scrub optimization

cht/scrub/manager.py

@@ -0,0 +1,92 @@
+"""Proxy manager — background generation and lifecycle of scrub proxies."""
+
+import logging
+from pathlib import Path
+from threading import Thread
+
+from gi.repository import GLib
+
+from cht.scrub.proxy import proxy_path_for, generate_proxy, cleanup_proxies, PROXY_HEIGHT
+
+log = logging.getLogger(__name__)
+
+
+class ProxyManager:
+    """Manages background proxy generation for scrub mode.
+
+    Usage:
+        pm = ProxyManager(session_id="20260403_120000")
+        pm.request(segment_path, on_ready=lambda path: ...)
+        pm.cancel()  # stop pending work
+    """
+
+    # Proxy states
+    PENDING = "pending"
+    GENERATING = "generating"
+    READY = "ready"
+    FAILED = "failed"
+
+    def __init__(self, session_id: str):
+        self._session_id = session_id
+        self._state: dict[str, str] = {}   # segment_path_str → state
+        self._proxies: dict[str, Path] = {}  # segment_path_str → proxy_path
+        self._cancelled = False
+
+    def request(self, segment_path: Path, on_ready=None, on_error=None) -> None:
+        """Request proxy for a segment. Calls back on GTK main thread when ready.
+
+        If proxy already exists, calls back immediately.
+        """
+        key = str(segment_path)
+
+        # Already ready
+        proxy = proxy_path_for(segment_path, self._session_id)
+        if proxy.exists():
+            self._state[key] = self.READY
+            self._proxies[key] = proxy
+            if on_ready:
+                GLib.idle_add(on_ready, proxy)
+            return
+
+        # Already generating
+        if self._state.get(key) == self.GENERATING:
+            return
+
+        self._state[key] = self.GENERATING
+
+        def _generate():
+            if self._cancelled:
+                return
+            try:
+                result = generate_proxy(segment_path, proxy)
+                self._state[key] = self.READY
+                self._proxies[key] = result
+                if on_ready and not self._cancelled:
+                    GLib.idle_add(on_ready, result)
+            except Exception as e:
+                self._state[key] = self.FAILED
+                log.error("Proxy generation failed: %s", e)
+                if on_error and not self._cancelled:
+                    GLib.idle_add(on_error, str(e))
+
+        Thread(target=_generate, daemon=True,
+               name=f"proxy_{segment_path.stem}").start()
+
+    def get_state(self, segment_path: Path) -> str | None:
+        """Return current state of proxy for segment, or None if not requested."""
+        return self._state.get(str(segment_path))
+
+    def get_proxy(self, segment_path: Path) -> Path | None:
+        """Return proxy path if ready, None otherwise."""
+        return self._proxies.get(str(segment_path))
+
+    def cancel(self) -> None:
+        """Cancel pending work. Already-running ffmpeg will finish but callbacks are suppressed."""
+        self._cancelled = True
+
+    def cleanup(self) -> None:
+        """Delete all proxies for this session."""
+        self.cancel()
+        cleanup_proxies(self._session_id)
+        self._state.clear()
+        self._proxies.clear()

cht/scrub/proxy.py

@@ -0,0 +1,81 @@
+"""Proxy generation — low-res MJPEG for frame-accurate scrubbing.
+
+Each completed recording segment gets a lightweight proxy video where every
+frame is a keyframe (MJPEG).  mpv can seek frame-accurately in these files
+with hr-seek=yes, giving DaVinci Resolve-style scrubbing speed.
+
+Proxies are ephemeral — stored in /tmp, regenerated on demand.
+"""
+
+import logging
+import shutil
+from pathlib import Path
+
+import ffmpeg as ffmpeg_lib
+
+log = logging.getLogger(__name__)
+
+PROXY_DIR = Path("/tmp/cht_proxy")
+PROXY_HEIGHT = 360  # pixels — low enough for speed, high enough to see content
+
+
+def proxy_path_for(segment_path: Path, session_id: str | None = None) -> Path:
+    """Return the proxy path for a given segment."""
+    subdir = session_id or "default"
+    return PROXY_DIR / subdir / f"{segment_path.stem}_proxy.avi"
+
+
+def generate_proxy(segment_path: Path, output_path: Path,
+                   height: int = PROXY_HEIGHT) -> Path:
+    """Transcode a segment to MJPEG proxy at reduced resolution.
+
+    Every frame is a keyframe — enables O(1) seeking.
+    Returns output_path on success.
+    """
+    output_path.parent.mkdir(parents=True, exist_ok=True)
+
+    stream = ffmpeg_lib.input(str(segment_path))
+    output = (
+        ffmpeg_lib.output(
+            stream, str(output_path),
+            vcodec="mjpeg",
+            vf=f"scale=-2:{height}",
+            # MJPEG: every frame is a keyframe by nature
+            **{"q:v": "5"},  # quality 2-31, lower = better
+            an=None,  # strip audio
+        )
+        .overwrite_output()
+        .global_args("-hide_banner", "-loglevel", "warning")
+    )
+
+    log.info("Generating proxy: %s → %s", segment_path.name, output_path)
+    try:
+        output.run(capture_stdout=True, capture_stderr=True)
+    except ffmpeg_lib.Error as e:
+        stderr = (e.stderr or b"").decode("utf-8", errors="replace")
+        log.error("Proxy generation failed for %s: %s", segment_path.name, stderr.strip())
+        raise
+
+    log.info("Proxy ready: %s (%.1f MB)",
+             output_path.name, output_path.stat().st_size / 1_000_000)
+    return output_path
+
+
+def ensure_proxy(segment_path: Path, session_id: str | None = None,
+                 height: int = PROXY_HEIGHT) -> Path:
+    """Return proxy path, generating it if missing."""
+    out = proxy_path_for(segment_path, session_id)
+    if out.exists():
+        return out
+    return generate_proxy(segment_path, out, height)
+
+
+def cleanup_proxies(session_id: str | None = None) -> None:
+    """Delete proxy files for a session, or all proxies if session_id is None."""
+    if session_id:
+        target = PROXY_DIR / session_id
+    else:
+        target = PROXY_DIR
+    if target.exists():
+        shutil.rmtree(target)
+        log.info("Cleaned up proxies: %s", target)

cht/session.py

@@ -1,12 +1,102 @@
-"""Session data loading — reads frame/transcript indexes, returns plain data."""
+"""Session data loading — reads frame/transcript indexes and segment manifests."""
 
