ref: 6d4ecd6bb7c46e508d89ae2bab911f5f3b206d94
parent: e68cc1702b1f63f540deafb5567f7dd347e3fe89
author: qwx <[email protected]>
date: Sun Feb 19 10:43:34 EST 2023
add audio/pcmmix: mix multiple pcm files and scale global volume
--- a/mkfile
+++ b/mkfile
@@ -1,7 +1,10 @@
</$objtype/mkfile
BIN=/$objtype/bin/audio
MAN=/sys/man/1
-TARG=pplay
+TARG=\
+ pcmmix\
+ pplay\
+
OFILES=\
chunk.$O\
cmd.$O\
@@ -10,4 +13,7 @@
util.$O\
HFILES=dat.h fns.h
-</sys/src/cmd/mkone
+</sys/src/cmd/mkmany
+
+$O.pcmmix: pcmmix.$O
+ $LD $LDFLAGS -o $target pcmmix.$O
--- /dev/null
+++ b/pcmmix.c
@@ -1,0 +1,82 @@
+#include <u.h>
+#include <libc.h>
+
+typedef struct File File;
+struct File{+ int fd;
+ char *path;
+ int n;
+ uchar buf[8192];
+};
+void
+usage(void)
+{+ fprint(2, "usage: %s [-f] [FILE..]\n", argv0);
+ exits("usage");+}
+
+void
+main(int argc, char **argv)
+{+ int n;
+ double f;
+ uchar u[8192], *p, *q;
+ s32int v;
+ int nf;
+ File *ftab, *fp;
+ Dir *d;
+
+ f = 1.0;
+ ARGBEGIN{+ case 'f': f = strtod(EARGF(usage()), nil); break;
+ default: usage();
+ }ARGEND
+ nf = argc + 1;
+ if((ftab = mallocz(nf * sizeof *ftab, 1)) == nil)
+ sysfatal("mallocz: %r");+ fp = ftab;
+ fp->path = "stdin";
+ if((d = dirfstat(0)) == nil)
+ sysfatal("dirfstat: %r");+ fp->fd = d->length > 0 ? 0 : -1;
+ free(d);
+ fp++;
+ while(*argv != nil){+ if((fp->fd = open(*argv, OREAD)) < 0)
+ sysfatal("open: %r");+ fp->path = *argv++;
+ fp++;
+ }
+ for(;;){+ n = 0;
+ for(fp=ftab; fp<ftab+nf; fp++){+ if(fp->fd < 0)
+ continue;
+ if((fp->n = read(fp->fd, fp->buf, sizeof fp->buf)) > 0)
+ continue;
+ fp->fd = -1;
+ if(fp->n < 0)
+ fprint(2, "file %s: read: %r\n", fp->path);
+ }
+ memset(u, 0, sizeof u);
+ for(fp=ftab; fp<ftab+nf; fp++){+ for(p=u, q=fp->buf; q<fp->buf+fp->n; p+=2, q+=2){+ v = (s16int)(q[1] << 8 | q[0]);
+ v *= f;
+ v += (s16int)(p[1] << 8 | p[0]);
+ if(v > 32767)
+ v = 32767;
+ else if(v < -32768)
+ v = -32768;
+ p[0] = v;
+ p[1] = v >> 8;
+ }
+ if(fp->n > n)
+ n = fp->n;
+ }
+ if(n == 0)
+ break;
+ write(1, u, n);
+ }
+ exits(nil);
+}