Validate a cut list against video-trim's rules before you submit

Video filter has a free /check endpoint; video trim does not, so a bad cut list fails after the request is made. Mirror the documented rules in a local function: the source must be 1800 s or shorter, the output between 0.2 s and 900 s, exactly one of end or duration must be sent, and output conforming needs precision: "exact". A cut list with 30 ranges then fails on your machine, not at $0.02 a range.

The rules, as codes

Each rule maps to a stable refusal code in the docs, which makes a local validator easy to test against the real API response.

A local check

Note the documented behavior at the end of the clip: an end past the source end clamps and the result carries the warning trim_clamped_to_source, so it is not an error. The sample's third range therefore passes; the second is a 0.1 s sliver that your validator should reject before sending.

def check(start, end, source_s, keyframe=False, output=None):
    """Return the stable video-trim code this request would hit, or None."""
    if source_s > 1800:
        return "source_duration_exceeded"
    if end is None:
        return "video_trim_range_required"
    if end <= start or end - start > 900:
        return "video_trim_range_empty"
    if end - start < 0.2:
        return "output under 0.2 s (schema)"
    if keyframe and output:
        return "video_trim_output_requires_exact"
    return None   # end > source_s only clamps, with trim_clamped_to_source

cuts = [(1.84, 9.1), (9.5, 9.6), (12.0, 1000.0)]
for s, e in cuts:
    print((s, e), check(s, e, 42.0))

Limits of a local check

• Worker-side codes (source_not_found, unsupported_media_type, source_duration_exceeded) depend on the real file, so a local function only needs your probe duration.
• Treat the validator as a guard rail, not the contract; confirm against the docs when limits change.
• Send an Idempotency-Key per trim so a retry does not queue a second billed job.