 import json
 import logging
 from pathlib import Path
 
+import ffmpeg as ffmpeg_lib
+
 log = logging.getLogger(__name__)
 
 
+# ---------------------------------------------------------------------------
+# Segment manifest — maps each recording segment to its global time offset
+# ---------------------------------------------------------------------------
+
+def probe_duration(path: Path) -> float:
+    """Probe a media file's duration via ffprobe. Returns 0.0 on failure."""
+    try:
+        info = ffmpeg_lib.probe(str(path))
+        dur = float(info.get("format", {}).get("duration", 0))
+        if dur > 0:
+            return dur
+        for s in info.get("streams", []):
+            sdur = float(s.get("duration", 0))
+            if sdur > 0:
+                return sdur
+    except Exception as e:
+        log.debug("probe_duration failed for %s: %s", path, e)
+    # Fallback: rough estimate from file size (~500kbps)
+    try:
+        return path.stat().st_size / 65_000
+    except Exception:
+        return 0.0
+
+
+def build_segment_manifest(stream_dir: Path) -> list[dict]:
+    """Probe all recording_*.mp4 in *stream_dir* and return a manifest.
+
+    Each entry: {path, index, duration, global_offset}.
+    Sorted by segment index.  Recomputable from files at any time.
+    """
+    segments = sorted(stream_dir.glob("recording_*.mp4"))
+    manifest = []
+    offset = 0.0
+    for i, seg in enumerate(segments):
+        dur = probe_duration(seg)
+        manifest.append({
+            "path": str(seg),
+            "index": i,
+            "duration": dur,
+            "global_offset": offset,
+        })
+        offset += dur
+    return manifest
+
+
+def write_segment_manifest(session_dir: Path, manifest: list[dict]) -> None:
+    """Write segments.json to *session_dir*."""
+    path = session_dir / "segments.json"
+    path.write_text(json.dumps(manifest, indent=2))
+
+
+def load_segment_manifest(session_dir: Path) -> list[dict]:
+    """Read segments.json. Returns [] if missing."""
+    path = session_dir / "segments.json"
+    if not path.exists():
+        return []
+    try:
+        return json.loads(path.read_text())
+    except (json.JSONDecodeError, IOError):
+        return []
+
+
+def rebuild_manifest(session_dir: Path) -> list[dict]:
+    """Recalculate segment manifest from actual files and write it."""
+    stream_dir = session_dir / "stream"
+    manifest = build_segment_manifest(stream_dir)
+    write_segment_manifest(session_dir, manifest)
+    log.info("Rebuilt manifest: %d segments, total %.1fs",
+             len(manifest),
+             sum(s["duration"] for s in manifest))
+    return manifest
+
+
+def global_time_to_segment(manifest: list[dict], global_time: float):
+    """Map a global timestamp to (segment_entry, local_time).
+
+    Returns the segment containing *global_time* and the time offset
+    within that segment.  Returns (None, 0.0) if manifest is empty.
+    """
+    if not manifest:
+        return None, 0.0
+    for seg in reversed(manifest):
+        if global_time >= seg["global_offset"]:
+            local = global_time - seg["global_offset"]
+            return seg, local
+    return manifest[0], global_time
+
+
 def load_frame_index(frames_dir: Path) -> list[dict]:
     """Read frames/index.json and return list of {id, path, timestamp}.
 

cht/stream/lifecycle.py

@@ -6,6 +6,7 @@ from threading import Thread
 from gi.repository import GLib
 
 from cht.config import TRANSCRIBE_MIN_CHUNK_S
+from cht.session import rebuild_manifest
 from cht.stream.manager import StreamManager
 from cht.stream.tracker import RecordingTracker
 
@@ -84,11 +85,19 @@ class StreamLifecycle:
             self._tracker = None
 
         readonly = self._stream_mgr.readonly if self._stream_mgr else True
+        session_dir = self._stream_mgr.session_dir if self._stream_mgr else None
         if self._stream_mgr:
             if not readonly:
                 self._stream_mgr.stop_all()
             self._stream_mgr = None
 
+        # Rebuild manifest now that all segments are finalized
+        if session_dir and not readonly:
+            try:
+                rebuild_manifest(session_dir)
+            except Exception as e:
+                log.error("Failed to rebuild manifest on stop: %s", e)
+
         self._streaming = False
         self._gone_live = False
         self._pending_transcript_audio.clear()
@@ -129,40 +138,51 @@ class StreamLifecycle:
             GLib.idle_add(self._on_scene_marker, f["timestamp"])
         self._on_new_frames(frames)
 
-    def _handle_new_audio(self, wav_path, start_time, duration):
+    def _handle_new_audio(self, wav_path, start_time, duration,
+                          segment_path=None, local_start=None):
         if not self._stream_mgr:
             return
+        # start_time is global; waveform uses global time
         self._waveform_engine.append_chunk(wav_path, start_time)
         peaks = self._waveform_engine.peaks
         bucket_dur = self._waveform_engine.bucket_duration
         GLib.idle_add(self._on_waveform_update, peaks.copy(), bucket_dur)
 
-        self._pending_transcript_audio.append((wav_path, start_time, duration))
+        self._pending_transcript_audio.append({
+            "wav": wav_path, "global_start": start_time, "duration": duration,
+            "segment_path": segment_path or self._stream_mgr.recording_path,
+            "local_start": local_start if local_start is not None else start_time,
+        })
         self._pending_transcript_duration += duration
         if self._pending_transcript_duration < TRANSCRIBE_MIN_CHUNK_S:
             return
 
