# Audio source editor workflows

Phases 69–79 use the existing bounded mono WAV reader. Stereo input is downmixed;
these are offline control-thread tools, not stereo restoration or time stretching.
The project format remains 16. No new dependencies are required.

## Phase 69 — Source inspection

Select an audio clip and use View / Sample editor or double-click it. The modal
editor loads an independent snapshot of the complete source, up to 4,194,304 frames
(about 87 seconds at 48 kHz). Drag or enter half-open native frame bounds; zoom
1..64 and View start control the visible region. Statistics show raw mono min/max,
RMS and mean/DC before clip gain, fades or mixer processing. Display clamps to
±1; sample statistics retain finite over-range values. Editing project MIDI still
opens the piano roll. This editor does not audition or stream long files.

## Phase 70

Trim clip to selection applies source-frame endpoints within the current audible clip. Start rounds up and end rounds down to musical ticks; empty sub-tick ranges reject. Leading removal moves the timeline start by the same amount, preserving alignment. Source content, reference and clip gain/fade settings remain intact; project Undo restores the prior trim.

## Phase 71

Export selected frames writes a new mono float32 WAV of the half-open selection at native rate. Save full copy and relink writes the complete source and relinks only the selected clip after successful preparation. The original source is never overwritten. Full-copy adoption requires matching source frame count/rate. Project undo restores the reference but retains the new file, which may be referenced by redo/history or other projects. Failed adoption removes its owned new file. Export/copy runs synchronously outside audio callbacks.

## Phase 72

Reverse selection changes only the chosen source frames in a new local snapshot. Undo / redo toggles the most recent processing step; selection and view are unchanged. Processing does not affect playback until Save full copy and relink. Close discards unsaved local processing. Sources are bounded to 16 MiB of float samples; preparing a new edit can temporarily retain three snapshots (48 MiB), then two (32 MiB).

## Phase 73

Invert polarity negates selected float samples; it is not time reversal. Over-range finite samples remain over-range; no implicit limiting is performed. Outside-selection frames are bit-preserved in the copied snapshot.

## Phase 74

Remove DC offset subtracts the mean of the selected range from only that range. This is a constant offset correction, not a high-pass filter. Selection boundaries may acquire discontinuities; use fades or zero-crossing tools where appropriate. Finite over-range results are retained; float overflow rejects the edit.

## Phase 75

Sample fades offers four offline curves: linear in/out and equal-power in/out (sinusoidal amplitude). The entire selection is the fade duration; both endpoints are included in the curve. Fewer than two frames reject. These curves change copied sample data and stack with existing playback clip fades after adoption; they do not form a linked clip crossfade.

## Phase 76

Gain / normalize processes only selected samples. Mode 0 accepts linear gain 0..16; mode 1 accepts a linear peak target above 0 and at most 1, rejecting silent selections or required gain above 16. Finite values above unity are not clipped; float overflow rejects atomically. This changes sample data in the local snapshot, unlike the existing clip-gain normalization command; it provides neither true-peak nor LUFS processing.

## Phase 77

Select audible bounds finds the first and last sample strictly above the chosen dBFS threshold and pads within the existing selection. It only changes selection; use Trim clip to selection to apply a nondestructive timeline trim, or export the selection. Entirely silent/below-threshold ranges leave selection unchanged. This is boundary detection, not automatic removal of internal gaps or a noise gate.

## Phase 78

Snap to zero crossings searches each selected boundary within a source-frame radius up to 65,536. It uses the mono source, chooses earlier positions on equal distance and changes both endpoints only if both searches yield a nonempty range. Source edges qualify only when their adjacent sample is zero. This can reduce boundary discontinuities but does not guarantee click-free output; musical-tick trimming/slicing can move a boundary away from the exact crossing.