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shairport-sync/hairtunes.c
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/*
* HairTunes - RAOP packet handler and slave-clocked replay engine
* Copyright (c) James Laird 2011
* All rights reserved.
*
* Permission is hereby granted, free of charge, to any person
* obtaining a copy of this software and associated documentation
* files (the "Software"), to deal in the Software without
* restriction, including without limitation the rights to use,
* copy, modify, merge, publish, distribute, sublicense, and/or
* sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
* OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
* HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
* WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
* OTHER DEALINGS IN THE SOFTWARE.
*/
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <sys/socket.h>
#include <sys/select.h>
#include <arpa/inet.h>
#include <netinet/in.h>
#include <pthread.h>
#include <openssl/aes.h>
#include <math.h>
#include <sys/stat.h>
#include "hairtunes.h"
#include <sys/signal.h>
#include <fcntl.h>
#include <ao/ao.h>
#ifdef FANCY_RESAMPLING
#include <samplerate.h>
#endif
#include <assert.h>
int debug = 0;
#include "alac.h"
// default buffer - about half a second
//Changed these values to make sound synchronized with airport express during multi-room broadcast.
#define BUFFER_FRAMES 512
#define START_FILL 282
#define MAX_PACKET 2048
typedef unsigned short seq_t;
// global options (constant after init)
unsigned char aeskey[16], aesiv[16];
AES_KEY aes;
char *rtphost = 0;
int dataport = 0, controlport = 0, timingport = 0;
int fmtp[32];
int sampling_rate;
int frame_size;
char *libao_driver = NULL;
char *libao_devicename = NULL;
char *libao_deviceid = NULL; // ao_options expects "char*"
// FIFO name and file handle
char *pipename = NULL;
int pipe_handle = -1;
#define FRAME_BYTES (4*frame_size)
// maximal resampling shift - conservative
#define OUTFRAME_BYTES (4*(frame_size+3))
alac_file *decoder_info;
#ifdef FANCY_RESAMPLING
int fancy_resampling = 1;
SRC_STATE *src;
#endif
int init_rtp(void);
void init_buffer(void);
int init_output(void);
void rtp_request_resend(seq_t first, seq_t last);
void ab_resync(void);
// interthread variables
// stdin->decoder
volatile double volume = 1.0;
volatile long fix_volume = 0x10000;
typedef struct audio_buffer_entry { // decoded audio packets
int ready;
signed short *data;
} abuf_t;
volatile abuf_t audio_buffer[BUFFER_FRAMES];
#define BUFIDX(seqno) ((seq_t)(seqno) % BUFFER_FRAMES)
// mutex-protected variables
volatile seq_t ab_read, ab_write;
int ab_buffering = 1, ab_synced = 0;
pthread_mutex_t ab_mutex = PTHREAD_MUTEX_INITIALIZER;
pthread_cond_t ab_buffer_ready = PTHREAD_COND_INITIALIZER;
void die(char *why) {
fprintf(stderr, "FATAL: %s\n", why);
exit(1);
}
int hex2bin(unsigned char *buf, char *hex) {
int i, j;
if (strlen(hex) != 0x20)
return 1;
for (i=0; i<0x10; i++) {
if (!sscanf(hex, "%2X", &j))
return 1;
hex += 2;
*buf++ = j;
}
return 0;
}
int init_decoder(void) {
alac_file *alac;
frame_size = fmtp[1]; // stereo samples
sampling_rate = fmtp[11];
int sample_size = fmtp[3];
if (sample_size != 16)
die("only 16-bit samples supported!");
alac = create_alac(sample_size, 2);
if (!alac)
return 1;
decoder_info = alac;
alac->setinfo_max_samples_per_frame = frame_size;
alac->setinfo_7a = fmtp[2];
alac->setinfo_sample_size = sample_size;
alac->setinfo_rice_historymult = fmtp[4];
alac->setinfo_rice_initialhistory = fmtp[5];
alac->setinfo_rice_kmodifier = fmtp[6];
alac->setinfo_7f = fmtp[7];
alac->setinfo_80 = fmtp[8];
alac->setinfo_82 = fmtp[9];
alac->setinfo_86 = fmtp[10];
alac->setinfo_8a_rate = fmtp[11];
allocate_buffers(alac);
return 0;
}
