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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