FAILURE MAP
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FA-50066 / PCM sample encoding / Open access

Pcm sample validity sideband: missing validity · case 01

Uncovered PCM samples are treated as valid despite absent validity metadata.

Verified by executionVariant 1 · 8 checks per implementationDownload source bundle ↓JSON ↗

ROOT CAUSE

Uncovered PCM samples are treated as valid despite absent validity metadata.

THE FAILURE

Uncovered PCM samples are treated as valid despite absent validity metadata.

Unsuccessful approach: Repeating the last flag extends metadata beyond its declared span.

Case contract

Decode PCM with a parallel validity vector, missing flags invalid, holding the most recent valid sample for invalid positions while retaining explicit validity metadata.

Why this case matters

Offline PCM interchange uses these exact bounded packet and sample representation decisions.

1 / The failure

Exit 1
"""Failure Map reference implementation. Python standard library only."""
import json

N = 1
observations = []
def solve(samples, validity, conceal):
    out=[]
    previous=conceal
    for index,sample in enumerate(samples):
        valid=validity[index] if index<len(validity) else True
        if valid:
            previous=sample
        out.append([sample if valid else previous,bool(valid)])
    return [out,previous]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('oracle 1', solve(*([1, 9, 3, 8], [True, False, True, False], 0)), [[[1, True], [1, False], [3, True], [3, False]], 3])
check('oracle 2', solve(*([9, 2], [False, True], 7)), [[[7, False], [2, True]], 2])
check('oracle 3', solve(*([1, 2, 3], [True], 0)), [[[1, True], [1, False], [1, False]], 1])
check('oracle 4', solve(*([], [], 4)), [[], 4])
check('oracle 5', solve(*([4, 5], [False, False], -1)), [[[-1, False], [-1, False]], -1])
check('oracle 6', solve(*([1, 2, 3], [False, True, False], 5)), [[[5, False], [2, True], [2, False]], 2])
check('oracle 7', solve(*([0], [True], 8)), [[[0, True]], 0])
if N == 1: check('variant packet 1', solve(*[[1, 9, 3, 8, 1, 9, 3, 8], [True, False, True, False], 0]), [[[1, True], [1, False], [3, True], [3, False], [3, False], [3, False], [3, False], [3, False]], 3])
if N == 2: check('variant packet 2', solve(*[[1, 9, 3, 8, 1, 9, 3, 8, 1, 9, 3, 8], [True, False, True, False], 0]), [[[1, True], [1, False], [3, True], [3, False], [3, False], [3, False], [3, False], [3, False], [3, False], [3, False], [3, False], [3, False]], 3])
if N == 3: check('variant packet 3', solve(*[[1, 9, 3, 8, 1, 9, 3, 8, 1, 9, 3, 8, 1, 9, 3, 8], [True, False, True, False], 0]), [[[1, True], [1, False], [3, True], [3, False], [3, False], [3, False], [3, False], [3, False], [3, False], [3, False], [3, False], [3, False], [3, False], [3, False], [3, False], [3, False]], 3])
if N == 4: check('variant packet 4', solve(*[[1, 9, 3, 8, 1, 9, 3, 8, 1, 9, 3, 8, 1, 9, 3, 8, 1, 9, 3, 8], [True, False, True, False], 0]), [[[1, True], [1, False], [3, True], [3, False], [3, False], [3, False], [3, False], [3, False], [3, False], [3, False], [3, False], [3, False], [3, False], [3, False], [3, False], [3, False], [3, False], [3, False], [3, False], [3, False]], 3])
if N == 5: check('variant packet 5', solve(*[[1, 9, 3, 8, 1, 9, 3, 8, 1, 9, 3, 8, 1, 9, 3, 8, 1, 9, 3, 8, 1, 9, 3, 8], [True, False, True, False], 0]), [[[1, True], [1, False], [3, True], [3, False], [3, False], [3, False], [3, False], [3, False], [3, False], [3, False], [3, False], [3, False], [3, False], [3, False], [3, False], [3, False], [3, False], [3, False], [3, False], [3, False], [3, False], [3, False], [3, False], [3, False]], 3])
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 fixtureActualExpectedOutcome
oracle 1[[[1, True], [1, False], [3, True], [3, False]], 3][[[1, True], [1, False], [3, True], [3, False]], 3]Passed
oracle 2[[[7, False], [2, True]], 2][[[7, False], [2, True]], 2]Passed
oracle 3[[[1, True], [2, True], [3, True]], 3][[[1, True], [1, False], [1, False]], 1]Failed
oracle 4[[], 4][[], 4]Passed
oracle 5[[[-1, False], [-1, False]], -1][[[-1, False], [-1, False]], -1]Passed
oracle 6[[[5, False], [2, True], [2, False]], 2][[[5, False], [2, True], [2, False]], 2]Passed
oracle 7[[[0, True]], 0][[[0, True]], 0]Passed
variant packet 1[[[1, True], [1, False], [3, True], [3, False], [1, True], [9, True], [3, True], [8, True]], 8][[[1, True], [1, False], [3, True], [3, False], [3, False], [3, False], [3, False], [3, False]], 3]Failed

