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.\" @(#)mpeg_play.1 2.1a 93/01/27 SMI;
.TH MPEG_PLAY 1 "28 May 1995"
.SH NAME
mpeg_play \- plays mpeg-1 encoded bitstreams using X11
.SH SYNOPSIS
.B mpeg_play
[
.B -nob
] [
.B -nop
] [
.B -display display_name
] [
.B -quality {on|off}
] [
.B -dither dither_option
] [
.B -loop 
] [
.B -eachstat 
] [
.B -seek offset
] [
.B -start num
] [
.B -end num
] [
.B -gamma gamma_correction_value
] [
.B -framerate num
] [
.B -no_display 
] [
.B -controls {on|off|none}
] [
.B -shmem_off 
] [
.B -l_range num
] [
.B -cr_range num
] [
.B -cb_range num
] [
.B -quiet 
]
.B file_name
.SH DESCRIPTION
.B mpeg_play
decodes and displays mpeg-1 encoded bitstreams on systems running X11.
The player will create a new window, display the bitstream, and exit.
Any error messages or notices are sent to stderr. 
.SH OPTIONS
.HP
.B -nob 
: causes the player to ignore and not display any B frames.
.HP
.B -nop 
: causes the player to ignore and not display any P and B frames.
.HP
.B -display display_name 
: causes the player to open the window on the display \fIdisplay_name\fP.
.HP
.B -quality {on|off}
: forces player to choose output quality over speed when on, and vice versa
when off.  When quality is on, the player uses a computationally expensive
IDCT and also improves playback through improved handling of half pixel
motion vectors.  The default can be set to on if you compile mpeg_play 
with the flag -DQUALITY.
.HP
.B -dither dither_option 
: selects from a variety of dither options. The possible values are:
.RS
.HP
ordered - ordered dither. 
.HP
ordered2 - a faster ordered dither. This is the default.
.HP
mbordered - ordered dithering at the macroblock level. Although there
is a noticeable decrease in dither quality, this is the fastest dither
available.
.HP
fs4 - Floyd-Steinberg dithering with 4 error values propagated.
.HP
fs2 - Floyd-Steinberg dithering with 2 error values propagated.
.HP
fs2fast - Fast Floyd-Steinberg dithering with 2 error values propagated.
.HP
hybrid - Hybrid dithering, a combination of ordered dithering for the luminance
channel and Floyd-Steinberg 2 error dithering for the chrominance channels. Errors
are NOT propagated properly and are dropped all together every two pixels in either
direction.
.HP
hybrid2 - Hybrid dithering as above, but with error propagation among pixels.
.HP
2x2 - A dithering technique using a 2x2 pixel area for each pixel. The image displayed
is 4 times larger than the original image encoded. Random error terms are added to 
each pixel to break up contours and gradients.
.HP
gray - Grayscale dithering. The image is dithered into 128 grayscales. Chrominance
information is thrown away.
.HP
gray256 - Grayscale dithering. The image is dithered into 256 grayscales
(requires private colormap). Chrominance information is thrown away.
.HP
color - Full color display (only available on 16/24 bit color displays).
.HP
color2 - Full color display with increased size (only available on 16/24
bit color displays).
.HP
none - no dithering is done, no image is displayed. Used to time decoding process.
.HP
mono - Floyd-Steinberg dithering for monochrome displays.
.HP
threshold - Floyd-simple dithering for monochrome displays.
.HP
ppm - Write a PPM file for each frame.
.RE
.HP
.B -loop
: makes the player loop back to the beginning after reaching the end.
.HP 
.B -owncm
: makes the player use a private colormap for the window.
.HP 
.B -step
: requires the user to press return for each new frame.
.HP 
.B -seek offset
: before playing the movie, seek to the given offset in the file (useful
for large movies).  In this case -end is redefined to give the number of
frames to play, and -start has no meaning.  The offset should point to a
Sequence or (closed) GOP header, but data will be discarded until one is
found.
The initial sequence header will be parsed before the seek.  The skipped
sections must not change the quantization matrices or the results are
undefined. 
