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FA-49396 / PCM sample encoding / Open access

Pcm silence run packets: run count · case 01

Silence run length loses its last sample.

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

ROOT CAUSE

Silence run length loses its last sample.

VERIFIED REPAIR

Use the stated conversion contract at run count.

Unsuccessful approach: Forcing a minimum inserts a sample for empty runs.

Case contract

Decode tagged PCM literal and silence-run packets up to a sample capacity, honoring the declared digital-silence code and skipping unknown 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(packets, zero, limit):
    out=[]
    for tag,payload in packets:
        if tag=='audio':
            out.extend(payload)
        elif tag=='silence':
            out.extend([zero]*max(0,payload-1))
        else:
            continue
        if len(out)>=limit:
            out=out[:limit]
            break
    return out
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('oracle 1', solve(*([['audio', [130, 131]], ['silence', 2], ['audio', [129]]], 128, 8)), [130, 131, 128, 128, 129])
check('oracle 2', solve(*([['silence', 0], ['audio', [5]]], 128, 5)), [5])
check('oracle 3', solve(*([['metadata', []], ['audio', [1, 2]]], 0, 4)), [1, 2])
check('oracle 4', solve(*([['audio', [1, 2, 3]], ['silence', 2]], 0, 2)), [1, 2])
check('oracle 5', solve(*([], 128, 5)), [])
check('oracle 6', solve(*([['silence', -1], ['silence', 2]], 128, 3)), [128, 128])
check('oracle 7', solve(*([['audio', [1]], ['audio', [2]]], 0, 0)), [])
if N == 1: check('variant packet 1', solve(*[[['audio', [130, 131]], ['silence', 2], ['audio', [129]], ['audio', [130, 131]], ['silence', 2], ['audio', [129]]], 128, 16]), [130, 131, 128, 128, 129, 130, 131, 128, 128, 129])
if N == 2: check('variant packet 2', solve(*[[['audio', [130, 131]], ['silence', 2], ['audio', [129]], ['audio', [130, 131]], ['silence', 2], ['audio', [129]], ['audio', [130, 131]], ['silence', 2], ['audio', [129]]], 128, 24]), [130, 131, 128, 128, 129, 130, 131, 128, 128, 129, 130, 131, 128, 128, 129])
if N == 3: check('variant packet 3', solve(*[[['audio', [130, 131]], ['silence', 2], ['audio', [129]], ['audio', [130, 131]], ['silence', 2], ['audio', [129]], ['audio', [130, 131]], ['silence', 2], ['audio', [129]], ['audio', [130, 131]], ['silence', 2], ['audio', [129]]], 128, 32]), [130, 131, 128, 128, 129, 130, 131, 128, 128, 129, 130, 131, 128, 128, 129, 130, 131, 128, 128, 129])
if N == 4: check('variant packet 4', solve(*[[['audio', [130, 131]], ['silence', 2], ['audio', [129]], ['audio', [130, 131]], ['silence', 2], ['audio', [129]], ['audio', [130, 131]], ['silence', 2], ['audio', [129]], ['audio', [130, 131]], ['silence', 2], ['audio', [129]], ['audio', [130, 131]], ['silence', 2], ['audio', [129]]], 128, 40]), [130, 131, 128, 128, 129, 130, 131, 128, 128, 129, 130, 131, 128, 128, 129, 130, 131, 128, 128, 129, 130, 131, 128, 128, 129])
if N == 5: check('variant packet 5', solve(*[[['audio', [130, 131]], ['silence', 2], ['audio', [129]], ['audio', [130, 131]], ['silence', 2], ['audio', [129]], ['audio', [130, 131]], ['silence', 2], ['audio', [129]], ['audio', [130, 131]], ['silence', 2], ['audio', [129]], ['audio', [130, 131]], ['silence', 2], ['audio', [129]], ['audio', [130, 131]], ['silence', 2], ['audio', [129]]], 128, 48]), [130, 131, 128, 128, 129, 130, 131, 128, 128, 129, 130, 131, 128, 128, 129, 130, 131, 128, 128, 129, 130, 131, 128, 128, 129, 130, 131, 128, 128, 129])
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[130, 131, 128, 129][130, 131, 128, 128, 129]Failed
oracle 2[5][5]Passed
oracle 3[1, 2][1, 2]Passed
oracle 4[1, 2][1, 2]Passed
oracle 5[][]Passed
oracle 6[128][128, 128]Failed
oracle 7[][]Passed
variant packet 1[130, 131, 128, 129, 130, 131, 128, 129][130, 131, 128, 128, 129, 130, 131, 128, 128, 129]Failed

