Initial commit: Børnetime app scaffold

FastAPI + Celery + Svelte app for English→Danish video translation with voice cloning. Includes diarization, STT, translation, TTS, and audio mixing pipeline.
2026-07-10 22:42:23 +02:00
commit 6851b26923
43 changed files with 3390 additions and 0 deletions
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+import subprocess
+import os
+import numpy as np
+import soundfile as sf
+from typing import Optional
+from ..config import settings
+
+
+def mix_audio(
+    video_path: str,
+    segments: list[dict],
+    output_path: str,
+):
+    temp_dir = settings.temp_dir
+
+    original_audio_path = os.path.join(temp_dir, "original_audio.wav")
+    _extract_audio(video_path, original_audio_path)
+
+    original_audio, orig_sr = sf.read(original_audio_path)
+    if len(original_audio.shape) > 1:
+        original_audio = original_audio.mean(axis=1)
+
+    target_sr = 24000
+    if orig_sr != target_sr:
+        import librosa
+
+        original_audio = librosa.resample(
+            original_audio, orig_sr=orig_sr, target_sr=target_sr
+        )
+
+    total_samples = len(original_audio)
+    danish_track = np.zeros(total_samples, dtype=np.float32)
+
+    for seg in segments:
+        danish_audio = seg.get("danish_audio")
+        if danish_audio is None or len(danish_audio) == 0:
+            continue
+
+        start_sample = int(seg["start_time"] * target_sr)
+        end_sample = min(start_sample + len(danish_audio), total_samples)
+        actual_len = end_sample - start_sample
+        danish_track[start_sample:end_sample] += danish_audio[:actual_len]
+
+    volume_envelope = np.ones(total_samples, dtype=np.float32)
+    for seg in segments:
+        start_sample = int(seg["start_time"] * target_sr)
+        end_sample = int(seg["end_time"] * target_sr)
+        volume_envelope[start_sample:end_sample] = 0.23
+
+    orig_adjusted = original_audio * volume_envelope
+
+    mixed = orig_adjusted + danish_track
+    peak = np.max(np.abs(mixed))
+    if peak > 0.99:
+        mixed = mixed / peak * 0.95
+
+    mixed_path = os.path.join(temp_dir, "mixed_audio.wav")
+    sf.write(mixed_path, mixed, target_sr)
+
+    _replace_audio(video_path, mixed_path, output_path)
+
+    for f in [original_audio_path, mixed_path]:
+        if os.path.exists(f):
+            os.remove(f)
+
+
+def _extract_audio(video_path: str, output_path: str):
+    cmd = [
+        "ffmpeg",
+        "-y",
+        "-i",
+        video_path,
+        "-vn",
+        "-acodec",
+        "pcm_s16le",
+        "-ar",
+        "24000",
+        "-ac",
+        "1",
+        output_path,
+    ]
+    result = subprocess.run(cmd, capture_output=True, text=True)
+    if result.returncode != 0:
+        raise RuntimeError(f"Audio extraction failed: {result.stderr}")
+
+
+def _replace_audio(video_path: str, audio_path: str, output_path: str):
+    cmd = [
+        "ffmpeg",
+        "-y",
+        "-i",
+        video_path,
+        "-i",
+        audio_path,
+        "-c:v",
+        "copy",
+        "-c:a",
+        "aac",
+        "-b:a",
+        "192k",
+        "-map",
+        "0:v:0",
+        "-map",
+        "1:a:0",
+        "-shortest",
+        output_path,
+    ]
+    result = subprocess.run(cmd, capture_output=True, text=True)
+    if result.returncode != 0:
+        raise RuntimeError(f"Audio replacement failed: {result.stderr}")