FAILURE MAP
← Case archive

FA-50041 / PCM sample encoding / Open access

Pcm channel status block: start resynchronization · case 01

A new status-block start does not terminate the partial prior PCM block.

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

ROOT CAUSE

A new status-block start does not terminate the partial prior PCM block.

VERIFIED REPAIR

Use the stated conversion contract at start resynchronization.

Unsuccessful approach: Only honoring start on an empty buffer also misses mid-block resynchronization.

Case contract

Group stipulated audio subframes into fixed-size channel-status blocks, preserving PCM samples and one status bit; a new start marks prior partial data incomplete.

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(subframes, block_length):
    blocks=[]
    current=[]
    for start,audio,status in subframes:
        if False:
            if current:
                blocks.append([current,False])
            current=[]
        current.append([audio,status&1])
        if len(current)==block_length:
            blocks.append([current,True])
            current=[]
    return [blocks,current]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('oracle 1', solve(*([[True, 1, 3], [False, 2, 0], [False, 3, 1]], 3)), [[[[[1, 1], [2, 0], [3, 1]], True]], []])
check('oracle 2', solve(*([[True, 1, 0], [True, 2, 1], [False, 3, 2]], 3)), [[[[[1, 0]], False]], [[2, 1], [3, 0]]])
check('oracle 3', solve(*([[False, 1, 1], [False, 2, 0], [False, 3, 1], [False, 4, 0]], 2)), [[[[[1, 1], [2, 0]], True], [[[3, 1], [4, 0]], True]], []])
check('oracle 4', solve(*([], 3)), [[], []])
check('oracle 5', solve(*([[True, 1, 1]], 1)), [[[[[1, 1]], True]], []])
check('oracle 6', solve(*([[False, 1, 2]], 3)), [[], [[1, 0]]])
check('oracle 7', solve(*([[True, 1, 0], [False, 2, 1], [True, 3, 0]], 2)), [[[[[1, 0], [2, 1]], True]], [[3, 0]]])
if N == 1: check('variant packet 1', solve(*[[[True, 1, 3], [False, 2, 0], [False, 3, 1], [True, 1, 3], [False, 2, 0], [False, 3, 1]], 3]), [[[[[1, 1], [2, 0], [3, 1]], True], [[[1, 1], [2, 0], [3, 1]], True]], []])
if N == 2: check('variant packet 2', solve(*[[[True, 1, 3], [False, 2, 0], [False, 3, 1], [True, 1, 3], [False, 2, 0], [False, 3, 1], [True, 1, 3], [False, 2, 0], [False, 3, 1]], 3]), [[[[[1, 1], [2, 0], [3, 1]], True], [[[1, 1], [2, 0], [3, 1]], True], [[[1, 1], [2, 0], [3, 1]], True]], []])
