zone previews

FEATURES.md

@@ -18,7 +18,7 @@ Features are grouped by priority. Check off items as they are implemented.
 
 - [x] [#006] **Volume / gain control** — per-selection or global audio gain slider. Every editor has this. Descript users constantly complain it's missing. Backend: `ffmpeg -af volume=Xdb`.
 
-- [ ] [#007] **Speed adjustment (4th zone type)** — add speed zones as the fourth editable timeline/transcript zone type (after cut, mute, gain), allowing slow/fast playback per range or globally. Backend: `ffmpeg -filter:v setpts` + `atempo`. Common use case: slightly speed up boring sections.
+- [x] [#007] **Speed adjustment (4th zone type)** — add speed zones as the fourth editable timeline/transcript zone type (after cut, mute, gain), allowing slow/fast playback per range or globally. Backend: `ffmpeg -filter:v setpts` + `atempo`. Common use case: slightly speed up boring sections.
 
 - [ ] [#008] **Cut preview** — before committing a delete, play what the audio will sound like with that section removed (pre-listen across the edit point). Pure frontend using Web Audio API — splice the AudioBuffer and play the join.
 

frontend/src/components/SettingsPanel.tsx

@@ -6,7 +6,7 @@ import { Bot, Cloud, Brain, RefreshCw } from 'lucide-react';
 
 export default function SettingsPanel() {
   const { providers, defaultProvider, setProviderConfig, setDefaultProvider } = useAIStore();
-  const { backendUrl } = useEditorStore();
+  const { backendUrl, zonePreviewPaddingSeconds, setZonePreviewPaddingSeconds } = useEditorStore();
   const [ollamaModels, setOllamaModels] = useState<string[]>([]);
   const [loadingModels, setLoadingModels] = useState(false);
 
@@ -37,7 +37,34 @@ export default function SettingsPanel() {
 
   return (
     <div className="p-4 space-y-6">
-      <h3 className="text-sm font-semibold">AI Settings</h3>
+      <h3 className="text-sm font-semibold">Settings</h3>
+
+      <ProviderSection title="Playback" icon={<RefreshCw className="w-4 h-4" />}>
+        <div className="space-y-1">
+          <label className="text-xs text-editor-text-muted">Zone preview padding (seconds before and after)</label>
+          <div className="flex items-center gap-2">
+            <input
+              type="range"
+              min={0}
+              max={10}
+              step={0.25}
+              value={zonePreviewPaddingSeconds}
+              onChange={(e) => setZonePreviewPaddingSeconds(Number(e.target.value) || 0)}
+              className="flex-1 h-1.5"
+            />
+            <input
+              type="number"
+              min={0}
+              max={10}
+              step={0.25}
+              value={zonePreviewPaddingSeconds}
+              onChange={(e) => setZonePreviewPaddingSeconds(Number(e.target.value) || 0)}
+              className="w-16 px-2 py-1 bg-editor-bg border border-editor-border rounded-lg text-xs text-editor-text focus:outline-none focus:border-editor-accent"
+            />
+            <span className="text-xs text-editor-text-muted w-6">s</span>
+          </div>
+        </div>
+      </ProviderSection>
 
       {/* Default provider selector */}
       <div className="space-y-2">
@@ -60,6 +87,8 @@ export default function SettingsPanel() {
         </div>
       </div>
 
+      <h4 className="text-xs font-semibold uppercase tracking-wide text-editor-text-muted">AI Settings</h4>
+
       {/* Ollama settings */}
       <ProviderSection title="Ollama (Local)" icon={providerIcons.ollama}>
         <InputField

frontend/src/components/ZoneEditor.tsx

@@ -1,15 +1,20 @@
-import { useState } from 'react';
+import { useCallback, useEffect, useRef, useState } from 'react';
 import { useEditorStore } from '../store/editorStore';
-import { Trash2, Scissors, Volume2, SlidersHorizontal, Gauge } from 'lucide-react';
+import { Trash2, Scissors, Volume2, SlidersHorizontal, Gauge, Play } from 'lucide-react';
 
 export default function ZoneEditor() {
   const [viewMode, setViewMode] = useState<'all' | 'cut' | 'mute' | 'gain' | 'speed'>('all');
+  const previewFrameRef = useRef<number | null>(null);
   
   const {
     cutRanges,
     muteRanges,
     gainRanges,
     speedRanges,
+    duration,
+    setCurrentTime,
+    zonePreviewPaddingSeconds,
+    setZonePreviewPaddingSeconds,
     globalGainDb,
     setGlobalGainDb,
     removeCutRange,
@@ -20,6 +25,57 @@ export default function ZoneEditor() {
     updateSpeedRange,
   } = useEditorStore();
 
