FA-11241 / Media timeline seeking / Open access
Duration from timebase endpoint · case 01
Duration ends at the final frame start and omits its displayed duration.
ROOT CAUSE
Duration ends at the final frame start and omits its displayed duration.
VERIFIED REPAIR
Preserve the media contract: For a nonempty constant-duration frame sequence, compute full duration from first/last start ticks plus final frame duration, divided by positive timescale.
Unsuccessful approach: Using an absolute final endpoint counts the nonzero start offset as duration.
Case contract
For a nonempty constant-duration frame sequence, compute full duration from first/last start ticks plus final frame duration, divided by positive timescale.
Why this case matters
A deterministic local media controller stage; metadata and downloaded data are supplied explicitly. No external player, service or codec is required.
1 / The failure
Exit 1"""Failure Map reference implementation. Python standard library only."""
import json
import math
N = 1
observations = []
def solve(first, last, frame_duration, timescale):
return (last-first)/timescale
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('fixture 1',solve(*(100, 140, 20, 100)),0.6)
check('fixture 2',solve(*(0, 0, 25, 100)),0.25)
check('fixture 3',solve(*(50, 50, 0, 100)),0)
check('fixture 4',solve(*(0, 75, 25, 100)),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 | 0.4 | 0.6 | Failed |
| fixture 2 | 0.0 | 0.25 | Failed |
| fixture 3 | 0.0 | 0 | Passed |
| fixture 4 | 0.75 | 1 | Failed |
SHA-256 / d3296361f865a962fb6870a2a5c37476c1f9a52efd046b00bba4d0cef8ca0c2c
2 / The unsuccessful fix
Exit 1"""Failure Map reference implementation. Python standard library only."""
import json
import math
N = 1
observations = []
def solve(first, last, frame_duration, timescale):
return (last+frame_duration)/timescale
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('fixture 1',solve(*(100, 140, 20, 100)),0.6)
check('fixture 2',solve(*(0, 0, 25, 100)),0.25)
check('fixture 3',solve(*(50, 50, 0, 100)),0)
check('fixture 4',solve(*(0, 75, 25, 100)),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 | 1.6 | 0.6 | Failed |
| fixture 2 | 0.25 | 0.25 | Passed |
| fixture 3 | 0.5 | 0 | Failed |
| fixture 4 | 1.0 | 1 | Passed |
SHA-256 / bbcb87a854c96d8ce3703d3c4a5cf96451f32bcfefe1fa52abd864306886ba7e
3 / The verified repair
Exit 0"""Failure Map reference implementation. Python standard library only."""
import json
import math
N = 1
observations = []
def solve(first, last, frame_duration, timescale):
return (last-first+frame_duration)/timescale
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('fixture 1',solve(*(100, 140, 20, 100)),0.6)
check('fixture 2',solve(*(0, 0, 25, 100)),0.25)
check('fixture 3',solve(*(50, 50, 0, 100)),0)
check('fixture 4',solve(*(0, 75, 25, 100)),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 | 0.6 | 0.6 | Passed |
| fixture 2 | 0.25 | 0.25 | Passed |
| fixture 3 | 0.0 | 0 | Passed |
| fixture 4 | 1.0 | 1 | Passed |
SHA-256 / 553e3da477420cb1e7f62038df9b383b61551374948003ff3487deb9f2c53021
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 2026-09-29T14:38:46.219057+00:00.
Case digest / d138204e9f3cc270fc25c62858c12ae87d155d1738ee335064246530dda41d52