FA-49141 / PCM sample encoding / Open access
Pcm slot status: validity polarity · case 01
The PCM invalid flag is interpreted as valid.
ROOT CAUSE
The PCM invalid flag is interpreted as valid.
VERIFIED REPAIR
Use the stated conversion contract at validity polarity.
Unsuccessful approach: Silence is used as a validity test instead of the status bit.
Case contract
Decode a stipulated slot: signed payload, one invalid bit, then even parity covering payload and invalid bit; invalid or corrupt samples return null plus status.
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(slots, width):
out=[]
mask=(1<<width)-1
for slot in slots:
payload=slot&mask
valid=bool(slot&(1<<width))
parity=(slot>>(width+1))&1
parity_ok=((bin(payload).count("1")+int(not valid)+parity)%2)==0
sample=payload-(1<<width) if payload&(1<<(width-1)) else payload
out.append([sample if valid and parity_ok else None,valid,parity_ok])
return out
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('oracle 1', solve(*([0, 1, 33, 16, 48], 4)), [[0, True, True], [None, True, False], [1, True, True], [None, False, False], [None, False, True]])
check('oracle 2', solve(*([15, 47, 8, 40], 4)), [[-1, True, True], [None, True, False], [None, True, False], [-8, True, True]])
check('oracle 3', solve(*([], 4)), [])
check('oracle 4', solve(*([0, 1, 2, 3, 4, 5, 6, 7], 1)), [[0, True, True], [None, True, False], [None, False, False], [None, False, True], [None, True, False], [-1, True, True], [None, False, True], [None, False, False]])
check('oracle 5', solve(*([7, 23, 8, 24], 3)), [[None, True, False], [-1, True, True], [None, False, False], [None, False, True]])
check('oracle 6', solve(*([2, 3, 4, 5, 6], 4)), [[None, True, False], [3, True, True], [None, True, False], [5, True, True], [6, True, True]])
check('oracle 7', solve(*([255, 767, 256, 768], 8)), [[-1, True, True], [None, True, False], [None, False, False], [None, False, True]])
if N == 1: check('variant packet 1', solve(*[[0, 1, 33, 16, 48, 0, 1, 33, 16, 48], 4]), [[0, True, True], [None, True, False], [1, True, True], [None, False, False], [None, False, True], [0, True, True], [None, True, False], [1, True, True], [None, False, False], [None, False, True]])
if N == 2: check('variant packet 2', solve(*[[0, 1, 33, 16, 48, 0, 1, 33, 16, 48, 0, 1, 33, 16, 48], 4]), [[0, True, True], [None, True, False], [1, True, True], [None, False, False], [None, False, True], [0, True, True], [None, True, False], [1, True, True], [None, False, False], [None, False, True], [0, True, True], [None, True, False], [1, True, True], [None, False, False], [None, False, True]])
if N == 3: check('variant packet 3', solve(*[[0, 1, 33, 16, 48, 0, 1, 33, 16, 48, 0, 1, 33, 16, 48, 0, 1, 33, 16, 48], 4]), [[0, True, True], [None, True, False], [1, True, True], [None, False, False], [None, False, True], [0, True, True], [None, True, False], [1, True, True], [None, False, False], [None, False, True], [0, True, True], [None, True, False], [1, True, True], [None, False, False], [None, False, True], [0, True, True], [None, True, False], [1, True, True], [None, False, False], [None, False, True]])
