MPEG_PLAY(1)

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.

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