Stabilize monitor retune across waterfall click restarts

routes/listening_post.py

@@ -1573,29 +1573,39 @@ def stream_audio() -> Response:
         if not audio_running:
             return Response(b'', mimetype='audio/wav', status=204)
 
-        def generate_shared():
-            global audio_running, audio_source
-            try:
-                from routes.waterfall_websocket import (
-                    get_shared_capture_status,
+        def generate_shared():
+            global audio_running, audio_source
+            try:
+                from routes.waterfall_websocket import (
+                    get_shared_capture_status,
                     read_shared_monitor_audio_chunk,
                 )
             except Exception:
                 return
 
-            # Browser expects an immediate WAV header.
-            yield _wav_header(sample_rate=48000)
-
-            while audio_running and audio_source == 'waterfall':
-                chunk = read_shared_monitor_audio_chunk(timeout=1.0)
-                if chunk:
-                    yield chunk
-                    continue
-                shared = get_shared_capture_status()
-                if not shared.get('running') or not shared.get('monitor_enabled'):
-                    audio_running = False
-                    audio_source = 'process'
-                    break
+            # Browser expects an immediate WAV header.
+            yield _wav_header(sample_rate=48000)
+            inactive_since: float | None = None
+
+            while audio_running and audio_source == 'waterfall':
+                chunk = read_shared_monitor_audio_chunk(timeout=1.0)
+                if chunk:
+                    inactive_since = None
+                    yield chunk
+                    continue
+                shared = get_shared_capture_status()
+                if shared.get('running') and shared.get('monitor_enabled'):
+                    inactive_since = None
+                    continue
+                if inactive_since is None:
+                    inactive_since = time.monotonic()
+                    continue
+                if (time.monotonic() - inactive_since) < 4.0:
+                    continue
+                if not shared.get('running') or not shared.get('monitor_enabled'):
+                    audio_running = False
+                    audio_source = 'process'
+                    break
 
         return Response(
             generate_shared(),

routes/waterfall_websocket.py

@@ -413,6 +413,10 @@ def init_waterfall_websocket(app: Flask):
                 cmd = data.get('cmd')
 
                 if cmd == 'start':
+                    shared_before = get_shared_capture_status()
+                    keep_monitor_enabled = bool(shared_before.get('monitor_enabled'))
+                    keep_monitor_modulation = str(shared_before.get('monitor_modulation', 'wfm'))
+                    keep_monitor_squelch = int(shared_before.get('monitor_squelch', 0) or 0)
                     # Stop any existing capture
                     was_restarting = iq_process is not None
                     stop_event.set()
@@ -441,6 +445,12 @@ def init_waterfall_websocket(app: Flask):
                     # Parse config
                     try:
                         center_freq_mhz = _parse_center_freq_mhz(data)
+                        requested_vfo_mhz = float(
+                            data.get(
+                                'vfo_freq_mhz',
+                                data.get('frequency_mhz', center_freq_mhz),
+                            )
+                        )
                         span_mhz = _parse_span_mhz(data)
                         gain_raw = data.get('gain')
                         if gain_raw is None or str(gain_raw).lower() == 'auto':
@@ -491,6 +501,9 @@ def init_waterfall_websocket(app: Flask):
                     effective_span_mhz = sample_rate / 1e6
                     start_freq = center_freq_mhz - effective_span_mhz / 2
                     end_freq = center_freq_mhz + effective_span_mhz / 2
+                    target_vfo_mhz = requested_vfo_mhz
+                    if not (start_freq <= target_vfo_mhz <= end_freq):
+                        target_vfo_mhz = center_freq_mhz
 
                     # Claim the device (retry when restarting to allow
                     # the kernel time to release the USB handle).
@@ -591,10 +604,10 @@ def init_waterfall_websocket(app: Flask):
                         sample_rate=sample_rate,
                     )
                     _set_shared_monitor(
-                        enabled=False,
-                        frequency_mhz=center_freq_mhz,
-                        modulation='wfm',
-                        squelch=0,
+                        enabled=keep_monitor_enabled,
+                        frequency_mhz=target_vfo_mhz,
+                        modulation=keep_monitor_modulation,
+                        squelch=keep_monitor_squelch,
                     )
 
                     # Send started confirmation
@@ -608,7 +621,7 @@ def init_waterfall_websocket(app: Flask):
                         'effective_span_mhz': effective_span_mhz,
                         'db_min': db_min,
                         'db_max': db_max,
-                        'vfo_freq_mhz': center_freq_mhz,
+                        'vfo_freq_mhz': target_vfo_mhz,
                     }))
 
                     # Start reader thread — puts frames on queue, never calls ws.send()

static/js/modes/waterfall.js

@@ -44,6 +44,7 @@ const Waterfall = (function () {
     let _startingMonitor = false;
     let _monitorSource = 'process';
     let _pendingSharedMonitorRearm = false;
+    let _pendingCaptureVfoMhz = null;
     let _audioConnectNonce = 0;
     let _audioAnalyser = null;
     let _audioContext = null;
@@ -1183,6 +1184,7 @@ const Waterfall = (function () {
     function _scanTuneTo(freqMhz) {
         const clamped = _clamp(freqMhz, 0.001, 6000.0);
         _monitorFreqMhz = clamped;
+        _pendingCaptureVfoMhz = clamped;
         _updateFreqDisplay();
 
         if (_monitoring && !_isSharedMonitorActive()) {
@@ -1873,6 +1875,7 @@ const Waterfall = (function () {
         if (input) input.value = clamped.toFixed(4);
 
