shithub: 9ferno

ref: 6966e8d72ae8fb72ebf98909acbd464aff84a3cc

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.TH MPEG 3
.SH NAME
mpeg \- Boffin mpeg decoder
.SH SYNOPSIS
.B
bind -b #E /dev
.PP
.B /dev/mpeg
.br
.B /dev/mpegctl
.SH DESCRIPTION
The
.I mpeg
device serves two files giving access to a Boffin MPEG-1 decoder.
.PP
The control file
.B mpegctl
when read returns lines of text giving the device's properties.
Each line starts
.B video
or
.B audio
followed by a list of capabilities.
The current device returns a fixed set:
.IP
.EX
video mpeg1,sif
.br
audio musicam,I musicam,II
.EE
.PP
The control file accepts the following commands:
.TF pause
.PD
.TP
.B init
Reinitialise the device's video and audio subsystems;
cancel the effect of
.B stop
or
.B pause
.TP
.B stop
Stop the display immediately.
.TP
.B pause
Suspend display.
.TP
.B video iso11172 mpeg1,sif
Set the output video mode and formats; only this precise setting is valid.
.TP
.BI audio " format rate"
There are two choices for
.IR format :
.B musicam,I
(MPEG audio layer 1),
with
.I rate
from 64000 to 448000 Hz,
and
.B musicam,II
(MPEG audio layer 2)
with
.I rate
from 48000 to 384000.
.TP
.BI 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.
.PP
The data file
.B mpeg
is an exclusive-use device.
Once the device has been initialised and an output window
set using the
.B init
and
.B window
commands to the control file,
and an audio format selected by the
.B audio
command,
MPEG data can be written in the agreed format to the
.B 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.
.SH SOURCE
.B /os/pc/devmpeg.c
.SH CONFIGURATION
.B "mpeg0=port=0x1e0 irq=15 dma=6
.SH SEE ALSO
.IR mpeg (2),
.I stream
in
.IR sys-read (2)
.SH DIAGNOSTICS
An error results on a write to the device once stopped.