if N == 3: check('variant packet 3', solve(*[[[True, 1, 3], [False, 2, 0], [False, 3, 1], [True, 1, 3], [False, 2, 0], [False, 3, 1], [True, 1, 3], [False, 2, 0], [False, 3, 1], [True, 1, 3], [False, 2, 0], [False, 3, 1]], 3]), [[[[[1, 1], [2, 0], [3, 1]], True], [[[1, 1], [2, 0], [3, 1]], True], [[[1, 1], [2, 0], [3, 1]], True], [[[1, 1], [2, 0], [3, 1]], True]], []])
if N == 4: check('variant packet 4', solve(*[[[True, 1, 3], [False, 2, 0], [False, 3, 1], [True, 1, 3], [False, 2, 0], [False, 3, 1], [True, 1, 3], [False, 2, 0], [False, 3, 1], [True, 1, 3], [False, 2, 0], [False, 3, 1], [True, 1, 3], [False, 2, 0], [False, 3, 1]], 3]), [[[[[1, 1], [2, 0], [3, 1]], True], [[[1, 1], [2, 0], [3, 1]], True], [[[1, 1], [2, 0], [3, 1]], True], [[[1, 1], [2, 0], [3, 1]], True], [[[1, 1], [2, 0], [3, 1]], True]], []])
if N == 5: check('variant packet 5', solve(*[[[True, 1, 3], [False, 2, 0], [False, 3, 1], [True, 1, 3], [False, 2, 0], [False, 3, 1], [True, 1, 3], [False, 2, 0], [False, 3, 1], [True, 1, 3], [False, 2, 0], [False, 3, 1], [True, 1, 3], [False, 2, 0], [False, 3, 1], [True, 1, 3], [False, 2, 0], [False, 3, 1]], 3]), [[[[[1, 1], [2, 0], [3, 1]], True], [[[1, 1], [2, 0], [3, 1]], True], [[[1, 1], [2, 0], [3, 1]], True], [[[1, 1], [2, 0], [3, 1]], True], [[[1, 1], [2, 0], [3, 1]], True], [[[1, 1], [2, 0], [3, 1]], True]], []])
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, 1], [2, 0], [3, 1]], True]], []][[[[[1, 1], [2, 0], [3, 1]], True]], []]Passed
oracle 2[[[[[1, 0], [2, 1], [3, 0]], True]], []][[[[[1, 0]], False]], [[2, 1], [3, 0]]]Failed
oracle 3[[[[[1, 1], [2, 0]], True], [[[3, 1], [4, 0]], True]], []][[[[[1, 1], [2, 0]], True], [[[3, 1], [4, 0]], True]], []]Passed
oracle 4[[], []][[], []]Passed
oracle 5[[[[[1, 1]], True]], []][[[[[1, 1]], True]], []]Passed
oracle 6[[], [[1, 0]]][[], [[1, 0]]]Passed
oracle 7[[[[[1, 0], [2, 1]], True]], [[3, 0]]][[[[[1, 0], [2, 1]], True]], [[3, 0]]]Passed
variant packet 1[[[[[1, 1], [2, 0], [3, 1]], True], [[[1, 1], [2, 0], [3, 1]], True]], []][[[[[1, 1], [2, 0], [3, 1]], True], [[[1, 1], [2, 0], [3, 1]], True]], []]Passed

