Files
video-ai-analysis/video_ai_analysis_poc/ffmpeg_sampler.py
2026-06-17 11:33:54 +08:00

244 lines
7.4 KiB
Python

from __future__ import annotations
import math
import subprocess
from pathlib import Path
from typing import Any
from .frames import build_frame_records
from .manifest import read_jsonl, write_manifest
from .timeline import DEFAULT_TIMEZONE, timeline_start_epoch
NVDEC_CODECS = {"h264", "hevc"}
def build_sample_command(
video_path: str | Path,
output_dir: str | Path,
video_id: str,
ffmpeg_config: dict[str, Any],
*,
codec_name: str | None,
max_frames: int | None = None,
max_duration_seconds: float | None = None,
) -> list[str]:
frame_dir = Path(output_dir).expanduser() / "frames" / video_id
frame_pattern = frame_dir / "%06d.jpg"
command = ["ffmpeg", "-hide_banner", "-y"]
codec = (codec_name or "").lower()
prefer_nvdec = bool(ffmpeg_config.get("prefer_nvdec", True))
allow_cpu_fallback = bool(ffmpeg_config.get("allow_cpu_fallback", False))
decoders = ffmpeg_config.get("codec_decoders", {})
decoder = decoders.get(codec) if isinstance(decoders, dict) else None
if prefer_nvdec and codec in NVDEC_CODECS and decoder:
command.extend(
[
"-hwaccel",
str(ffmpeg_config.get("hwaccel", "cuda")),
"-c:v",
str(decoder),
]
)
elif not allow_cpu_fallback:
raise ValueError(
f"NVDEC decoder is required for codec {codec_name!r}; CPU fallback is disabled"
)
frame_fps = ffmpeg_config.get("frame_fps", 1)
frame_width = ffmpeg_config.get("frame_width", 640)
jpeg_quality = ffmpeg_config.get("jpeg_quality", 4)
command.extend(
[
"-i",
str(Path(video_path).expanduser()),
]
)
if max_duration_seconds is not None and max_duration_seconds > 0:
command.extend(["-t", f"{max_duration_seconds:g}"])
command.extend(
[
"-vf",
f"fps={frame_fps},scale={frame_width}:-2",
"-q:v",
str(jpeg_quality),
]
)
if max_frames is not None and max_frames > 0:
command.extend(["-frames:v", str(max_frames)])
command.append(str(frame_pattern))
return command
def sample_video_frames(
video_record: dict[str, Any],
output_dir: str | Path,
ffmpeg_config: dict[str, Any],
*,
manifest_path: str | Path | None = None,
) -> list[dict[str, Any]]:
video_id = str(video_record["video_id"])
output_root = Path(output_dir).expanduser().resolve(strict=False)
frame_dir = output_root / "frames" / video_id
frame_dir.mkdir(parents=True, exist_ok=True)
try:
max_frames = _max_output_frames(video_record, ffmpeg_config)
timezone_name = str(ffmpeg_config.get("timezone", DEFAULT_TIMEZONE))
start_epoch = timeline_start_epoch(video_record)
command = build_sample_command(
video_record.get("path") or video_record.get("source_path"),
output_root,
video_id,
ffmpeg_config,
codec_name=video_record.get("codec_name"),
max_frames=max_frames,
max_duration_seconds=_record_duration_seconds(video_record),
)
completed = subprocess.run(
command,
capture_output=True,
text=True,
check=True,
timeout=int(ffmpeg_config.get("timeout_seconds_per_video", 3600)),
)
records = build_frame_records(
video_id,
output_root,
frame_dir.glob("*.jpg"),
frame_fps=float(ffmpeg_config.get("frame_fps", 1)),
timeline_start_epoch=start_epoch,
timezone_name=timezone_name,
)
_attach_success_evidence(
records,
command,
stderr=completed.stderr,
)
except subprocess.CalledProcessError as exc:
records = build_frame_records(
video_id,
output_root,
frame_dir.glob("*.jpg"),
frame_fps=float(ffmpeg_config.get("frame_fps", 1)),
timeline_start_epoch=start_epoch,
timezone_name=timezone_name,
)
if records and (max_frames is None or len(records) >= max_frames):
_attach_success_evidence(
records,
command,
stderr=exc.stderr,
)
else:
records = [_failure_record(video_id, exc)]
except (subprocess.TimeoutExpired, ValueError) as exc:
records = [_failure_record(video_id, exc)]
if manifest_path is not None:
_replace_video_records(Path(manifest_path), video_id, records)
return records
def _replace_video_records(
manifest_path: Path,
video_id: str,
new_records: list[dict[str, Any]],
) -> None:
existing = [
record
for record in read_jsonl(manifest_path)
if str(record.get("video_id")) != video_id
]
write_manifest(manifest_path, [*existing, *new_records])
def _failure_record(video_id: str, exc: BaseException) -> dict[str, Any]:
return {
"video_id": video_id,
"frame_id": None,
"frame_path": None,
"offset_seconds": None,
"timecode": None,
"pts_time": None,
"status": "sample_failed",
"retry_count": 0,
"last_error": _error_text(exc),
}
def _attach_success_evidence(
records: list[dict[str, Any]],
command: list[str],
*,
stderr: str | None,
) -> None:
evidence = {
"ffmpeg_command": command,
"decoder": _command_value_after(command, "-c:v"),
"hwaccel": _command_value_after(command, "-hwaccel"),
"stderr_summary": _stderr_summary(stderr),
}
for record in records:
record.update(evidence)
def _command_value_after(command: list[str], flag: str) -> str | None:
try:
index = command.index(flag)
except ValueError:
return None
if index + 1 >= len(command):
return None
return command[index + 1]
def _stderr_summary(stderr: str | None, *, limit: int = 2000) -> str:
if not stderr:
return ""
text = stderr.strip()
if len(text) <= limit:
return text
return text[:limit]
def _error_text(exc: BaseException) -> str:
if isinstance(exc, subprocess.CalledProcessError):
return str(exc.stderr or exc.stdout or exc)
if isinstance(exc, subprocess.TimeoutExpired):
return f"ffmpeg timed out after {exc.timeout}s"
return str(exc)
def _max_output_frames(
video_record: dict[str, Any],
ffmpeg_config: dict[str, Any],
) -> int | None:
frame_fps = _optional_float(ffmpeg_config.get("frame_fps", 1))
if frame_fps is None or frame_fps <= 0:
return None
duration_seconds = _record_duration_seconds(video_record)
if duration_seconds is None or duration_seconds <= 0:
return None
return max(1, math.ceil(duration_seconds * frame_fps) + 1)
def _record_duration_seconds(video_record: dict[str, Any]) -> float | None:
for begin_key, end_key in (
("actual_begin", "actual_end"),
("requested_begin", "requested_end"),
):
begin = _optional_float(video_record.get(begin_key))
end = _optional_float(video_record.get(end_key))
if begin is not None and end is not None and end > begin:
return end - begin
return _optional_float(video_record.get("duration_seconds"))
def _optional_float(value: Any) -> float | None:
if value is None or value == "":
return None
return float(value)