-        first_start = self._pending_transcript_audio[0][1]
+        first = self._pending_transcript_audio[0]
+        first_global = first["global_start"]
+        first_local = first["local_start"]
+        seg_path = first["segment_path"]
         total_dur = self._pending_transcript_duration
         self._pending_transcript_audio.clear()
         self._pending_transcript_duration = 0.0
 
         mgr = self._stream_mgr
-        chunk_wav = mgr.audio_dir / f"transcript_{int(first_start):06d}.wav"
+        chunk_wav = mgr.audio_dir / f"transcript_{int(first_global):06d}.wav"
 
         def _transcribe():
             from cht.stream import ffmpeg as ff
             try:
+                # Extract audio using local time within the segment file
                 ff.extract_audio_chunk(
-                    mgr.recording_path, chunk_wav,
+                    seg_path, chunk_wav,
-                    start_time=first_start, duration=total_dur,
+                    start_time=first_local, duration=total_dur,
                 )
             except Exception as e:
                 log.error("Transcript audio extraction failed: %s", e)
                 return
             if not chunk_wav.exists():
                 return
-            new_segs = self._transcriber.transcribe_chunk(chunk_wav, time_offset=first_start)
+            # Transcribe with global time offset so segment timestamps are global
+            new_segs = self._transcriber.transcribe_chunk(chunk_wav, time_offset=first_global)
             self._transcriber.save_index(mgr.transcript_dir / "index.json")
             if new_segs:
                 GLib.idle_add(self._on_transcript_ready, new_segs)

cht/stream/manager.py

@@ -65,6 +65,7 @@ class StreamManager:
         self._threads = {}
         self._stop_flags = set()
         self._segment = 0
+        self._segment_offsets = {0: 0.0}  # segment_index → global_offset
         self.scene_threshold = SCENE_THRESHOLD
         self.readonly = False  # True when loaded from existing session
         log.info("Session: %s", session_id)
@@ -72,6 +73,7 @@ class StreamManager:
     @classmethod
     def from_existing(cls, session_id):
         """Load an existing session without starting any ffmpeg processes."""
+        from cht.session import rebuild_manifest
         mgr = cls(session_id=session_id)
         if not mgr.session_dir.exists():
             raise FileNotFoundError(f"Session not found: {session_id}")
@@ -80,10 +82,35 @@ class StreamManager:
         segments = mgr.recording_segments
         if segments:
             mgr._segment = len(segments) - 1
+        mgr._rebuild_offsets()
+        rebuild_manifest(mgr.session_dir)
         log.info("Loaded existing session: %s (%d segments, %d frames)",
                  session_id, len(segments), mgr.frame_count)
         return mgr
 
+    @property
+    def current_global_offset(self) -> float:
+        """Global time offset for the current recording segment."""
+        return self._segment_offsets.get(self._segment, 0.0)
+
+    def _rebuild_offsets(self):
+        """Compute global offsets from all segments on disk."""
+        from cht.session import probe_duration
+        offset = 0.0
+        self._segment_offsets = {}
+        for i, seg in enumerate(self.recording_segments):
+            self._segment_offsets[i] = offset
+            offset += probe_duration(seg)
+
+    def _advance_segment_offset(self, completed_segment_path):
+        """Update offsets after a segment completes and a new one begins."""
+        from cht.session import probe_duration
+        dur = probe_duration(completed_segment_path)
+        prev_offset = self._segment_offsets.get(self._segment, 0.0)
+        self._segment_offsets[self._segment + 1] = prev_offset + dur
+        log.info("Segment %d completed (%.1fs), next offset: %.1fs",
+                 self._segment, dur, prev_offset + dur)
+
     @property
     def frame_count(self):
         index_path = self.frames_dir / "index.json"
@@ -144,6 +171,7 @@ class StreamManager:
         # Start after existing segments (for resumed sessions)
         existing = self.recording_segments
         self._segment = len(existing)
+        self._rebuild_offsets()
         self._launch_recorder()
 
     def restart_recorder(self):
@@ -151,8 +179,11 @@ class StreamManager:
         old = self._procs.pop("recorder", None)
         if old:
             ff.stop_proc(old)
+        completed_path = self.recording_path
+        self._advance_segment_offset(completed_path)
         self._segment += 1
-        log.info("Restarting recorder → segment %d", self._segment)
+        log.info("Restarting recorder → segment %d (offset %.1fs)",
+                 self._segment, self.current_global_offset)
         self._launch_recorder()
 
     def recorder_alive(self):
@@ -297,6 +328,7 @@ class StreamManager:
         index_path = self.frames_dir / "index.json"
         index = json.loads(index_path.read_text()) if index_path.exists() else []
 
+        offset = self.current_global_offset
         frame_num = start_number
         for line in stderr.splitlines():
             if "showinfo" not in line:
@@ -309,7 +341,7 @@ class StreamManager:
                 if frame_path.exists():
                     entry = {
                         "id": frame_id,
-                        "timestamp": pts_time,
+                        "timestamp": pts_time + offset,
                         "path": str(frame_path),
                         "sent_to_agent": False,
                     }
@@ -332,7 +364,8 @@ class StreamManager:
                 log.warning("capture_now: recording too short")
                 return
 
-            timestamp = safe_duration - 1
+            local_timestamp = safe_duration - 1
+            timestamp = local_timestamp + self.current_global_offset
             index_path = self.frames_dir / "index.json"
             index = json.loads(index_path.read_text()) if index_path.exists() else []
             frame_num = len(index) + 1
@@ -340,7 +373,7 @@ class StreamManager:
             frame_path = self.frames_dir / f"{frame_id}.jpg"
 
             try:
-                ff.extract_frame_at(self.recording_path, frame_path, timestamp)
+                ff.extract_frame_at(self.recording_path, frame_path, local_timestamp)
             except Exception as e:
                 log.error("capture_now failed: %s", e)
                 return
@@ -421,10 +454,14 @@ class StreamManager:
                     continue
 
                 if wav_path.exists() and wav_path.stat().st_size > 100:
-                    log.info("Audio chunk: %s (%.1fs → %.1fs)",
+                    global_start = processed_time + self.current_global_offset
-                             wav_path.name, processed_time, process_to)
+                    log.info("Audio chunk: %s (%.1fs → %.1fs, global %.1fs)",
+                             wav_path.name, processed_time, process_to, global_start)
                     if self._on_new_audio:
-                        self._on_new_audio(wav_path, processed_time, chunk_duration)
+                        self._on_new_audio(
+                            wav_path, global_start, chunk_duration,
+                            segment_path=seg, local_start=processed_time,
+                        )
                     chunk_num += 1
 
                 processed_time = process_to

cht/ui/frames_panel.py

@@ -24,12 +24,14 @@ class FramesPanel(Gtk.Box):
         "selection-changed": (GObject.SignalFlags.RUN_FIRST, None, ()),
         "capture-requested": (GObject.SignalFlags.RUN_FIRST, None, ()),
         "threshold-changed": (GObject.SignalFlags.RUN_FIRST, None, (float,)),
+        "seek-requested": (GObject.SignalFlags.RUN_FIRST, None, (float,)),
     }
 
     def __init__(self, **kwargs):
         super().__init__(orientation=Gtk.Orientation.VERTICAL, spacing=0, **kwargs)
 
         self._widgets: dict[str, Gtk.Box] = {}
+        self._timestamps: dict[str, float] = {}
         self._order: list[str] = []
         self._selected: str | None = None
 
