FA-10836 / Audio frame buffers / Open access

Frame slice multiplies channel stride · case 01

Frame offsets and lengths are applied as individual sample offsets.

Verified by executionVariant 1 · 4 checks per implementationDownload source bundle ↓JSON ↗

ROOT CAUSE

Frame offsets and lengths are applied as individual sample offsets.

THE FAILURE

Frame offsets and lengths are applied as individual sample offsets.

Unsuccessful approach: Scaling only the start still truncates each multichannel frame count.

Case contract

Return count complete frames from in-bounds frame offset start in interleaved PCM with positive channel count.

Why this case matters

A pure Python local audio pipeline stage with explicit sample formats and frame conventions; no real-time device or signal-spectrum claims.

1 / The failure

Exit 1

"""Failure Map reference implementation. Python standard library only."""
import json
import math
N = 1
observations = []
def solve(samples, channels, start, count):
    return samples[start:start+count]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('fixture 1',solve(*([1, 2, 3, 4, 5, 6], 2, 1, 2)),[3, 4, 5, 6])
check('fixture 2',solve(*([1, 2], 2, 0, 1)),[1, 2])
check('fixture 3',solve(*([1, 2], 2, 1, 0)),[])
check('fixture 4',solve(*([1, 2, 3], 1, 1, 1)),[2])
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
fixture 1	`[2, 3]`	`[3, 4, 5, 6]`	Failed
fixture 2	`[1]`	`[1, 2]`	Failed
fixture 3	`[]`	`[]`	Passed
fixture 4	`[2]`	`[2]`	Passed

SHA-256 / a4e67be6088409b1f5713b9d2bb8a67d21168e63dd57fac978c4df469a04814a

2 / The unsuccessful fix

Exit 1

"""Failure Map reference implementation. Python standard library only."""
import json
import math
N = 1
observations = []
def solve(samples, channels, start, count):
    return samples[start*channels:start*channels+count]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('fixture 1',solve(*([1, 2, 3, 4, 5, 6], 2, 1, 2)),[3, 4, 5, 6])
check('fixture 2',solve(*([1, 2], 2, 0, 1)),[1, 2])
check('fixture 3',solve(*([1, 2], 2, 1, 0)),[])
check('fixture 4',solve(*([1, 2, 3], 1, 1, 1)),[2])
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
fixture 1	`[3, 4]`	`[3, 4, 5, 6]`	Failed
fixture 2	`[1]`	`[1, 2]`	Failed
fixture 3	`[]`	`[]`	Passed
fixture 4	`[2]`	`[2]`	Passed

SHA-256 / c6601c5b5761636e5ad4272a85289218a7407dcc459a250f02aa73a2acd1b4e4

HELD IN THE MEMBER ARCHIVE

The verified repair and its recorded checks are member-only.

This mechanism has 4 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

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 2026-09-29T14:38:42.617534+00:00.

Case digest / 66c836d5302a9ece4b6357d8ca05b503913285e8c2fcacdf2d213d8accfadc77