ref: c1d40df49550393f3afe53fb6e6d500dfa8eb7a8
dir: /sys/src/cmd/audio/wavdec/wavdec.c/
#include <u.h> #include <libc.h> typedef struct Wave Wave; struct Wave { int rate; int channels; int framesz; int bits; int fmt; }; ulong get2(void) { uchar buf[2]; if(readn(0, buf, 2) != 2) sysfatal("read: %r"); return buf[0] | buf[1]<<8; } ulong get4(void) { uchar buf[4]; if(readn(0, buf, 4) != 4) sysfatal("read: %r"); return buf[0] | buf[1]<<8 | buf[2]<<16 | buf[3]<<24; } char* getcc(char tag[4]) { if(readn(0, tag, 4) != 4) sysfatal("read: %r"); return tag; } void usage(void) { fprint(2, "usage: %s [ -s SECONDS ]\n", argv0); exits("usage"); } void main(int argc, char **argv) { char buf[1024], fmt[32]; double seekto; ulong len, n; Wave wav; seekto = 0.0; ARGBEGIN{ case 's': seekto = atof(EARGF(usage())); break; default: usage(); }ARGEND if(memcmp(getcc(buf), "RIFF", 4) != 0) sysfatal("no riff format"); get4(); if(memcmp(getcc(buf), "WAVE", 4) != 0) sysfatal("not a wave file"); for(;;){ getcc(buf); len = get4(); if(memcmp(buf, "data", 4) == 0) break; if(memcmp(buf, "fmt ", 4) == 0){ if(len < 2+2+4+4+2+2) sysfatal("format chunk too small"); wav.fmt = get2(); wav.channels = get2(); wav.rate = get4(); get4(); wav.framesz = get2(); wav.bits = get2(); len -= 2+2+4+4+2+2; } while(len > 0){ n = sizeof(buf); if(len < n) n = len; n = read(0, buf, n); if(n <= 0) sysfatal("read: %r"); len -= n; } } switch(wav.fmt){ case 1: snprint(fmt, sizeof(fmt), "%c%dr%dc%d", wav.bits == 8 ? 'u' : 's', wav.bits, wav.rate, wav.channels); break; case 3: snprint(fmt, sizeof(fmt), "f32r%dc%d", wav.rate, wav.channels); break; case 6: snprint(fmt, sizeof(fmt), "a8r%dc%d", wav.rate, wav.channels); break; case 7: snprint(fmt, sizeof(fmt), "µ8r%dc%d", wav.rate, wav.channels); break; default: sysfatal("wave format (0x%lux) not supported", (ulong)wav.fmt); } if(seekto != 0.0){ if(seek(0, (ulong)seekto*wav.rate*wav.framesz & ~wav.framesz, 1) < 1) seekto = 0.0; fprint(2, "time: %g\n", seekto); } snprint(buf, sizeof(buf), "%lud", len); execl("/bin/audio/pcmconv", "pcmconv", "-i", fmt, "-l", buf, nil); }