MPEG_PLAY(1) MPEG_PLAY(1)
28 May 1995
NAME
mpeg_play - plays mpeg-1 encoded bitstreams using X11
SYNOPSIS
mpeg_play [ -nob ] [ -nop ] [ -display display_name ] [ -quality
{on|off} ] [ -dither dither_option ] [ -loop ] [ -eachstat ] [ -seek
offset ] [ -start num ] [ -end num ] [ -gamma gamma_correction_value ]
[ -framerate num ] [ -no_display ] [ -controls {on|off|none} ] [ -
shmem_off ] [ -l_range num ] [ -cr_range num ] [ -cb_range num ] [ -
quiet ] file_name
DESCRIPTION
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.
OPTIONS
-nob : causes the player to ignore and not display any B frames.
-nop : causes the player to ignore and not display any P and B frames.
-display display_name : causes the player to open the window on the
display display_name.
-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.
-dither dither_option : selects from a variety of dither options. The
possible values are:
ordered - ordered dither.
ordered2 - a faster ordered dither. This is the default.
mbordered - ordered dithering at the macroblock level. Although
there is a noticeable decrease in dither quality, this is
the fastest dither available.
fs4 - Floyd-Steinberg dithering with 4 error values propagated.
fs2 - Floyd-Steinberg dithering with 2 error values propagated.
fs2fast - Fast Floyd-Steinberg dithering with 2 error values
propagated.
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MPEG_PLAY(1) MPEG_PLAY(1)
28 May 1995
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.
hybrid2 - Hybrid dithering as above, but with error propagation
among pixels.
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.
gray - Grayscale dithering. The image is dithered into 128
grayscales. Chrominance information is thrown away.
gray256 - Grayscale dithering. The image is dithered into 256
grayscales (requires private colormap). Chrominance
information is thrown away.
color - Full color display (only available on 16/24 bit color
displays).
color2 - Full color display with increased size (only available
on 16/24 bit color displays).
none - no dithering is done, no image is displayed. Used to time
decoding process.
mono - Floyd-Steinberg dithering for monochrome displays.
threshold - Floyd-simple dithering for monochrome displays.
ppm - Write a PPM file for each frame.
-loop : makes the player loop back to the beginning after reaching the
end.
-owncm : makes the player use a private colormap for the window.
-step : requires the user to press return for each new frame.
-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.
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MPEG_PLAY(1) MPEG_PLAY(1)
28 May 1995
-start num : Waits to start display until this frame number (previous
frames are parsed).
-end num : ends display at this frame number (except when -seek is
used).
-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.
-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.
-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).
-quiet : suppresses printing of frame numbers, timing information, and
most error messages.
-eachstat : causes statistics to be displayed after each frame. Only
valid when compiled with -DANALYSIS.
-shmem_off : turns shared memory off.
-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.
-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.
-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.
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MPEG_PLAY(1) MPEG_PLAY(1)
28 May 1995
-no_display : dithers, but does not display, usually used for testing
and timing purposes.
NOTES
The player expects video streams only. It can handle multiplexed MPEG
streams (video+audio streams) by discarding the audio. Some streams do
not end with the proper sequence end code and will probably generate
an "Improper sequence end code." error when done playing. 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. The player does not play
MPEG-1 D-frame streams, but they are a rarity. If the player is
compiled without the controlbar, then it can play multiple streams in
different windows.
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.
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.)
AUTHORS
Ketan Patel - University of California, Berkeley,
kpatel@cs.berkeley.edu
Brian Smith - University of California, Berkeley,
bsmith@cs.berkeley.edu
Henry Chi-To Ma - University of California, Berkeley,
cma@cs.berkeley.edu
Kim Man Liu - University of California, Berkeley, kliu@cs.berkeley.edu
Steve Smoot - University of California, Berkeley,
smoot@cs.berkeley.edu
Eugene Hung - University of California, Berkeley,
eyhung@cs.berkeley.edu
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