int hairtunes_init(char *pAeskey, char *pAesiv, char *fmtpstr, int pCtrlPort, int pTimingPort,
int pDataPort, char *pRtpHost, char*pPipeName, char *pLibaoDriver, char *pLibaoDeviceName, char *pLibaoDeviceId)
{
if(pAeskey != NULL)
memcpy(aeskey, pAeskey, sizeof(aeskey));
if(pAesiv != NULL)
memcpy(aesiv, pAesiv, sizeof(aesiv));
if(pRtpHost != NULL)
rtphost = pRtpHost;
if(pPipeName != NULL)
pipename = pPipeName;
if(pLibaoDriver != NULL)
libao_driver = pLibaoDriver;
if(pLibaoDeviceName != NULL)
libao_devicename = pLibaoDeviceName;
if(pLibaoDeviceId != NULL)
libao_deviceid = pLibaoDeviceId;
controlport = pCtrlPort;
timingport = pTimingPort;
dataport = pDataPort;
AES_set_decrypt_key(aeskey, 128, &aes);
memset(fmtp, 0, sizeof(fmtp));
int i = 0;
char *arg;
while ( (arg = strsep(&fmtpstr, " \t")) )
fmtp[i++] = atoi(arg);
init_decoder();
init_buffer();
init_rtp(); // open a UDP listen port and start a listener; decode into ring buffer
fflush(stdout);
init_output(); // resample and output from ring buffer
char line[128];
int in_line = 0;
int n;
double f;
while (fgets(line + in_line, sizeof(line) - in_line, stdin)) {
n = strlen(line);
if (line[n-1] != '\n') {
in_line = strlen(line) - 1;
if (n == sizeof(line)-1)
in_line = 0;
continue;
}
if (sscanf(line, "vol: %lf\n", &f)) {
assert(f<=0);
if (debug)
fprintf(stderr, "VOL: %lf\n", f);
volume = pow(10.0,0.05*f);
fix_volume = 65536.0 * volume;
continue;
}
if (!strcmp(line, "exit\n")) {
exit(0);
}
if (!strcmp(line, "flush\n")) {
pthread_mutex_lock(&ab_mutex);
ab_resync();
pthread_mutex_unlock(&ab_mutex);
if (debug)
fprintf(stderr, "FLUSH\n");
}
}
fprintf(stderr, "bye!\n");
fflush(stderr);
return EXIT_SUCCESS;
}
#ifndef DONT_USE_HAIRTUNES_MAIN
int main(int argc, char **argv) {
char *hexaeskey = 0, *hexaesiv = 0;
char *fmtpstr = 0;
char *arg;
assert(RAND_MAX >= 0x10000); // XXX move this to compile time
while ( (arg = *++argv) ) {
if (!strcasecmp(arg, "iv")) {
hexaesiv = *++argv;
argc--;
} else
if (!strcasecmp(arg, "key")) {
hexaeskey = *++argv;
argc--;
} else
if (!strcasecmp(arg, "fmtp")) {
fmtpstr = *++argv;
} else
if (!strcasecmp(arg, "cport")) {
controlport = atoi(*++argv);
} else
if (!strcasecmp(arg, "tport")) {
timingport = atoi(*++argv);
} else
if (!strcasecmp(arg, "dport")) {
dataport = atoi(*++argv);
} else
if (!strcasecmp(arg, "host")) {
rtphost = *++argv;
} else
if (!strcasecmp(arg, "pipe")) {
if (libao_driver || libao_devicename || libao_deviceid ) {
die("Option 'pipe' may not be combined with 'ao_driver', 'ao_devicename' or 'ao_deviceid'");
}
pipename = *++argv;
} else
if (!strcasecmp(arg, "ao_driver")) {
if (pipename) {
die("Option 'ao_driver' may not be combined with 'pipe'");
}
libao_driver = *++argv;
} else
if (!strcasecmp(arg, "ao_devicename")) {
if (pipename || libao_deviceid ) {
die("Option 'ao_devicename' may not be combined with 'pipe' or 'ao_deviceid'");
}
libao_devicename = *++argv;
} else
if (!strcasecmp(arg, "ao_deviceid")) {
if (pipename || libao_devicename) {
die("Option 'ao_deviceid' may not be combined with 'pipe' or 'ao_devicename'");
}
libao_deviceid = *++argv;
}
#ifdef FANCY_RESAMPLING
else
if (!strcasecmp(arg, "resamp")) {
fancy_resampling = atoi(*++argv);
}
#endif
}
if (!hexaeskey || !hexaesiv)
die("Must supply AES key and IV!");
if (hex2bin(aesiv, hexaesiv))
die("can't understand IV");
if (hex2bin(aeskey, hexaeskey))
die("can't understand key");
return hairtunes_init(NULL, NULL, fmtpstr, controlport, timingport, dataport,
NULL, NULL, NULL, NULL, NULL);
}
#endif
void init_buffer(void) {
int i;
for (i=0; i<BUFFER_FRAMES; i++)
audio_buffer[i].data = malloc(OUTFRAME_BYTES);
ab_resync();
}
void ab_resync(void) {
int i;
for (i=0; i<BUFFER_FRAMES; i++)
audio_buffer[i].ready = 0;
ab_synced = 0;
}
// the sequence numbers will wrap pretty often.
