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serial_audio_catcher
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recieves serial audio from esp32 and pipes them into pulseaudio for other apps to enjoy

master
jake 2025-11-15 09:51:40 +00:00
commit a58f026d35
11 changed files with 355 additions and 0 deletions
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import serial
import pyaudio
import numpy as np
SERIAL_PORT = '/dev/ttyACM0' # Change this to your serial port
BAUD_RATE = 1500000
CHUNK_SIZE = 256 # Number of frames in each block
p = pyaudio.PyAudio()
stream = p.open(format=pyaudio.paInt16,
channels=2,
rate=16000,
output=True)
ser = serial.Serial(SERIAL_PORT, BAUD_RATE)
print("Streaming audio...")
try:
while True:
data = ser.read(CHUNK_SIZE * 4) # 2 channels × 2 bytes
if not data:
break
audio_data = np.frombuffer(data, dtype=np.int16)
stream.write(audio_data.tobytes())
except KeyboardInterrupt:
print("Stopping audio stream...")
finally:
stream.stop_stream()
stream.close()
p.terminate()
ser.close()

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import serial
import numpy as np
import wave
import time
SERIAL_PORT = '/dev/ttyACM0' # Adjust if needed
BAUD_RATE = 1500000
CHUNK_SIZE = 256 # frames per block
RATE = 16000 # sample rate
CHANNELS = 2 # stereo
# open serial
ser = serial.Serial(SERIAL_PORT, BAUD_RATE)
print("Recording 3 seconds of audio...")
frames = []
start = time.time()
try:
while time.time() - start < 3.0:
# 2 channels × 2 bytes per sample = 4 bytes per frame
data = ser.read(CHUNK_SIZE * 4)
if not data:
break
frames.append(data)
finally:
ser.close()
# write to wav
with wave.open("capture.wav", "wb") as wf:
wf.setnchannels(CHANNELS)
wf.setsampwidth(2) # 16‑bit samples = 2 bytes
wf.setframerate(RATE)
wf.writeframes(b"".join(frames))
print("Saved capture.wav")

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#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <termios.h>
#include <time.h>
#include <stdint.h>
#include <sys/types.h>
#include <sys/stat.h>
#define SERIAL_PORT "/dev/ttyACM1"
#define BAUD_RATE B1500000
#define RATE 16000
#define CHANNELS 2
#define SAMPLE_WIDTH 2 // 16-bit
#define CHUNK_SIZE 256 // frames per block
#define DURATION 3 // seconds
// Write a simple WAV header
void write_wav_header(FILE *f, int data_size) {
int byte_rate = RATE * CHANNELS * SAMPLE_WIDTH;
int block_align = CHANNELS * SAMPLE_WIDTH;
// RIFF header
fwrite("RIFF", 1, 4, f);
int chunk_size = 36 + data_size;
fwrite(&chunk_size, 4, 1, f);
fwrite("WAVE", 1, 4, f);
// fmt subchunk
fwrite("fmt ", 1, 4, f);
int subchunk1_size = 16;
fwrite(&subchunk1_size, 4, 1, f);
short audio_format = 1; // PCM
fwrite(&audio_format, 2, 1, f);
short num_channels = CHANNELS;
fwrite(&num_channels, 2, 1, f);
int sample_rate = RATE;
fwrite(&sample_rate, 4, 1, f);
fwrite(&byte_rate, 4, 1, f);
fwrite(&block_align, 2, 1, f);
short bits_per_sample = SAMPLE_WIDTH * 8;
fwrite(&bits_per_sample, 2, 1, f);
// data subchunk
fwrite("data", 1, 4, f);
fwrite(&data_size, 4, 1, f);
}
int main() {
// Open serial port
int fd = open(SERIAL_PORT, O_RDONLY | O_NOCTTY);
if (fd < 0) {
perror("open");
return 1;
}
// Configure serial
struct termios tty;
memset(&tty, 0, sizeof tty);
if (tcgetattr(fd, &tty) != 0) {
perror("tcgetattr");
return 1;
}
cfsetospeed(&tty, BAUD_RATE);
cfsetispeed(&tty, BAUD_RATE);
tty.c_cflag |= (CLOCAL | CREAD);
tty.c_cflag &= ~CSIZE;
tty.c_cflag |= CS8;
tty.c_cflag &= ~PARENB;
tty.c_cflag &= ~CSTOPB;
tcsetattr(fd, TCSANOW, &tty);
FILE *out = fopen("capture.wav", "wb");
if (!out) {
perror("fopen");
return 1;
}
// Reserve space for header
fseek(out, 44, SEEK_SET);
int total_bytes = 0;
char buf[CHUNK_SIZE * CHANNELS * SAMPLE_WIDTH];
time_t start = time(NULL);
while (time(NULL) - start < DURATION) {
int n = read(fd, buf, sizeof(buf));
if (n > 0) {
fwrite(buf, 1, n, out);
total_bytes += n;
}
}
// Write header at beginning
fseek(out, 0, SEEK_SET);
write_wav_header(out, total_bytes);
fclose(out);
close(fd);
printf("Saved capture.wav (%d bytes of audio)\n", total_bytes);
return 0;
}