SHA-256 / 55a51052f98d495b3067e760456542e437efc8af5079fdb40b1f37d93f484f20

2 / The unsuccessful fix

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

N = 1
observations = []
def solve(subframes, block_length):
    blocks=[]
    current=[]
    for start,audio,status in subframes:
        if start and not current:
            if current:
                blocks.append([current,False])
            current=[]
        current.append([audio,status&1])
        if len(current)==block_length:
            blocks.append([current,True])
            current=[]
    return [blocks,current]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('oracle 1', solve(*([[True, 1, 3], [False, 2, 0], [False, 3, 1]], 3)), [[[[[1, 1], [2, 0], [3, 1]], True]], []])
check('oracle 2', solve(*([[True, 1, 0], [True, 2, 1], [False, 3, 2]], 3)), [[[[[1, 0]], False]], [[2, 1], [3, 0]]])
check('oracle 3', solve(*([[False, 1, 1], [False, 2, 0], [False, 3, 1], [False, 4, 0]], 2)), [[[[[1, 1], [2, 0]], True], [[[3, 1], [4, 0]], True]], []])
check('oracle 4', solve(*([], 3)), [[], []])
check('oracle 5', solve(*([[True, 1, 1]], 1)), [[[[[1, 1]], True]], []])
check('oracle 6', solve(*([[False, 1, 2]], 3)), [[], [[1, 0]]])
check('oracle 7', solve(*([[True, 1, 0], [False, 2, 1], [True, 3, 0]], 2)), [[[[[1, 0], [2, 1]], True]], [[3, 0]]])
if N == 1: check('variant packet 1', solve(*[[[True, 1, 3], [False, 2, 0], [False, 3, 1], [True, 1, 3], [False, 2, 0], [False, 3, 1]], 3]), [[[[[1, 1], [2, 0], [3, 1]], True], [[[1, 1], [2, 0], [3, 1]], True]], []])
if N == 2: check('variant packet 2', solve(*[[[True, 1, 3], [False, 2, 0], [False, 3, 1], [True, 1, 3], [False, 2, 0], [False, 3, 1], [True, 1, 3], [False, 2, 0], [False, 3, 1]], 3]), [[[[[1, 1], [2, 0], [3, 1]], True], [[[1, 1], [2, 0], [3, 1]], True], [[[1, 1], [2, 0], [3, 1]], True]], []])
if N == 3: check('variant packet 3', solve(*[[[True, 1, 3], [False, 2, 0], [False, 3, 1], [True, 1, 3], [False, 2, 0], [False, 3, 1], [True, 1, 3], [False, 2, 0], [False, 3, 1], [True, 1, 3], [False, 2, 0], [False, 3, 1]], 3]), [[[[[1, 1], [2, 0], [3, 1]], True], [[[1, 1], [2, 0], [3, 1]], True], [[[1, 1], [2, 0], [3, 1]], True], [[[1, 1], [2, 0], [3, 1]], True]], []])
if N == 4: check('variant packet 4', solve(*[[[True, 1, 3], [False, 2, 0], [False, 3, 1], [True, 1, 3], [False, 2, 0], [False, 3, 1], [True, 1, 3], [False, 2, 0], [False, 3, 1], [True, 1, 3], [False, 2, 0], [False, 3, 1], [True, 1, 3], [False, 2, 0], [False, 3, 1]], 3]), [[[[[1, 1], [2, 0], [3, 1]], True], [[[1, 1], [2, 0], [3, 1]], True], [[[1, 1], [2, 0], [3, 1]], True], [[[1, 1], [2, 0], [3, 1]], True], [[[1, 1], [2, 0], [3, 1]], True]], []])
if N == 5: check('variant packet 5', solve(*[[[True, 1, 3], [False, 2, 0], [False, 3, 1], [True, 1, 3], [False, 2, 0], [False, 3, 1], [True, 1, 3], [False, 2, 0], [False, 3, 1], [True, 1, 3], [False, 2, 0], [False, 3, 1], [True, 1, 3], [False, 2, 0], [False, 3, 1], [True, 1, 3], [False, 2, 0], [False, 3, 1]], 3]), [[[[[1, 1], [2, 0], [3, 1]], True], [[[1, 1], [2, 0], [3, 1]], True], [[[1, 1], [2, 0], [3, 1]], True], [[[1, 1], [2, 0], [3, 1]], True], [[[1, 1], [2, 0], [3, 1]], True], [[[1, 1], [2, 0], [3, 1]], True]], []])
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, 1], [2, 0], [3, 1]], True]], []][[[[[1, 1], [2, 0], [3, 1]], True]], []]Passed
oracle 2[[[[[1, 0], [2, 1], [3, 0]], True]], []][[[[[1, 0]], False]], [[2, 1], [3, 0]]]Failed
oracle 3[[[[[1, 1], [2, 0]], True], [[[3, 1], [4, 0]], True]], []][[[[[1, 1], [2, 0]], True], [[[3, 1], [4, 0]], True]], []]Passed
oracle 4[[], []][[], []]Passed
oracle 5[[[[[1, 1]], True]], []][[[[[1, 1]], True]], []]Passed
oracle 6[[], [[1, 0]]][[], [[1, 0]]]Passed
oracle 7[[[[[1, 0], [2, 1]], True]], [[3, 0]]][[[[[1, 0], [2, 1]], True]], [[3, 0]]]Passed
variant packet 1[[[[[1, 1], [2, 0], [3, 1]], True], [[[1, 1], [2, 0], [3, 1]], True]], []][[[[[1, 1], [2, 0], [3, 1]], True], [[[1, 1], [2, 0], [3, 1]], True]], []]Passed

SHA-256 / eab4527bfb34753be2a75f4473d010bd10ed479eb7809e6247166b7185a91189

3 / The verified repair

Exit 0
"""Failure Map reference implementation. Python standard library only."""
import json

