Initial CutScript release - Open-source AI-powered text-based video editor

CutScript is a local-first, Descript-like video editor where you edit video by editing text.
Delete a word from the transcript and it's cut from the video.

Features:
- Word-level transcription with WhisperX
- Text-based video editing with undo/redo
- AI filler word removal (Ollama/OpenAI/Claude)
- AI clip creation for shorts
- Waveform timeline with virtualized transcript
- FFmpeg stream-copy (fast) and re-encode (4K) export
- Caption burn-in and sidecar SRT generation
- Studio Sound audio enhancement (DeepFilterNet)
- Keyboard shortcuts (J/K/L, Space, Delete, Ctrl+Z/S/E)
- Encrypted API key storage
- Project save/load (.aive files)

Architecture:
- Electron + React + Tailwind (frontend)
- FastAPI + Python (backend)
- WhisperX for transcription
- FFmpeg for video processing
- Multi-provider AI support

Performance optimizations:
- RAF-throttled time updates
- Zustand selectors for granular subscriptions
- Dual-canvas waveform rendering
- Virtualized transcript with react-virtuoso

Built on top of DataAnts-AI/VideoTranscriber, completely rewritten as a desktop application.

License: MIT

backend/services/caption_generator.py

@@ -0,0 +1,148 @@
+"""
+Generate caption files (SRT, VTT, ASS) from word-level timestamps.
+"""
+
+import logging
+from pathlib import Path
+from typing import List, Optional
+
+logger = logging.getLogger(__name__)
+
+
+def _format_srt_time(seconds: float) -> str:
+    h = int(seconds // 3600)
+    m = int((seconds % 3600) // 60)
+    s = int(seconds % 60)
+    ms = int((seconds % 1) * 1000)
+    return f"{h:02d}:{m:02d}:{s:02d},{ms:03d}"
+
+
+def _format_vtt_time(seconds: float) -> str:
+    h = int(seconds // 3600)
+    m = int((seconds % 3600) // 60)
+    s = int(seconds % 60)
+    ms = int((seconds % 1) * 1000)
+    return f"{h:02d}:{m:02d}:{s:02d}.{ms:03d}"
+
+
+def _format_ass_time(seconds: float) -> str:
+    h = int(seconds // 3600)
+    m = int((seconds % 3600) // 60)
+    s = int(seconds % 60)
+    cs = int((seconds % 1) * 100)
+    return f"{h}:{m:02d}:{s:02d}.{cs:02d}"
+
+
+def generate_srt(
+    words: List[dict],
+    deleted_indices: Optional[set] = None,
+    words_per_line: int = 8,
+) -> str:
+    """Generate SRT caption content from word-level timestamps."""
+    deleted_indices = deleted_indices or set()
+    active_words = [(i, w) for i, w in enumerate(words) if i not in deleted_indices]
+
+    lines = []
+    counter = 1
+    for chunk_start in range(0, len(active_words), words_per_line):
+        chunk = active_words[chunk_start:chunk_start + words_per_line]
+        if not chunk:
+            continue
+
+        start_time = chunk[0][1]["start"]
+        end_time = chunk[-1][1]["end"]
+        text = " ".join(w["word"] for _, w in chunk)
+
+        lines.append(str(counter))
+        lines.append(f"{_format_srt_time(start_time)} --> {_format_srt_time(end_time)}")
+        lines.append(text)
+        lines.append("")
+        counter += 1
+
+    return "\n".join(lines)
+
+
+def generate_vtt(
+    words: List[dict],
+    deleted_indices: Optional[set] = None,
+    words_per_line: int = 8,
+) -> str:
+    """Generate WebVTT caption content."""
+    deleted_indices = deleted_indices or set()
+    active_words = [(i, w) for i, w in enumerate(words) if i not in deleted_indices]
+
+    lines = ["WEBVTT", ""]
+    for chunk_start in range(0, len(active_words), words_per_line):
+        chunk = active_words[chunk_start:chunk_start + words_per_line]
+        if not chunk:
+            continue
+
+        start_time = chunk[0][1]["start"]
+        end_time = chunk[-1][1]["end"]
+        text = " ".join(w["word"] for _, w in chunk)
+
+        lines.append(f"{_format_vtt_time(start_time)} --> {_format_vtt_time(end_time)}")
+        lines.append(text)
+        lines.append("")
+
+    return "\n".join(lines)
+
+
+def generate_ass(
+    words: List[dict],
+    deleted_indices: Optional[set] = None,
+    words_per_line: int = 8,
+    style: Optional[dict] = None,
+) -> str:
+    """Generate ASS subtitle content with styling."""
+    deleted_indices = deleted_indices or set()
+    active_words = [(i, w) for i, w in enumerate(words) if i not in deleted_indices]
+
+    s = style or {}
+    font = s.get("fontName", "Arial")
+    size = s.get("fontSize", 48)
+    color = s.get("fontColor", "&H00FFFFFF")
+    bold = "-1" if s.get("bold", True) else "0"
+    alignment = 2
+
+    header = f"""[Script Info]
+Title: AI Video Editor Captions
+ScriptType: v4.00+
+PlayResX: 1920
+PlayResY: 1080
+
+[V4+ Styles]
+Format: Name, Fontname, Fontsize, PrimaryColour, SecondaryColour, OutlineColour, BackColour, Bold, Italic, Underline, StrikeOut, ScaleX, ScaleY, Spacing, Angle, BorderStyle, Outline, Shadow, Alignment, MarginL, MarginR, MarginV, Encoding
+Style: Default,{font},{size},{color},&H000000FF,&H00000000,&H80000000,{bold},0,0,0,100,100,0,0,1,2,1,{alignment},20,20,40,1
+
+[Events]
+Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text
+"""
+
+    events = []
+    for chunk_start in range(0, len(active_words), words_per_line):
+        chunk = active_words[chunk_start:chunk_start + words_per_line]
+        if not chunk:
+            continue
+
+        start_time = chunk[0][1]["start"]
+        end_time = chunk[-1][1]["end"]
+        text = " ".join(w["word"] for _, w in chunk)
+
+        events.append(
+            f"Dialogue: 0,{_format_ass_time(start_time)},{_format_ass_time(end_time)},Default,,0,0,0,,{text}"
+        )
+
+    return header + "\n".join(events) + "\n"
+
+
+def save_captions(
+    content: str,
+    output_path: str,
+) -> str:
+    """Write caption content to a file."""
+    output_path = Path(output_path)
+    output_path.parent.mkdir(parents=True, exist_ok=True)
+    output_path.write_text(content, encoding="utf-8")
+    logger.info(f"Saved captions to {output_path}")
+    return str(output_path)