ref: dbfc9b6d9bc6aa9f337eadc21d0d6dfbdbc3e3d7
dir: /mixer.c/
/*
* standalone sound mixer based on rxi's cmixer.
*/
#include <u.h>
#include <libc.h>
#include <thread.h>
#include "mixer.h"
static Mixer mixer;
static int
min(int a, int b)
{
return a < b? a: b;
}
static int
max(int a, int b)
{
return a > b? a: b;
}
static int
clamp(int n, int min, int max)
{
return n < min? min: n > max? max: n;
}
static double
fclamp(double n, double min, double max)
{
return n < min? min: n > max? max: n;
}
static int
float2fixed(double n)
{
return n*FIXED_UNIT;
}
static int
fixedlerp(int a, int b, int t)
{
return a + ((b - a)*t >> FIXED_BITS);
}
//static void
//fprintsource(int fd, AudioSource *src)
//{
// fprint(fd, "src 0x%p:\n"
// "udata\t0x%p\n"
// "samplerate\t%d\n"
// "length\t%d\n"
// "end\t%d\n"
// "state\t%d\n"
// "position\t%lld\n"
// "gain l/r\t%d/%d\n"
// "rate\t%d\n"
// "nextfill\t%d\n"
// "loop\t%d\n"
// "rewind\t%d\n"
// "active\t%d\n"
// "gain\t%g\n"
// "pan\t%g\n",
// src, src->udata, src->samplerate, src->length, src->end, src->state, src->position,
// src->lgain, src->rgain, src->rate, src->nextfill, src->loop, src->rewind,
// src->active, src->gain, src->pan);
//
//}
static void
pcm_handler(AudioEvent *e)
{
Pcm *pcm;
s16int *dst;
int len, i, n;
pcm = e->udata;
switch(e->type){
case AUDIO_EVENT_DESTROY:
free(pcm->data);
free(pcm);
break;
case AUDIO_EVENT_SAMPLES:
dst = e->buffer;
len = e->length/2;
Fillbuf:
n = min(len, pcm->len - pcm->off);
len -= n;
while(n--){
i = 2*pcm->off;
dst[0] = ((s16int*)pcm->data)[i];
dst[1] = ((s16int*)pcm->data)[i+1];
dst += 2;
pcm->off++;
}
if(len > 0){
pcm->off = 0;
goto Fillbuf;
}
break;
case AUDIO_EVENT_REWIND:
pcm->off = 0;
break;
}
}
/* TODO generalize the *decproc procedures */
static void
wavdecproc(void *arg)
{
int *pfd, fd;
pfd = arg;
fd = pfd[2];
close(pfd[0]);
dup(fd, 0);
close(fd);
dup(pfd[1], 1);
close(pfd[1]);
execl("/bin/audio/wavdec", "wavdec", nil);
threadexitsall("execl: %r");
}
static void
mp3decproc(void *arg)
{
int *pfd, fd;
pfd = arg;
fd = pfd[2];
close(pfd[0]);
dup(fd, 0);
close(fd);
dup(pfd[1], 1);
close(pfd[1]);
execl("/bin/audio/mp3dec", "mp3dec", nil);
threadexitsall("execl: %r");
}
static int
loadaudio(AudioSourceInfo *info, int fd, void (*decfn)(void*))
{
Pcm *pcm;
void *data;
uchar buf[1024];
int pfd[3], n, len;
data = nil;
len = 0;
if(pipe(pfd) < 0){
werrstr("pipe: %r");
return -1;
}
pfd[2] = fd;
procrfork(decfn, pfd, mainstacksize, RFFDG|RFNAMEG|RFNOTEG);
close(pfd[1]);
while((n = read(pfd[0], buf, sizeof buf)) > 0){
data = realloc(data, len+n);
if(data == nil){
werrstr("realloc: %r");
return -1;
}
memmove((uchar*)data+len, buf, n);
len += n;
}
close(pfd[0]);
pcm = malloc(sizeof *pcm);
if(pcm == nil){
free(data);
werrstr("malloc: %r");
return -1;
}
pcm->depth = 16;
pcm->chans = 2;
pcm->rate = 44100;
pcm->data = data;
pcm->len = len/(pcm->depth/8)/pcm->chans;
info->udata = pcm;
info->handler = pcm_handler;
info->samplerate = pcm->rate;
info->length = pcm->len;
// fprint(2, "pcm 0x%p:\ndata 0x%p\nlen %d\ndepth %d\nchans %d\nrate %d\n",
