FAILURE MAP
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FA-49381 / PCM sample encoding / Open access

Pcm channel reconstruction: frame retention · case 01

Decoded PCM frame boundaries are discarded.

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

ROOT CAUSE

Decoded PCM frame boundaries are discarded.

THE FAILURE

Decoded PCM frame boundaries are discarded.

Unsuccessful approach: Returning seed frames ignores every decoded residual.

Case contract

Decode channel-banked residual PCM, resetting predictors only at specified frame boundaries and exporting final per-channel amplitudes.

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(frames, seeds, resets):
    state=list(seeds)
    out=[]
    for index,frame in enumerate(frames):
        if index in resets:
            state=list(seeds)
        reconstructed=[]
        for channel,residual in enumerate(frame):
            state[channel]+=residual
            reconstructed.append(state[channel])
        out.extend(reconstructed)
    return [out,state]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('oracle 1', solve(*([[3, 2], [2, -1]], [2, 8], [])), [[[5, 10], [7, 9]], [7, 9]])
check('oracle 2', solve(*([[1, 2], [2, 3], [4, 1]], [1, 2], [1])), [[[2, 4], [3, 5], [7, 6]], [7, 6]])
check('oracle 3', solve(*([], [3, 4], [])), [[], [3, 4]])
check('oracle 4', solve(*([[1], [2], [-1]], [0], [2])), [[[1], [3], [-1]], [-1]])
check('oracle 5', solve(*([[-1, -1], [2, -2]], [-1, 4], [])), [[[-2, 3], [0, 1]], [0, 1]])
check('oracle 6', solve(*([[1, 2, 3]], [3, 2, 1], [0])), [[[4, 4, 4]], [4, 4, 4]])
check('oracle 7', solve(*([[0, 0], [0, 0]], [1, -1], [])), [[[1, -1], [1, -1]], [1, -1]])
if N == 1: check('variant packet 1', solve(*[[[3, 2], [2, -1], [3, 2], [2, -1]], [2, 8], []]), [[[5, 10], [7, 9], [10, 11], [12, 10]], [12, 10]])
if N == 2: check('variant packet 2', solve(*[[[3, 2], [2, -1], [3, 2], [2, -1], [3, 2], [2, -1]], [2, 8], []]), [[[5, 10], [7, 9], [10, 11], [12, 10], [15, 12], [17, 11]], [17, 11]])
if N == 3: check('variant packet 3', solve(*[[[3, 2], [2, -1], [3, 2], [2, -1], [3, 2], [2, -1], [3, 2], [2, -1]], [2, 8], []]), [[[5, 10], [7, 9], [10, 11], [12, 10], [15, 12], [17, 11], [20, 13], [22, 12]], [22, 12]])
if N == 4: check('variant packet 4', solve(*[[[3, 2], [2, -1], [3, 2], [2, -1], [3, 2], [2, -1], [3, 2], [2, -1], [3, 2], [2, -1]], [2, 8], []]), [[[5, 10], [7, 9], [10, 11], [12, 10], [15, 12], [17, 11], [20, 13], [22, 12], [25, 14], [27, 13]], [27, 13]])
if N == 5: check('variant packet 5', solve(*[[[3, 2], [2, -1], [3, 2], [2, -1], [3, 2], [2, -1], [3, 2], [2, -1], [3, 2], [2, -1], [3, 2], [2, -1]], [2, 8], []]), [[[5, 10], [7, 9], [10, 11], [12, 10], [15, 12], [17, 11], [20, 13], [22, 12], [25, 14], [27, 13], [30, 15], [32, 14]], [32, 14]])
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[[5, 10, 7, 9], [7, 9]][[[5, 10], [7, 9]], [7, 9]]Failed
oracle 2[[2, 4, 3, 5, 7, 6], [7, 6]][[[2, 4], [3, 5], [7, 6]], [7, 6]]Failed
oracle 3[[], [3, 4]][[], [3, 4]]Passed
oracle 4[[1, 3, -1], [-1]][[[1], [3], [-1]], [-1]]Failed
oracle 5[[-2, 3, 0, 1], [0, 1]][[[-2, 3], [0, 1]], [0, 1]]Failed
oracle 6[[4, 4, 4], [4, 4, 4]][[[4, 4, 4]], [4, 4, 4]]Failed
oracle 7[[1, -1, 1, -1], [1, -1]][[[1, -1], [1, -1]], [1, -1]]Failed
variant packet 1[[5, 10, 7, 9, 10, 11, 12, 10], [12, 10]][[[5, 10], [7, 9], [10, 11], [12, 10]], [12, 10]]Failed

