for‐
ward and backward vectors, then interpolate.
Cross2 means find those two vectors, then see what
backward vector best matches the best forward vec‐
tor, and vice versa. Exhaustive does an n-squared
search and is EXTREMELY slow in relation to the
others (Cross2 is about twice as slow as Simple).

IQSCALE
use n as the qscale for I-frames

PQSCALE
use n as the qscale for P-frames

BQSCALE
use n as the qscale for B-frames

REFERENCE_FRAME
If ORIGINAL is specified, then the original images
are used when computing motion vectors. To be
more accurate, use DECODED, in which the decoded
images are used. This should increase the quality
of the image, but will take a bit longer to
encode.
The following lines are optional:

FORCE_I_ALIGN
This option is only relevant for parallel
execution (see below). It forces each pro‐
cessor to encode a block of N frames, where
N must be a multiple of the pattern length.
Since the first frame in any pattern is an
I-frame, this forces each block encoded by
a processor to begin with an I-frame.
foo

NOTES
If the BASE_FILE_FORMAT is YUV, then the parameter file must contain:
YUV_SIZE x
where w = width, h = height (in pixels) of image, and
YUV_FORMAT .
See the file doc/INPUT.FORMAT for more information.

If the -combine-gops option is used, then only the YUV_SIZE and OUTPUT
values need be specified in the parameter file. In addition, the
parameter file may specify input GOP files in the same manner as normal
input files — except instead of using INPUT_DIR, INPUT, and END_INPUT,
use GOP_INPUT_DIR, GOP_INPUT, and GOP_END_INPUT. If no input GOP files
are specified, then the default is to use the output file name with
suffix “.gop.” starting from 0 as the input files.

If the -combine-frames option is used, then only the YUV_SIZE,
GOP_SIZE, and OUTPUT values need be specified in the parameter file.
In addition, the parameter file may specify input frame files in the
same manner as normal input files — except instead of using INPUT_DIR,
INPUT, and END_INPUT, use FRAME_INPUT_DIR, FRAME_INPUT, and
FRAME_END_INPUT. If no input frame files are specified, then the
default is to use the output file name with suffix “.frame.
starting from 0 as the input files.

Any number of spaces and tabs may come between each option and value.
Lines beginning with ‘#’ are ignored. Any other lines are ignored
except for those between INPUT and END_INPUT. This allows you to use
the same parameter file for normal usage and for -combine_gops and
-combine_frames.

The encoder is case-sensitive so, except for file names and directo‐
ries, everything should be in upper case.

The lines may appear in any order, except the following exceptions.
INPUT must appear before END_INPUT (also, GOP_INPUT before
GOP_END_INPUT and FRAME_INPUT before FRAME_END_INPUT). All lines
between INPUT and END_INPUT must be the frames in play order.

The encoder is prepared to handle up to 16 B frames between reference
frames when encoding with input from stdin. To increase this amount,
change the constant B_FRAME_RUN in frame.c and recompile.

PARALLEL OPERATION
The encoder may be run on multiple machines at once. To do so, add a
line “PARALLEL” in the parameter file, followed by a listing, one
machine per line, then “END_PARALLEL”. Each of the lines should be in
one of two forms. If the machine has access to the file server, then
the line should be:

The executable is normally ppmtompeg (you may need to give the complete
path if you’ve built for different architectures). If the machine is a
remote machine, then the line should be:

REMOTE

Full paths should generally be used when describing executables and
parameter files. This INCLUDES the parameter file given as an argument
to the original call to ppmtompeg. Also, .rhosts files on the appro‐
priate machines should have the appropriate information.

The encoder will use the original machine for the master and I/O server
processes, and uses the listed machines as slaves to do the computa‐
tion.

Optional lines are

RSH
The encoder uses the remote shell command to start processes on
other machines. The default command is ‘rsh.’ If your machine
supports a different command, specify it here.

PARALLEL_TEST_FRAMES
n is the number of frames to encode initially on each processor

PARALLEL_TIME_CHUNKS
subsequently, each slave processor will be asked to encode for
approximately t seconds. Smaller values of increase commu‐
nication, but improve load balancing.

The default values for these two options are n = 3 frames and t
= 30 seconds.

PARALLEL_PERFECT
If this line is present, then scheduling is done on the assump‐
tion that work distribution will be perfectly even — meaning
that each machine is about the same speed. The frames will sim‐
ply be divided up evenly between the processors. This has the
advantage of very minimal scheduling overhead, but is obviously
wrong if machines have varying speeds, or if the network load
makes performance uneven.

VERSION
This is version 1.5 it contins new features and bug fixes from version
1.3.

BUGS

Not really a bug, but at least a limitation: If writing to an output
file, ppmtompeg sometimes uses .* as temporary files.

No known bugs, but if you find any, report them to mpeg-
bugs@plateau.cs.berkeley.edu.

AUTHORS
Kevin Gong – University of California, Berkeley, keving@cs.berkeley.edu

Ketan Patel – University of California, Berkeley, kpatel@cs.berke‐
ley.edu

Dan Wallach – University of California, Berkeley, dwallach@cs.berke‐
ley.edu

Darryl Brown – University of California, Berkeley, darryl@cs.berke‐
ley.edu

Eugene Hung – University of California, Berkeley, eyhung@cs.berke‐
ley.edu

Steve Smoot – University of California, Berkeley, smoot@cs.berkeley.edu

1 February 1995 PPMTOMPEG(1)

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