// pcm, pcm->data, pcm->len, pcm->depth, pcm->chans, pcm->rate);
// fprint(2, "info 0x%p:\nudata 0x%p\nhandler 0x%p\nsamplerate %d\nlength %d\n",
// info, info->udata, info->handler, info->samplerate, info->length);
return 0;
}
void
initaudio(int samplerate)
{
mixer.samplerate = samplerate;
mixer.sources = nil;
mixer.gain = FIXED_UNIT;
}
void
audio_set_master_gain(double gain)
{
mixer.gain = float2fixed(gain);
}
static void
rewind_source(AudioSource *src)
{
AudioEvent e;
e.type = AUDIO_EVENT_REWIND;
e.udata = src->udata;
src->handler(&e);
src->position = 0;
src->rewind = 0;
src->end = src->length;
src->nextfill = 0;
}
static void
fill_source_buffer(AudioSource *src, int offset, int length)
{
AudioEvent e;
e.type = AUDIO_EVENT_SAMPLES;
e.udata = src->udata;
e.buffer = src->buffer + offset;
e.length = length;
src->handler(&e);
}
static void
process_source(AudioSource *src, int len)
{
int i, n, a, b, p;
int frame, count;
s32int *dst;
dst = mixer.buffer;
/* Do rewind if flag is set */
if(src->rewind)
rewind_source(src);
/* Process audio */
while(len > 0){
/* Get current position frame */
frame = src->position >> FIXED_BITS;
/* Fill buffer if required */
if(frame + 3 >= src->nextfill){
fill_source_buffer(src, 2*src->nextfill & MIXBUFMASK, MIXBUFSIZE/2);
src->nextfill += MIXBUFSIZE/4;
}
/* Handle reaching the end of the playthrough */
if(frame >= src->end){
/*
* As streams continously fill the raw buffer in a loop we simply
* increment the end idx by one length and continue reading from it for
* another play-through
*/
src->end = frame + src->length;
/* Set state and stop processing if we're not set to loop */
if(!src->loop){
src->state = AUDIO_STATE_STOPPED;
break;
}
}
/* Work out how many frames we should process in the loop */
n = min(src->nextfill - 2, src->end) - frame;
count = (n << FIXED_BITS) / src->rate;
count = max(count, 1);
count = min(count, len/2);
len -= count * 2;
/* Add audio to master buffer */
if(src->rate == FIXED_UNIT){
/* Add audio to buffer -- basic */
n = 2*frame;
for(i = 0; i < count; i++){
dst[0] += (src->buffer[n&MIXBUFMASK] * src->lgain) >> FIXED_BITS;
dst[1] += (src->buffer[(n+1)&MIXBUFMASK] * src->rgain) >> FIXED_BITS;
n += 2;
dst += 2;
}
src->position += count * FIXED_UNIT;
}else{
/* Add audio to buffer -- interpolated */
for(i = 0; i < count; i++){
n = (src->position >> FIXED_BITS) * 2;
p = src->position & FIXED_MASK;
a = src->buffer[n & MIXBUFMASK];
b = src->buffer[(n+2) & MIXBUFMASK];
dst[0] += fixedlerp(a, b, p)*src->lgain >> FIXED_BITS;
n++;
a = src->buffer[n & MIXBUFMASK];
b = src->buffer[(n+2) & MIXBUFMASK];
dst[1] += fixedlerp(a, b, p)*src->rgain >> FIXED_BITS;
src->position += src->rate;
dst += 2;
}
}
}
}
void
processaudio(s16int *dst, int len)
{
int i, x;
AudioSource **s;
/* Process in chunks of MIXBUFSIZE if `len` is larger than MIXBUFSIZE */
while(len > MIXBUFSIZE){
processaudio(dst, MIXBUFSIZE);
dst += MIXBUFSIZE;
len -= MIXBUFSIZE;
}
/* Zeroset internal buffer */
memset(mixer.buffer, 0, len * sizeof(mixer.buffer[0]));
