FA-10816 / PCM sample encoding / Open access

Unsigned eight bit silence padding · case 01

Zero bytes pad unsigned audio with maximum negative amplitude.

Verified by executionVariant 1 · 4 checks per implementationDownload source bundle ↓JSON ↗

ROOT CAUSE

Zero bytes pad unsigned audio with maximum negative amplitude.

THE FAILURE

Zero bytes pad unsigned audio with maximum negative amplitude.

Unsuccessful approach: Trimming existing samples turns padding into destructive resize.

Case contract

Pad unsigned8 PCM to at least nonnegative size with midpoint silence, preserving existing samples even when already longer.

Why this case matters

A pure Python local audio pipeline stage with explicit sample formats and frame conventions; no real-time device or signal-spectrum claims.

1 / The failure

Exit 1

"""Failure Map reference implementation. Python standard library only."""
import json
import math
N = 1
observations = []
def solve(samples, size):
    return list(samples)+[0]*max(0,size-len(samples))
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('fixture 1',solve(*([130], 3)),[130, 128, 128])
check('fixture 2',solve(*([], 2)),[128, 128])
check('fixture 3',solve(*([1, 2, 3], 2)),[1, 2, 3])
check('fixture 4',solve(*([128], 1)),[128])
print(json.dumps({"observations": observations, "passed": all(x["passed"] for x in observations)}, ensure_ascii=False))
raise SystemExit(0 if all(x["passed"] for x in observations) else 1)

Boundary fixture	Actual	Expected	Outcome
fixture 1	`[130, 0, 0]`	`[130, 128, 128]`	Failed
fixture 2	`[0, 0]`	`[128, 128]`	Failed
fixture 3	`[1, 2, 3]`	`[1, 2, 3]`	Passed
fixture 4	`[128]`	`[128]`	Passed

SHA-256 / a6ea73f4903b8ab9ba8d812c7a709d49052bac6d16bb9c5866cf4010e53020d0

2 / The unsuccessful fix

Exit 1

"""Failure Map reference implementation. Python standard library only."""
import json
import math
N = 1
observations = []
def solve(samples, size):
    return list(samples[:size])+[128]*max(0,size-len(samples))
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('fixture 1',solve(*([130], 3)),[130, 128, 128])
check('fixture 2',solve(*([], 2)),[128, 128])
check('fixture 3',solve(*([1, 2, 3], 2)),[1, 2, 3])
check('fixture 4',solve(*([128], 1)),[128])
print(json.dumps({"observations": observations, "passed": all(x["passed"] for x in observations)}, ensure_ascii=False))
raise SystemExit(0 if all(x["passed"] for x in observations) else 1)

Boundary fixture	Actual	Expected	Outcome
fixture 1	`[130, 128, 128]`	`[130, 128, 128]`	Passed
fixture 2	`[128, 128]`	`[128, 128]`	Passed
fixture 3	`[1, 2]`	`[1, 2, 3]`	Failed
fixture 4	`[128]`	`[128]`	Passed

SHA-256 / a82463c33830b4e931cdea064d3a5aa586fdd6921cd1f5df17d8487950530312

HELD IN THE MEMBER ARCHIVE

The verified repair and its recorded checks are member-only.

This mechanism has 4 recorded checks per implementation. The open-access tier publishes the failure and the unsuccessful fix; the repaired source that passes every check, and the observations that prove it, are available to members.

Every case sharing this mechanism uses the same contract and the same repair, so this one record is held back for all of them.

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Verification & scope

This reproducer isolates one failure mechanism. Results cover the supplied fixtures. Variants within a family share a test contract and should remain grouped when constructing evaluation splits. Related mechanisms with a shared evaluation_group must also remain together; these controlled models are not independent production incidents.

Observations recorded using Python 3.12.14 at 2026-09-29T14:38:42.491916+00:00.

Case digest / 870f0825bce0ea911a27e10c094a9deea8cd81d9309cb6c945de98a42e2969d4