FA-49821 / PCM sample encoding / Open access
Pcm adaptation table: current delta · case 01
Adaptation always scales the minimum rather than evolving delta.
ROOT CAUSE
Adaptation always scales the minimum rather than evolving delta.
VERIFIED REPAIR
Use the stated conversion contract at current delta.
Unsuccessful approach: Adding factor mixes fixed-point ratio and amplitude units.
Case contract
Apply a stipulated 16-code fixed-point PCM adaptation table sequentially, enforcing a minimum positive amplitude delta and returning continuation scale.
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(codes, delta, minimum, table):
out=[]
for code in codes:
factor=table[code&15]
product=minimum*factor
delta=max(minimum,product//256)
out.append(delta)
return [out,delta]
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('oracle 1', solve(*([0, 7, 8, 15], 20, 4, [230, 230, 230, 230, 307, 409, 512, 614, 614, 512, 409, 307, 230, 230, 230, 230])), [[17, 40, 95, 85], 85])
check('oracle 2', solve(*([0, 0, 0, 0], 5, 4, [128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128])), [[4, 4, 4, 4], 4])
check('oracle 3', solve(*([1, 2, 3], 10, 1, [200, 210, 220, 230, 240, 250, 260, 270, 280, 290, 300, 310, 320, 330, 340, 350])), [[8, 6, 5], 5])
check('oracle 4', solve(*([], 8, 2, [256, 256, 256, 256, 256, 256, 256, 256, 256, 256, 256, 256, 256, 256, 256, 256])), [[], 8])
check('oracle 5', solve(*([15, 8, 0], 9, 3, [200, 208, 216, 224, 232, 240, 248, 256, 264, 272, 280, 288, 296, 304, 312, 320])), [[11, 11, 8], 8])
check('oracle 6', solve(*([7, 7], 4, 4, [256, 256, 256, 256, 256, 256, 256, 512, 256, 256, 256, 256, 256, 256, 256, 256])), [[8, 16], 16])
check('oracle 7', solve(*([0, 1], 1, 1, [128, 768, 256, 256, 256, 256, 256, 256, 256, 256, 256, 256, 256, 256, 256, 256])), [[1, 3], 3])
if N == 1: check('variant packet 1', solve(*[[0, 7, 8, 15, 0, 7, 8, 15], 20, 4, [230, 230, 230, 230, 307, 409, 512, 614, 614, 512, 409, 307, 230, 230, 230, 230]]), [[17, 40, 95, 85, 76, 182, 436, 391], 391])
if N == 2: check('variant packet 2', solve(*[[0, 7, 8, 15, 0, 7, 8, 15, 0, 7, 8, 15], 20, 4, [230, 230, 230, 230, 307, 409, 512, 614, 614, 512, 409, 307, 230, 230, 230, 230]]), [[17, 40, 95, 85, 76, 182, 436, 391, 351, 841, 2017, 1812], 1812])
if N == 3: check('variant packet 3', solve(*[[0, 7, 8, 15, 0, 7, 8, 15, 0, 7, 8, 15, 0, 7, 8, 15], 20, 4, [230, 230, 230, 230, 307, 409, 512, 614, 614, 512, 409, 307, 230, 230, 230, 230]]), [[17, 40, 95, 85, 76, 182, 436, 391, 351, 841, 2017, 1812, 1627, 3902, 9358, 8407], 8407])