if N == 4: check('variant packet 4', solve(*[[0, 1, 33, 16, 48, 0, 1, 33, 16, 48, 0, 1, 33, 16, 48, 0, 1, 33, 16, 48, 0, 1, 33, 16, 48], 4]), [[0, True, True], [None, True, False], [1, True, True], [None, False, False], [None, False, True], [0, True, True], [None, True, False], [1, True, True], [None, False, False], [None, False, True], [0, True, True], [None, True, False], [1, True, True], [None, False, False], [None, False, True], [0, True, True], [None, True, False], [1, True, True], [None, False, False], [None, False, True], [0, True, True], [None, True, False], [1, True, True], [None, False, False], [None, False, True]])
if N == 5: check('variant packet 5', solve(*[[0, 1, 33, 16, 48, 0, 1, 33, 16, 48, 0, 1, 33, 16, 48, 0, 1, 33, 16, 48, 0, 1, 33, 16, 48, 0, 1, 33, 16, 48], 4]), [[0, True, True], [None, True, False], [1, True, True], [None, False, False], [None, False, True], [0, True, True], [None, True, False], [1, True, True], [None, False, False], [None, False, True], [0, True, True], [None, True, False], [1, True, True], [None, False, False], [None, False, True], [0, True, True], [None, True, False], [1, True, True], [None, False, False], [None, False, True], [0, True, True], [None, True, False], [1, True, True], [None, False, False], [None, False, True], [0, True, True], [None, True, False], [1, True, True], [None, False, False], [None, False, 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 fixture | Actual | Expected | Outcome |
|---|---|---|---|
| oracle 1 | [[None, False, False], [None, False, True], [None, False, False], [0, True, True], [None, True, False]] | [[0, True, True], [None, True, False], [1, True, True], [None, False, False], [None, False, True]] | Failed |
| oracle 2 | [[None, False, False], [None, False, True], [None, False, True], [None, False, False]] | [[-1, True, True], [None, True, False], [None, True, False], [-8, True, True]] | Failed |
| oracle 3 | [] | [] | Passed |
| oracle 4 | [[None, False, False], [None, False, True], [0, True, True], [None, True, False], [None, False, True], [None, False, False], [None, True, False], [-1, True, True]] | [[0, True, True], [None, True, False], [None, False, False], [None, False, True], [None, True, False], [-1, True, True], [None, False, True], [None, False, False]] | Failed |
| oracle 5 | [[None, False, True], [None, False, False], [0, True, True], [None, True, False]] | [[None, True, False], [-1, True, True], [None, False, False], [None, False, True]] | Failed |
| oracle 6 | [[None, False, True], [None, False, False], [None, False, True], [None, False, False], [None, False, False]] | [[None, True, False], [3, True, True], [None, True, False], [5, True, True], [6, True, True]] | Failed |
| oracle 7 | [[None, False, False], [None, False, True], [0, True, True], [None, True, False]] | [[-1, True, True], [None, True, False], [None, False, False], [None, False, True]] | Failed |
| variant packet 1 | [[None, False, False], [None, False, True], [None, False, False], [0, True, True], [None, True, False], [None, False, False], [None, False, True], [None, False, False], [0, True, True], [None, True, False]] | [[0, True, True], [None, True, False], [1, True, True], [None, False, False], [None, False, True], [0, True, True], [None, True, False], [1, True, True], [None, False, False], [None, False, True]] | Failed |
SHA-256 / 4bf1ce67f7d956aa50fb0a64b287e6fbd79d5fe8c96caf7f45d1d0b8e0cdc5b4
2 / The unsuccessful fix
Exit 1"""Failure Map reference implementation. Python standard library only."""
