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85b485a | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 | """Video helpers: audio extraction, duration probing, single-frame grabbing.
All heavy lifting is delegated to ffmpeg/ffprobe (already on PATH). ffmpeg's
``-ss`` before ``-i`` is both fast and frame-accurate in modern builds, which we
rely on for precise frame extraction at a given timestamp.
"""
from __future__ import annotations
import subprocess
from pathlib import Path
from . import config
class FFmpegError(RuntimeError):
"""Raised when an ffmpeg/ffprobe subprocess fails."""
def _run(cmd: list[str]) -> subprocess.CompletedProcess:
proc = subprocess.run(cmd, capture_output=True, text=True)
if proc.returncode != 0:
raise FFmpegError(
f"Command failed ({proc.returncode}): {' '.join(cmd)}\n{proc.stderr.strip()}"
)
return proc
def get_duration(video_path: str | Path) -> float:
"""Return the media duration in seconds (0.0 if it cannot be determined)."""
try:
proc = _run(
[
config.FFPROBE_BIN,
"-v", "error",
"-show_entries", "format=duration",
"-of", "default=noprint_wrappers=1:nokey=1",
str(video_path),
]
)
return float(proc.stdout.strip())
except (FFmpegError, ValueError):
return 0.0
def extract_audio(video_path: str | Path, out_wav: str | Path) -> Path:
"""Extract a 16 kHz mono WAV (the format faster-whisper expects)."""
out_wav = Path(out_wav)
out_wav.parent.mkdir(parents=True, exist_ok=True)
_run(
[
config.FFMPEG_BIN,
"-y",
"-i", str(video_path),
"-vn", # drop video
"-ac", "1", # mono
"-ar", "16000", # 16 kHz
"-f", "wav",
str(out_wav),
]
)
return out_wav
def extract_frame(video_path: str | Path, timestamp: float, out_png: str | Path) -> Path:
"""Save a single frame at ``timestamp`` seconds as a PNG.
``-ss`` is placed before ``-i`` for fast, frame-accurate seeking.
"""
out_png = Path(out_png)
out_png.parent.mkdir(parents=True, exist_ok=True)
_run(
[
config.FFMPEG_BIN,
"-y",
"-ss", f"{max(timestamp, 0.0):.3f}",
"-i", str(video_path),
"-frames:v", "1",
"-q:v", "2",
str(out_png),
]
)
return out_png
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