/* Process active sources */
s = &mixer.sources;
while(*s){
process_source(*s, len);
/* Remove source from list if it is no longer playing */
if((*s)->state != AUDIO_STATE_PLAYING){
(*s)->active = 0;
*s = (*s)->next;
}else
s = &(*s)->next;
}
/* Copy internal buffer to destination and clip */
for(i = 0; i < len; i++){
x = (mixer.buffer[i] * mixer.gain) >> FIXED_BITS;
dst[i] = clamp(x, -32768, 32767);
}
}
AudioSource *
newaudiosource(AudioSourceInfo *info)
{
AudioSource *src;
src = malloc(sizeof *src);
if(src == nil){
werrstr("allocation failed");
return nil;
}
memset(src, 0, sizeof *src);
src->handler = info->handler;
src->length = info->length;
src->samplerate = info->samplerate;
src->udata = info->udata;
audio_set_gain(src, 1);
audio_set_pan(src, 0);
audio_set_pitch(src, 1);
audio_set_loop(src, 0);
stopaudio(src);
return src;
}
AudioSource *
loadaudiosource(char *path)
{
AudioSourceInfo info;
uchar buf[12];
int fd;
fd = open(path, OREAD);
if(fd < 0)
return nil;
memset(buf, 0, sizeof buf);
readn(fd, buf, sizeof buf);
seek(fd, 0, 0);
if(memcmp(buf, "ID3", 3) == 0 || (buf[0] == 0xFF && buf[1] == 0xFB)){
if(loadaudio(&info, fd, mp3decproc) < 0){
close(fd);
return nil;
}
}else if(memcmp(buf+8, "WAVE", 4) == 0){
if(loadaudio(&info, fd, wavdecproc) < 0){
close(fd);
return nil;
}
}else{
werrstr("unsupported file format");
close(fd);
return nil;
}
close(fd);
return newaudiosource(&info);
}
void
delaudiosource(AudioSource *src)
{
AudioSource **s;
AudioEvent e;
if(src->active){
s = &mixer.sources;
while(*s) /* TODO potential spinlock. no bueno */
if(*s == src){
*s = src->next;
break;
}
}
e.type = AUDIO_EVENT_DESTROY;
e.udata = src->udata;
src->handler(&e);
free(src);
}
double
audio_get_length(AudioSource *src)
{
return src->length / (double)src->samplerate;
}
double
audio_get_position(AudioSource *src)
{
return ((src->position >> FIXED_BITS) % src->length) / (double)src->samplerate;
}
int
audio_get_state(AudioSource *src)
{
return src->state;
}
static void
recalc_source_gains(AudioSource *src)
{
double l, r;
double pan;
pan = src->pan;
l = src->gain * (pan <= 0 ? 1 : 1.0 - pan);
r = src->gain * (pan >= 0 ? 1 : 1.0 + pan);
src->lgain = float2fixed(l);
src->rgain = float2fixed(r);
}
void
audio_set_gain(AudioSource *src, double gain)
{
src->gain = gain;
recalc_source_gains(src);
}
void
audio_set_pan(AudioSource *src, double pan)
{
src->pan = fclamp(pan, -1.0, 1.0);
recalc_source_gains(src);
}
void
audio_set_pitch(AudioSource *src, double pitch)
{
double rate;
if(pitch > 0)
rate = (double)src->samplerate / mixer.samplerate * pitch;
else
rate = 0.001;
src->rate = float2fixed(rate);
}
void
audio_set_loop(AudioSource *src, int loop)
{
src->loop = loop;
}
void
playaudio(AudioSource *src)
{
src->state = AUDIO_STATE_PLAYING;
if(!src->active){
src->active = 1;
src->next = mixer.sources;
mixer.sources = src;
}
}
void
pauseaudio(AudioSource *src)
{
src->state = AUDIO_STATE_PAUSED;
}
void
stopaudio(AudioSource *src)
{
src->state = AUDIO_STATE_STOPPED;
src->rewind = 1;
}