@@ -105,10 +107,11 @@ class FramesPanel(Gtk.Box):
         box.append(label)
 
         gesture = Gtk.GestureClick()
-        gesture.connect("released", lambda g, n, x, y, fid=frame_id: self.select(fid))
+        gesture.connect("released", self._on_frame_click, frame_id)
         box.add_controller(gesture)
 
         self._widgets[frame_id] = box
+        self._timestamps[frame_id] = timestamp
         self._order.append(frame_id)
         self._strip.append(box)
 
@@ -117,6 +120,12 @@ class FramesPanel(Gtk.Box):
 
         log.info("Thumbnail: %s at %.1fs", frame_id, timestamp)
 
+    def _on_frame_click(self, gesture, n_press, x, y, frame_id):
+        self.select(frame_id)
+        if n_press == 2:
+            ts = self._timestamps.get(frame_id, 0)
+            self.emit("seek-requested", ts)
+
     def load_items(self, items: list[dict]):
         """Bulk load. Each dict has 'id', 'pixbuf', 'timestamp'."""
         self.clear()
@@ -171,6 +180,7 @@ class FramesPanel(Gtk.Box):
         """Remove all items and reset state."""
         self._selected = None
         self._widgets.clear()
+        self._timestamps.clear()
         self._order.clear()
         while child := self._strip.get_first_child():
             self._strip.remove(child)

cht/ui/monitor.py

@@ -51,6 +51,8 @@ class MonitorWidget(Gtk.Box):
         self._live_loaded = False
 
         self._review_player = None
+        self._scrub_offset = 0.0  # global offset of the loaded scrub source
+        self._scrub_active = False  # True when scrub source is loaded
 
         self._stack = Gtk.Stack()
         self._stack.set_hexpand(True)
@@ -87,6 +89,21 @@ class MonitorWidget(Gtk.Box):
         self._recording_path = path
         log.info("Recording path: %s", path)
 
+    def set_scrub_source(self, proxy_path, global_offset=0.0):
+        """Load a proxy file for frame-accurate scrubbing."""
+        self._recording_path = proxy_path
+        self._scrub_offset = global_offset
+        self._scrub_active = True
+        if self._review_player:
+            self._review_player.load_at(proxy_path, 0, pause=True, hr_seek=True)
+        self._stack.set_visible_child_name("review")
+        log.info("Scrub source: %s (offset %.1fs)", proxy_path, global_offset)
+
+    def scrub_to(self, seconds):
+        """Seek the review player to an exact frame (for scrub bar dragging)."""
+        if self._review_player:
+            self._review_player.show_frame_at(seconds)
+
     def get_live_position(self):
         """Return the live player's current time_pos, or None."""
         if self._live_player:
@@ -105,6 +122,8 @@ class MonitorWidget(Gtk.Box):
         self._live_source_url = None
         self._recording_path = None
         self._live_loaded = False
+        self._scrub_active = False
+        self._scrub_offset = 0.0
         if self._live_player:
             self._live_player.command("stop")
         if self._review_player:
@@ -180,6 +199,7 @@ class MonitorWidget(Gtk.Box):
         current = self._stack.get_visible_child_name()
 
         if s.live:
+            self._scrub_active = False
             # Ensure live player is loaded and playing
             if self._live_player and not self._live_loaded and self._live_source_url:
                 self._live_player.load_live(self._live_source_url)
@@ -190,17 +210,22 @@ class MonitorWidget(Gtk.Box):
             if current != "live":
                 self._stack.set_visible_child_name("live")
         else:
-            # Scrub mode
+            # Scrub / review mode
-            if current == "live":
+            if self._scrub_active:
+                # Scrub mode: driven directly by scrub_to(), not by timeline
+                if current != "review":
+                    self._stack.set_visible_child_name("review")
+                return
+            elif current == "live":
                 # Transitioning from live: load MKV at cursor position atomically
-                pos = s.cursor  # already set by toggle_live()
+                pos = s.cursor
                 if self._review_player and self._recording_path:
                     self._review_player.load_at(self._recording_path, pos, pause=s.paused)
                     if not s.paused:
                         self._review_player.play()
                 self._stack.set_visible_child_name("review")
             else:
-                # Already in review: seek if cursor moved, then apply pause/play
+                # Already in review (non-scrub): seek if cursor moved
                 if self._review_player:
                     player_pos = self._review_player.time_pos or 0
                     if abs(s.cursor - player_pos) > 1.0:
@@ -212,9 +237,12 @@ class MonitorWidget(Gtk.Box):
 
     def _sync_cursor_from_player(self):
         s = self._timeline.state
+        if self._scrub_active:
+            # Scrub mode: don't sync cursor from player — scrub bar drives cursor
+            return True
         if not s.live and not s.paused and self._review_player:
             pos = self._review_player.time_pos
             if pos is not None and pos > 0:
                 self._timeline.set_cursor(pos)
-        # Live mode: cursor driven by tick_live() in window.py
+        # Live mode: cursor driven by tick_live()
         return True

cht/ui/mpv.py

@@ -92,9 +92,11 @@ class Player:
         log.info("mpv load: %s", path)
         self._player.loadfile(str(path), mode="replace")
 