import json
N = 1
observations = []
def solve(slots, width):
out=[]
mask=(1<<width)-1
for slot in slots:
payload=slot&mask
valid=not bool(payload)
parity=(slot>>(width+1))&1
parity_ok=((bin(payload).count("1")+int(not valid)+parity)%2)==0
sample=payload-(1<<width) if payload&(1<<(width-1)) else payload
out.append([sample if valid and parity_ok else None,valid,parity_ok])
return out
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('oracle 1', solve(*([0, 1, 33, 16, 48], 4)), [[0, True, True], [None, True, False], [1, True, True], [None, False, False], [None, False, True]])
check('oracle 2', solve(*([15, 47, 8, 40], 4)), [[-1, True, True], [None, True, False], [None, True, False], [-8, True, True]])
check('oracle 3', solve(*([], 4)), [])
check('oracle 4', solve(*([0, 1, 2, 3, 4, 5, 6, 7], 1)), [[0, True, True], [None, True, False], [None, False, False], [None, False, True], [None, True, False], [-1, True, True], [None, False, True], [None, False, False]])
check('oracle 5', solve(*([7, 23, 8, 24], 3)), [[None, True, False], [-1, True, True], [None, False, False], [None, False, True]])
check('oracle 6', solve(*([2, 3, 4, 5, 6], 4)), [[None, True, False], [3, True, True], [None, True, False], [5, True, True], [6, True, True]])
check('oracle 7', solve(*([255, 767, 256, 768], 8)), [[-1, True, True], [None, True, False], [None, False, False], [None, False, True]])
if N == 1: check('variant packet 1', solve(*[[0, 1, 33, 16, 48, 0, 1, 33, 16, 48], 4]), [[0, True, True], [None, True, False], [1, True, True], [None, False, False], [None, False, True], [0, True, True], [None, True, False], [1, True, True], [None, False, False], [None, False, True]])
if N == 2: check('variant packet 2', solve(*[[0, 1, 33, 16, 48, 0, 1, 33, 16, 48, 0, 1, 33, 16, 48], 4]), [[0, True, True], [None, True, False], [1, True, True], [None, False, False], [None, False, True], [0, True, True], [None, True, False], [1, True, True], [None, False, False], [None, False, True], [0, True, True], [None, True, False], [1, True, True], [None, False, False], [None, False, True]])
if N == 3: check('variant packet 3', solve(*[[0, 1, 33, 16, 48, 0, 1, 33, 16, 48, 0, 1, 33, 16, 48, 0, 1, 33, 16, 48], 4]), [[0, True, True], [None, True, False], [1, True, True], [None, False, False], [None, False, True], [0, True, True], [None, True, False], [1, True, True], [None, False, False], [None, False, True], [0, True, True], [None, True, False], [1, True, True], [None, False, False], [None, False, True], [0, True, True], [None, True, False], [1, True, True], [None, False, False], [None, False, True]])
if N == 4: check('variant packet 4', solve(*[[0, 1, 33, 16, 48, 0, 1, 33, 16, 48, 0, 1, 33, 16, 48, 0, 1, 33, 16, 48, 0, 1, 33, 16, 48], 4]), [[0, True, True], [None, True, False], [1, True, True], [None, False, False], [None, False, True], [0, True, True], [None, True, False], [1, True, True], [None, False, False], [None, False, True], [0, True, True], [None, True, False], [1, True, True], [None, False, False], [None, False, True], [0, True, True], [None, True, False], [1, True, True], [None, False, False], [None, False, True], [0, True, True], [None, True, False], [1, True, True], [None, False, False], [None, False, True]])
if N == 5: check('variant packet 5', solve(*[[0, 1, 33, 16, 48, 0, 1, 33, 16, 48, 0, 1, 33, 16, 48, 0, 1, 33, 16, 48, 0, 1, 33, 16, 48, 0, 1, 33, 16, 48], 4]), [[0, True, True], [None, True, False], [1, True, True], [None, False, False], [None, False, True], [0, True, True], [None, True, False], [1, True, True], [None, False, False], [None, False, True], [0, True, True], [None, True, False], [1, True, True], [None, False, False], [None, False, True], [0, True, True], [None, True, False], [1, True, True], [None, False, False], [None, False, True], [0, True, True], [None, True, False], [1, True, True], [None, False, False], [None, False, True], [0, True, True], [None, True, False], [1, True, True], [None, False, False], [None, False, 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 fixture | Actual | Expected | Outcome |
|---|---|---|---|
