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