µlaw audio support (from erik quanstro)

4 files changed, 378 insertions, 2 deletions

diff --git a/sys/src/cmd/audio/mkfile b/sys/src/cmd/audio/mkfile
index b85ff65c2..ddc4af14d 100644
--- a/sys/src/cmd/audio/mkfile
+++ b/sys/src/cmd/audio/mkfile
@@ -1,7 +1,7 @@
 </$objtype/mkfile
 
 LIBS=libogg libvorbis libFLAC
-PROGS=pcmconv oggdec oggenc mp3dec mp3enc flacdec wavdec
+PROGS=pcmconv oggdec oggenc mp3dec mp3enc flacdec wavdec µlawdec
 #libs must be made first
 DIRS=$LIBS $PROGS
 
diff --git a/sys/src/cmd/audio/pcmconv/pcmconv.c b/sys/src/cmd/audio/pcmconv/pcmconv.c
index 7ae6fb7b0..ee7e999fa 100644
--- a/sys/src/cmd/audio/pcmconv/pcmconv.c
+++ b/sys/src/cmd/audio/pcmconv/pcmconv.c
@@ -249,7 +249,7 @@ main(int argc, char *argv[])
 	Chan ch[8];
 	Desc i, o;
 	ulong delta;
-	int k, r, n, m, p;
+	int k, r, n, m;
 	vlong l;
 