if N == 4: check('variant packet 4', solve(*[[0, 7, 8, 15, 0, 7, 8, 15, 0, 7, 8, 15, 0, 7, 8, 15, 0, 7, 8, 15], 20, 4, [230, 230, 230, 230, 307, 409, 512, 614, 614, 512, 409, 307, 230, 230, 230, 230]]), [[17, 40, 95, 85, 76, 182, 436, 391, 351, 841, 2017, 1812, 1627, 3902, 9358, 8407, 7553, 18115, 43447, 39034], 39034])
if N == 5: check('variant packet 5', solve(*[[0, 7, 8, 15, 0, 7, 8, 15, 0, 7, 8, 15, 0, 7, 8, 15, 0, 7, 8, 15, 0, 7, 8, 15], 20, 4, [230, 230, 230, 230, 307, 409, 512, 614, 614, 512, 409, 307, 230, 230, 230, 230]]), [[17, 40, 95, 85, 76, 182, 436, 391, 351, 841, 2017, 1812, 1627, 3902, 9358, 8407, 7553, 18115, 43447, 39034, 35069, 84110, 201732, 181243], 181243])
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 | [[4, 9, 9, 4], 4] | [[17, 40, 95, 85], 85] | Failed |
| oracle 2 | [[4, 4, 4, 4], 4] | [[4, 4, 4, 4], 4] | Passed |
| oracle 3 | [[1, 1, 1], 1] | [[8, 6, 5], 5] | Failed |
| oracle 4 | [[], 8] | [[], 8] | Passed |
| oracle 5 | [[3, 3, 3], 3] | [[11, 11, 8], 8] | Failed |
| oracle 6 | [[8, 8], 8] | [[8, 16], 16] | Failed |
| oracle 7 | [[1, 3], 3] | [[1, 3], 3] | Passed |
| variant packet 1 | [[4, 9, 9, 4, 4, 9, 9, 4], 4] | [[17, 40, 95, 85, 76, 182, 436, 391], 391] | Failed |
SHA-256 / c2700a7b3310993079f889a9caa55c546832da2c784fefcbc7d2d8df36182034
2 / The unsuccessful fix
Exit 1"""Failure Map reference implementation. Python standard library only."""
import json
N = 1
observations = []
def solve(codes, delta, minimum, table):
out=[]
for code in codes:
factor=table[code&15]
product=delta+factor
delta=max(minimum,product//256)
out.append(delta)
return [out,delta]
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('oracle 1', solve(*([0, 7, 8, 15], 20, 4, [230, 230, 230, 230, 307, 409, 512, 614, 614, 512, 409, 307, 230, 230, 230, 230])), [[17, 40, 95, 85], 85])
check('oracle 2', solve(*([0, 0, 0, 0], 5, 4, [128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128])), [[4, 4, 4, 4], 4])
check('oracle 3', solve(*([1, 2, 3], 10, 1, [200, 210, 220, 230, 240, 250, 260, 270, 280, 290, 300, 310, 320, 330, 340, 350])), [[8, 6, 5], 5])
check('oracle 4', solve(*([], 8, 2, [256, 256, 256, 256, 256, 256, 256, 256, 256, 256, 256, 256, 256, 256, 256, 256])), [[], 8])
check('oracle 5', solve(*([15, 8, 0], 9, 3, [200, 208, 216, 224, 232, 240, 248, 256, 264, 272, 280, 288, 296, 304, 312, 320])), [[11, 11, 8], 8])
check('oracle 6', solve(*([7, 7], 4, 4, [256, 256, 256, 256, 256, 256, 256, 512, 256, 256, 256, 256, 256, 256, 256, 256])), [[8, 16], 16])
check('oracle 7', solve(*([0, 1], 1, 1, [128, 768, 256, 256, 256, 256, 256, 256, 256, 256, 256, 256, 256, 256, 256, 256])), [[1, 3], 3])
if N == 1: check('variant packet 1', solve(*[[0, 7, 8, 15, 0, 7, 8, 15], 20, 4, [230, 230, 230, 230, 307, 409, 512, 614, 614, 512, 409, 307, 230, 230, 230, 230]]), [[17, 40, 95, 85, 76, 182, 436, 391], 391])
