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Timmy-time-dashboard/src/content/extraction/clipper.py

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Python

"""FFmpeg-based frame-accurate clip extraction from recorded stream segments.
Each highlight dict must have:
source_path : str — path to the source video file
start_time : float — clip start in seconds
end_time : float — clip end in seconds
highlight_id: str — unique identifier (used for output filename)
Clips are written to ``settings.content_clips_dir``.
FFmpeg is treated as an optional runtime dependency — if the binary is not
found, :func:`extract_clip` returns a failure result instead of crashing.
"""
from __future__ import annotations
import asyncio
import logging
import shutil
from dataclasses import dataclass
from pathlib import Path
from config import settings
logger = logging.getLogger(__name__)
@dataclass
class ClipResult:
"""Result of a single clip extraction operation."""
highlight_id: str
success: bool
output_path: str | None = None
error: str | None = None
duration: float = 0.0
def _ffmpeg_available() -> bool:
"""Return True if the ffmpeg binary is on PATH."""
return shutil.which("ffmpeg") is not None
def _build_ffmpeg_cmd(
source: str,
start: float,
end: float,
output: str,
) -> list[str]:
"""Build an ffmpeg command for frame-accurate clip extraction.
Uses ``-ss`` before ``-i`` for fast seek, then re-seeks with ``-ss``
after ``-i`` for frame accuracy. ``-avoid_negative_ts make_zero``
ensures timestamps begin at 0 in the output.
"""
duration = end - start
return [
"ffmpeg",
"-y", # overwrite output
"-ss", str(start),
"-i", source,
"-t", str(duration),
"-avoid_negative_ts", "make_zero",
"-c:v", settings.default_video_codec,
"-c:a", "aac",
"-movflags", "+faststart",
output,
]
async def extract_clip(
highlight: dict,
output_dir: str | None = None,
) -> ClipResult:
"""Extract a single clip from a source video using FFmpeg.
Parameters
----------
highlight:
Dict with keys ``source_path``, ``start_time``, ``end_time``,
and ``highlight_id``.
output_dir:
Directory to write the clip. Defaults to
``settings.content_clips_dir``.
Returns
-------
ClipResult
Always returns a result; never raises.
"""
hid = highlight.get("highlight_id", "unknown")
if not _ffmpeg_available():
logger.warning("ffmpeg not found — clip extraction disabled")
return ClipResult(highlight_id=hid, success=False, error="ffmpeg not found")
source = highlight.get("source_path", "")
if not source or not Path(source).exists():
return ClipResult(
highlight_id=hid,
success=False,
error=f"source_path not found: {source!r}",
)
start = float(highlight.get("start_time", 0))
end = float(highlight.get("end_time", 0))
if end <= start:
return ClipResult(
highlight_id=hid,
success=False,
error=f"invalid time range: start={start} end={end}",
)
dest_dir = Path(output_dir or settings.content_clips_dir)
dest_dir.mkdir(parents=True, exist_ok=True)
output_path = dest_dir / f"{hid}.mp4"
cmd = _build_ffmpeg_cmd(source, start, end, str(output_path))
logger.debug("Running: %s", " ".join(cmd))
try:
proc = await asyncio.create_subprocess_exec(
*cmd,
stdout=asyncio.subprocess.PIPE,
stderr=asyncio.subprocess.PIPE,
)
_, stderr = await asyncio.wait_for(proc.communicate(), timeout=300)
if proc.returncode != 0:
err = stderr.decode(errors="replace")[-500:]
logger.warning("ffmpeg failed for %s: %s", hid, err)
return ClipResult(highlight_id=hid, success=False, error=err)
duration = end - start
return ClipResult(
highlight_id=hid,
success=True,
output_path=str(output_path),
duration=duration,
)
except TimeoutError:
return ClipResult(highlight_id=hid, success=False, error="ffmpeg timed out")
except Exception as exc:
logger.warning("Clip extraction error for %s: %s", hid, exc)
return ClipResult(highlight_id=hid, success=False, error=str(exc))
async def extract_clips(
highlights: list[dict],
output_dir: str | None = None,
) -> list[ClipResult]:
"""Extract multiple clips concurrently.
Parameters
----------
highlights:
List of highlight dicts (see :func:`extract_clip`).
output_dir:
Shared output directory for all clips.
Returns
-------
list[ClipResult]
One result per highlight in the same order.
"""
tasks = [extract_clip(h, output_dir) for h in highlights]
return list(await asyncio.gather(*tasks))