// this returns true if the second arg is after the first
static inline int seq_order(seq_t a, seq_t b) {
signed short d = b - a;
return d > 0;
}
void alac_decode(short *dest, char *buf, int len) {
unsigned char packet[MAX_PACKET];
assert(len<=MAX_PACKET);
unsigned char iv[16];
int i;
memcpy(iv, aesiv, sizeof(iv));
for (i=0; i+16<=len; i += 16)
AES_cbc_encrypt((unsigned char*)buf+i, packet+i, 0x10, &aes, iv, AES_DECRYPT);
if (len & 0xf)
memcpy(packet+i, buf+i, len & 0xf);
int outsize;
decode_frame(decoder_info, packet, dest, &outsize);
assert(outsize == FRAME_BYTES);
}
void buffer_put_packet(seq_t seqno, char *data, int len) {
volatile abuf_t *abuf = 0;
short read;
short buf_fill;
pthread_mutex_lock(&ab_mutex);
if (!ab_synced) {
ab_write = seqno;
ab_read = seqno-1;
ab_synced = 1;
}
if (seqno == ab_write+1) { // expected packet
abuf = audio_buffer + BUFIDX(seqno);
ab_write = seqno;
} else if (seq_order(ab_write, seqno)) { // newer than expected
rtp_request_resend(ab_write, seqno-1);
abuf = audio_buffer + BUFIDX(seqno);
ab_write = seqno;
} else if (seq_order(ab_read, seqno)) { // late but not yet played
abuf = audio_buffer + BUFIDX(seqno);
} else { // too late.
fprintf(stderr, "\nlate packet %04X (%04X:%04X)\n", seqno, ab_read, ab_write);
}
buf_fill = ab_write - ab_read;
pthread_mutex_unlock(&ab_mutex);
if (abuf) {
alac_decode(abuf->data, data, len);
abuf->ready = 1;
}
if (ab_buffering && buf_fill >= START_FILL)
pthread_cond_signal(&ab_buffer_ready);
if (!ab_buffering) {
// check if the t+10th packet has arrived... last-chance resend
read = ab_read + 10;
abuf = audio_buffer + BUFIDX(read);
if (!abuf->ready)
rtp_request_resend(read, read);
}
}
static int rtp_sockets[2]; // data, control
#ifdef AF_INET6
struct sockaddr_in6 rtp_client;
#else
struct sockaddr_in rtp_client;
#endif
void *rtp_thread_func(void *arg) {
socklen_t si_len = sizeof(rtp_client);
char packet[MAX_PACKET];
char *pktp;
seq_t seqno;
ssize_t plen;
int sock = rtp_sockets[0], csock = rtp_sockets[1];
int readsock;
char type;
fd_set fds;
FD_ZERO(&fds);
FD_SET(sock, &fds);
FD_SET(csock, &fds);
while (select(csock>sock ? csock+1 : sock+1, &fds, 0, 0, 0)!=-1) {
if (FD_ISSET(sock, &fds)) {
readsock = sock;
} else {
readsock = csock;
}
FD_SET(sock, &fds);
FD_SET(csock, &fds);
plen = recvfrom(readsock, packet, sizeof(packet), 0, (struct sockaddr*)&rtp_client, &si_len);
if (plen < 0)
continue;
assert(plen<=MAX_PACKET);
type = packet[1] & ~0x80;
if (type == 0x60 || type == 0x56) { // audio data / resend
pktp = packet;
if (type==0x56) {
pktp += 4;
plen -= 4;
}
seqno = ntohs(*(unsigned short *)(pktp+2));
buffer_put_packet(seqno, pktp+12, plen-12);
}
}
return 0;
}
void rtp_request_resend(seq_t first, seq_t last) {
if (seq_order(last, first))
return;
fprintf(stderr, "requesting resend on %d packets (port %d)\n", last-first+1, controlport);
char req[8]; // *not* a standard RTCP NACK
req[0] = 0x80;
req[1] = 0x55|0x80; // Apple 'resend'
*(unsigned short *)(req+2) = htons(1); // our seqnum
*(unsigned short *)(req+4) = htons(first); // missed seqnum
