FA-10821 / Audio frame buffers / Open access

Interleave stereo frame order · case 01

Concatenating channel planes does not produce interleaved frames.

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

ROOT CAUSE

Concatenating channel planes does not produce interleaved frames.

VERIFIED REPAIR

Apply the explicit PCM/playback contract: Interleave equal-length left/right sample arrays into L,R frame order.

Unsuccessful approach: Interleaving right first swaps stereo position.

Case contract

Interleave equal-length left/right sample arrays into L,R frame order.

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(left, right):
    return list(left)+list(right)
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('fixture 1',solve(*([1, 2], [3, 4])),[1, 3, 2, 4])
check('fixture 2',solve(*([], [])),[])
check('fixture 3',solve(*([5], [6])),[5, 6])
check('fixture 4',solve(*([-1, 0], [0, 1])),[-1, 0, 0, 1])
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	`[1, 2, 3, 4]`	`[1, 3, 2, 4]`	Failed
fixture 2	`[]`	`[]`	Passed
fixture 3	`[5, 6]`	`[5, 6]`	Passed
fixture 4	`[-1, 0, 0, 1]`	`[-1, 0, 0, 1]`	Passed

SHA-256 / 58df13019346e6894d8e0925dedc9ba88c560abaf30700a1e56582bac5736160

2 / The unsuccessful fix

Exit 1

"""Failure Map reference implementation. Python standard library only."""
import json
import math
N = 1
observations = []
def solve(left, right):
    return [x for pair in zip(right,left) for x in pair]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('fixture 1',solve(*([1, 2], [3, 4])),[1, 3, 2, 4])
check('fixture 2',solve(*([], [])),[])
check('fixture 3',solve(*([5], [6])),[5, 6])
check('fixture 4',solve(*([-1, 0], [0, 1])),[-1, 0, 0, 1])
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, 1, 4, 2]`	`[1, 3, 2, 4]`	Failed
fixture 2	`[]`	`[]`	Passed
fixture 3	`[6, 5]`	`[5, 6]`	Failed
fixture 4	`[0, -1, 1, 0]`	`[-1, 0, 0, 1]`	Failed

SHA-256 / 17d090819965d1a844b7ae84371c24997d572f7de06272f1433eb88994785b96

3 / The verified repair

Exit 0

"""Failure Map reference implementation. Python standard library only."""
import json
import math
N = 1
observations = []
def solve(left, right):
    return [x for pair in zip(left,right) for x in pair]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('fixture 1',solve(*([1, 2], [3, 4])),[1, 3, 2, 4])
check('fixture 2',solve(*([], [])),[])
check('fixture 3',solve(*([5], [6])),[5, 6])
check('fixture 4',solve(*([-1, 0], [0, 1])),[-1, 0, 0, 1])
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	`[1, 3, 2, 4]`	`[1, 3, 2, 4]`	Passed
fixture 2	`[]`	`[]`	Passed
fixture 3	`[5, 6]`	`[5, 6]`	Passed
fixture 4	`[-1, 0, 0, 1]`	`[-1, 0, 0, 1]`	Passed

SHA-256 / 9618d8e0ad399f7d79bf749299802d5889a752d7d3af7775e535c811a81b3376

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 2026-09-29T14:38:42.534686+00:00.

Case digest / cd478a6f9f05491abdda46b829f10f884b6d43b90c79792f43b2063fc20b6a76