84 lines
2.8 KiB
Python
84 lines
2.8 KiB
Python
"""Proxy generation — low-res MJPEG for frame-accurate scrubbing.
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Each completed recording segment gets a lightweight proxy video where every
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frame is a keyframe (MJPEG). mpv can seek frame-accurately in these files
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with hr-seek=yes, giving DaVinci Resolve-style scrubbing speed.
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Proxies are ephemeral — stored in /tmp, regenerated on demand.
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"""
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import logging
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import shutil
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from pathlib import Path
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import ffmpeg as ffmpeg_lib
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log = logging.getLogger(__name__)
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from cht.config import DATA_DIR
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PROXY_DIR = DATA_DIR / "proxies"
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PROXY_HEIGHT = 360 # pixels — low enough for speed, high enough to see content
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def proxy_path_for(segment_path: Path, session_id: str | None = None) -> Path:
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"""Return the proxy path for a given segment."""
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subdir = session_id or "default"
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return PROXY_DIR / subdir / f"{segment_path.stem}_proxy.avi"
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def generate_proxy(segment_path: Path, output_path: Path,
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height: int = PROXY_HEIGHT) -> Path:
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"""Transcode a segment to MJPEG proxy at reduced resolution.
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Every frame is a keyframe — enables O(1) seeking.
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Returns output_path on success.
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"""
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output_path.parent.mkdir(parents=True, exist_ok=True)
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stream = ffmpeg_lib.input(str(segment_path), hwaccel="cuda")
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output = (
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ffmpeg_lib.output(
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stream, str(output_path),
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vcodec="mjpeg",
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vf=f"scale=-2:{height}",
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# MJPEG: every frame is a keyframe by nature
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**{"q:v": "5"}, # quality 2-31, lower = better
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an=None, # strip audio
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)
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.overwrite_output()
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.global_args("-hide_banner", "-loglevel", "warning")
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)
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log.info("Generating proxy: %s → %s", segment_path.name, output_path)
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try:
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output.run(capture_stdout=True, capture_stderr=True)
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except ffmpeg_lib.Error as e:
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stderr = (e.stderr or b"").decode("utf-8", errors="replace")
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log.error("Proxy generation failed for %s: %s", segment_path.name, stderr.strip())
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raise
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log.info("Proxy ready: %s (%.1f MB)",
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output_path.name, output_path.stat().st_size / 1_000_000)
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return output_path
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def ensure_proxy(segment_path: Path, session_id: str | None = None,
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height: int = PROXY_HEIGHT) -> Path:
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"""Return proxy path, generating it if missing."""
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out = proxy_path_for(segment_path, session_id)
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if out.exists():
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return out
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return generate_proxy(segment_path, out, height)
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def cleanup_proxies(session_id: str | None = None) -> None:
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"""Delete proxy files for a session, or all proxies if session_id is None."""
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if session_id:
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target = PROXY_DIR / session_id
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else:
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target = PROXY_DIR
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if target.exists():
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shutil.rmtree(target)
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log.info("Cleaned up proxies: %s", target)
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