SHA-256 / 6aebc4274ec717cdecc81bee9563a298ab24cb9c6145c9fce39af60192d22daf

2 / The unsuccessful fix

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

N = 1
observations = []
def solve(packets, zero, limit):
    out=[]
    for tag,payload in packets:
        if tag=='audio':
            out.extend(payload)
        elif tag=='silence':
            out.extend([zero]*max(1,payload))
        else:
            continue
        if len(out)>=limit:
            out=out[:limit]
            break
    return out
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('oracle 1', solve(*([['audio', [130, 131]], ['silence', 2], ['audio', [129]]], 128, 8)), [130, 131, 128, 128, 129])
check('oracle 2', solve(*([['silence', 0], ['audio', [5]]], 128, 5)), [5])
check('oracle 3', solve(*([['metadata', []], ['audio', [1, 2]]], 0, 4)), [1, 2])
check('oracle 4', solve(*([['audio', [1, 2, 3]], ['silence', 2]], 0, 2)), [1, 2])
check('oracle 5', solve(*([], 128, 5)), [])
check('oracle 6', solve(*([['silence', -1], ['silence', 2]], 128, 3)), [128, 128])
check('oracle 7', solve(*([['audio', [1]], ['audio', [2]]], 0, 0)), [])
if N == 1: check('variant packet 1', solve(*[[['audio', [130, 131]], ['silence', 2], ['audio', [129]], ['audio', [130, 131]], ['silence', 2], ['audio', [129]]], 128, 16]), [130, 131, 128, 128, 129, 130, 131, 128, 128, 129])
if N == 2: check('variant packet 2', solve(*[[['audio', [130, 131]], ['silence', 2], ['audio', [129]], ['audio', [130, 131]], ['silence', 2], ['audio', [129]], ['audio', [130, 131]], ['silence', 2], ['audio', [129]]], 128, 24]), [130, 131, 128, 128, 129, 130, 131, 128, 128, 129, 130, 131, 128, 128, 129])
if N == 3: check('variant packet 3', solve(*[[['audio', [130, 131]], ['silence', 2], ['audio', [129]], ['audio', [130, 131]], ['silence', 2], ['audio', [129]], ['audio', [130, 131]], ['silence', 2], ['audio', [129]], ['audio', [130, 131]], ['silence', 2], ['audio', [129]]], 128, 32]), [130, 131, 128, 128, 129, 130, 131, 128, 128, 129, 130, 131, 128, 128, 129, 130, 131, 128, 128, 129])
if N == 4: check('variant packet 4', solve(*[[['audio', [130, 131]], ['silence', 2], ['audio', [129]], ['audio', [130, 131]], ['silence', 2], ['audio', [129]], ['audio', [130, 131]], ['silence', 2], ['audio', [129]], ['audio', [130, 131]], ['silence', 2], ['audio', [129]], ['audio', [130, 131]], ['silence', 2], ['audio', [129]]], 128, 40]), [130, 131, 128, 128, 129, 130, 131, 128, 128, 129, 130, 131, 128, 128, 129, 130, 131, 128, 128, 129, 130, 131, 128, 128, 129])
if N == 5: check('variant packet 5', solve(*[[['audio', [130, 131]], ['silence', 2], ['audio', [129]], ['audio', [130, 131]], ['silence', 2], ['audio', [129]], ['audio', [130, 131]], ['silence', 2], ['audio', [129]], ['audio', [130, 131]], ['silence', 2], ['audio', [129]], ['audio', [130, 131]], ['silence', 2], ['audio', [129]], ['audio', [130, 131]], ['silence', 2], ['audio', [129]]], 128, 48]), [130, 131, 128, 128, 129, 130, 131, 128, 128, 129, 130, 131, 128, 128, 129, 130, 131, 128, 128, 129, 130, 131, 128, 128, 129, 130, 131, 128, 128, 129])
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[130, 131, 128, 128, 129][130, 131, 128, 128, 129]Passed
oracle 2[128, 5][5]Failed
oracle 3[1, 2][1, 2]Passed
oracle 4[1, 2][1, 2]Passed
oracle 5[][]Passed
oracle 6[128, 128, 128][128, 128]Failed
oracle 7[][]Passed
variant packet 1[130, 131, 128, 128, 129, 130, 131, 128, 128, 129][130, 131, 128, 128, 129, 130, 131, 128, 128, 129]Passed