-    def load_at(self, path, seconds, pause=True):
+    def load_at(self, path, seconds, pause=True, hr_seek=False):
         """Load a file and seek to position atomically. Avoids async seek race."""
-        log.info("mpv load_at: %s at %.1fs pause=%s", path, seconds, pause)
+        log.info("mpv load_at: %s at %.1fs pause=%s hr_seek=%s", path, seconds, pause, hr_seek)
+        if hr_seek:
+            self._player["hr-seek"] = "yes"
         self._player["pause"] = pause
         self._player.loadfile(str(path), mode="replace", start=str(seconds))
 

cht/ui/scrub_bar.py

@@ -0,0 +1,245 @@
+"""ScrubBar: tall segmented block bar for frame-accurate scrubbing.
+
+Replaces the thin timeline slider with a horizontal row of blocks,
+one per recording segment, proportional in width to duration.
+
+Click a block to activate it (trigger proxy generation).
+Drag within a block to scrub frame-by-frame at mouse speed.
+"""
+
+import logging
+
+import gi
+gi.require_version("Gtk", "4.0")
+from gi.repository import Gtk, Gdk, GLib, GObject, Pango
+
+import cairo
+
+log = logging.getLogger(__name__)
+
+BAR_HEIGHT = 50
+BLOCK_GAP = 2
+BLOCK_COLOR = (0.25, 0.25, 0.30)
+BLOCK_ACTIVE_COLOR = (0.35, 0.45, 0.60)
+BLOCK_HOVER_COLOR = (0.30, 0.35, 0.40)
+BLOCK_GENERATING_COLOR = (0.30, 0.40, 0.35)
+CURSOR_COLOR = (0.9, 0.2, 0.2)
+MARKER_COLOR = (0.9, 0.8, 0.2)
+TEXT_COLOR = (0.8, 0.8, 0.8)
+
+
+class ScrubBar(Gtk.DrawingArea):
+    """Segmented block bar for scrubbing through recording segments."""
+
+    __gsignals__ = {
+        "segment-activated": (GObject.SignalFlags.RUN_FIRST, None, (int,)),
+        "scrub-position": (GObject.SignalFlags.RUN_FIRST, None, (float,)),
+    }
+
+    def __init__(self, **kwargs):
+        super().__init__(**kwargs)
+        self.set_content_height(BAR_HEIGHT)
+        self.set_hexpand(True)
+
+        self._manifest = []       # list of {path, index, duration, global_offset}
+        self._total_duration = 0.0
+        self._cursor = 0.0        # global cursor position
+        self._active_index = -1   # currently active segment index
+        self._hover_index = -1    # segment under mouse
+        self._proxy_states = {}   # segment_index → "generating" | "ready"
+        self._scene_markers = []  # global timestamps
+        self._scrubbing = False
+
+        self.set_draw_func(self._draw)
+
+        # Mouse events
+        click = Gtk.GestureClick()
+        click.connect("pressed", self._on_pressed)
+        click.connect("released", self._on_released)
+        self.add_controller(click)
+
+        motion = Gtk.EventControllerMotion()
+        motion.connect("motion", self._on_motion)
+        motion.connect("leave", self._on_leave)
+        self.add_controller(motion)
+
+        drag = Gtk.GestureDrag()
+        drag.connect("drag-begin", self._on_drag_begin)
+        drag.connect("drag-update", self._on_drag_update)
+        drag.connect("drag-end", self._on_drag_end)
+        self.add_controller(drag)
+
+    # -- Public API --
+
+    def set_manifest(self, manifest: list[dict]) -> None:
+        """Update the segment manifest. Triggers redraw."""
+        self._manifest = manifest
+        self._total_duration = sum(s["duration"] for s in manifest)
+        self.queue_draw()
+
+    def set_cursor(self, global_time: float) -> None:
+        """Update the cursor position (from Timeline)."""
+        self._cursor = global_time
+        self.queue_draw()
+
+    def set_scene_markers(self, markers: list[float]) -> None:
+        """Set scene change marker positions."""
+        self._scene_markers = markers
+        self.queue_draw()
+
+    def set_active_segment(self, index: int) -> None:
+        """Set which segment is active (loaded for scrubbing)."""
+        self._active_index = index
+        self.queue_draw()
+
+    def set_proxy_state(self, segment_index: int, state: str) -> None:
+        """Update proxy state for a segment ('generating', 'ready')."""
+        self._proxy_states[segment_index] = state
+        self.queue_draw()
+
+    # -- Drawing --
+
+    def _draw(self, area, cr, width, height):
+        if not self._manifest or self._total_duration <= 0:
+            cr.set_source_rgb(0.15, 0.15, 0.15)
+            cr.rectangle(0, 0, width, height)
+            cr.fill()
+            return
+
+        # Draw segment blocks
+        for seg in self._manifest:
+            x, w = self._segment_rect(seg, width)
+            idx = seg["index"]
+
+            # Block color based on state
+            if idx == self._active_index:
+                cr.set_source_rgb(*BLOCK_ACTIVE_COLOR)
+            elif idx == self._hover_index:
+                cr.set_source_rgb(*BLOCK_HOVER_COLOR)
+            elif self._proxy_states.get(idx) == "generating":
+                cr.set_source_rgb(*BLOCK_GENERATING_COLOR)
+            else:
+                cr.set_source_rgb(*BLOCK_COLOR)
+
+            cr.rectangle(x, 0, w, height)
+            cr.fill()
+
+            # Segment label
+            dur = seg["duration"]
+            m, s = divmod(int(dur), 60)
+            label = f"S{idx}" if w < 40 else f"S{idx} {m}:{s:02d}"
+            cr.set_source_rgb(*TEXT_COLOR)
+            cr.set_font_size(11)
+            cr.move_to(x + 4, height - 6)
+            cr.show_text(label)
+
+            # Proxy state indicator
+            state = self._proxy_states.get(idx)
+            if state == "ready":
+                cr.set_source_rgb(0.3, 0.7, 0.3)
+                cr.arc(x + w - 8, 8, 3, 0, 6.28)
+                cr.fill()
+            elif state == "generating":
+                cr.set_source_rgb(0.7, 0.7, 0.3)
+                cr.arc(x + w - 8, 8, 3, 0, 6.28)
+                cr.fill()
+
+        # Scene markers
+        cr.set_source_rgb(*MARKER_COLOR)
+        for ts in self._scene_markers:
+            mx = self._global_to_x(ts, width)
+            if 0 <= mx <= width:
+                cr.rectangle(mx, 0, 1, 6)
+                cr.fill()
+
+        # Cursor
+        cx = self._global_to_x(self._cursor, width)
+        if 0 <= cx <= width:
+            cr.set_source_rgb(*CURSOR_COLOR)
+            cr.rectangle(cx - 1, 0, 2, height)
+            cr.fill()
+
+    # -- Geometry helpers --
+
+    def _segment_rect(self, seg, total_width):
+        """Return (x, width) for a segment block."""
+        if self._total_duration <= 0:
+            return 0, 0
+        x = (seg["global_offset"] / self._total_duration) * total_width + BLOCK_GAP / 2
+        w = (seg["duration"] / self._total_duration) * total_width - BLOCK_GAP
+        return max(0, x), max(1, w)
+
+    def _global_to_x(self, global_time, total_width):
+        """Map global time to pixel x position."""
+        if self._total_duration <= 0:
+            return 0
+        return (global_time / self._total_duration) * total_width
+
+    def _x_to_global(self, x, total_width):
+        """Map pixel x to global time."""
+        if total_width <= 0 or self._total_duration <= 0:
+            return 0.0
+        return (x / total_width) * self._total_duration
+
+    def _segment_at_x(self, x, total_width):
+        """Return the segment index at pixel x, or -1."""
+        for seg in self._manifest:
+            sx, sw = self._segment_rect(seg, total_width)
+            if sx <= x <= sx + sw:
+                return seg["index"]
+        return -1
+
+    # -- Mouse handlers --
+
+    def _on_pressed(self, gesture, n_press, x, y):
+        width = self.get_width()
+        idx = self._segment_at_x(x, width)
+        if idx >= 0:
+            if idx != self._active_index:
+                # New segment — activate it (proxy will be requested)
+                self._active_index = idx
+                self.emit("segment-activated", idx)
+            else:
+                # Already active — seek to click position
+                gt = self._x_to_global(x, width)
+                self.emit("scrub-position", gt)
+            self.queue_draw()
+
+    def _on_released(self, gesture, n_press, x, y):
+        self._scrubbing = False
+
+    def _on_motion(self, controller, x, y):
+        width = self.get_width()
+        old_hover = self._hover_index
+        self._hover_index = self._segment_at_x(x, width)
+        if self._hover_index != old_hover:
+            self.queue_draw()
+
+        # If scrubbing (dragging within active block), emit position
+        if self._scrubbing and self._active_index >= 0:
+            gt = self._x_to_global(x, width)
+            self.emit("scrub-position", gt)
+
+    def _on_leave(self, controller):
+        if self._hover_index != -1:
+            self._hover_index = -1
+            self.queue_draw()
+
+    def _on_drag_begin(self, gesture, start_x, start_y):
+        width = self.get_width()
+        idx = self._segment_at_x(start_x, width)
+        if idx >= 0 and idx == self._active_index:
+            self._scrubbing = True
+
+    def _on_drag_update(self, gesture, offset_x, offset_y):
+        if self._scrubbing:
+            ok, start_x, start_y = gesture.get_start_point()
+            if ok:
+                x = start_x + offset_x
+                width = self.get_width()
+                gt = self._x_to_global(x, width)
+                gt = max(0, min(gt, self._total_duration))
+                self.emit("scrub-position", gt)
+
+    def _on_drag_end(self, gesture, offset_x, offset_y):
+        self._scrubbing = False

