performance updates

docs/DJ_WORKSTATION.md

@@ -7,7 +7,7 @@ The main window has two tabs: **Karaoke** and **DJ Studio**. Playback, MIDI hand
 - Use the DJ browser’s Import Files / Folder button for DJ music. It has its own `DJ/Library.sqlite`, `DJ/Media` and playlists under the app support folder. It starts empty; existing karaoke songs are not migrated. The tested recursive importer is reused with audio-only import, without CDG graphics. MP3, WAV, M4A, MP4/M4V/MOV audio, AIFF/AIF, CAF, FLAC and AAC extensions are accepted; decoding depends on macOS format support. Imports support progress, cancellation and duplicate detection.
 - Select a DJ library row and use Load A/B, use the row’s A/B buttons, or drag a DJ library song onto a deck. Loading is paused, with no brief autoplay. Finder audio files can also be dropped onto either deck’s header, platter area or centre waveform. Back-to-back drops are queued while a copy/import is running; re-dropping existing media still loads the selected deck. Dropping onto a playing deck asks for confirmation before importing or replacing anything; Cancel preserves playback and Replace & Load explicitly overrides protection. Library loads also respect the active-deck protection preference.
 - Cyan identifies A; amber identifies B. Each platter’s angle follows actual source playback time, including tempo changes, pauses and seeks. Drag around a platter to jog two source seconds per revolution. This is seek-based jogging, not vinyl scratching.
-- Waveforms come from decoded audio and reuse existing waveform caches. Drag outside an active loop to seek. Green IN/OUT grips resize the loop; dragging inside its region moves it without changing its length. Shift-drag creates a loop in either waveform. The scrolling viewport freezes during a drag and resumes following playback afterwards.
+- Waveforms come from decoded audio and reuse existing waveform caches. Drag outside an active loop to seek. Green IN/OUT grips resize the loop; dragging inside its region moves it without changing its length. Shift-drag creates a loop in either waveform. Native mouse tracking supports scrubbing in the overview and scrolling spectrum while paused or playing. In the large spectrum, hold the left mouse button and drag left to advance or right to rewind, relative to the initial position without a click jump; the waveform follows the hand. The overview remains an absolute position selector. The scrolling viewport freezes during a drag and resumes following playback afterwards. Waveform scrolling, playheads and platter rotation use the audio clock at up to 60 display frames per second, with interpolated waveform amplitudes.
 - High/mid/low EQ and the bipolar filter are beside each platter. Gain and level knobs have been removed from the on-screen decks. Drag a knob vertically; double-click to reset. Knobs expose adjustable accessibility actions and current values. EQ uses the existing three-band filters; filter is low-pass left, bypass centre, high-pass right.
 - Play/pause, stop-to-start, set/return cue and four set/jump hot cues are per deck. Right-click a hot cue to clear it. Use the cue-time editor to set an exact cue in seconds or capture the current playhead without moving playback. Loop ✎ opens exact start/end fields with millisecond display and Use Playhead buttons; Activate Loop validates and applies the region without pausing playback. Manual IN/OUT loops do not need BPM. Beat loops require an estimated, entered or tapped BPM; choose 1–32 beats. Loop toggles off on a second press and continues correctly at the end of a track. Changing the loop size resizes an active loop immediately, preserving its start and continuing playback; the end is clamped to track duration.
 - Loading estimates BPM conservatively from up to the first 90 seconds of audio, searching 70–180 BPM; silence and steady tones remain unknown. Estimates show BPM~ and can be replaced by entering source BPM (40–240) or tapping at least three beats. Sync buttons start grey and unlit. Clicking A makes B follow A’s effective BPM; clicking B makes A follow B’s effective BPM. Both buttons then show active. Press either again to unlink and restore both original tempos. Sync follows changes to the clicked leader’s tempo; it does not align beat phase or detect a beat grid. Use the jog/nudge buttons to align beats. Tempo adjustment preserves pitch, using AVAudioUnitTimePitch.
@@ -60,7 +60,7 @@ The deck area is now one continuous console following the supplied reference: tr
 
 Settings now use an icon-category toolbar with separate Karaoke and DJ selectors. DJ Settings opens directly in DJ scope; Audio Routing and MIDI open the corresponding DJ categories. Karaoke device routing applies only to the singer deck. DJ General, Sound, Library, Appearance and Advanced preferences are persisted independently in DJ/DJSettings.json. Working options include paused/automatic load, active-deck protection, reset EQ/filter on load, ±8/16/50% tempo range and inversion, equal-power/linear crossfade curves, output headroom, waveform colours/window/grid, rotating marker, inactive-deck dimming, library font/row height and optional hot-cue autoplay. MIDI learning is cancelled when leaving its settings category. Singer Web is available only in Karaoke settings, with its existing server controls preserved.
 
-Waveform beat guides use BPM and source time zero, with stronger marks every four beats; they are not analysed downbeats. Active loops have green regions and IN/OUT boundary markers. DVS, Neural Mix, booth/microphone input, recording, Spotify and cloud sync are not implemented.
+Waveform beat guides use BPM and source time zero, with stronger yellow marks and numbered guides every four beats; they are not analysed downbeats. Active loops have green regions and IN/OUT boundary markers. DVS, Neural Mix, booth/microphone input, recording, Spotify and cloud sync are not implemented.
 
 ## Import integrity