N = 1
observations = []
def solve(subframes, block_length):
    blocks=[]
    current=[]
    for start,audio,status in subframes:
        if start:
            if current:
                blocks.append([current,False])
            current=[]
        current.append([audio,status&1])
        if len(current)==block_length:
            blocks.append([current,True])
            current=[]
    return [blocks,current]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('oracle 1', solve(*([[True, 1, 3], [False, 2, 0], [False, 3, 1]], 3)), [[[[[1, 1], [2, 0], [3, 1]], True]], []])
check('oracle 2', solve(*([[True, 1, 0], [True, 2, 1], [False, 3, 2]], 3)), [[[[[1, 0]], False]], [[2, 1], [3, 0]]])
check('oracle 3', solve(*([[False, 1, 1], [False, 2, 0], [False, 3, 1], [False, 4, 0]], 2)), [[[[[1, 1], [2, 0]], True], [[[3, 1], [4, 0]], True]], []])
check('oracle 4', solve(*([], 3)), [[], []])
check('oracle 5', solve(*([[True, 1, 1]], 1)), [[[[[1, 1]], True]], []])
check('oracle 6', solve(*([[False, 1, 2]], 3)), [[], [[1, 0]]])
check('oracle 7', solve(*([[True, 1, 0], [False, 2, 1], [True, 3, 0]], 2)), [[[[[1, 0], [2, 1]], True]], [[3, 0]]])
if N == 1: check('variant packet 1', solve(*[[[True, 1, 3], [False, 2, 0], [False, 3, 1], [True, 1, 3], [False, 2, 0], [False, 3, 1]], 3]), [[[[[1, 1], [2, 0], [3, 1]], True], [[[1, 1], [2, 0], [3, 1]], True]], []])
if N == 2: check('variant packet 2', solve(*[[[True, 1, 3], [False, 2, 0], [False, 3, 1], [True, 1, 3], [False, 2, 0], [False, 3, 1], [True, 1, 3], [False, 2, 0], [False, 3, 1]], 3]), [[[[[1, 1], [2, 0], [3, 1]], True], [[[1, 1], [2, 0], [3, 1]], True], [[[1, 1], [2, 0], [3, 1]], True]], []])
if N == 3: check('variant packet 3', solve(*[[[True, 1, 3], [False, 2, 0], [False, 3, 1], [True, 1, 3], [False, 2, 0], [False, 3, 1], [True, 1, 3], [False, 2, 0], [False, 3, 1], [True, 1, 3], [False, 2, 0], [False, 3, 1]], 3]), [[[[[1, 1], [2, 0], [3, 1]], True], [[[1, 1], [2, 0], [3, 1]], True], [[[1, 1], [2, 0], [3, 1]], True], [[[1, 1], [2, 0], [3, 1]], True]], []])
if N == 4: check('variant packet 4', solve(*[[[True, 1, 3], [False, 2, 0], [False, 3, 1], [True, 1, 3], [False, 2, 0], [False, 3, 1], [True, 1, 3], [False, 2, 0], [False, 3, 1], [True, 1, 3], [False, 2, 0], [False, 3, 1], [True, 1, 3], [False, 2, 0], [False, 3, 1]], 3]), [[[[[1, 1], [2, 0], [3, 1]], True], [[[1, 1], [2, 0], [3, 1]], True], [[[1, 1], [2, 0], [3, 1]], True], [[[1, 1], [2, 0], [3, 1]], True], [[[1, 1], [2, 0], [3, 1]], True]], []])
if N == 5: check('variant packet 5', solve(*[[[True, 1, 3], [False, 2, 0], [False, 3, 1], [True, 1, 3], [False, 2, 0], [False, 3, 1], [True, 1, 3], [False, 2, 0], [False, 3, 1], [True, 1, 3], [False, 2, 0], [False, 3, 1], [True, 1, 3], [False, 2, 0], [False, 3, 1], [True, 1, 3], [False, 2, 0], [False, 3, 1]], 3]), [[[[[1, 1], [2, 0], [3, 1]], True], [[[1, 1], [2, 0], [3, 1]], True], [[[1, 1], [2, 0], [3, 1]], True], [[[1, 1], [2, 0], [3, 1]], True], [[[1, 1], [2, 0], [3, 1]], True], [[[1, 1], [2, 0], [3, 1]], True]], []])
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, 1], [2, 0], [3, 1]], True]], []][[[[[1, 1], [2, 0], [3, 1]], True]], []]Passed
oracle 2[[[[[1, 0]], False]], [[2, 1], [3, 0]]][[[[[1, 0]], False]], [[2, 1], [3, 0]]]Passed
oracle 3[[[[[1, 1], [2, 0]], True], [[[3, 1], [4, 0]], True]], []][[[[[1, 1], [2, 0]], True], [[[3, 1], [4, 0]], True]], []]Passed
oracle 4[[], []][[], []]Passed
oracle 5[[[[[1, 1]], True]], []][[[[[1, 1]], True]], []]Passed
oracle 6[[], [[1, 0]]][[], [[1, 0]]]Passed
oracle 7[[[[[1, 0], [2, 1]], True]], [[3, 0]]][[[[[1, 0], [2, 1]], True]], [[3, 0]]]Passed
variant packet 1[[[[[1, 1], [2, 0], [3, 1]], True], [[[1, 1], [2, 0], [3, 1]], True]], []][[[[[1, 1], [2, 0], [3, 1]], True], [[[1, 1], [2, 0], [3, 1]], True]], []]Passed

SHA-256 / c41b704bd8b43b25e554e943106b5f09fd1afc04f10dd4761e5e27b1e1318b8d

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 2026-09-29T14:45:05.469632+00:00.

Case digest / 3d0099bc722c7d56beea80b25dc0a532a5bb05bbba3cfba1ef4806ec0e76f600