feat: v0.3.2 — disk-based snapshot engine, no go2rtc polling for grid

main.go

@@ -57,6 +57,11 @@ func main() {
 		app.go2rtc = go2rtc
 	}
 
+	// Start snapshot engine for all enabled cameras.
+	snaps := NewSnapshotEngine(cfg.Storage)
+	snaps.StartAll(cfg.Cameras)
+	app.snapshots = snaps
+
 	// Start the HTTP server (blocks).
 	errCh := make(chan error, 1)
 	go func() {
@@ -104,6 +109,7 @@ type App struct {
 	ConfigPath string
 	server     *Server
 	go2rtc     *Go2RTCManager
+	snapshots  *SnapshotEngine
 }
 
 // StartServer initializes and starts the HTTP server.
@@ -118,6 +124,9 @@ func (a *App) StartServer() error {
 
 // Shutdown performs a graceful shutdown of all services.
 func (a *App) Shutdown() {
+	if a.snapshots != nil {
+		a.snapshots.StopAll()
+	}
 	if a.go2rtc != nil {
 		a.go2rtc.Stop()
 	}

public/app.js

@@ -64,7 +64,6 @@ async function loadCameras() {
 function renderLiveGrid() {
     const grid = document.getElementById('grid');
     grid.innerHTML = '';
-    const tiles = [];
     for (let i = 0; i < 8; i++) {
         const cam = cameras[i];
         const tile = document.createElement('div');
@@ -72,38 +71,29 @@ function renderLiveGrid() {
         tile.dataset.camId = cam ? cam.id : '';
 
         if (cam && cam.enabled) {
-            const snapshotURL = `http://${location.hostname}:1984/api/frame.jpeg?src=${cam.id}_sub`;
+            // Static snapshot from disk — updated every 2s by the backend.
+            // Cache-bust with timestamp to force refresh.
+            const snapURL = `/recordings/snapshots/${cam.id}.jpg?t=${Date.now()}`;
             tile.innerHTML = `
-                <img src="" class="grid-snap" onerror="this.parentElement.classList.add('offline')"
-                     style="width:100%;height:100%;object-fit:cover;position:absolute;inset:0" alt="${cam.name}" loading="lazy">
+                <img src="${snapURL}" class="grid-snap" loading="lazy"
+                     onerror="this.parentElement.classList.add('offline')"
+                     style="width:100%;height:100%;object-fit:cover;position:absolute;inset:0" alt="${cam.name}">
                 <span class="tile-status online"></span>
                 <span class="tile-label">${cam.name}</span>
             `;
+            // Auto-refresh every 3 seconds — no flooding, simple reload.
+            setInterval(() => {
+                const img = tile.querySelector('img');
+                if (img && !tile.classList.contains('offline')) {
+                    img.src = `/recordings/snapshots/${cam.id}.jpg?t=${Date.now()}`;
+                }
+            }, 3000);
             tile.addEventListener('click', () => openFocus(cam));
-            tiles.push({ tile, url: snapshotURL, cam });
         } else {
             tile.innerHTML = '<span class="tile-placeholder">No Camera</span>';
         }
         grid.appendChild(tile);
     }
-
-    // Stagger snapshot loading — one every 300ms to avoid flooding go2rtc.
-    let idx = 0;
-    function loadNext() {
-        if (idx >= tiles.length) return;
-        const { tile, url } = tiles[idx];
-        const img = tile.querySelector('img');
-        if (img) {
-            img.src = url + '&t=' + Date.now();
-            // Refresh this tile every 3 seconds (staggered per camera).
-            setInterval(() => {
-                img.src = url + '&t=' + Date.now();
-            }, 3000 + idx * 200);
-        }
-        idx++;
-        setTimeout(loadNext, 300);
-    }
-    loadNext();
 }
 