if N == 2: check('variant packet 2', solve(*[[0, 7, 8, 15, 0, 7, 8, 15, 0, 7, 8, 15], 20, 4, [230, 230, 230, 230, 307, 409, 512, 614, 614, 512, 409, 307, 230, 230, 230, 230]]), [[17, 40, 95, 85, 76, 182, 436, 391, 351, 841, 2017, 1812], 1812])
if N == 3: check('variant packet 3', solve(*[[0, 7, 8, 15, 0, 7, 8, 15, 0, 7, 8, 15, 0, 7, 8, 15], 20, 4, [230, 230, 230, 230, 307, 409, 512, 614, 614, 512, 409, 307, 230, 230, 230, 230]]), [[17, 40, 95, 85, 76, 182, 436, 391, 351, 841, 2017, 1812, 1627, 3902, 9358, 8407], 8407])
if N == 4: check('variant packet 4', solve(*[[0, 7, 8, 15, 0, 7, 8, 15, 0, 7, 8, 15, 0, 7, 8, 15, 0, 7, 8, 15], 20, 4, [230, 230, 230, 230, 307, 409, 512, 614, 614, 512, 409, 307, 230, 230, 230, 230]]), [[17, 40, 95, 85, 76, 182, 436, 391, 351, 841, 2017, 1812, 1627, 3902, 9358, 8407, 7553, 18115, 43447, 39034], 39034])
if N == 5: check('variant packet 5', solve(*[[0, 7, 8, 15, 0, 7, 8, 15, 0, 7, 8, 15, 0, 7, 8, 15, 0, 7, 8, 15, 0, 7, 8, 15], 20, 4, [230, 230, 230, 230, 307, 409, 512, 614, 614, 512, 409, 307, 230, 230, 230, 230]]), [[17, 40, 95, 85, 76, 182, 436, 391, 351, 841, 2017, 1812, 1627, 3902, 9358, 8407, 7553, 18115, 43447, 39034, 35069, 84110, 201732, 181243], 181243])
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 | [[4, 4, 4, 4], 4] | [[17, 40, 95, 85], 85] | Failed |
| oracle 2 | [[4, 4, 4, 4], 4] | [[4, 4, 4, 4], 4] | Passed |
| oracle 3 | [[1, 1, 1], 1] | [[8, 6, 5], 5] | Failed |
| oracle 4 | [[], 8] | [[], 8] | Passed |
| oracle 5 | [[3, 3, 3], 3] | [[11, 11, 8], 8] | Failed |
| oracle 6 | [[4, 4], 4] | [[8, 16], 16] | Failed |
| oracle 7 | [[1, 3], 3] | [[1, 3], 3] | Passed |
| variant packet 1 | [[4, 4, 4, 4, 4, 4, 4, 4], 4] | [[17, 40, 95, 85, 76, 182, 436, 391], 391] | Failed |
SHA-256 / 29009c538ef0c4c615cfd4a531812119aa410e6a1fcf537d82d211ae55b6bdc0
3 / The verified repair
Exit 0"""Failure Map reference implementation. Python standard library only."""
import json
N = 1
observations = []
def solve(codes, delta, minimum, table):
out=[]
for code in codes:
factor=table[code&15]
product=delta*factor
delta=max(minimum,product//256)
out.append(delta)
return [out,delta]
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('oracle 1', solve(*([0, 7, 8, 15], 20, 4, [230, 230, 230, 230, 307, 409, 512, 614, 614, 512, 409, 307, 230, 230, 230, 230])), [[17, 40, 95, 85], 85])
check('oracle 2', solve(*([0, 0, 0, 0], 5, 4, [128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128])), [[4, 4, 4, 4], 4])
check('oracle 3', solve(*([1, 2, 3], 10, 1, [200, 210, 220, 230, 240, 250, 260, 270, 280, 290, 300, 310, 320, 330, 340, 350])), [[8, 6, 5], 5])
check('oracle 4', solve(*([], 8, 2, [256, 256, 256, 256, 256, 256, 256, 256, 256, 256, 256, 256, 256, 256, 256, 256])), [[], 8])