         _monitorFreqMhz = clamped;
+        _pendingCaptureVfoMhz = clamped;
         const currentSpan = _endMhz - _startMhz;
         const configuredSpan = _clamp(_currentSpan(), 0.05, 30.0);
         const activeSpan = Number.isFinite(currentSpan) && currentSpan > 0 ? currentSpan : configuredSpan;
@@ -1930,6 +1933,8 @@ const Waterfall = (function () {
         if (!msg || msg.status !== 'retune_required') return false;
         _setStatus(msg.message || 'Retuning SDR capture...');
         if (Number.isFinite(msg.vfo_freq_mhz)) {
+            _monitorFreqMhz = Number(msg.vfo_freq_mhz);
+            _pendingCaptureVfoMhz = _monitorFreqMhz;
             const input = document.getElementById('wfCenterFreq');
             if (input) input.value = Number(msg.vfo_freq_mhz).toFixed(4);
         }
@@ -2210,7 +2215,6 @@ const Waterfall = (function () {
         const spanMhz = _clamp(_currentSpan(), 0.05, 30.0);
         _startMhz = centerMhz - spanMhz / 2;
         _endMhz = centerMhz + spanMhz / 2;
-        _monitorFreqMhz = centerMhz;
         _peakLine = null;
         _drawFreqAxis();
 
@@ -2239,11 +2243,13 @@ const Waterfall = (function () {
     function _sendWsStartCmd() {
         if (!_ws || _ws.readyState !== WebSocket.OPEN) return;
         const cfg = _waterfallRequestConfig();
+        const targetVfoMhz = Number.isFinite(_monitorFreqMhz) ? _monitorFreqMhz : cfg.centerMhz;
 
         const payload = {
             cmd: 'start',
             center_freq_mhz: cfg.centerMhz,
             center_freq: cfg.centerMhz,
+            vfo_freq_mhz: targetVfoMhz,
             span_mhz: cfg.spanMhz,
             gain: cfg.gain,
             sdr_type: cfg.device.sdrType,
@@ -2492,7 +2498,10 @@ const Waterfall = (function () {
                     _scanAwaitingCapture = false;
                     _scanStartPending = false;
                     _scanRestartAttempts = 0;
-                    if (Number.isFinite(msg.vfo_freq_mhz)) {
+                    if (Number.isFinite(_pendingCaptureVfoMhz)) {
+                        _monitorFreqMhz = _pendingCaptureVfoMhz;
+                        _pendingCaptureVfoMhz = null;
+                    } else if (Number.isFinite(msg.vfo_freq_mhz)) {
                         _monitorFreqMhz = Number(msg.vfo_freq_mhz);
                     }
                     if (Number.isFinite(msg.start_freq) && Number.isFinite(msg.end_freq)) {
@@ -2502,15 +2511,20 @@ const Waterfall = (function () {
                     }
                     _setStatus(`Streaming ${_startMhz.toFixed(4)} - ${_endMhz.toFixed(4)} MHz`);
                     _setVisualStatus('RUNNING');
-                    if (_pendingSharedMonitorRearm) {
+                    if (_monitoring) {
+                        _pendingSharedMonitorRearm = false;
+                        // After any capture restart, always retune monitor
+                        // audio to the current VFO frequency.
+                        _queueMonitorRetune(_monitorSource === 'waterfall' ? 120 : 80);
+                    } else if (_pendingSharedMonitorRearm) {
                         _pendingSharedMonitorRearm = false;
-                        if (_monitoring && _monitorSource === 'waterfall') {
-                            _queueMonitorRetune(120);
-                        }
                     }
                 } else if (msg.status === 'tuned') {
                     if (_onRetuneRequired(msg)) return;
-                    if (Number.isFinite(msg.vfo_freq_mhz)) {
+                    if (Number.isFinite(_pendingCaptureVfoMhz)) {
+                        _monitorFreqMhz = _pendingCaptureVfoMhz;
+                        _pendingCaptureVfoMhz = null;
+                    } else if (Number.isFinite(msg.vfo_freq_mhz)) {
                         _monitorFreqMhz = Number(msg.vfo_freq_mhz);
                     }
                     _updateFreqDisplay();
@@ -2520,6 +2534,7 @@ const Waterfall = (function () {
                     return;
                 } else if (msg.status === 'stopped') {
                     _running = false;
+                    _pendingCaptureVfoMhz = null;
                     _scanAwaitingCapture = false;
                     _scanStartPending = false;
                     _scanRestartAttempts = 0;
@@ -2531,6 +2546,7 @@ const Waterfall = (function () {
                     _setVisualStatus('STOPPED');
                 } else if (msg.status === 'error') {
                     _running = false;
+                    _pendingCaptureVfoMhz = null;
                     _scanStartPending = false;
                     _pendingSharedMonitorRearm = false;
                     // If the monitor was using the shared IQ stream that
@@ -2915,6 +2931,7 @@ const Waterfall = (function () {
         _monitoring = false;
         _monitorSource = 'process';
         _pendingSharedMonitorRearm = false;
+        _pendingCaptureVfoMhz = null;
         _syncMonitorButtons();
         _setMonitorState('No audio monitor');
 
@@ -3107,6 +3124,7 @@ const Waterfall = (function () {
         _clearWsFallbackTimer();
         _wsOpened = false;
         _pendingSharedMonitorRearm = false;
+        _pendingCaptureVfoMhz = null;
         // Reset in-flight monitor start flag so the button is not left
         // disabled after a waterfall stop/restart cycle.
         if (_startingMonitor) {
@@ -3386,6 +3404,7 @@ const Waterfall = (function () {
         _setUnlockVisible(false);
         _audioUnlockRequired = false;
         _pendingSharedMonitorRearm = false;
+        _pendingCaptureVfoMhz = null;
         _sseStartConfigKey = '';
         _sseStartPromise = null;
     }