.HP
.B -start num
: Waits to start display until this frame number (previous frames are
parsed).
.HP 
.B -end num
: ends display at this frame number (except when -seek is used).
.HP
.B -gamma gamma_correction_param
: specifies the amount of gamma correction.  Default is 1.0.  Use higher
values if movie looks dark and hard to see.
.HP 
.B -framerate num
: sets the framerate of the playback to num frames per second.  A value of
0 indicates that the stream should be played as fast as possible.  The
default is to play at the rate specified in the stream (if possible).  Note
this is merely a framerate limiter, it will not discard frames to meet the
rate.
.HP
.B -controls {on|off|none}
: determines the initial interactive X user interface control bar
state (if available).  The value on (default) opens the control bar at
initialization and enters pause mode after displaying the first frame.
The value off leaves the control bar initially hidden and begins
playback without pausing (similar to the old behavior).  The control bar
can be toggled on and off 
at any time by clicking in the video display window, unless the
-controls none option is specified, in which case the control bar is
unavailable and playback functions as though the player were built
without interactive controls (exactly the old behavior).
.HP 
.B -quiet
: suppresses printing of frame numbers, timing information, and most error
messages.
.HP
.B -eachstat
: causes statistics to be displayed after each frame. Only valid when
compiled with -DANALYSIS.
.HP
.B -shmem_off
: turns shared memory off.
.HP
.B -l_range num_colors
: sets the number of colors assigned to the luminance component when
dithering the image.  The product of l_range, cr_range and cb_range
should be less than the number of colors on the display.
.HP
.B -cr_range num_colors
: sets the number of colors assigned to the red component of the
chrominance range when dithering the image.  The product of l_range,
cr_range and cb_range should be less than the number of colors on the
display.
.HP
.B -cb_range num_colors
: sets the number of colors assigned to the blue component of the
chrominance range when dithering the image.  The product of l_range,
cr_range and cb_range should be less than the number of colors on the
display.
.HP
.B -no_display
: dithers, but does not display, usually used for testing and timing
purposes.
.SH NOTES
The player expects video streams only. It can handle multiplexed MPEG streams
(video+audio streams) by discarding the audio. 
.LP
Some streams do not end with the proper sequence end code and will probably generate
an "Improper sequence end code." error when done playing.
.LP
This player can play XING data files. Be aware that XING makes no use of temporal 
redundancy or motion vector information. In other words, they do not use any P or 
B frames in their streams. Instead, XING data is simply a sequence of I frames. Since
I frames take significantly longer to decode, performance of the player using XING
data is not representative of the player's ability.
.LP
The player does not play MPEG-1 D-frame streams, but they are a rarity.
.LP
If the player is compiled without the controlbar, then it can play
multiple streams in different windows.
.SH VERSION
This is version 2.1a, containing some new features since 2.0, and several bug
fixes.  It is a major change since version 1.0.
.SH BUGS
The only known bug is that multiple mpeg_plays cannot seem to be run
simultaneously on a multiprocessor SPARC 20 or a SparcCenter 2000E using
shared memory
(in particular:  "On a bi-processor Sparc 20/20 sparc-processor 2000E running 
Solaris 2.3 or 2.4, it is not possible to run two concurrent 'mpeg_play -loop'
on the same bitstream.  One of the mpeg_play dies when it loops."  This
may be a problem with the X shared memory library and not our code.)
.SH AUTHORS
.HP
Ketan Patel - University of California, Berkeley, kpatel@cs.berkeley.edu
.HP
Brian Smith - University of California, Berkeley, bsmith@cs.berkeley.edu
.HP
Henry Chi-To Ma - University of California, Berkeley, cma@cs.berkeley.edu
.HP
Kim Man Liu - University of California, Berkeley, kliu@cs.berkeley.edu
.HP
Steve Smoot - University of California, Berkeley, smoot@cs.berkeley.edu
.HP
Eugene Hung - University of California, Berkeley, eyhung@cs.berkeley.edu