check('oracle 5', solve(*([15, 8, 0], 9, 3, [200, 208, 216, 224, 232, 240, 248, 256, 264, 272, 280, 288, 296, 304, 312, 320])), [[11, 11, 8], 8])
check('oracle 6', solve(*([7, 7], 4, 4, [256, 256, 256, 256, 256, 256, 256, 512, 256, 256, 256, 256, 256, 256, 256, 256])), [[8, 16], 16])
check('oracle 7', solve(*([0, 1], 1, 1, [128, 768, 256, 256, 256, 256, 256, 256, 256, 256, 256, 256, 256, 256, 256, 256])), [[1, 3], 3])
if N == 1: check('variant packet 1', solve(*[[0, 7, 8, 15, 0, 7, 8, 15], 20, 4, [230, 230, 230, 230, 307, 409, 512, 614, 614, 512, 409, 307, 230, 230, 230, 230]]), [[17, 40, 95, 85, 76, 182, 436, 391], 391])
if N == 2: check('variant packet 2', solve(*[[0, 7, 8, 15, 0, 7, 8, 15, 0, 7, 8, 15], 20, 4, [230, 230, 230, 230, 307, 409, 512, 614, 614, 512, 409, 307, 230, 230, 230, 230]]), [[17, 40, 95, 85, 76, 182, 436, 391, 351, 841, 2017, 1812], 1812])
if N == 3: check('variant packet 3', solve(*[[0, 7, 8, 15, 0, 7, 8, 15, 0, 7, 8, 15, 0, 7, 8, 15], 20, 4, [230, 230, 230, 230, 307, 409, 512, 614, 614, 512, 409, 307, 230, 230, 230, 230]]), [[17, 40, 95, 85, 76, 182, 436, 391, 351, 841, 2017, 1812, 1627, 3902, 9358, 8407], 8407])
if N == 4: check('variant packet 4', solve(*[[0, 7, 8, 15, 0, 7, 8, 15, 0, 7, 8, 15, 0, 7, 8, 15, 0, 7, 8, 15], 20, 4, [230, 230, 230, 230, 307, 409, 512, 614, 614, 512, 409, 307, 230, 230, 230, 230]]), [[17, 40, 95, 85, 76, 182, 436, 391, 351, 841, 2017, 1812, 1627, 3902, 9358, 8407, 7553, 18115, 43447, 39034], 39034])
if N == 5: check('variant packet 5', solve(*[[0, 7, 8, 15, 0, 7, 8, 15, 0, 7, 8, 15, 0, 7, 8, 15, 0, 7, 8, 15, 0, 7, 8, 15], 20, 4, [230, 230, 230, 230, 307, 409, 512, 614, 614, 512, 409, 307, 230, 230, 230, 230]]), [[17, 40, 95, 85, 76, 182, 436, 391, 351, 841, 2017, 1812, 1627, 3902, 9358, 8407, 7553, 18115, 43447, 39034, 35069, 84110, 201732, 181243], 181243])
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 | [[17, 40, 95, 85], 85] | [[17, 40, 95, 85], 85] | Passed |
| oracle 2 | [[4, 4, 4, 4], 4] | [[4, 4, 4, 4], 4] | Passed |
| oracle 3 | [[8, 6, 5], 5] | [[8, 6, 5], 5] | Passed |
| oracle 4 | [[], 8] | [[], 8] | Passed |
| oracle 5 | [[11, 11, 8], 8] | [[11, 11, 8], 8] | Passed |
| oracle 6 | [[8, 16], 16] | [[8, 16], 16] | Passed |
| oracle 7 | [[1, 3], 3] | [[1, 3], 3] | Passed |
| variant packet 1 | [[17, 40, 95, 85, 76, 182, 436, 391], 391] | [[17, 40, 95, 85, 76, 182, 436, 391], 391] | Passed |
SHA-256 / ac398c765caeb6f955461bf73fe9a2e69eb45dc120cf4f4fe5f557e917274543
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 2026-09-29T14:45:03.552031+00:00.
Case digest / c93de5392b40767f56d0732a022de5cb4e7550e479d8b09c5f51a6cfa68212cf