 // ── Focus Overlay ──

snapshot.go

@@ -0,0 +1,113 @@
+// NextNVR v0.3.2 — Snapshot engine
+// Grabs a single JPEG frame from each camera every 2 seconds.
+// Writes to /mnt/recordings/snapshots/{cam_id}.jpg via atomic rename.
+// The web UI loads these static images — no go2rtc polling, no CORS, no flooding.
+package main
+
+import (
+	"fmt"
+	"log"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"sync"
+	"time"
+)
+
+// SnapshotEngine manages per-camera snapshot goroutines.
+type SnapshotEngine struct {
+	mu       sync.Mutex
+	stopChs  map[string]chan struct{}
+	config   StorageConfig
+}
+
+// NewSnapshotEngine creates a new snapshot engine.
+func NewSnapshotEngine(cfg StorageConfig) *SnapshotEngine {
+	return &SnapshotEngine{
+		stopChs: make(map[string]chan struct{}),
+		config:  cfg,
+	}
+}
+
+// StartAll launches a snapshot goroutine for each enabled camera.
+func (se *SnapshotEngine) StartAll(cameras []CameraConfig) {
+	outDir := filepath.Join(se.config.RecordingsPath, "snapshots")
+	if err := os.MkdirAll(outDir, 0755); err != nil {
+		log.Printf("snapshot: mkdir %s failed: %v", outDir, err)
+		return
+	}
+
+	for _, cam := range cameras {
+		if !cam.Enabled {
+			continue
+		}
+		stopCh := make(chan struct{})
+		se.mu.Lock()
+		se.stopChs[cam.ID] = stopCh
+		se.mu.Unlock()
+		go se.snapshotLoop(cam, outDir, stopCh)
+	}
+	log.Printf("snapshot: %d cameras started → %s", len(se.stopChs), outDir)
+}
+
+// StopAll terminates all snapshot goroutines.
+func (se *SnapshotEngine) StopAll() {
+	se.mu.Lock()
+	defer se.mu.Unlock()
+	for id, ch := range se.stopChs {
+		close(ch)
+		log.Printf("snapshot: stopped camera %s", id)
+	}
+	se.stopChs = make(map[string]chan struct{})
+}
+
+// snapshotLoop grabs a JPEG frame every 2 seconds and writes it atomically.
+func (se *SnapshotEngine) snapshotLoop(cam CameraConfig, outDir string, stopCh chan struct{}) {
+	rtspURL := cam.RTSPSub
+	if rtspURL == "" {
+		rtspURL = fmt.Sprintf("rtsp://%s:%s@%s:554/Streaming/Channels/102",
+			cam.Username, cam.Password, cam.IP)
+	}
+
+	outFile := filepath.Join(outDir, cam.ID+".jpg")
+	tmpFile := outFile + ".tmp"
+	interval := 2 * time.Second
+
+	log.Printf("snapshot: %s → %s (every %v)", cam.ID, outFile, interval)
+
+	// Immediately grab the first frame.
+	se.grabFrame(rtspURL, tmpFile, outFile, cam.ID)
+
+	ticker := time.NewTicker(interval)
+	defer ticker.Stop()
+
+	for {
+		select {
+		case <-stopCh:
+			return
+		case <-ticker.C:
+			se.grabFrame(rtspURL, tmpFile, outFile, cam.ID)
+		}
+	}
+}
+
+// grabFrame launches ffmpeg to capture a single JPEG frame.
+func (se *SnapshotEngine) grabFrame(rtspURL, tmpFile, outFile, camID string) {
+	cmd := exec.Command("ffmpeg",
+		"-hide_banner", "-loglevel", "error",
+		"-rtsp_transport", "tcp",
+		"-i", rtspURL,
+		"-vframes", "1",    // exactly one frame
+		"-q:v", "5",        // good JPEG quality (2-31, lower=better)
+		"-f", "image2",
+		"-y",               // overwrite
+		tmpFile,
+	)
+
+	cmd.Run() // ignore errors — camera may be offline
+
+	// Atomic rename: if ffmpeg succeeded, tmpFile exists.
+	if _, err := os.Stat(tmpFile); err == nil {
+		os.Rename(tmpFile, outFile)
+	}
+}