 	void (*oconv)(int *, uchar *, int, int, int) = nil;
diff --git a/sys/src/cmd/audio/µlawdec/mkfile b/sys/src/cmd/audio/µlawdec/mkfile
new file mode 100644
index 000000000..c4ed6668c
--- /dev/null
+++ b/sys/src/cmd/audio/µlawdec/mkfile
@@ -0,0 +1,8 @@
+</$objtype/mkfile
+<../config
+
+OFILES=µlawdec.$O
+
+TARG=µlawdec
+
+</sys/src/cmd/mkone
diff --git a/sys/src/cmd/audio/µlawdec/µlawdec.c b/sys/src/cmd/audio/µlawdec/µlawdec.c
new file mode 100644
index 000000000..3c55f83f8
--- /dev/null
+++ b/sys/src/cmd/audio/µlawdec/µlawdec.c
@@ -0,0 +1,368 @@
+#include <u.h>
+#include <libc.h>
+#include <bio.h>
+
+enum {
+	Qmask	= 0xf,		/* quantization mask */
+	Nsegs	= 8,		/* A-law segments */
+	Segshift	= 4,
+	Segmask	= 0x70,
+};
+
+static short segend[Nsegs] = {
+	0xff,	0x1ff,	0x3ff,	0x7ff,
+	0xfff,	0x1fff,	0x3fff,	0x7fff
+};
+
+/* copy from CCITT G.711 specifications */
+static uchar u2a[128] = {			/* μ- to A-law conversions */
+	1,	1,	2,	2,	3,	3,	4,	4,
+	5,	5,	6,	6,	7,	7,	8,	8,
+	9,	10,	11,	12,	13,	14,	15,	16,
+	17,	18,	19,	20,	21,	22,	23,	24,
+	25,	27,	29,	31,	33,	34,	35,	36,
+	37,	38,	39,	40,	41,	42,	43,	44,
+	46,	48,	49,	50,	51,	52,	53,	54,
+	55,	56,	57,	58,	59,	60,	61,	62,
+	64,	65,	66,	67,	68,	69,	70,	71,
+	72,	73,	74,	75,	76,	77,	78,	79,
+	81,	82,	83,	84,	85,	86,	87,	88,
+	89,	90,	91,	92,	93,	94,	95,	96,
+	97,	98,	99,	100,	101,	102,	103,	104,
+	105,	106,	107,	108,	109,	110,	111,	112,
+	113,	114,	115,	116,	117,	118,	119,	120,
+	121,	122,	123,	124,	125,	126,	127,	128
+};
+
+static uchar a2u[128] = {			/* A- to μ-law conversions */
+	1,	3,	5,	7,	9,	11,	13,	15,
+	16,	17,	18,	19,	20,	21,	22,	23,
+	24,	25,	26,	27,	28,	29,	30,	31,
+	32,	32,	33,	33,	34,	34,	35,	35,
+	36,	37,	38,	39,	40,	41,	42,	43,
+	44,	45,	46,	47,	48,	48,	49,	49,
+	50,	51,	52,	53,	54,	55,	56,	57,
+	58,	59,	60,	61,	62,	63,	64,	64,
+	65,	66,	67,	68,	69,	70,	71,	72,
+	73,	74,	75,	76,	77,	78,	79,	79,
+	80,	81,	82,	83,	84,	85,	86,	87,
+	88,	89,	90,	91,	92,	93,	94,	95,
+	96,	97,	98,	99,	100,	101,	102,	103,
+	104,	105,	106,	107,	108,	109,	110,	111,
+	112,	113,	114,	115,	116,	117,	118,	119,
+	120,	121,	122,	123,	124,	125,	126,	127
+};
+
+/* speed doesn't matter.  table has 8 entires */
+static int
+search(int val, short *table, int size)
+{
+	int i;
+
+	for (i = 0; i < size; i++) {
+		if (val <= *table++)
+			return i;
+	}
+	return size;
+}
+
+/*
+ * linear2alaw() - Convert a 16-bit linear PCM value to 8-bit A-law
+ *
+ * linear2alaw() accepts an 16-bit integer and encodes it as A-law data.
+ *
+ *		Linear Input Code	Compressed Code
+ *	------------------------	---------------
+ *	0000000wxyza			000wxyz
+ *	0000001wxyza			001wxyz
+ *	000001wxyzab			010wxyz
+ *	00001wxyzabc			011wxyz
+ *	0001wxyzabcd			100wxyz
+ *	001wxyzabcde			101wxyz
+ *	01wxyzabcdef			110wxyz
+ *	1wxyzabcdefg			111wxyz
+ *
+ * For further information see John C. Bellamy's Digital Telephony, 1982,
+ * John Wiley & Sons, pps 98-111 and 472-476.
+ */
+uchar
+linear2alaw(int pcm)	/* 2's complement (16-bit range) */
+{
+	uchar aval;
+	int mask, seg;
+
+	if (pcm >= 0) {
+		mask = 0xd5;		/* sign (7th) bit = 1 */
+	} else {
+		mask = 0x55;		/* sign bit = 0 */
+		pcm = -pcm - 8;
+	}
+
+	/* Convert the scaled magnitude to segment number. */
+	seg = search(pcm, segend, 8);
+
+	/* Combine the sign, segment, and quantization bits. */
+	if (seg >= 8)
+		/* out of range, return maximum value. */
+		return 0x7f ^ mask;
+	else {
+		aval = seg << Segshift;
+		if (seg < 2)
+			aval |= pcm>>4 & Qmask;
+		else
+			aval |= pcm>>(seg + 3) & Qmask;
+		return aval ^ mask;
+	}
+}
+
+/*
+ * alaw2linear() - Convert an A-law value to 16-bit linear PCM
+ *
+ */
+int
+alaw2linear(uchar a)
+{
+	int t, seg;
+
+	a ^= 0x55;
+
+	t = (a & Qmask) << 4;
+	seg = (a & Segmask) >> Segshift;
+	switch (seg) {
+	case 0:
+		t += 8;
+		break;
+	case 1:
+		t += 0x108;
+		break;
+	default:
+		t += 0x108;
+		t <<= seg - 1;
+	}
+	return (a & 0x80) ? t : -t;
+}
+
+enum {
+	Bias	= 0x84,		/* Bias for linear code. */
+};
+
+/*
+ * linear2μlaw() - Convert a linear PCM value to μ-law
+ *
+ * In order to simplify the encoding process, the original linear magnitude
+ * is biased by adding 33 which shifts the encoding range from (0 - 8158) to
+ * (33 - 8191). The result can be seen in the following encoding table:
+ *
+ *	Biased Linear Input Code	Compressed Code
+ *	------------------------	---------------
+ *	00000001wxyza			000wxyz
+ *	0000001wxyzab			001wxyz
