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.TH SCREAM 1
.SH NAME
screamsend, screamrecv, screamenc, screamdec \- multicast audio protocol
.SH SYNOPSIS
.B audio/screamsend
[
.I interfaceip
]...
.br
.B audio/screamrecv
[
.I interfaceip
]...
.br
.B audio/screamenc
.br
.B audio/screamdec
.SH DESCRIPTION
.PP
Scream is a simple network protocol for transmitting PCM audio on a local network.
It sends UDP packets at a constant rate to the multicast address
.B 239.255.77.77
on port
.BR 4010 .
Each packet starts with a small 5-byte header that contains information about the
sample-rate and data format followed raw PCM data payload (maximum 1157 bytes).
.PP
.I Screamsend
reads PCM audio from
.B /dev/audio
and sends scream packets to the local network on the interface given by
.IR interfaceip.
When
.I interfaceip
is omitted, it uses first IPv4 interface ip address from
.B /net/ipselftab
as a default.
.PP
.I Screamrecv
listens for packets from the local network on the interfaces
selected by
.IR interfaceip
and writes PCM audio to
.BR /dev/audio .
When no
.I interfaceip
addresses where given, it will listen on all interfaces with an IPv4 address.
.PP
Both
.I screamsend
and
.I screamrecv
are usually run after
.I audio/mixfs
(see
.IR audio (1))
to provide loopback audio source as well as mixing for multiple senders.
.PP
.I Screamenc
reads PCM audio from standard-input and writes scream packets to standard-output.
.PP
.I Screamdec
reads scream packets from standard-input, and writes PCM audio to standard-output.
It spawns
.I audio/pcmconv
(see
.IR audio (1))
to convert the audio in case the scream packet format is not
the default of 16-bit little-endian stereo samples at 44100 Hz.
It exits when no packets have arrived for 500 milliseconds.
.SH SOURCE
.B /sys/src/cmd/audio/scream
.SH SEE ALSO
.IR audio (1).
.br
.B https://github.com/duncanthrax/scream
|