+  const stopPreviewLoop = useCallback(() => {
+    if (previewFrameRef.current !== null) {
+      cancelAnimationFrame(previewFrameRef.current);
+      previewFrameRef.current = null;
+    }
+  }, []);
+
+  useEffect(() => stopPreviewLoop, [stopPreviewLoop]);
+
+  const previewZone = useCallback((start: number, end: number) => {
+    const video = document.querySelector('video');
+    if (!(video instanceof HTMLVideoElement)) return;
+
+    stopPreviewLoop();
+
+    const previewStart = Math.max(0, start - zonePreviewPaddingSeconds);
+    const maxDuration = Number.isFinite(duration) && duration > 0 ? duration : video.duration;
+    const previewEnd = Math.min(maxDuration || end + zonePreviewPaddingSeconds, end + zonePreviewPaddingSeconds);
+
+    video.currentTime = previewStart;
+    setCurrentTime(previewStart);
+
+    const tick = () => {
+      if (video.paused || video.ended) {
+        previewFrameRef.current = null;
+        return;
+      }
+      if (video.currentTime >= previewEnd) {
+        video.pause();
+        video.currentTime = previewEnd;
+        setCurrentTime(previewEnd);
+        previewFrameRef.current = null;
+        return;
+      }
+      previewFrameRef.current = requestAnimationFrame(tick);
+    };
+
+    void video.play();
+    previewFrameRef.current = requestAnimationFrame(tick);
+  }, [duration, setCurrentTime, stopPreviewLoop, zonePreviewPaddingSeconds]);
+
+  const renderPreviewButton = (start: number, end: number, accentClass: string) => (
+    <button
+      onClick={() => previewZone(start, end)}
+      className={`p-1 rounded opacity-0 group-hover:opacity-100 transition-opacity ${accentClass}`}
+      title={`Play ${zonePreviewPaddingSeconds.toFixed(2)}s before and after zone`}
+    >
+      <Play className="w-3.5 h-3.5" />
+    </button>
+  );
+
   const totalZones = cutRanges.length + muteRanges.length + gainRanges.length + speedRanges.length;
 
   const getZoneTypeColor = (type: 'cut' | 'mute' | 'gain' | 'speed') => {
@@ -39,13 +95,35 @@ export default function ZoneEditor() {
     <div className="p-4 space-y-4">
       <div className="space-y-2">
         <div className="space-y-1">
-          <h3 className="text-sm font-semibold flex items-center gap-2">
+          <div className="flex items-start justify-between gap-3">
-            <div className="w-4 h-4 rounded bg-editor-accent/30" />
+            <div>
-            Zone Editor
+              <h3 className="text-sm font-semibold flex items-center gap-2">
-          </h3>
+                Zone Editor
-          <p className="text-xs text-editor-text-muted">
+              </h3>
-            Manage all timeline zones ({totalZones} total)
+              <p className="text-xs text-editor-text-muted">
-          </p>
+                Manage all timeline zones ({totalZones} total)
+              </p>
+            </div>
+            <div className="min-w-[160px] rounded border border-editor-border bg-editor-surface px-2 py-1.5">
+              <div className="flex items-center justify-between gap-2">
+                <span className="text-[10px] uppercase tracking-wide text-editor-text-muted">Preview</span>
+                <span className="text-[10px] text-editor-text-muted">before/after</span>
+              </div>
+              <div className="mt-1 flex items-center gap-1.5">
+                <input
+                  type="number"
+                  min={0}
+                  max={10}
+                  step={0.25}
+                  value={zonePreviewPaddingSeconds}
+                  onChange={(e) => setZonePreviewPaddingSeconds(Number(e.target.value) || 0)}
+                  className="w-16 px-2 py-1 bg-editor-bg border border-editor-border rounded text-xs text-editor-text focus:outline-none focus:border-editor-accent"
+                  title="Preview time before and after each zone"
+                />
+                <span className="text-xs text-editor-text-muted">sec</span>
+              </div>
+            </div>
+          </div>
         </div>
         
         {/* View Mode Toggle */}
@@ -130,6 +208,7 @@ export default function ZoneEditor() {
                       </div>
                       <div className="text-editor-text-muted text-[10px]">{range.id}</div>
                     </div>
+                    {renderPreviewButton(range.start, range.end, 'hover:bg-red-500/20 text-red-500/70 hover:text-red-500')}
                     <button
                       onClick={() => removeCutRange(range.id)}
                       className="p-1 rounded hover:bg-red-500/20 text-red-500/70 hover:text-red-500 opacity-0 group-hover:opacity-100 transition-opacity"
@@ -162,6 +241,7 @@ export default function ZoneEditor() {
                       </div>
                       <div className="text-editor-text-muted text-[10px]">{range.id}</div>
                     </div>
+                    {renderPreviewButton(range.start, range.end, 'hover:bg-orange-500/20 text-orange-500/70 hover:text-orange-500')}
                     <button
                       onClick={() => removeMuteRange(range.id)}
                       className="p-1 rounded hover:bg-orange-500/20 text-orange-500/70 hover:text-orange-500 opacity-0 group-hover:opacity-100 transition-opacity"
@@ -233,6 +313,7 @@ export default function ZoneEditor() {
                       className="w-16 px-1.5 py-0.5 text-xs bg-editor-surface border border-editor-border rounded focus:border-editor-accent focus:outline-none"
                       title="Gain dB"
                     />
+                    {renderPreviewButton(range.start, range.end, 'hover:bg-amber-500/20 text-amber-500/70 hover:text-amber-500')}
                     <button
                       onClick={() => removeGainRange(range.id)}
                       className="p-1 rounded hover:bg-amber-500/20 text-amber-500/70 hover:text-amber-500 opacity-0 group-hover:opacity-100 transition-opacity"
@@ -277,6 +358,7 @@ export default function ZoneEditor() {
                       className="w-16 px-1.5 py-0.5 text-xs bg-editor-surface border border-editor-border rounded focus:border-editor-accent focus:outline-none"
                       title="Speed multiplier"
                     />
+                    {renderPreviewButton(range.start, range.end, 'hover:bg-emerald-500/20 text-emerald-500/70 hover:text-emerald-500')}
                     <button
                       onClick={() => removeSpeedRange(range.id)}
                       className="p-1 rounded hover:bg-emerald-500/20 text-emerald-500/70 hover:text-emerald-500 opacity-0 group-hover:opacity-100 transition-opacity"