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#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <termios.h>
#define DEFAULT_PORT "/dev/ttyESP32_A"
#define DEFAULT_BAUD B1500000
int open_serial(const char *path, speed_t baud) {
int fd = open(path, O_RDONLY | O_NOCTTY);
if (fd < 0) { perror("open"); return -1; }
struct termios tio;
if (tcgetattr(fd, &tio) != 0) { perror("tcgetattr"); close(fd); return -1; }
cfsetispeed(&tio, baud);
cfsetospeed(&tio, baud);
// Raw mode
tio.c_iflag &= ~(IGNBRK | BRKINT | ICRNL | INLCR | IXON | IXOFF | IXANY |
PARMRK | INPCK | ISTRIP);
tio.c_oflag &= ~(OPOST);
tio.c_lflag &= ~(ECHO | ECHONL | ICANON | IEXTEN | ISIG);
tio.c_cflag &= ~(CSIZE | PARENB | CSTOPB | CRTSCTS);
tio.c_cflag |= (CS8 | CLOCAL | CREAD);
tio.c_cc[VMIN] = 1;
tio.c_cc[VTIME] = 0;
if (tcsetattr(fd, TCSANOW, &tio) != 0) { perror("tcsetattr"); close(fd); return -1; }
return fd;
}
int main(int argc, char *argv[]) {
const char *port = (argc > 1) ? argv[1] : DEFAULT_PORT;
speed_t baud = DEFAULT_BAUD;
int fd = open_serial(port, baud);
if (fd < 0) return 1;
uint8_t buf[8192];
while (1) {
ssize_t n = read(fd, buf, sizeof(buf));
if (n > 0) {
fwrite(buf, 1, n, stdout);
fflush(stdout);
}
}
close(fd);
return 0;
}

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// serial_to_wav.c
#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <termios.h>
#include <signal.h>
#include <sys/types.h>
#include <sys/stat.h>
#define SERIAL_PORT "/dev/ttyESP32_A"
#define BAUD_RATE B1500000
#define RATE 16000
#define CHANNELS 2
#define BPS 16
static volatile sig_atomic_t stop_flag = 0;
void on_sigint(int sig) { (void)sig; stop_flag = 1; }
// Write RIFF/WAVE header placeholders; sizes will be patched on exit
void write_wav_header(FILE *f, uint32_t data_bytes) {
uint32_t byte_rate = RATE * CHANNELS * (BPS/8);
uint16_t block_align = CHANNELS * (BPS/8);
uint32_t riff_size = 36 + data_bytes;
fseek(f, 0, SEEK_SET);
fwrite("RIFF", 1, 4, f);
fwrite(&riff_size, 4, 1, f);
fwrite("WAVE", 1, 4, f);
fwrite("fmt ", 1, 4, f);
uint32_t fmt_size = 16;
fwrite(&fmt_size, 4, 1, f);
uint16_t audio_fmt = 1;
fwrite(&audio_fmt, 2, 1, f);
uint16_t ch = CHANNELS;
fwrite(&ch, 2, 1, f);
uint32_t sr = RATE;
fwrite(&sr, 4, 1, f);
fwrite(&byte_rate, 4, 1, f);
fwrite(&block_align, 2, 1, f);
uint16_t bits = BPS;
fwrite(&bits, 2, 1, f);
fwrite("data", 1, 4, f);
fwrite(&data_bytes, 4, 1, f);
}
// Configure serial port for raw 8N1, no flow control, blocking reads
int open_serial(const char *path) {
int fd = open(path, O_RDONLY | O_NOCTTY);
if (fd < 0) { perror("open"); return -1; }
struct termios tio;
if (tcgetattr(fd, &tio) != 0) { perror("tcgetattr"); close(fd); return -1; }
cfsetispeed(&tio, BAUD_RATE);
cfsetospeed(&tio, BAUD_RATE);
// Raw mode: disable all translations
tio.c_iflag &= ~(IGNBRK | BRKINT | ICRNL | INLCR | IXON | IXOFF | IXANY | PARMRK | INPCK | ISTRIP);
tio.c_oflag &= ~(OPOST);
tio.c_lflag &= ~(ECHO | ECHONL | ICANON | IEXTEN | ISIG);
tio.c_cflag &= ~(CSIZE | PARENB | CSTOPB | CRTSCTS);
tio.c_cflag |= (CS8 | CLOCAL | CREAD);
// Blocking read: return when at least N bytes available
tio.c_cc[VMIN] = 1; // at least 1 byte
tio.c_cc[VTIME] = 0; // no timeout
if (tcsetattr(fd, TCSANOW, &tio) != 0) { perror("tcsetattr"); close(fd); return -1; }
return fd;
}
int main() {
signal(SIGINT, on_sigint);
int fd = open_serial(SERIAL_PORT);
if (fd < 0) return 1;
FILE *out = fopen("capture.wav", "wb+");
if (!out) { perror("fopen"); close(fd); return 1; }
// Reserve header space
uint32_t data_bytes = 0;
fseek(out, 44, SEEK_SET);
// Capture loop
uint8_t buf[8192];
while (!stop_flag) {
ssize_t n = read(fd, buf, sizeof(buf));
if (n > 0) {
fwrite(buf, 1, (size_t)n, out);
data_bytes += (uint32_t)n;
}
}
// Finalize header
write_wav_header(out, data_bytes);
fflush(out);
fclose(out);
close(fd);
fprintf(stderr, "Saved capture.wav with %u bytes of audio\n", data_bytes);
return 0;
}

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#!/bin/bash
# Start ESP32 audio capture into PulseAudio
# 1. Ensure null sink exists at 16kHz
pactl unload-module module-null-sink 2>/dev/null
pactl load-module module-null-sink sink_name=esp32 rate=16000 channels=2 format=s16le
# 2. Run serial capture and feed into sink
/home/littlesophia/serial_audio_catcher/serial_to_stdout /dev/ttyESP32_A | \
pacat --raw --rate=16000 --channels=2 --format=s16le --device=esp32

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