cht/ui/timeline.py

@@ -144,54 +144,54 @@ class Timeline(GObject.Object):
 
 
 class TimelineControls(Gtk.Box):
-    """Slider + LIVE toggle. Scrub mode is always paused (seek-only, like a video editor).
+    """Scrub bar + time labels + LIVE toggle.
 
-    LIVE button is a toggle — active style when live=True.
+    The scrub bar shows segment blocks; labels and LIVE button sit below.
-    Slider is insensitive in live mode.
     """
 
     def __init__(self, timeline, **kwargs):
-        super().__init__(orientation=Gtk.Orientation.HORIZONTAL, spacing=4, **kwargs)
+        super().__init__(orientation=Gtk.Orientation.VERTICAL, spacing=2, **kwargs)
         self._timeline = timeline
-        self._dragging = False
 
         self.set_margin_start(4)
         self.set_margin_end(4)
         self.set_margin_top(2)
         self.set_margin_bottom(4)
 
-        # Current time label
+        # Scrub bar (segment blocks)
+        from cht.ui.scrub_bar import ScrubBar
+        self._scrub_bar = ScrubBar()
+        self.append(self._scrub_bar)
+
+        # Bottom row: time label + duration + LIVE button
+        bottom = Gtk.Box(orientation=Gtk.Orientation.HORIZONTAL, spacing=4)
+
         self._time_label = Gtk.Label(label="00:00")
         self._time_label.set_width_chars(6)
-        self.append(self._time_label)
+        bottom.append(self._time_label)
 
-        # Slider — disabled in live mode, scrub-seeks on release
+        spacer = Gtk.Box()
-        self._slider = Gtk.Scale(orientation=Gtk.Orientation.HORIZONTAL)
+        spacer.set_hexpand(True)
-        self._slider.set_hexpand(True)
+        bottom.append(spacer)
-        self._slider.set_range(0, 1)
-        self._slider.set_draw_value(False)
-        self._slider.connect("value-changed", self._on_slider_value_changed)
 
-        press_ctrl = Gtk.GestureClick()
-        press_ctrl.connect("pressed", self._on_slider_pressed)
-        press_ctrl.connect("released", self._on_slider_released)
-        press_ctrl.set_propagation_phase(Gtk.PropagationPhase.CAPTURE)
-        self._slider.add_controller(press_ctrl)
-        self.append(self._slider)
-
-        # Duration label
         self._duration_label = Gtk.Label(label="00:00 / 00:00")
         self._duration_label.set_width_chars(14)
-        self.append(self._duration_label)
+        bottom.append(self._duration_label)
 
-        # LIVE toggle button
         self._live_btn = Gtk.Button(label="LIVE")
         self._live_btn.connect("clicked", self._on_live_clicked)
-        self.append(self._live_btn)
+        bottom.append(self._live_btn)
+
+        self.append(bottom)
 
         timeline.connect("changed", self._on_changed)
         GLib.timeout_add(1000, self._tick_total)
 
