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FA-50096 / PCM sample encoding / Open access

Pcm seeded adaptive block: block predictor reset · case 01

Adaptive block reconstruction ignores its encoded anchor.

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

ROOT CAUSE

Adaptive block reconstruction ignores its encoded anchor.

THE FAILURE

Adaptive block reconstruction ignores its encoded anchor.

Unsuccessful approach: Using preceding block amplitude ignores independently decodable block seeds.

Case contract

Decode independent seeded differential PCM blocks; seed is the first presented sample and declared sample count includes it, excluding padded residuals.

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(blocks):
    out=[]
    for seed,deltas,declared in blocks:
        decoded=[seed]
        previous=0
        for delta in deltas:
            previous+=delta
            decoded.append(previous)
        out.extend(decoded[:max(0,declared)])
    return out
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('oracle 1', solve(*([[10, [1, 2], 3], [2, [-1, 3], 3]],)), [10, 11, 13, 2, 1, 4])
check('oracle 2', solve(*([[7, [1, 1], 1]],)), [7])
check('oracle 3', solve(*([[4, [], 0], [5, [], 1]],)), [5])
check('oracle 4', solve(*([],)), [])
check('oracle 5', solve(*([[-3, [2, -2], 2]],)), [-3, -1])
check('oracle 6', solve(*([[1, [1, 1, 1], 8]],)), [1, 2, 3, 4])
check('oracle 7', solve(*([[9, [1], 0], [3, [2], 2]],)), [3, 5])
if N == 1: check('variant packet 1', solve(*[[[10, [1, 2], 3], [2, [-1, 3], 3], [10, [1, 2], 3], [2, [-1, 3], 3]]]), [10, 11, 13, 2, 1, 4, 10, 11, 13, 2, 1, 4])
if N == 2: check('variant packet 2', solve(*[[[10, [1, 2], 3], [2, [-1, 3], 3], [10, [1, 2], 3], [2, [-1, 3], 3], [10, [1, 2], 3], [2, [-1, 3], 3]]]), [10, 11, 13, 2, 1, 4, 10, 11, 13, 2, 1, 4, 10, 11, 13, 2, 1, 4])
if N == 3: check('variant packet 3', solve(*[[[10, [1, 2], 3], [2, [-1, 3], 3], [10, [1, 2], 3], [2, [-1, 3], 3], [10, [1, 2], 3], [2, [-1, 3], 3], [10, [1, 2], 3], [2, [-1, 3], 3]]]), [10, 11, 13, 2, 1, 4, 10, 11, 13, 2, 1, 4, 10, 11, 13, 2, 1, 4, 10, 11, 13, 2, 1, 4])
if N == 4: check('variant packet 4', solve(*[[[10, [1, 2], 3], [2, [-1, 3], 3], [10, [1, 2], 3], [2, [-1, 3], 3], [10, [1, 2], 3], [2, [-1, 3], 3], [10, [1, 2], 3], [2, [-1, 3], 3], [10, [1, 2], 3], [2, [-1, 3], 3]]]), [10, 11, 13, 2, 1, 4, 10, 11, 13, 2, 1, 4, 10, 11, 13, 2, 1, 4, 10, 11, 13, 2, 1, 4, 10, 11, 13, 2, 1, 4])
if N == 5: check('variant packet 5', solve(*[[[10, [1, 2], 3], [2, [-1, 3], 3], [10, [1, 2], 3], [2, [-1, 3], 3], [10, [1, 2], 3], [2, [-1, 3], 3], [10, [1, 2], 3], [2, [-1, 3], 3], [10, [1, 2], 3], [2, [-1, 3], 3], [10, [1, 2], 3], [2, [-1, 3], 3]]]), [10, 11, 13, 2, 1, 4, 10, 11, 13, 2, 1, 4, 10, 11, 13, 2, 1, 4, 10, 11, 13, 2, 1, 4, 10, 11, 13, 2, 1, 4, 10, 11, 13, 2, 1, 4])
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[10, 1, 3, 2, -1, 2][10, 11, 13, 2, 1, 4]Failed
oracle 2[7][7]Passed
oracle 3[5][5]Passed
oracle 4[][]Passed
oracle 5[-3, 2][-3, -1]Failed
oracle 6[1, 1, 2, 3][1, 2, 3, 4]Failed
oracle 7[3, 2][3, 5]Failed
variant packet 1[10, 1, 3, 2, -1, 2, 10, 1, 3, 2, -1, 2][10, 11, 13, 2, 1, 4, 10, 11, 13, 2, 1, 4]Failed