frontend/src/store/editorStore.ts

@@ -43,6 +43,7 @@ interface EditorState {
   exportProgress: number;
 
   backendUrl: string;
+  zonePreviewPaddingSeconds: number;
 }
 
 interface EditorActions {
@@ -82,12 +83,23 @@ interface EditorActions {
   removeSilenceTrimGroup: (groupId: string) => void;
   setTranscribing: (active: boolean, progress?: number, status?: string) => void;
   setExporting: (active: boolean, progress?: number) => void;
+  setZonePreviewPaddingSeconds: (seconds: number) => void;
   getKeepSegments: () => Array<{ start: number; end: number }>;
   getWordAtTime: (time: number) => number;
   loadProject: (projectData: any) => void;
   reset: () => void;
 }
 
+const ZONE_PREVIEW_PADDING_KEY = 'talkedit-zone-preview-padding-seconds';
+
+function getStoredZonePreviewPaddingSeconds() {
+  if (typeof window === 'undefined') return 1;
+  const stored = window.localStorage.getItem(ZONE_PREVIEW_PADDING_KEY);
+  const parsed = stored ? Number(stored) : 1;
+  if (!Number.isFinite(parsed)) return 1;
+  return Math.max(0, Math.min(10, parsed));
+}
+
 const initialState: EditorState = {
   videoPath: null,
   videoUrl: null,
@@ -113,6 +125,7 @@ const initialState: EditorState = {
   isExporting: false,
   exportProgress: 0,
   backendUrl: 'http://127.0.0.1:8000',
+  zonePreviewPaddingSeconds: getStoredZonePreviewPaddingSeconds(),
 };
 
 let nextRangeId = 1;
@@ -184,11 +197,12 @@ export const useEditorStore = create<EditorState & EditorActions>()(
       },
 
       loadVideo: (path) => {
-        const backend = get().backendUrl;
+        const { backendUrl, zonePreviewPaddingSeconds } = get();
-        const url = `${backend}/file?path=${encodeURIComponent(path)}`;
+        const url = `${backendUrl}/file?path=${encodeURIComponent(path)}`;
         set({
           ...initialState,
-          backendUrl: backend,
+          backendUrl,
+          zonePreviewPaddingSeconds,
           videoPath: path,
           videoUrl: url,
         });
@@ -407,6 +421,14 @@ export const useEditorStore = create<EditorState & EditorActions>()(
           exportProgress: progress ?? (active ? 0 : 100),
         }),
 
+      setZonePreviewPaddingSeconds: (seconds) => {
+        const nextSeconds = Math.max(0, Math.min(10, seconds));
+        if (typeof window !== 'undefined') {
+          window.localStorage.setItem(ZONE_PREVIEW_PADDING_KEY, String(nextSeconds));
+        }
+        set({ zonePreviewPaddingSeconds: nextSeconds });
+      },
+
       getKeepSegments: () => {
         const { words, cutRanges, duration } = get();
         if (words.length === 0) return [{ start: 0, end: duration }];
@@ -456,8 +478,8 @@ export const useEditorStore = create<EditorState & EditorActions>()(
       },
 
       loadProject: (data) => {
-        const backend = get().backendUrl;
+        const { backendUrl, zonePreviewPaddingSeconds } = get();
-        const url = `${backend}/file?path=${encodeURIComponent(data.videoPath)}`;
+        const url = `${backendUrl}/file?path=${encodeURIComponent(data.videoPath)}`;
 
         let globalIdx = 0;
         const annotatedSegments = (data.segments || []).map((seg: Segment) => {
@@ -468,7 +490,8 @@ export const useEditorStore = create<EditorState & EditorActions>()(
 
         set({
           ...initialState,
-          backendUrl: backend,
+          backendUrl,
+          zonePreviewPaddingSeconds,
           videoPath: data.videoPath,
           videoUrl: url,
           words: data.words || [],
@@ -489,7 +512,10 @@ export const useEditorStore = create<EditorState & EditorActions>()(
         });
       },
 
-      reset: () => set(initialState),
+      reset: () => {
+        const { zonePreviewPaddingSeconds } = get();
+        set({ ...initialState, zonePreviewPaddingSeconds });
+      },
     }),
     { limit: 100 },
   ),