| oracle 1 | [[0, True, True], [None, False, True], [None, False, False], [0, True, True], [None, True, False]] | [[0, True, True], [None, True, False], [1, True, True], [None, False, False], [None, False, True]] | Failed |
| oracle 2 | [[None, False, False], [None, False, True], [None, False, True], [None, False, False]] | [[-1, True, True], [None, True, False], [None, True, False], [-8, True, True]] | Failed |
| oracle 3 | [] | [] | Passed |
| oracle 4 | [[0, True, True], [None, False, True], [0, True, True], [None, False, True], [None, True, False], [None, False, False], [None, True, False], [None, False, False]] | [[0, True, True], [None, True, False], [None, False, False], [None, False, True], [None, True, False], [-1, True, True], [None, False, True], [None, False, False]] | Failed |
| oracle 5 | [[None, False, True], [None, False, False], [0, True, True], [None, True, False]] | [[None, True, False], [-1, True, True], [None, False, False], [None, False, True]] | Failed |
| oracle 6 | [[None, False, True], [None, False, False], [None, False, True], [None, False, False], [None, False, False]] | [[None, True, False], [3, True, True], [None, True, False], [5, True, True], [6, True, True]] | Failed |
| oracle 7 | [[None, False, False], [None, False, True], [0, True, True], [None, True, False]] | [[-1, True, True], [None, True, False], [None, False, False], [None, False, True]] | Failed |
| variant packet 1 | [[0, True, True], [None, False, True], [None, False, False], [0, True, True], [None, True, False], [0, True, True], [None, False, True], [None, False, False], [0, True, True], [None, True, False]] | [[0, True, True], [None, True, False], [1, True, True], [None, False, False], [None, False, True], [0, True, True], [None, True, False], [1, True, True], [None, False, False], [None, False, True]] | Failed |
SHA-256 / 9229921f76365b2981df2d185f3ef51b88dff0aa9b2417cc1ce29e3c5203ae65
3 / The verified repair
Exit 0"""Failure Map reference implementation. Python standard library only."""
import json
N = 1
observations = []
def solve(slots, width):
out=[]
mask=(1<<width)-1
for slot in slots:
payload=slot&mask
valid=not bool(slot&(1<<width))
parity=(slot>>(width+1))&1
parity_ok=((bin(payload).count("1")+int(not valid)+parity)%2)==0
sample=payload-(1<<width) if payload&(1<<(width-1)) else payload
out.append([sample if valid and parity_ok else None,valid,parity_ok])
return out
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('oracle 1', solve(*([0, 1, 33, 16, 48], 4)), [[0, True, True], [None, True, False], [1, True, True], [None, False, False], [None, False, True]])
check('oracle 2', solve(*([15, 47, 8, 40], 4)), [[-1, True, True], [None, True, False], [None, True, False], [-8, True, True]])
check('oracle 3', solve(*([], 4)), [])
check('oracle 4', solve(*([0, 1, 2, 3, 4, 5, 6, 7], 1)), [[0, True, True], [None, True, False], [None, False, False], [None, False, True], [None, True, False], [-1, True, True], [None, False, True], [None, False, False]])
check('oracle 5', solve(*([7, 23, 8, 24], 3)), [[None, True, False], [-1, True, True], [None, False, False], [None, False, True]])
check('oracle 6', solve(*([2, 3, 4, 5, 6], 4)), [[None, True, False], [3, True, True], [None, True, False], [5, True, True], [6, True, True]])
check('oracle 7', solve(*([255, 767, 256, 768], 8)), [[-1, True, True], [None, True, False], [None, False, False], [None, False, True]])
if N == 1: check('variant packet 1', solve(*[[0, 1, 33, 16, 48, 0, 1, 33, 16, 48], 4]), [[0, True, True], [None, True, False], [1, True, True], [None, False, False], [None, False, True], [0, True, True], [None, True, False], [1, True, True], [None, False, False], [None, False, True]])
if N == 2: check('variant packet 2', solve(*[[0, 1, 33, 16, 48, 0, 1, 33, 16, 48, 0, 1, 33, 16, 48], 4]), [[0, True, True], [None, True, False], [1, True, True], [None, False, False], [None, False, True], [0, True, True], [None, True, False], [1, True, True], [None, False, False], [None, False, True], [0, True, True], [None, True, False], [1, True, True], [None, False, False], [None, False, True]])