*(unsigned short *)(req+6) = htons(last-first+1); // count
#ifdef AF_INET6
rtp_client.sin6_port = htons(controlport);
#else
rtp_client.sin_port = htons(controlport);
#endif
sendto(rtp_sockets[1], req, sizeof(req), 0, (struct sockaddr *)&rtp_client, sizeof(struct sockaddr_in));
}
int init_rtp(void) {
struct sockaddr_in si;
int type = AF_INET;
struct sockaddr* si_p = (struct sockaddr*)&si;
socklen_t si_len = sizeof(si);
unsigned short *sin_port = &si.sin_port;
memset(&si, 0, sizeof(si));
#ifdef AF_INET6
struct sockaddr_in6 si6;
type = AF_INET6;
si_p = (struct sockaddr*)&si6;
si_len = sizeof(si6);
sin_port = &si6.sin6_port;
memset(&si6, 0, sizeof(si6));
#endif
si.sin_family = AF_INET;
#ifdef SIN_LEN
si.sin_len = sizeof(si);
#endif
si.sin_addr.s_addr = htonl(INADDR_ANY);
#ifdef AF_INET6
si6.sin6_family = AF_INET6;
#ifdef SIN6_LEN
si6.sin6_len = sizeof(si);
#endif
si6.sin6_addr = in6addr_any;
si6.sin6_flowinfo = 0;
#endif
int sock = -1, csock = -1; // data and control (we treat the streams the same here)
unsigned short port = 6000;
while(1) {
if(sock < 0)
sock = socket(type, SOCK_DGRAM, IPPROTO_UDP);
#ifdef AF_INET6
if(sock==-1 && type == AF_INET6) {
// try fallback to IPv4
type = AF_INET;
si_p = (struct sockaddr*)&si;
si_len = sizeof(si);
sin_port = &si.sin_port;
continue;
}
#endif
if (sock==-1)
die("Can't create data socket!");
if(csock < 0)
csock = socket(type, SOCK_DGRAM, IPPROTO_UDP);
if (csock==-1)
die("Can't create control socket!");
*sin_port = htons(port);
int bind1 = bind(sock, si_p, si_len);
*sin_port = htons(port + 1);
int bind2 = bind(csock, si_p, si_len);
if(bind1 != -1 && bind2 != -1) break;
if(bind1 != -1) { close(sock); sock = -1; }
if(bind2 != -1) { close(csock); csock = -1; }
port += 3;
}
printf("port: %d\n", port); // let our handler know where we end up listening
printf("cport: %d\n", port+1);
pthread_t rtp_thread;
rtp_sockets[0] = sock;
rtp_sockets[1] = csock;
pthread_create(&rtp_thread, NULL, rtp_thread_func, (void *)rtp_sockets);
return port;
}
static inline short dithered_vol(short sample) {
static short rand_a, rand_b;
long out;
rand_b = rand_a;
rand_a = rand() & 0xffff;
out = (long)sample * fix_volume;
if (fix_volume < 0x10000) {
out += rand_a;
out -= rand_b;
}
return out>>16;
}
typedef struct {
double hist[2];
double a[2];
double b[3];
} biquad_t;
static void biquad_init(biquad_t *bq, double a[], double b[]) {
bq->hist[0] = bq->hist[1] = 0.0;
memcpy(bq->a, a, 2*sizeof(double));
memcpy(bq->b, b, 3*sizeof(double));
}
static void biquad_lpf(biquad_t *bq, double freq, double Q) {
double w0 = 2*M_PI*freq/((float)sampling_rate/(float)frame_size);
double alpha = sin(w0)/(2.0*Q);
double a_0 = 1.0 + alpha;
double b[3], a[2];
b[0] = (1.0-cos(w0))/(2.0*a_0);
b[1] = (1.0-cos(w0))/a_0;
b[2] = b[0];
a[0] = -2.0*cos(w0)/a_0;
a[1] = (1-alpha)/a_0;
biquad_init(bq, a, b);
}
static double biquad_filt(biquad_t *bq, double in) {
double w = in - bq->a[0]*bq->hist[0] - bq->a[1]*bq->hist[1];
double out __attribute__((unused)) = bq->b[1]*bq->hist[0] + bq->b[2]*bq->hist[1] + bq->b[0]*w;