SHA-256 / f23282ac5f67b03133a0f606c882bc1344fe18dd0e50d192b822116499ef5ba5

2 / The unsuccessful fix

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

N = 1
observations = []
def solve(frames, seeds, resets):
    state=list(seeds)
    out=[]
    for index,frame in enumerate(frames):
        if index in resets:
            state=list(seeds)
        reconstructed=[]
        for channel,residual in enumerate(frame):
            state[channel]+=residual
            reconstructed.append(state[channel])
        out.append(list(seeds))
    return [out,state]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('oracle 1', solve(*([[3, 2], [2, -1]], [2, 8], [])), [[[5, 10], [7, 9]], [7, 9]])
check('oracle 2', solve(*([[1, 2], [2, 3], [4, 1]], [1, 2], [1])), [[[2, 4], [3, 5], [7, 6]], [7, 6]])
check('oracle 3', solve(*([], [3, 4], [])), [[], [3, 4]])
check('oracle 4', solve(*([[1], [2], [-1]], [0], [2])), [[[1], [3], [-1]], [-1]])
check('oracle 5', solve(*([[-1, -1], [2, -2]], [-1, 4], [])), [[[-2, 3], [0, 1]], [0, 1]])
check('oracle 6', solve(*([[1, 2, 3]], [3, 2, 1], [0])), [[[4, 4, 4]], [4, 4, 4]])
check('oracle 7', solve(*([[0, 0], [0, 0]], [1, -1], [])), [[[1, -1], [1, -1]], [1, -1]])
if N == 1: check('variant packet 1', solve(*[[[3, 2], [2, -1], [3, 2], [2, -1]], [2, 8], []]), [[[5, 10], [7, 9], [10, 11], [12, 10]], [12, 10]])
if N == 2: check('variant packet 2', solve(*[[[3, 2], [2, -1], [3, 2], [2, -1], [3, 2], [2, -1]], [2, 8], []]), [[[5, 10], [7, 9], [10, 11], [12, 10], [15, 12], [17, 11]], [17, 11]])
if N == 3: check('variant packet 3', solve(*[[[3, 2], [2, -1], [3, 2], [2, -1], [3, 2], [2, -1], [3, 2], [2, -1]], [2, 8], []]), [[[5, 10], [7, 9], [10, 11], [12, 10], [15, 12], [17, 11], [20, 13], [22, 12]], [22, 12]])
if N == 4: check('variant packet 4', solve(*[[[3, 2], [2, -1], [3, 2], [2, -1], [3, 2], [2, -1], [3, 2], [2, -1], [3, 2], [2, -1]], [2, 8], []]), [[[5, 10], [7, 9], [10, 11], [12, 10], [15, 12], [17, 11], [20, 13], [22, 12], [25, 14], [27, 13]], [27, 13]])
if N == 5: check('variant packet 5', solve(*[[[3, 2], [2, -1], [3, 2], [2, -1], [3, 2], [2, -1], [3, 2], [2, -1], [3, 2], [2, -1], [3, 2], [2, -1]], [2, 8], []]), [[[5, 10], [7, 9], [10, 11], [12, 10], [15, 12], [17, 11], [20, 13], [22, 12], [25, 14], [27, 13], [30, 15], [32, 14]], [32, 14]])
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[[[2, 8], [2, 8]], [7, 9]][[[5, 10], [7, 9]], [7, 9]]Failed
oracle 2[[[1, 2], [1, 2], [1, 2]], [7, 6]][[[2, 4], [3, 5], [7, 6]], [7, 6]]Failed
oracle 3[[], [3, 4]][[], [3, 4]]Passed
oracle 4[[[0], [0], [0]], [-1]][[[1], [3], [-1]], [-1]]Failed
oracle 5[[[-1, 4], [-1, 4]], [0, 1]][[[-2, 3], [0, 1]], [0, 1]]Failed
oracle 6[[[3, 2, 1]], [4, 4, 4]][[[4, 4, 4]], [4, 4, 4]]Failed
oracle 7[[[1, -1], [1, -1]], [1, -1]][[[1, -1], [1, -1]], [1, -1]]Passed
variant packet 1[[[2, 8], [2, 8], [2, 8], [2, 8]], [12, 10]][[[5, 10], [7, 9], [10, 11], [12, 10]], [12, 10]]Failed

SHA-256 / fd35c6d698877142fd22fa3ffe97c5d9891aa75ec221e9ee9df8f451c4e9591b

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 2026-09-29T14:44:59.565152+00:00.

Case digest / a8467bdf1371af26d7be86a6ac1e5b828c886f1490e9a50f14499435463cd6ee