FA-10881 / Audio frame buffers / Open access
Overrun drops oldest frames · case 01
Truncating the tail retains stale buffered audio and drops newest input.
ROOT CAUSE
Truncating the tail retains stale buffered audio and drops newest input.
VERIFIED REPAIR
Apply the explicit PCM/playback contract: Append mono samples and retain the newest at most nonnegative capacity samples for a drop-oldest real-time buffer.
Unsuccessful approach: Replacing the buffer with only incoming audio discards still-useful old samples before capacity is reached.
Case contract
Append mono samples and retain the newest at most nonnegative capacity samples for a drop-oldest real-time buffer.
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(buffer, incoming, capacity):
return (list(buffer)+list(incoming))[:capacity]
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('fixture 1',solve(*([1, 2], [3, 4], 3)),[2, 3, 4])
check('fixture 2',solve(*([1], [2], 3)),[1, 2])
check('fixture 3',solve(*([], [1, 2], 1)),[2])
check('fixture 4',solve(*([1], [2], 0)),[])
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] | [2, 3, 4] | Failed |
| fixture 2 | [1, 2] | [1, 2] | Passed |
| fixture 3 | [1] | [2] | Failed |
| fixture 4 | [] | [] | Passed |
SHA-256 / cc171a3a2a3c4c72c734d0d8ef734d8d0f4c6b0e5f703ab2eb26313d70e200d0
2 / The unsuccessful fix
Exit 1"""Failure Map reference implementation. Python standard library only."""
import json
import math
N = 1
observations = []
def solve(buffer, incoming, capacity):
return list(incoming[-capacity:]) if capacity else []
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('fixture 1',solve(*([1, 2], [3, 4], 3)),[2, 3, 4])
check('fixture 2',solve(*([1], [2], 3)),[1, 2])
check('fixture 3',solve(*([], [1, 2], 1)),[2])
check('fixture 4',solve(*([1], [2], 0)),[])
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] | [2, 3, 4] | Failed |
| fixture 2 | [2] | [1, 2] | Failed |
| fixture 3 | [2] | [2] | Passed |
| fixture 4 | [] | [] | Passed |
SHA-256 / fd71ce966e1bdc64fd34d224bc0efa492e49a650844da08b07bd93dec7212267
3 / The verified repair
Exit 0"""Failure Map reference implementation. Python standard library only."""
import json
import math
N = 1
observations = []
def solve(buffer, incoming, capacity):
return (list(buffer)+list(incoming))[-capacity:] if capacity else []
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('fixture 1',solve(*([1, 2], [3, 4], 3)),[2, 3, 4])
check('fixture 2',solve(*([1], [2], 3)),[1, 2])
check('fixture 3',solve(*([], [1, 2], 1)),[2])
check('fixture 4',solve(*([1], [2], 0)),[])
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, 4] | [2, 3, 4] | Passed |
| fixture 2 | [1, 2] | [1, 2] | Passed |
| fixture 3 | [2] | [2] | Passed |
| fixture 4 | [] | [] | Passed |
SHA-256 / d961728abc99b77e5a70e112d3bee639cd6f127f33e0d6941ec24433aa6e82bb
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 2026-09-29T14:38:43.109261+00:00.
Case digest / 0c131fecd7be182019ad9b0e92610fca26343ef0851c36470110f757755ebe78