bq->hist[1] = bq->hist[0];
bq->hist[0] = w;
return w;
}
double bf_playback_rate = 1.0;
static double bf_est_drift = 0.0; // local clock is slower by
static biquad_t bf_drift_lpf;
static double bf_est_err = 0.0, bf_last_err;
static biquad_t bf_err_lpf, bf_err_deriv_lpf;
static double desired_fill;
static int fill_count;
void bf_est_reset(short fill) {
biquad_lpf(&bf_drift_lpf, 1.0/180.0, 0.3);
biquad_lpf(&bf_err_lpf, 1.0/10.0, 0.25);
biquad_lpf(&bf_err_deriv_lpf, 1.0/2.0, 0.2);
fill_count = 0;
bf_playback_rate = 1.0;
bf_est_err = bf_last_err = 0;
desired_fill = fill_count = 0;
}
void bf_est_update(short fill) {
if (fill_count < 1000) {
desired_fill += (double)fill/1000.0;
fill_count++;
return;
}
#define CONTROL_A (1e-4)
#define CONTROL_B (1e-1)
double buf_delta = fill - desired_fill;
bf_est_err = biquad_filt(&bf_err_lpf, buf_delta);
double err_deriv = biquad_filt(&bf_err_deriv_lpf, bf_est_err - bf_last_err);
bf_est_drift = biquad_filt(&bf_drift_lpf, CONTROL_B*(bf_est_err*CONTROL_A + err_deriv) + bf_est_drift);
if (debug)
fprintf(stderr, "bf %d err %f drift %f desiring %f ed %f estd %f\r", fill, bf_est_err, bf_est_drift, desired_fill, err_deriv, err_deriv + CONTROL_A*bf_est_err);
bf_playback_rate = 1.0 + CONTROL_A*bf_est_err + bf_est_drift;
bf_last_err = bf_est_err;
}
// get the next frame, when available. return 0 if underrun/stream reset.
short *buffer_get_frame(void) {
short buf_fill;
seq_t read;
pthread_mutex_lock(&ab_mutex);
buf_fill = ab_write - ab_read;
if (buf_fill < 1 || !ab_synced) { // init or underrun. stop and wait
if (ab_synced)
fprintf(stderr, "\nunderrun.\n");
ab_buffering = 1;
pthread_cond_wait(&ab_buffer_ready, &ab_mutex);
ab_read++;
buf_fill = ab_write - ab_read;
pthread_mutex_unlock(&ab_mutex);
bf_est_reset(buf_fill);
return 0;
}
if (buf_fill >= BUFFER_FRAMES) { // overrunning! uh-oh. restart at a sane distance
fprintf(stderr, "\noverrun.\n");
ab_read = ab_write - START_FILL;
}
read = ab_read;
ab_read++;
pthread_mutex_unlock(&ab_mutex);
buf_fill = ab_write - ab_read;
bf_est_update(buf_fill);
volatile abuf_t *curframe = audio_buffer + BUFIDX(read);
if (!curframe->ready) {
fprintf(stderr, "\nmissing frame.\n");
memset(curframe->data, 0, FRAME_BYTES);
}
curframe->ready = 0;
return curframe->data;
}
int stuff_buffer(double playback_rate, short *inptr, short *outptr) {
int i;
int stuffsamp = frame_size;
int stuff = 0;
double p_stuff;
p_stuff = 1.0 - pow(1.0 - fabs(playback_rate-1.0), frame_size);
if ((float)rand()/((float)RAND_MAX) < p_stuff) {
stuff = playback_rate > 1.0 ? -1 : 1;
stuffsamp = rand() % (frame_size - 1);
}
for (i=0; i<stuffsamp; i++) { // the whole frame, if no stuffing
*outptr++ = dithered_vol(*inptr++);
*outptr++ = dithered_vol(*inptr++);
};
if (stuff) {
if (stuff==1) {
if (debug)
fprintf(stderr, "+++++++++\n");
// interpolate one sample
*outptr++ = dithered_vol(((long)inptr[-2] + (long)inptr[0]) >> 1);
*outptr++ = dithered_vol(((long)inptr[-1] + (long)inptr[1]) >> 1);
} else if (stuff==-1) {
if (debug)
fprintf(stderr, "---------\n");