SHA-256 / 2f6953a1dd147b5893a6e19fb8bf4ce437331793f91e910f413e960d45fe4865

2 / The unsuccessful fix

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

N = 1
observations = []
def solve(blocks):
    out=[]
    for seed,deltas,declared in blocks:
        decoded=[seed]
        previous=out[-1] if out else seed
        for delta in deltas:
            previous+=delta
            decoded.append(previous)
        out.extend(decoded[:max(0,declared)])
    return out
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('oracle 1', solve(*([[10, [1, 2], 3], [2, [-1, 3], 3]],)), [10, 11, 13, 2, 1, 4])
check('oracle 2', solve(*([[7, [1, 1], 1]],)), [7])
check('oracle 3', solve(*([[4, [], 0], [5, [], 1]],)), [5])
check('oracle 4', solve(*([],)), [])
check('oracle 5', solve(*([[-3, [2, -2], 2]],)), [-3, -1])
check('oracle 6', solve(*([[1, [1, 1, 1], 8]],)), [1, 2, 3, 4])
check('oracle 7', solve(*([[9, [1], 0], [3, [2], 2]],)), [3, 5])
if N == 1: check('variant packet 1', solve(*[[[10, [1, 2], 3], [2, [-1, 3], 3], [10, [1, 2], 3], [2, [-1, 3], 3]]]), [10, 11, 13, 2, 1, 4, 10, 11, 13, 2, 1, 4])
if N == 2: check('variant packet 2', solve(*[[[10, [1, 2], 3], [2, [-1, 3], 3], [10, [1, 2], 3], [2, [-1, 3], 3], [10, [1, 2], 3], [2, [-1, 3], 3]]]), [10, 11, 13, 2, 1, 4, 10, 11, 13, 2, 1, 4, 10, 11, 13, 2, 1, 4])
if N == 3: check('variant packet 3', solve(*[[[10, [1, 2], 3], [2, [-1, 3], 3], [10, [1, 2], 3], [2, [-1, 3], 3], [10, [1, 2], 3], [2, [-1, 3], 3], [10, [1, 2], 3], [2, [-1, 3], 3]]]), [10, 11, 13, 2, 1, 4, 10, 11, 13, 2, 1, 4, 10, 11, 13, 2, 1, 4, 10, 11, 13, 2, 1, 4])
if N == 4: check('variant packet 4', solve(*[[[10, [1, 2], 3], [2, [-1, 3], 3], [10, [1, 2], 3], [2, [-1, 3], 3], [10, [1, 2], 3], [2, [-1, 3], 3], [10, [1, 2], 3], [2, [-1, 3], 3], [10, [1, 2], 3], [2, [-1, 3], 3]]]), [10, 11, 13, 2, 1, 4, 10, 11, 13, 2, 1, 4, 10, 11, 13, 2, 1, 4, 10, 11, 13, 2, 1, 4, 10, 11, 13, 2, 1, 4])
if N == 5: check('variant packet 5', solve(*[[[10, [1, 2], 3], [2, [-1, 3], 3], [10, [1, 2], 3], [2, [-1, 3], 3], [10, [1, 2], 3], [2, [-1, 3], 3], [10, [1, 2], 3], [2, [-1, 3], 3], [10, [1, 2], 3], [2, [-1, 3], 3], [10, [1, 2], 3], [2, [-1, 3], 3]]]), [10, 11, 13, 2, 1, 4, 10, 11, 13, 2, 1, 4, 10, 11, 13, 2, 1, 4, 10, 11, 13, 2, 1, 4, 10, 11, 13, 2, 1, 4, 10, 11, 13, 2, 1, 4])
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[10, 11, 13, 2, 12, 15][10, 11, 13, 2, 1, 4]Failed
oracle 2[7][7]Passed
oracle 3[5][5]Passed
oracle 4[][]Passed
oracle 5[-3, -1][-3, -1]Passed
oracle 6[1, 2, 3, 4][1, 2, 3, 4]Passed
oracle 7[3, 5][3, 5]Passed
variant packet 1[10, 11, 13, 2, 12, 15, 10, 16, 18, 2, 17, 20][10, 11, 13, 2, 1, 4, 10, 11, 13, 2, 1, 4]Failed

SHA-256 / 64f00b911f2ad98099397b38d8d0f0e412edb9731e8273308d84d2e502f869ff

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 2026-09-29T14:45:06.110410+00:00.

Case digest / 89e26d90fbb45c14e2b1f420e543b8829745e624870a88535639e0c45b18bc1a