+    @property
+    def scrub_bar(self):
+        """Access the ScrubBar widget for signal connections."""
+        return self._scrub_bar
+
     def set_live_toggle_callback(self, cb):
         """Override the LIVE button handler."""
         self._live_toggle_cb = cb
@@ -202,32 +202,16 @@ class TimelineControls(Gtk.Box):
         else:
             self._timeline.toggle_live()
 
-    def _on_slider_value_changed(self, slider):
-        if self._dragging:
-            self._time_label.set_text(self._fmt_time(slider.get_value()))
-
-    def _on_slider_pressed(self, gesture, n_press, x, y):
-        self._dragging = True
-
-    def _on_slider_released(self, gesture, n_press, x, y):
-        if self._dragging:
-            self._dragging = False
-            self._timeline.seek(self._slider.get_value())
-
     def _on_changed(self, timeline):
         s = timeline.state
 
-        self._slider.set_sensitive(not s.live)
-
         if s.live:
             self._live_btn.add_css_class("suggested-action")
         else:
             self._live_btn.remove_css_class("suggested-action")
 
-        if not self._dragging:
+        self._scrub_bar.set_cursor(s.cursor)
-            self._slider.set_range(0, max(s.duration, 0.1))
+        self._scrub_bar.set_scene_markers(s.scene_markers)
-            self._slider.set_value(s.cursor)
-
         self._time_label.set_text(self._fmt_time(s.cursor))
         self._update_duration_label()
 

cht/ui/transcript_panel.py

@@ -23,6 +23,7 @@ class TranscriptPanel(Gtk.Box):
         "selection-changed": (GObject.SignalFlags.RUN_FIRST, None, ()),
         "min-chunk-changed": (GObject.SignalFlags.RUN_FIRST, None, (float,)),
         "lines-per-group-changed": (GObject.SignalFlags.RUN_FIRST, None, (int,)),
+        "seek-requested": (GObject.SignalFlags.RUN_FIRST, None, (float,)),
     }
 
     def __init__(self, **kwargs):
@@ -30,6 +31,7 @@ class TranscriptPanel(Gtk.Box):
 
         self._rows: dict[str, Gtk.ListBoxRow] = {}
         self._texts: dict[str, str] = {}
+        self._timestamps: dict[str, float] = {}
         self._order: list[str] = []
         self._selected: list[str] = []
 
@@ -176,6 +178,7 @@ class TranscriptPanel(Gtk.Box):
         self._selected.clear()
         self._rows.clear()
         self._texts.clear()
+        self._timestamps.clear()
         self._order.clear()
         while child := self._list.get_first_child():
             self._list.remove(child)
@@ -186,6 +189,10 @@ class TranscriptPanel(Gtk.Box):
         seg_id = getattr(row, "_seg_id", None)
         if seg_id:
             self.select(seg_id)
+            # Double-activation (Enter key on focused row) → seek
+            ts = self._timestamps.get(seg_id)
+            if ts is not None:
+                self.emit("seek-requested", ts)
 
     def _make_row(self, seg):
         m1, s1 = divmod(int(seg.start), 60)
@@ -208,6 +215,7 @@ class TranscriptPanel(Gtk.Box):
         self._list.append(row)
         self._rows[seg.id] = row
         self._texts[seg.id] = seg.text
+        self._timestamps[seg.id] = seg.start
         self._order.append(seg.id)
 
     def _clear_visual(self):

cht/window.py

@@ -1,6 +1,7 @@
 """Main application window — wires Timeline to all components."""
 
 import logging
+from pathlib import Path
 
 import gi
 gi.require_version("Gtk", "4.0")
@@ -24,7 +25,8 @@ from cht.transcriber.engine import TranscriberEngine
 from cht.stream.manager import StreamManager, list_sessions
 from cht.stream.lifecycle import StreamLifecycle
 from cht.ui.session_dialog import SessionDialog
-from cht.session import load_frame_index
+from cht.session import load_frame_index, load_segment_manifest, rebuild_manifest, global_time_to_segment
+from cht.scrub.manager import ProxyManager
 from cht.agent.runner import AgentRunner, check_claude_cli
 
 log = logging.getLogger(__name__)
@@ -36,6 +38,10 @@ class ChtWindow(Adw.ApplicationWindow):
         self.set_title(APP_NAME)
         self.set_default_size(1400, 900)
         self._known_frames = set()
+        self._proxy_mgr = None
+        self._manifest = []
+        self._pending_scrub_global = 0.0
+        self._scrub_pending = False  # throttle flag for scrub updates
 
         # Core components
         self._timeline = Timeline()
@@ -103,6 +109,9 @@ class ChtWindow(Adw.ApplicationWindow):
         self._transcript_panel.connect("selection-changed", self._on_transcript_selection_changed)
         self._transcript_panel.connect("min-chunk-changed", self._on_min_chunk_changed)
         self._transcript_panel.connect("lines-per-group-changed", self._on_lines_per_group_changed)
+        # Seek-to-timestamp from panels (double-click)
+        self._frames_panel.connect("seek-requested", self._on_panel_seek)
+        self._transcript_panel.connect("seek-requested", self._on_panel_seek)
 
         log.info("Window initialized")
         GLib.idle_add(self._check_agent_auth)
@@ -129,7 +138,11 @@ class ChtWindow(Adw.ApplicationWindow):
             self._start_stream(session_id=session_id)
 
     def _on_capture_clicked(self):
-        if self._lifecycle.stream_mgr:
+        if not self._timeline.state.live and self._manifest:
+            # Scrub mode: capture full-res from current scrub position
+            self._capture_at_scrub_position()
+        elif self._lifecycle.stream_mgr:
+            # Live mode: capture from current recording position
             self._lifecycle.stream_mgr.capture_now(
                 on_new_frames=self._lifecycle._handle_new_scene_frames
             )
@@ -212,6 +225,7 @@ class ChtWindow(Adw.ApplicationWindow):
 
             Thread(target=_compute_waveform, daemon=True, name="waveform_load").start()
 
+        self._update_scrub_bar_manifest()
         self._populate_model_dropdown()
 
     # -- Streaming --
@@ -241,6 +255,132 @@ class ChtWindow(Adw.ApplicationWindow):
         pos = self._monitor.get_live_position()
         self._timeline.toggle_live(live_player_pos=pos)
 
