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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.

          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.

     -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.

     -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