inptr++;
inptr++;
}
for (i=stuffsamp; i<frame_size + stuff; i++) {
*outptr++ = dithered_vol(*inptr++);
*outptr++ = dithered_vol(*inptr++);
}
}
return frame_size + stuff;
}
void *audio_thread_func(void *arg) {
ao_device* dev = arg;
int play_samples;
signed short buf_fill __attribute__((unused));
signed short *inbuf, *outbuf;
outbuf = malloc(OUTFRAME_BYTES);
#ifdef FANCY_RESAMPLING
float *frame, *outframe;
SRC_DATA srcdat;
if (fancy_resampling) {
frame = malloc(frame_size*2*sizeof(float));
outframe = malloc(2*frame_size*2*sizeof(float));
srcdat.data_in = frame;
srcdat.data_out = outframe;
srcdat.input_frames = FRAME_BYTES;
srcdat.output_frames = 2*FRAME_BYTES;
srcdat.src_ratio = 1.0;
srcdat.end_of_input = 0;
}
#endif
while (1) {
do {
inbuf = buffer_get_frame();
} while (!inbuf);
#ifdef FANCY_RESAMPLING
if (fancy_resampling) {
int i;
for (i=0; i<2*FRAME_BYTES; i++) {
frame[i] = (float)inbuf[i] / 32768.0;
frame[i] *= volume;
}
srcdat.src_ratio = bf_playback_rate;
src_process(src, &srcdat);
assert(srcdat.input_frames_used == FRAME_BYTES);
src_float_to_short_array(outframe, outbuf, FRAME_BYTES*2);
play_samples = srcdat.output_frames_gen;
} else
#endif
play_samples = stuff_buffer(bf_playback_rate, inbuf, outbuf);
if (pipename) {
if (pipe_handle == -1) {
// attempt to open pipe - block if there are no readers
pipe_handle = open(pipename, O_WRONLY);
}
// only write if pipe open (there's a reader)
if (pipe_handle != -1) {
if (write(pipe_handle, outbuf, play_samples*4) == -1) {
// write failed - do anything here?
// SIGPIPE is handled elsewhere...
}
}
} else {
ao_play(dev, (char *)outbuf, play_samples*4);
}
}
return 0;
}
#define NUM_CHANNELS 2
void handle_broken_fifo() {
close(pipe_handle);
pipe_handle = -1;
}
void init_pipe(char* pipe) {
// make the FIFO and catch the broken pipe signal
mknod(pipe, S_IFIFO | 0644, 0);
signal(SIGPIPE, handle_broken_fifo);
}
void* init_ao() {
ao_initialize();
int driver;
if (libao_driver) {
// if a libao driver is specified on the command line, use that
driver = ao_driver_id(libao_driver);
if (driver == -1) {
die("Could not find requested ao driver");
}
} else {
// otherwise choose the default
driver = ao_default_driver_id();
}
ao_sample_format fmt;
memset(&fmt, 0, sizeof(fmt));
fmt.bits = 16;
fmt.rate = sampling_rate;
fmt.channels = NUM_CHANNELS;
fmt.byte_format = AO_FMT_NATIVE;
ao_option *ao_opts = NULL;
if(libao_deviceid) {
ao_append_option(&ao_opts, "id", libao_deviceid);
} else if(libao_devicename){
ao_append_option(&ao_opts, "dev", libao_devicename);
}
ao_device *dev = ao_open_live(driver, &fmt, ao_opts);
if (dev == NULL) {
die("Could not open ao device");
}
return dev;
}
int init_output(void) {
void* arg = 0;
if (pipename) {
init_pipe(pipename);
} else {
arg = init_ao();
}
#ifdef FANCY_RESAMPLING
int err;
if (fancy_resampling)
src = src_new(SRC_SINC_MEDIUM_QUALITY, 2, &err);
else
src = 0;
#endif
pthread_t audio_thread;
pthread_create(&audio_thread, NULL, audio_thread_func, arg);
return 0;
}
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