no more pulseaudio, stream straight to /tmp/esp32_audio

new_latency_test.py

@@ -0,0 +1,16 @@
+import numpy as np
+import time
+
+SAMPLERATE = 16000
+CHANNELS = 1
+BLOCKSIZE = 256
+
+with open("/tmp/esp32_audio", "rb") as f:
+    while True:
+        data = f.read(BLOCKSIZE * CHANNELS * 2)  # 2 bytes per sample
+        if not data:
+            continue
+        audio = np.frombuffer(data, dtype=np.int16)
+        peak = np.max(np.abs(audio))
+        bar = "#" * int(peak * 50 / 32767)
+        print(f"[{bar:<50}] {peak}", flush=True)

service/esp32-audio.service

@@ -1,34 +1,18 @@
 [Unit]
-Description=ESP32 Serial Audio to PulseAudio
+Description=ESP32 Audio Stream to FIFO
-After=pulseaudio.service
+After=default.target
-Requires=pulseaudio.service
+Requires=dev-ttyESP32.device
-# Tie service start to the device node so it won’t launch until udev creates it
+BindsTo=dev-ttyESP32.device
-Requires=dev-ttyESP32_A.device
-After=dev-ttyESP32_A.device
 
 [Service]
-# Ensure PulseAudio runtime dir is set so pactl can connect
+ExecStartPre=/bin/mkdir -p /tmp
-Environment=XDG_RUNTIME_DIR=/run/user/%U
+ExecStartPre=/bin/rm -f /tmp/esp32_audio
-Environment=LANG=en_US.UTF-8
+ExecStartPre=/usr/bin/mkfifo /tmp/esp32_audio
-WorkingDirectory=/home/littlesophia/serial_audio_catcher
 
-# Wait until PulseAudio socket and serial device exist
+ExecStart=/bin/sh -c '/home/radxa/serial_audio_catcher/serial_to_stdout /dev/ttyESP32 > /tmp/esp32_audio'
-ExecStartPre=/bin/sh -c 'until [ -S "$XDG_RUNTIME_DIR/pulse/native" ] && [ -e /dev/ttyESP32_A ]; do sleep 2; done'
 
-# Create the null sink before starting the pipeline
-ExecStartPre=/usr/bin/pactl unload-module module-null-sink
-ExecStartPre=/usr/bin/pactl load-module module-null-sink sink_name=esp32 rate=16000 channels=2 format=s16le
-
-# Run the pipeline through a shell so the pipe is interpreted correctly
-ExecStart=/bin/sh -c '/home/littlesophia/serial_audio_catcher/serial_to_stdout /dev/ttyESP32_A | /usr/bin/pacat --raw --rate=16000 --channels=2 --format=s16le --device=esp32'
-
-# Restart automatically if it crashes or exits
 Restart=always
-RestartSec=5
+RestartSec=2
-
-# Log output to journal
-StandardOutput=journal
-StandardError=journal
 
 [Install]
 WantedBy=default.target

wavemonitor.c

@@ -0,0 +1,57 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdint.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <string.h>
+
+#define BLOCK_FRAMES 256       // ~16 ms at 16 kHz
+#define CHANNELS 1             // adjust to 2 if stereo
+#define SAMPLE_RATE 16000
+#define BYTES_PER_SAMPLE 2     // s16le
+
+int main(void) {
+    int fd = open("/tmp/esp32_audio", O_RDONLY);
+    if (fd < 0) {
+        perror("open");
+        return 1;
+    }
+
+    size_t block_bytes = BLOCK_FRAMES * CHANNELS * BYTES_PER_SAMPLE;
+    int16_t *buffer = malloc(block_bytes);
+
+    if (!buffer) {
+        perror("malloc");
+        close(fd);
+        return 1;
+    }
+
+    while (1) {
+        ssize_t n = read(fd, buffer, block_bytes);
+        if (n <= 0) {
+            usleep(1000);
+            continue;
+        }
+
+        // compute peak
+        int16_t peak = 0;
+        for (ssize_t i = 0; i < n / 2; i++) {
+            int16_t sample = buffer[i];
+            if (sample < 0) sample = -sample;
+            if (sample > peak) peak = sample;
+        }
+
+        // scale to 50 chars
+        int bar_len = (peak * 50) / 32767;
+        char bar[51];
+        memset(bar, '#', bar_len);
+        bar[bar_len] = '\0';
+
+        printf("[%s]\r", bar);
+        fflush(stdout);
+    }
+
+    free(buffer);
+    close(fd);
+    return 0;
+}