{"abstract":"Applying the same fade gain to both sources changes total gain and source weighting.","category":"Audio channel mixing","checks":4,"contract":"Crossfade equal-length sources at fixed normalized amount with complementary linear gains, without saturation.","evaluation_group":"xaud-crossfade-complementary-gains","failed_approach":"Fading in only the second source leaves the first source audible at the endpoint.","family":"xaud-crossfade-complementary-gains","id":"FA-10911","implementations":{"attempt":{"sha256":"9539a0f368552a184a849bb7e8430723184db7b62233ed447f66a8eb0b1ca27a","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\nimport math\nN = 1\nobservations = []\ndef solve(a, b, amount):\n    return [x+y*amount for x,y in zip(a,b)]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('fixture 1',solve(*([1, 0], [0, 1], 0.25)),[0.75, 0.25])\ncheck('fixture 2',solve(*([1], [1], 0.5)),[1])\ncheck('fixture 3',solve(*([1], [2], 0)),[1])\ncheck('fixture 4',solve(*([1], [2], 1)),[2])\nprint(json.dumps({\"observations\": observations, \"passed\": all(x[\"passed\"] for x in observations)}, ensure_ascii=False))\nraise SystemExit(0 if all(x[\"passed\"] for x in observations) else 1)\n"},"broken":{"sha256":"bb9f1b6c43eb5bb1a99717e20bbb812cf5868d8005997cca9161adb424d9d379","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\nimport math\nN = 1\nobservations = []\ndef solve(a, b, amount):\n    return [x*amount+y*amount for x,y in zip(a,b)]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('fixture 1',solve(*([1, 0], [0, 1], 0.25)),[0.75, 0.25])\ncheck('fixture 2',solve(*([1], [1], 0.5)),[1])\ncheck('fixture 3',solve(*([1], [2], 0)),[1])\ncheck('fixture 4',solve(*([1], [2], 1)),[2])\nprint(json.dumps({\"observations\": observations, \"passed\": all(x[\"passed\"] for x in observations)}, ensure_ascii=False))\nraise SystemExit(0 if all(x[\"passed\"] for x in observations) else 1)\n"},"fixed":{"sha256":"68f1fc29f920a7a13da721895405cf792db108901e2a307b733b5caf152b727b","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\nimport math\nN = 1\nobservations = []\ndef solve(a, b, amount):\n    return [x*(1-amount)+y*amount for x,y in zip(a,b)]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('fixture 1',solve(*([1, 0], [0, 1], 0.25)),[0.75, 0.25])\ncheck('fixture 2',solve(*([1], [1], 0.5)),[1])\ncheck('fixture 3',solve(*([1], [2], 0)),[1])\ncheck('fixture 4',solve(*([1], [2], 1)),[2])\nprint(json.dumps({\"observations\": observations, \"passed\": all(x[\"passed\"] for x in observations)}, ensure_ascii=False))\nraise SystemExit(0 if all(x[\"passed\"] for x in observations) else 1)\n"}},"limitations":" 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.","method":"Deterministic executable model with adversarial boundary fixtures.","provenance":{"created_by":"Failure Map","dependencies":"Python standard library","family":"xaud-crossfade-complementary-gains","generated_at":"2026-09-29T14:38:43.228641+00:00","license":"CC0-1.0","python":"3.12.14","seed":1,"split":"open-access"},"relevance":"A pure Python local audio pipeline stage with explicit sample formats and frame conventions; no real-time device or signal-spectrum claims.","repair":"Apply the explicit PCM/playback contract: Crossfade equal-length sources at fixed normalized amount with complementary linear gains, without saturation.","root_cause":"Applying the same fade gain to both sources changes total gain and source weighting.","sha256":"9100fff20e8225ab4654b126dfc030b82dab7665147cbe0a6b061ff27ff6ca55","title":"Crossfade complementary gains · case 01","variant":1,"variant_policy":"Five numbered records share a model and may reuse boundary fixtures.","verification":{"attempt":{"elapsed_ms":37.166,"exit_code":1,"observations":[{"actual":[1.0,0.25],"check":"fixture 1","expected":[0.75,0.25],"passed":false},{"actual":[1.5],"check":"fixture 2","expected":[1],"passed":false},{"actual":[1],"check":"fixture 3","expected":[1],"passed":true},{"actual":[3],"check":"fixture 4","expected":[2],"passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"fixture 1\", \"actual\": [1.0, 0.25], \"expected\": [0.75, 0.25], \"passed\": false}, {\"check\": \"fixture 2\", \"actual\": [1.5], \"expected\": [1], \"passed\": false}, {\"check\": \"fixture 3\", \"actual\": [1], \"expected\": [1], \"passed\": true}, {\"check\": \"fixture 4\", \"actual\": [3], \"expected\": [2], \"passed\": false}], \"passed\": false}\n"},"broken":{"elapsed_ms":36.751,"exit_code":1,"observations":[{"actual":[0.25,0.25],"check":"fixture 1","expected":[0.75,0.25],"passed":false},{"actual":[1.0],"check":"fixture 2","expected":[1],"passed":true},{"actual":[0],"check":"fixture 3","expected":[1],"passed":false},{"actual":[3],"check":"fixture 4","expected":[2],"passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"fixture 1\", \"actual\": [0.25, 0.25], \"expected\": [0.75, 0.25], \"passed\": false}, {\"check\": \"fixture 2\", \"actual\": [1.0], \"expected\": [1], \"passed\": true}, {\"check\": \"fixture 3\", \"actual\": [0], \"expected\": [1], \"passed\": false}, {\"check\": \"fixture 4\", \"actual\": [3], \"expected\": [2], \"passed\": false}], \"passed\": false}\n"},"fixed":{"elapsed_ms":38.556,"exit_code":0,"observations":[{"actual":[0.75,0.25],"check":"fixture 1","expected":[0.75,0.25],"passed":true},{"actual":[1.0],"check":"fixture 2","expected":[1],"passed":true},{"actual":[1],"check":"fixture 3","expected":[1],"passed":true},{"actual":[2],"check":"fixture 4","expected":[2],"passed":true}],"passed":true,"stderr":"","stdout":"{\"observations\": [{\"check\": \"fixture 1\", \"actual\": [0.75, 0.25], \"expected\": [0.75, 0.25], \"passed\": true}, {\"check\": \"fixture 2\", \"actual\": [1.0], \"expected\": [1], \"passed\": true}, {\"check\": \"fixture 3\", \"actual\": [1], \"expected\": [1], \"passed\": true}, {\"check\": \"fixture 4\", \"actual\": [2], \"expected\": [2], \"passed\": true}], \"passed\": true}\n"}},"verified":true,"visibility":"public"}