SHA-256 / d416bc72613de1794f9c815375bba1f214660819115296a660bf94e1ab5cf225

3 / The verified repair

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

N = 1
observations = []
def solve(packets, zero, limit):
    out=[]
    for tag,payload in packets:
        if tag=='audio':
            out.extend(payload)
        elif tag=='silence':
            out.extend([zero]*max(0,payload))
        else:
            continue
        if len(out)>=limit:
            out=out[:limit]
            break
    return out
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('oracle 1', solve(*([['audio', [130, 131]], ['silence', 2], ['audio', [129]]], 128, 8)), [130, 131, 128, 128, 129])
check('oracle 2', solve(*([['silence', 0], ['audio', [5]]], 128, 5)), [5])
check('oracle 3', solve(*([['metadata', []], ['audio', [1, 2]]], 0, 4)), [1, 2])
check('oracle 4', solve(*([['audio', [1, 2, 3]], ['silence', 2]], 0, 2)), [1, 2])
check('oracle 5', solve(*([], 128, 5)), [])
check('oracle 6', solve(*([['silence', -1], ['silence', 2]], 128, 3)), [128, 128])
check('oracle 7', solve(*([['audio', [1]], ['audio', [2]]], 0, 0)), [])
if N == 1: check('variant packet 1', solve(*[[['audio', [130, 131]], ['silence', 2], ['audio', [129]], ['audio', [130, 131]], ['silence', 2], ['audio', [129]]], 128, 16]), [130, 131, 128, 128, 129, 130, 131, 128, 128, 129])
if N == 2: check('variant packet 2', solve(*[[['audio', [130, 131]], ['silence', 2], ['audio', [129]], ['audio', [130, 131]], ['silence', 2], ['audio', [129]], ['audio', [130, 131]], ['silence', 2], ['audio', [129]]], 128, 24]), [130, 131, 128, 128, 129, 130, 131, 128, 128, 129, 130, 131, 128, 128, 129])
if N == 3: check('variant packet 3', solve(*[[['audio', [130, 131]], ['silence', 2], ['audio', [129]], ['audio', [130, 131]], ['silence', 2], ['audio', [129]], ['audio', [130, 131]], ['silence', 2], ['audio', [129]], ['audio', [130, 131]], ['silence', 2], ['audio', [129]]], 128, 32]), [130, 131, 128, 128, 129, 130, 131, 128, 128, 129, 130, 131, 128, 128, 129, 130, 131, 128, 128, 129])
if N == 4: check('variant packet 4', solve(*[[['audio', [130, 131]], ['silence', 2], ['audio', [129]], ['audio', [130, 131]], ['silence', 2], ['audio', [129]], ['audio', [130, 131]], ['silence', 2], ['audio', [129]], ['audio', [130, 131]], ['silence', 2], ['audio', [129]], ['audio', [130, 131]], ['silence', 2], ['audio', [129]]], 128, 40]), [130, 131, 128, 128, 129, 130, 131, 128, 128, 129, 130, 131, 128, 128, 129, 130, 131, 128, 128, 129, 130, 131, 128, 128, 129])
if N == 5: check('variant packet 5', solve(*[[['audio', [130, 131]], ['silence', 2], ['audio', [129]], ['audio', [130, 131]], ['silence', 2], ['audio', [129]], ['audio', [130, 131]], ['silence', 2], ['audio', [129]], ['audio', [130, 131]], ['silence', 2], ['audio', [129]], ['audio', [130, 131]], ['silence', 2], ['audio', [129]], ['audio', [130, 131]], ['silence', 2], ['audio', [129]]], 128, 48]), [130, 131, 128, 128, 129, 130, 131, 128, 128, 129, 130, 131, 128, 128, 129, 130, 131, 128, 128, 129, 130, 131, 128, 128, 129, 130, 131, 128, 128, 129])
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[130, 131, 128, 128, 129][130, 131, 128, 128, 129]Passed
oracle 2[5][5]Passed
oracle 3[1, 2][1, 2]Passed
oracle 4[1, 2][1, 2]Passed
oracle 5[][]Passed
oracle 6[128, 128][128, 128]Passed
oracle 7[][]Passed
variant packet 1[130, 131, 128, 128, 129, 130, 131, 128, 128, 129][130, 131, 128, 128, 129, 130, 131, 128, 128, 129]Passed

SHA-256 / 3564ee83964e727d419515e371414bd9730c01bd6ce4cca7cf4536b2a29c8f0b

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 2026-09-29T14:44:59.689478+00:00.

Case digest / 252be8593eae8d13c07e67a536455d58e1d651efed14d7976cf86a43b8f64fe0