MPEG(3)                                                   MPEG(3)

     NAME
          mpeg - Boffin mpeg decoder

     SYNOPSIS
          bind -b #E /dev

          /dev/mpeg
          /dev/mpegctl

     DESCRIPTION
          The mpeg device serves two files giving access to a Boffin
          MPEG-1 decoder.

          The control file mpegctl when read returns lines of text
          giving the device's properties.  Each line starts video or
          audio followed by a list of capabilities.  The current
          device returns a fixed set:

               video mpeg1,sif
               audio musicam,I musicam,II

          The control file accepts the following commands:

          init   Reinitialise the device's video and audio subsystems;
                 cancel the effect of stop or pause

          stop   Stop the display immediately.

          pause  Suspend display.

          video iso11172 mpeg1,sif
                 Set the output video mode and formats; only this pre-
                 cise setting is valid.

          audio format rate
                 There are two choices for format: musicam,I (MPEG
                 audio layer 1), with rate from 64000 to 448000 Hz,
                 and musicam,II (MPEG audio layer 2) with rate from
                 48000 to 384000.

          window minx miny maxx maxy
                 Sets the overlay window on the screen, in screen
                 coordinates.  If the window size exceeds 320x240, the
                 image is scaled accordingly, separately in each
                 dimension.

          The data file mpeg is an exclusive-use device.  Once the
          device has been initialised and an output window set using
          the init and window commands to the control file, and an

     MPEG(3)                                                   MPEG(3)

          audio format selected by the audio command, MPEG data can be
          written in the agreed format to the mpeg file, for display
          in the output window.  The driver buffers the data written
          and implements flow control between application and the
          hardware.  When closed, the device waits for the last block
          of data to display before returning to the application.

     SOURCE
          /os/pc/devmpeg.c

     CONFIGURATION
          mpeg0=port=0x1e0 irq=15 dma=6

     SEE ALSO
          mpeg(2), stream in sys-read(2)

     DIAGNOSTICS
          An error results on a write to the device once stopped.