+    # -- Scrub --
+
+    def _update_scrub_bar_manifest(self):
+        """Refresh the scrub bar with the current session's segment manifest."""
+        mgr = self._lifecycle.stream_mgr
+        if not mgr:
+            return
+        self._manifest = load_segment_manifest(mgr.session_dir)
+        if not self._manifest:
+            self._manifest = rebuild_manifest(mgr.session_dir)
+        self._timeline_controls.scrub_bar.set_manifest(self._manifest)
+
+    def _on_segment_activated(self, scrub_bar, segment_index):
+        """User clicked a segment block — request its proxy."""
+        if not self._manifest or segment_index >= len(self._manifest):
+            return
+        seg = self._manifest[segment_index]
+        seg_path = Path(seg["path"])
+
+        if not self._proxy_mgr:
+            mgr = self._lifecycle.stream_mgr
+            sid = mgr.session_id if mgr else "unknown"
+            self._proxy_mgr = ProxyManager(sid)
+
+        scrub_bar.set_proxy_state(segment_index, "generating")
+        # Store pending seek position (the click position)
+        self._pending_scrub_global = seg["global_offset"]
+
+        def _on_ready(proxy_path):
+            scrub_bar.set_proxy_state(segment_index, "ready")
+            scrub_bar.set_active_segment(segment_index)
+            self._monitor.set_scrub_source(proxy_path, global_offset=seg["global_offset"])
+            # Apply pending seek now that proxy is loaded
+            gt = self._pending_scrub_global
+            local = gt - seg["global_offset"]
+            self._timeline.state.cursor = gt
+            self._timeline.state.live = False
+            self._timeline.state.paused = True
+            self._timeline.emit("changed")
+            self._monitor.scrub_to(max(0.0, local))
+
+        self._proxy_mgr.request(seg_path, on_ready=_on_ready)
+
+    def _on_panel_seek(self, panel, timestamp):
+        """Handle seek request from frames or transcript panel (double-click)."""
+        if not self._manifest:
+            return
+        seg, local_time = global_time_to_segment(self._manifest, timestamp)
+        if not seg:
+            return
+        self._pending_scrub_global = timestamp
+        self._on_segment_activated(self._timeline_controls.scrub_bar, seg["index"])
+
+    def _on_scrub_position(self, scrub_bar, global_time):
+        """User is scrubbing — drive monitor directly, throttled."""
+        global_time = max(0.0, min(global_time, self._timeline.state.duration))
+        self._timeline.state.cursor = global_time
+        self._timeline.state.live = False
+        self._timeline.state.paused = True
+        # Update scrub bar cursor directly (cheap)
+        scrub_bar.set_cursor(global_time)
+        # Throttle monitor seeks to avoid flooding mpv
+        if not self._scrub_pending:
+            self._scrub_pending = True
+            seg, local_time = global_time_to_segment(self._manifest, global_time)
+            if seg:
+                self._monitor.scrub_to(local_time)
+            GLib.timeout_add(16, self._scrub_tick)  # ~60fps cap
+
+    def _scrub_tick(self):
+        """Release throttle so next scrub motion can update monitor."""
+        self._scrub_pending = False
+        # Apply latest cursor position to monitor
+        seg, local_time = global_time_to_segment(
+            self._manifest, self._timeline.state.cursor
+        )
+        if seg:
+            self._monitor.scrub_to(local_time)
+        return False
+
+    def _capture_at_scrub_position(self):
+        """Capture a full-res frame at the current scrub position."""
+        mgr = self._lifecycle.stream_mgr
+        if not mgr or not self._manifest:
+            return
+        seg, local_time = global_time_to_segment(
+            self._manifest, self._timeline.state.cursor
+        )
+        if not seg:
+            return
+        seg_path = Path(seg["path"])
+        global_time = self._timeline.state.cursor
+
+        from cht.stream import ffmpeg as ff
+        import json
+
+        def _capture():
+            index_path = mgr.frames_dir / "index.json"
+            index = json.loads(index_path.read_text()) if index_path.exists() else []
+            frame_num = len(index) + 1
+            frame_id = f"F{frame_num:04d}"
+            frame_path = mgr.frames_dir / f"{frame_id}.jpg"
+
+            try:
+                ff.extract_frame_at(seg_path, frame_path, local_time)
+            except Exception as e:
+                log.error("Scrub capture failed: %s", e)
+                return
+            if not frame_path.exists():
+                return
+
+            entry = {
+                "id": frame_id,
+                "timestamp": global_time,
+                "path": str(frame_path),
+                "sent_to_agent": False,
+            }
+            index.append(entry)
+            index_path.write_text(json.dumps(index, indent=2))
+            log.info("Scrub capture: %s at %.1fs (local %.1fs in %s)",
+                     frame_id, global_time, local_time, seg_path.name)
+            # Reload frames to show the new capture
+            GLib.idle_add(self._load_existing_frames)
+
+        Thread(target=_capture, daemon=True, name="scrub_capture").start()
+
     def _stop_stream(self, reload_session=False):
         log.info("Stopping stream...")
         mgr = self._lifecycle.stream_mgr
@@ -248,7 +388,13 @@ class ChtWindow(Adw.ApplicationWindow):
 
         self._lifecycle.stop()
 
+        if self._proxy_mgr:
+            self._proxy_mgr.cancel()
+            self._proxy_mgr = None
+        self._manifest = []
+
         self._timeline.reset()
+        self._timeline_controls.scrub_bar.set_manifest([])
         self._monitor.reset()
         self._waveform_engine.reset()
         self._waveform_widget.set_peaks(None, 0.05)
@@ -299,9 +445,11 @@ class ChtWindow(Adw.ApplicationWindow):
         top_paned.set_position(650)
         right_box.append(top_paned)
 
-        # Timeline slider
+        # Timeline controls + scrub bar
         self._timeline_controls = TimelineControls(self._timeline)
         self._timeline_controls.set_live_toggle_callback(self._on_live_toggle)
+        self._timeline_controls.scrub_bar.connect("segment-activated", self._on_segment_activated)
+        self._timeline_controls.scrub_bar.connect("scrub-position", self._on_scrub_position)
         right_box.append(self._timeline_controls)
 
         # Frames