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audio/scream: multicast audio protocol

diff: cannot open b/sys/src/cmd/audio/scream//null: file does not exist: 'b/sys/src/cmd/audio/scream//null'

--- /dev/null

+++ b/sys/man/1/scream

@@ -1,0 +1,77 @@

+.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

+

--- a/sys/src/cmd/audio/mkfile

+++ b/sys/src/cmd/audio/mkfile

@@ -1,7 +1,7 @@

 </$objtype/mkfile

 LIBS=libogg libvorbis libFLAC libtags

-PROGS=pcmconv oggdec oggenc mp3dec mp3enc flacdec flacenc wavdec sundec mixfs readtags zuke

+PROGS=pcmconv oggdec oggenc mp3dec mp3enc flacdec flacenc wavdec sundec mixfs readtags zuke scream

 #libs must be made first

 DIRS=$LIBS $PROGS

--- /dev/null

+++ b/sys/src/cmd/audio/scream/mkfile

@@ -1,0 +1,21 @@

+</$objtype/mkfile

+<../config

+

+TARG=screamenc screamdec

+RC=screamsend screamrecv

+

+</sys/src/cmd/mkmany

+

+$O.screamenc: screamenc.$O

+$O.screamdec: screamdec.$O

+

+# Override install target to install rc.

+install:V:

+	for (i in $TARG)

+		mk $MKFLAGS $i.install

+	for (i in $RC)

+		mk $MKFLAGS $i.rcinstall

+

+%.rcinstall:V:

+	cp $stem $BIN/$stem

+	chmod +x $BIN/$stem

--- /dev/null

+++ b/sys/src/cmd/audio/scream/screamdec.c

@@ -1,0 +1,71 @@

+#include <u.h>

+#include <libc.h>

+

+char deffmt[] = "s16c2r44100";

+char fmt[64];

+uchar hdr[5];

+uchar buf[2048];

+int pfd[2];

+

+char*

+getformat(uchar hdr[5])

+{

+	int freq, bits, chan;

+

+	if(hdr[0] & 0x80)

+		freq = 44100;

+	else

+		freq = 48000;

+	freq *= hdr[0] & 0x7F;

+	bits = hdr[1];

+	chan = hdr[2];

+	snprint(fmt, sizeof(fmt), "s%dc%dr%d", bits, chan, freq);

+	return fmt;

+}

+

+void

+main(void)

+{

+	int n;

+

+	for(;;){

+		alarm(500);

+

+		n = read(0, buf, sizeof(buf));

+		if(n < sizeof(hdr))

+			break;

+

+		if(pfd[1] == 0 || memcmp(buf, hdr, sizeof(hdr)) != 0){

+			if(pfd[1] > 1){

+				close(pfd[1]);

+				waitpid();

+			}

+			if(strcmp(getformat(buf), deffmt) == 0){

+				pfd[1] = 1;

+			} else {

+				if(pipe(pfd) < 0)

+					sysfatal("pipe: %r");

+				switch(fork()){

+				case -1:

+					sysfatal("fork: %r");

+				case 0:

+					close(pfd[1]);

+					dup(pfd[0], 0);

+					execl("/bin/audio/pcmconv", "pcmconv", "-i", fmt, nil);

+					sysfatal("exec: %r");

+					return;

+				}

+				close(pfd[0]);

+			}

+			memmove(hdr, buf, sizeof(hdr));

+		}

+

+		n -= sizeof(hdr);

+		if(n <= 0)

+			continue;

+

+		if(write(pfd[1], buf+sizeof(hdr), n) != n)

+			break;

+	}

+	exits(nil);

+}

--- /dev/null

+++ b/sys/src/cmd/audio/scream/screamenc.c

@@ -1,0 +1,32 @@

+#include <u.h>

+#include <libc.h>

+

+int freq = 44100;

+int chan = 2;

+int bps = 16;

+int delay = 5;

+

+uchar buf[2048];

+

+void

+main(void)

+{

+	int n, m;

+

+	if((freq % 44100) == 0){

+		buf[0] = 0x80 | (freq / 44100);

+	} else {

+		buf[0] = freq / 48000;

+	}

+	buf[1] = bps;

+	buf[2] = chan;

+	buf[3] = 0;

+	buf[4] = 0;

+

+	n = (bps/8)*chan*((delay*freq+999)/1000);

+	while((m = read(0, buf+5, n)) > 0){

+		if(write(1, buf, 5+m) < 0)

+			sysfatal("write: %r");

+	}

+	exits(nil);

+}

--- /dev/null

+++ b/sys/src/cmd/audio/scream/screamrecv

@@ -1,0 +1,13 @@

+#!/bin/rc

+rfork e

+lifc=()

+while(~ $1 *.*.*.*){

+	lifc=($lifc $1)

+	shift

+}

+if(! ~ $#* 0){

+	echo 'Usage: audio/screamrecv [interfaceip]...' >[1=2]

+	exit 'usage'

+}

+if(~ $#lifc 0) lifc=`{awk '/4u/{print $1}' /net/ipselftab}

+exec aux/listen1 -t -p4 -O^'addmulti '^$lifc udp!239.255.77.77!4010 rc -c 'exec audio/screamdec > /dev/audio'

--- /dev/null

+++ b/sys/src/cmd/audio/scream/screamsend

@@ -1,0 +1,13 @@

+#!/bin/rc

+rfork e

+lifc=()

+while(~ $1 *.*.*.*){

+	lifc=($lifc $1)

+	shift

+}

+if(! ~ $#* 0){

+	echo 'Usage: audio/screamsend [interfaceip]...' >[1=2]

+	exit 'usage'

+}

+if(~ $#lifc 0) lifc=`{awk '/4u/{print $1}' /net/ipselftab}

+exec audio/screamenc < /dev/audio | exec aux/trampoline -o^'addmulti '^$lifc udp!239.255.77.77!4010