FA-10856 / Audio frame buffers / Open access
Replace one channel · case 01
A mono channel update overwrites every channel in its frame.
ROOT CAUSE
A mono channel update overwrites every channel in its frame.
VERIFIED REPAIR
Apply the explicit PCM/playback contract: Replace one valid channel in every frame with corresponding per-frame values; values length equals frame count.
Unsuccessful approach: Repeating the first replacement sample loses the replacement waveform over time.
Case contract
Replace one valid channel in every frame with corresponding per-frame values; values length equals frame 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(frames, channel, values):
return [[values[i] for x in frame] for i,frame in enumerate(frames)]
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, [8, 9])),[[1, 8], [3, 9]])
check('fixture 2',solve(*([[1, 2]], 0, [0])),[[0, 2]])
check('fixture 3',solve(*([], 0, [])),[])
check('fixture 4',solve(*([[1], [2]], 0, [4, 5])),[[4], [5]])
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 | [[8, 8], [9, 9]] | [[1, 8], [3, 9]] | Failed |
| fixture 2 | [[0, 0]] | [[0, 2]] | Failed |
| fixture 3 | [] | [] | Passed |
| fixture 4 | [[4], [5]] | [[4], [5]] | Passed |
SHA-256 / 60ad1ac977bd0b9f0589dcf35fec4986e36baccbc59db64bb5372f8160c16705
2 / The unsuccessful fix
Exit 1"""Failure Map reference implementation. Python standard library only."""
import json
import math
N = 1
observations = []
def solve(frames, channel, values):
return [[values[0] if c==channel else x for c,x in enumerate(frame)] for frame in frames]
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, [8, 9])),[[1, 8], [3, 9]])
check('fixture 2',solve(*([[1, 2]], 0, [0])),[[0, 2]])
check('fixture 3',solve(*([], 0, [])),[])
check('fixture 4',solve(*([[1], [2]], 0, [4, 5])),[[4], [5]])
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, 8], [3, 8]] | [[1, 8], [3, 9]] | Failed |
| fixture 2 | [[0, 2]] | [[0, 2]] | Passed |
| fixture 3 | [] | [] | Passed |
| fixture 4 | [[4], [4]] | [[4], [5]] | Failed |
SHA-256 / dff29e4ee8541d791705dd4483806df9c0aa931da8c3679308a06d48d954fa05
3 / The verified repair
Exit 0"""Failure Map reference implementation. Python standard library only."""
import json
import math
N = 1
observations = []
def solve(frames, channel, values):
return [[values[i] if c==channel else x for c,x in enumerate(frame)] for i,frame in enumerate(frames)]
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, [8, 9])),[[1, 8], [3, 9]])
check('fixture 2',solve(*([[1, 2]], 0, [0])),[[0, 2]])
check('fixture 3',solve(*([], 0, [])),[])
check('fixture 4',solve(*([[1], [2]], 0, [4, 5])),[[4], [5]])
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, 8], [3, 9]] | [[1, 8], [3, 9]] | Passed |
| fixture 2 | [[0, 2]] | [[0, 2]] | Passed |
| fixture 3 | [] | [] | Passed |
| fixture 4 | [[4], [5]] | [[4], [5]] | Passed |
SHA-256 / 7ce5a6f9fda5c0b1160414087c1e28c976a485bf519320d997eecfc77463a2e7
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 2026-09-29T14:38:42.858577+00:00.
Case digest / 10b66e80c9c5d87789f5e3db217511cf9c23fa6d0aafe434887f3fd033d6996c