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vumeter.c
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vumeter.c
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#include <stdint.h>
#include <stdbool.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <pthread.h>
#include <stdio.h>
#include <sys/mman.h>
#include <unistd.h> // write
#include <stdlib.h> // exit
#include <string.h> // memcpy
#include <math.h> // sqrt
#include "squeeze_vis.h"
// whether to use the pthread lock
//#define USE_LOCKS
// led banner definitions
#define WIDTH 80
#define HEIGHT 8
// mmap the file
static bool do_mmap(const char *filename)
{
int vis_fd;
#if USE_LOCKS
vis_fd = open(filename, O_RDWR, 0666);
#else
vis_fd = open(filename, O_RDONLY, 0);
#endif
if (vis_fd <= 0) {
perror("open failed");
return false;
}
#if USE_LOCKS
vis_mmap = (struct vis_t *)mmap(0, sizeof(struct vis_t), PROT_READ | PROT_WRITE, MAP_SHARED, vis_fd, 0);
#else
vis_mmap = (struct vis_t *)mmap(0, sizeof(struct vis_t), PROT_READ, MAP_SHARED, vis_fd, 0);
#endif
if (vis_mmap == MAP_FAILED) {
perror("mmap failed");
return false;
}
return true;
}
// calculates rms values for left and right channel (0..32768)
static void calc_rms(s16_t *buf, int samples, int *rms_l, int *rms_r)
{
s16_t l,r;
int i;
int suml = 0;
int sumr = 0;
for (i = 0; i < samples; i += 2) {
l = buf[i];
r = buf[i+1];
suml += (l * l) >> 16;
sumr += (r * r) >> 16;
}
if (samples > 0) {
suml /= samples;
sumr /= samples;
} else {
suml = 0;
sumr = 0;
}
*rms_l = sqrt(suml << 8);
*rms_r = sqrt(sumr << 8);
}
// outputs a frame to stdout
static void output(uint8_t frame[HEIGHT][WIDTH][3], int size)
{
write(1, frame, size);
}
#define MIN(x,y) ((x)<(y)?(x):(y))
#define MAX(x,y) ((x)>(y)?(x):(y))
// draws a vu meter pixel
static void vu_pixel(uint8_t frame[HEIGHT][WIDTH][3], int x, int c)
{
x = MAX(x, 2);
x = MIN(x, (WIDTH - 3));
int r,g,b;
if (c < 25) {
r = 0;
g = 8 * c;
b = 0;
} else if (c < 50) {
r = (c - 25) * 10;
g = 200;
b = 0;
} else if (c < 75) {
r = 250;
g = 200 - (c - 50) * 8;
b = 0;
} else {
r = 255;
g = 0;
b = 0;
}
int y;
for (y = 2; y < 6; y++) {
frame[y][x][0] = r;
frame[y][x][1] = g;
frame[y][x][2] = b;
}
}
// maps rms value to bitmap size
static int map(int rms)
{
int v = rms / 8;
if (v >= (WIDTH-1)) {
v = WIDTH-1;
}
return v;
}
struct peak_t {
int level;
int time;
};
// calculates the peak value
static void calc_peak(struct peak_t *p, int level)
{
if (level > p->level) {
p->level = level;
p->time = 50;
} else {
if (p->time > 0) {
p->time--;
} else {
if (p->level > 0) {
p->level--;
}
}
}
}
// draw a dual VU
static void draw_vu(uint8_t frame[HEIGHT][WIDTH][3], int l, int r)
{
int i;
int x, y;
static struct peak_t peak_l;
static struct peak_t peak_r;
// blue line around VU
memset(frame, 0, WIDTH*HEIGHT*3);
for (x = 0; x < WIDTH; x++) {
frame[0][x][2] = 0xFF;
frame[HEIGHT - 1][x][2] = 0xFF;
}
for (y = 0; y < HEIGHT; y++) {
frame[y][0][2] = 0xFF;
frame[y][WIDTH - 1][2] = 0xFF;
}
// left VU bar
int il = map(l);
for (i = 0; i < il; i++) {
x = (WIDTH - i - 1) / 2;
vu_pixel(frame, x, i);
}
// right VU bar
int ir = map(r);
for (i = 0; i < ir; i++) {
x = (WIDTH + i + 1) / 2;
vu_pixel(frame, x, i);
}
// left peak indicator
calc_peak(&peak_l, il);
vu_pixel(frame, (WIDTH - peak_l.level - 1) / 2, 1000);
// right peak indicator
calc_peak(&peak_r, ir);
vu_pixel(frame, (WIDTH + peak_r.level + 1) / 2, 1000);
}
// argv[1] = name of /dev/shm file created by squeezelite
// argv[2] = number of seconds to run (if not present: forever)
int main(int argc, char *argv[])
{
uint8_t banner[HEIGHT][WIDTH][3];
// mmap file
const char *filename = "/dev/shm/squeezelite-00:21:00:02:cc:45";
if (argc > 1) {
filename = argv[1];
}
if (!do_mmap(filename)) {
exit(-1);
}
// max runtime
int seconds = 0;
int runtime = 0;
if (argc > 2) {
runtime = atoi(argv[2]);
}
time_t now;
time_t then = time(NULL);
int fps = 0;
u32_t buf_index = 0;
int rms_l, rms_r;
int l = 0;
int r = 0;
while (vis_mmap->running) {
#ifdef USE_LOCKS
// lock
pthread_rwlock_rdlock(&vis_mmap->rwlock);
#endif
// process
bool have_new_data = (vis_mmap->buf_index != buf_index);
if (have_new_data) {
buf_index = vis_mmap->buf_index;
// calculate rms over buffer
calc_rms(vis_mmap->buffer, vis_mmap->buf_size / 2, &rms_l, &rms_r);
// average rms value
l += (rms_l - l) / 2;
r += (rms_r - r) / 2;
}
#ifdef USE_LOCKS
// unlock
pthread_rwlock_unlock(&vis_mmap->rwlock);
#endif
// update led banner
if (have_new_data) {
draw_vu(banner, l, r);
output(banner, sizeof(banner));
fps++;
}
// stats
now = time(NULL);
if (now != then) {
fprintf(stderr, "fps=%d\n", fps);
then = now;
fps = 0;
seconds++;
}
// check max runtime
if ((runtime > 0) && (seconds > runtime)) {
break;
}
// wait some time
usleep(10000);
}
return 0;
}