if N == 3: check('variant packet 3', solve(*[[0, 1, 33, 16, 48, 0, 1, 33, 16, 48, 0, 1, 33, 16, 48, 0, 1, 33, 16, 48], 4]), [[0, True, True], [None, True, False], [1, True, True], [None, False, False], [None, False, True], [0, True, True], [None, True, False], [1, True, True], [None, False, False], [None, False, True], [0, True, True], [None, True, False], [1, True, True], [None, False, False], [None, False, True], [0, True, True], [None, True, False], [1, True, True], [None, False, False], [None, False, True]])
if N == 4: check('variant packet 4', solve(*[[0, 1, 33, 16, 48, 0, 1, 33, 16, 48, 0, 1, 33, 16, 48, 0, 1, 33, 16, 48, 0, 1, 33, 16, 48], 4]), [[0, True, True], [None, True, False], [1, True, True], [None, False, False], [None, False, True], [0, True, True], [None, True, False], [1, True, True], [None, False, False], [None, False, True], [0, True, True], [None, True, False], [1, True, True], [None, False, False], [None, False, True], [0, True, True], [None, True, False], [1, True, True], [None, False, False], [None, False, True], [0, True, True], [None, True, False], [1, True, True], [None, False, False], [None, False, True]])
if N == 5: check('variant packet 5', solve(*[[0, 1, 33, 16, 48, 0, 1, 33, 16, 48, 0, 1, 33, 16, 48, 0, 1, 33, 16, 48, 0, 1, 33, 16, 48, 0, 1, 33, 16, 48], 4]), [[0, True, True], [None, True, False], [1, True, True], [None, False, False], [None, False, True], [0, True, True], [None, True, False], [1, True, True], [None, False, False], [None, False, True], [0, True, True], [None, True, False], [1, True, True], [None, False, False], [None, False, True], [0, True, True], [None, True, False], [1, True, True], [None, False, False], [None, False, True], [0, True, True], [None, True, False], [1, True, True], [None, False, False], [None, False, True], [0, True, True], [None, True, False], [1, True, True], [None, False, False], [None, False, 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 fixture | Actual | Expected | Outcome |
|---|---|---|---|
| oracle 1 | [[0, True, True], [None, True, False], [1, True, True], [None, False, False], [None, False, True]] | [[0, True, True], [None, True, False], [1, True, True], [None, False, False], [None, False, True]] | Passed |
| oracle 2 | [[-1, True, True], [None, True, False], [None, True, False], [-8, True, True]] | [[-1, True, True], [None, True, False], [None, True, False], [-8, True, True]] | Passed |
| oracle 3 | [] | [] | Passed |
| oracle 4 | [[0, True, True], [None, True, False], [None, False, False], [None, False, True], [None, True, False], [-1, True, True], [None, False, True], [None, False, False]] | [[0, True, True], [None, True, False], [None, False, False], [None, False, True], [None, True, False], [-1, True, True], [None, False, True], [None, False, False]] | Passed |
| oracle 5 | [[None, True, False], [-1, True, True], [None, False, False], [None, False, True]] | [[None, True, False], [-1, True, True], [None, False, False], [None, False, True]] | Passed |
| oracle 6 | [[None, True, False], [3, True, True], [None, True, False], [5, True, True], [6, True, True]] | [[None, True, False], [3, True, True], [None, True, False], [5, True, True], [6, True, True]] | Passed |
| oracle 7 | [[-1, True, True], [None, True, False], [None, False, False], [None, False, True]] | [[-1, True, True], [None, True, False], [None, False, False], [None, False, True]] | Passed |
| variant packet 1 | [[0, True, True], [None, True, False], [1, True, True], [None, False, False], [None, False, True], [0, True, True], [None, True, False], [1, True, True], [None, False, False], [None, False, True]] | [[0, True, True], [None, True, False], [1, True, True], [None, False, False], [None, False, True], [0, True, True], [None, True, False], [1, True, True], [None, False, False], [None, False, True]] | Passed |
SHA-256 / 898fdb7733ffec8b0307105871c3f75c9420c3c20f29d769a3c8257da617da82
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 2026-09-29T14:44:57.245458+00:00.
Case digest / 9839335f237c7f6fc689c8eaf38792c727a7b4fe94257eccf6bc67e5b1813933