SHA-256 / f00658372d745216a81be9f7da4b8da9a508cd668b3d6e822653d891072c1bf6

2 / The unsuccessful fix

Exit 1
"""Failure Map reference implementation. Python standard library only."""
import json

N = 1
observations = []
def solve(samples, validity, conceal):
    out=[]
    previous=conceal
    for index,sample in enumerate(samples):
        valid=validity[index] if index<len(validity) else (validity[-1] if validity else True)
        if valid:
            previous=sample
        out.append([sample if valid else previous,bool(valid)])
    return [out,previous]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('oracle 1', solve(*([1, 9, 3, 8], [True, False, True, False], 0)), [[[1, True], [1, False], [3, True], [3, False]], 3])
check('oracle 2', solve(*([9, 2], [False, True], 7)), [[[7, False], [2, True]], 2])
check('oracle 3', solve(*([1, 2, 3], [True], 0)), [[[1, True], [1, False], [1, False]], 1])
check('oracle 4', solve(*([], [], 4)), [[], 4])
check('oracle 5', solve(*([4, 5], [False, False], -1)), [[[-1, False], [-1, False]], -1])
check('oracle 6', solve(*([1, 2, 3], [False, True, False], 5)), [[[5, False], [2, True], [2, False]], 2])
check('oracle 7', solve(*([0], [True], 8)), [[[0, True]], 0])
if N == 1: check('variant packet 1', solve(*[[1, 9, 3, 8, 1, 9, 3, 8], [True, False, True, False], 0]), [[[1, True], [1, False], [3, True], [3, False], [3, False], [3, False], [3, False], [3, False]], 3])
if N == 2: check('variant packet 2', solve(*[[1, 9, 3, 8, 1, 9, 3, 8, 1, 9, 3, 8], [True, False, True, False], 0]), [[[1, True], [1, False], [3, True], [3, False], [3, False], [3, False], [3, False], [3, False], [3, False], [3, False], [3, False], [3, False]], 3])
if N == 3: check('variant packet 3', solve(*[[1, 9, 3, 8, 1, 9, 3, 8, 1, 9, 3, 8, 1, 9, 3, 8], [True, False, True, False], 0]), [[[1, True], [1, False], [3, True], [3, False], [3, False], [3, False], [3, False], [3, False], [3, False], [3, False], [3, False], [3, False], [3, False], [3, False], [3, False], [3, False]], 3])
if N == 4: check('variant packet 4', solve(*[[1, 9, 3, 8, 1, 9, 3, 8, 1, 9, 3, 8, 1, 9, 3, 8, 1, 9, 3, 8], [True, False, True, False], 0]), [[[1, True], [1, False], [3, True], [3, False], [3, False], [3, False], [3, False], [3, False], [3, False], [3, False], [3, False], [3, False], [3, False], [3, False], [3, False], [3, False], [3, False], [3, False], [3, False], [3, False]], 3])
if N == 5: check('variant packet 5', solve(*[[1, 9, 3, 8, 1, 9, 3, 8, 1, 9, 3, 8, 1, 9, 3, 8, 1, 9, 3, 8, 1, 9, 3, 8], [True, False, True, False], 0]), [[[1, True], [1, False], [3, True], [3, False], [3, False], [3, False], [3, False], [3, False], [3, False], [3, False], [3, False], [3, False], [3, False], [3, False], [3, False], [3, False], [3, False], [3, False], [3, False], [3, False], [3, False], [3, False], [3, False], [3, False]], 3])
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 fixtureActualExpectedOutcome
oracle 1[[[1, True], [1, False], [3, True], [3, False]], 3][[[1, True], [1, False], [3, True], [3, False]], 3]Passed
oracle 2[[[7, False], [2, True]], 2][[[7, False], [2, True]], 2]Passed
oracle 3[[[1, True], [2, True], [3, True]], 3][[[1, True], [1, False], [1, False]], 1]Failed
oracle 4[[], 4][[], 4]Passed
oracle 5[[[-1, False], [-1, False]], -1][[[-1, False], [-1, False]], -1]Passed
oracle 6[[[5, False], [2, True], [2, False]], 2][[[5, False], [2, True], [2, False]], 2]Passed
oracle 7[[[0, True]], 0][[[0, True]], 0]Passed
variant packet 1[[[1, True], [1, False], [3, True], [3, False], [3, False], [3, False], [3, False], [3, False]], 3][[[1, True], [1, False], [3, True], [3, False], [3, False], [3, False], [3, False], [3, False]], 3]Passed

SHA-256 / ac4c06518c56b285de2f18c1f44cdf485f426c1c62d63b6e701289acb5e583d1

HELD IN THE MEMBER ARCHIVE

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

This mechanism has 8 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

Stipulated finite model; no claim of hardware timing or full file-format conformance. 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 2026-09-29T14:45:05.919362+00:00.

Case digest / 16351112aed4013dad080c8dc7bbf0b1f48666d0b6e80e7747e392a0e7fc31eb