NAME

	screamsend, screamrecv, screamenc, screamdec – multicast audio protocol

SYNOPSIS

	audio/screamsend [ interfaceip ]... audio/screamrecv [ interfaceip ]... audio/screamenc audio/screamdec

DESCRIPTION

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 239.255.77.77 on port 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). Screamsend reads PCM audio from /dev/audio and sends scream packets to the local network on the interface given by interfaceip. When interfaceip is omitted, it uses first IPv4 interface ip address from /net/ipselftab as a default. Screamrecv listens for packets from the local network on the interfaces selected by interfaceip and writes PCM audio to /dev/audio. When no interfaceip addresses where given, it will listen on all interfaces with an IPv4 address. Both screamsend and screamrecv are usually run after audio/mixfs (see audio(1)) to provide loopback audio source as well as mixing for multiple senders. Screamenc reads PCM audio from standard–input and writes scream packets to standard–output. Screamdec reads scream packets from standard–input, and writes PCM audio to standard–output. It spawns audio/pcmconv (see 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.

SOURCE

	/sys/src/cmd/audio/scream

SEE ALSO

	audio(1). https://github.com/duncanthrax/scream