affaan-m/ECC · error · ValueError

reference probe duration must be finite and positive

Error message

reference probe duration must be finite and positive

What it means

_validate_probe requires the probe result's "duration" field to be a finite, non-boolean real number strictly greater than zero. This error is raised when duration is missing (None), not a number, a bool, NaN/inf, or <= 0. Duration anchors all temporal validation (sample_times, scene_changes, style sample times must fall within it), so an invalid duration makes the entire probe payload unusable.

Solutions

  1. Ensure the probe callable always returns a positive finite "duration"; supply a measured or fallback duration for media lacking container metadata.
  2. Only feed video/3d media with real duration metadata into the workflow; check `ffprobe -show_format` reports a duration > 0 before running.
  3. For still images used as references, wrap them in a container or have the custom probe return an explicit nominal duration (e.g. 1.0).
  4. Fix custom probes/tests to include "duration" in the returned dict rather than omitting it.
  5. Handle 'N/A' duration strings explicitly instead of relying on `or 0`, which silently converts them to the rejected 0.0.

Example fix

// before
video = {}  # image: no video stream
duration = float(video.get("duration") or payload.get("format", {}).get("duration") or 0)  # -> 0.0
// after
duration = float(video.get("duration") or payload.get("format", {}).get("duration") or 0)
if not math.isfinite(duration) or duration <= 0:
    raise MediaToolUnavailable(f"source has no measurable duration: {path}")
Defensive patterns

Strategy: validation

Validate before calling

import json, subprocess

def reference_has_positive_duration(path) -> bool:
    out = subprocess.run(
        ["ffprobe", "-v", "error", "-show_format", "-of", "json", str(path)],
        capture_output=True, text=True, check=True,
    ).stdout
    duration = json.loads(out).get("format", {}).get("duration")
    try:
        return duration is not None and float(duration) > 0
    except (TypeError, ValueError):
        return False

# preflight every reference in the contract before run_workflow

Type guard

def has_valid_duration(measured: dict) -> bool:
    import math
    d = measured.get("duration")
    return (
        isinstance(d, (int, float))
        and not isinstance(d, bool)
        and math.isfinite(d)
        and float(d) > 0
    )

Try / catch

try:
    receipt = run_workflow("contract.json", "out/", probe=my_probe)
except ValueError as e:
    if "duration must be finite and positive" in str(e):
        logger.error("reference has no measurable duration; supply a probe with an explicit positive duration")
        receipt = run_workflow("contract.json", "out/", probe=probe_with_fallback_duration)
    else:
        raise

Prevention

When it happens

Trigger: run_workflow() -> _validate_probe(measured) where measured lacks "duration", or measured["duration"] is None/0/negative/nan — e.g. a probe on an image-like or stream file where ffprobe reports no duration and probe_media's `or 0` fallback yields 0.0, or a custom probe forgets the field.

Common situations: Probing a still image or a live/raw stream with no duration metadata; a custom probe returning an empty dict; ffprobe output with 'duration': 'N/A' coerced through `or 0`; audio-only files where the video stream lacks duration and format.duration is also absent.

Understand the failure class

Background: "invalid duration" / "failed to parse duration": why your timeout, interval, or TTL string is rejected and which formats each library accepts — this error's family across 32 libraries.

Related errors

AI-assisted analysis of affaan-m/ECC@8321021c54 (2026-09-16). Data as JSON: /api/errors/e840139a2b3d1d1b. Report an issue: GitHub.

Appendix: source

Thrown at skills/taste-application/scripts/tasteforge/workflow.py:145

    def require_finite_evidence(value: Any) -> None:
        if isinstance(value, bool):
            raise ValueError(  # noqa: TRY004 - one bounded invalid-media error family
                "reference probe numeric evidence must be finite real values"
            )
        if isinstance(value, (int, float)):
            if not math.isfinite(value):
                raise ValueError("reference probe numeric evidence must be finite real values")
        elif isinstance(value, dict):
            for nested in value.values():
                require_finite_evidence(nested)
        elif isinstance(value, list):
            for nested in value:
                require_finite_evidence(nested)

    require_finite_evidence(measured)
    duration = measured.get("duration")
    if not _finite_real(duration):
        raise ValueError("reference probe duration must be finite and positive")
    duration = cast(float, duration)
    if float(duration) <= 0:
        raise ValueError("reference probe duration must be finite and positive")
    for field in ("sample_times", "scene_changes"):
        values = measured.get(field, [])
        if not isinstance(values, list) or any(
            not _finite_real(value) or float(value) < 0 or float(value) > float(duration)
            for value in values
        ):
            raise ValueError(f"reference probe {field} must contain finite in-duration times")
    samples = measured.get("style_samples", [])
    if not isinstance(samples, list) or any(
        not isinstance(sample, dict)
        or not _finite_real(sample.get("time"))
        or float(cast(float, sample["time"])) < 0
        or float(cast(float, sample["time"])) > float(duration)
        for sample in samples
    ):

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