+ *	000001wxyzabc			010wxyz
+ *	00001wxyzabcd			011wxyz
+ *	0001wxyzabcde			100wxyz
+ *	001wxyzabcdef			101wxyz
+ *	01wxyzabcdefg			110wxyz
+ *	1wxyzabcdefgh			111wxyz
+ *
+ * Each biased linear code has a leading 1 which identifies the segment
+ * number. The value of the segment number is equal to 7 minus the number
+ * of leading 0's. The quantization interval is directly available as the
+ * four bits wxyz.  * The trailing bits (a - h) are ignored.
+ *
+ * Ordinarily the complement of the resulting code word is used for
+ * transmission, and so the code word is complemented before it is returned.
+ *
+ * For further information see John C. Bellamy's Digital Telephony, 1982,
+ * John Wiley & Sons, pps 98-111 and 472-476.
+ */
+uchar
+linear2μlaw(int pcm)
+{
+	int mask, seg;
+	uchar uval;
+
+	/* Get the sign and the magnitude of the value. */
+	if (pcm < 0) {
+		pcm = Bias - pcm;
+		mask = 0x7f;
+	} else {
+		pcm += Bias;
+		mask = 0xff;
+	}
+
+	/* Convert the scaled magnitude to segment number. */
+	seg = search(pcm, segend, 8);
+
+	/*
+	 * Combine the sign, segment, quantization bits;
+	 * and complement the code word.
+	 */
+	if (seg >= 8)
+		/* out of range, return maximum value. */
+		return 0x7f ^ mask;
+	else {
+		uval = seg<< 4 | ((pcm >> (seg + 3)) & 0xf);
+		return uval ^ mask;
+	}
+}
+
+/*
+ * μlaw2linear() - Convert a μ-law value to 16-bit linear PCM
+ *
+ * First, a biased linear code is derived from the code word. An unbiased
+ * output can then be obtained by subtracting 33 from the biased code.
+ *
+ * Note that this function expects to be passed the complement of the
+ * original code word. This is in keeping with ISDN conventions.
+ */
+int
+μlaw2linear(uchar μ)
+{
+	int t;
+
+	/* Complement to obtain normal μ-law value. */
+	μ = ~μ;
+
+	/*
+	 * Extract and bias the quantization bits. Then
+	 * shift up by the segment number and subtract out the bias.
+	 */
+	t = ((μ & Qmask) << 3) + Bias;
+	t <<= (μ & Segmask) >> Segshift;
+
+	return μ & 0x80? Bias - t: t - Bias;
+}
+
+/* A-law to μ-law conversion */
+uchar
+alaw2μlaw(uchar a)
+{
+//	a &= 0xff;
+	if(a & 0x80)
+		return 0xff ^ a2u[a ^ 0xd5];
+	else
+		return 0x7f ^ a2u[a ^ 0x55];
+}
+
+/* μ-law to A-law conversion */
+uchar
+μlaw2alaw(uchar μ)
+{
+//	μ &= 0xff;
+	if(μ & 0x80)
+		return 0xd5 ^ u2a[0xff ^ μ] - 1;
+	else
+		return 0x55 ^ u2a[0x7f ^ μ] - 1;
+}
+
+static void
+setrate(int rate)
+{
+	int fd;
+
+	fd = open("/dev/volume", OWRITE);
+	if(fd == -1){
+		fprint(2, "μlawdec: can't set rate %d: open: %r\n", rate);
+		return;
+	}
+	if(fprint(fd, "speed %d", rate) == -1)
+		fprint(2, "μlawdec: can't set rate %d: fprint: %r\n", rate);
+	else
+		fprint(2, "μlawdec: rate %d\n", rate);
+	close(fd);
+}
+
+enum {
+	Sig	= 0,
+	Offset	= 1,
+	Enc	= 3,
+	Rate	= 4,
+	Nchan	= 5,
+};
+
+u32int
+μlawword(uchar *buf, int w)
+{
+	buf += 4*w;
+	return buf[0]<<24 | buf[1]<<16 | buf[2]<<8 | buf[3];
+}
+
+int
+pcmconv(char *fmt)
+{
+	int pid, pfd[2];
+
+	if(pipe(pfd) < 0)
+		return -1;
+	pid = fork();
+	if(pid < 0){
+		close(pfd[0]);
+		close(pfd[1]);
+		return -1;
+	}
+	if(pid == 0){
+		dup(pfd[1], 0);
+		close(pfd[1]);
+		close(pfd[0]);
+		execl("/bin/audio/pcmconv", "pcmconv", "-i", fmt, 0);
+		sysfatal("exec: %r");
+	}
+	close(pfd[1]);
+	return pfd[0];
+}
+
+void
+main(void)
+{
+	int fd, n;
+	uchar buf[5*4];
+	char fmt[32];
+	vlong off;
+	Biobuf i, o;
+
+	if(Binit(&i, 0, OREAD) == -1)
+		sysfatal("μlawdec: Binit: %r");
+	if(Bread(&i, buf, sizeof buf) != sizeof buf)
+		sysfatal("μlawdec: Bread: %r");
+	off = μlawword(buf, Offset);
+	if(off < 24)
+		sysfatal("μlawdec: bad offset: %lld", off);
+	if(μlawword(buf, Sig) != 0x2e736e64)
+		sysfatal("μlawdec: not .au file");
+	if(μlawword(buf, Enc) != 1)
+		sysfatal("μlawdec: not μlaw");
+
+	snprint(fmt, sizeof(fmt), "s16c1r%d", μlawword(buf, Rate));
+	fd = pcmconv(fmt);
+	if(fd < 0)
+		sysfatal("μlawdec: pcmconv: %r");
+
+	if(Binit(&o, fd, OWRITE) == -1)
+		sysfatal("μlawdec: Binit: %r");
+
+	while(off > 0){
+		n = sizeof(buf);
+		if(off < n)
+			n = off;
+		if(Bread(&i, buf, n) != n)
+			sysfatal("μlawdec: Bread: %r");
+		off -= n;
+	}
+
+	for(;;){
+		switch(Bread(&i, buf, 1)){
+		case 0:
+			goto done;
+		case -1:
+			sysfatal("μlawdec: Bread: %r");
+		}
+		n = μlaw2linear(buf[0]);
+		buf[0] = n&0xff;
+		buf[1] = (n&0xff00)>>8;
+		if(Bwrite(&o, buf, 2) != 2)
+			sysfatal("μlawdec: Bwrite: %r");
+	}
+done:
+	Bterm(&o);
+	Bterm(&i);
+}