{
  "title": "ConferenceCaptioning live captioning benchmark: NASA Artemis II news conference",
  "page": "https://conferencecaptioning.com/benchmark/",
  "source_video": "https://www.youtube.com/watch?v=Ir2X1-FjDxg&t=398s",
  "updated": "2026-10-05",
  "license": {
    "data": "CC BY 4.0",
    "url": "https://creativecommons.org/licenses/by/4.0/",
    "attribution": "ConferenceCaptioning, https://conferencecaptioning.com/benchmark/",
    "scoring_script": "MIT"
  },
  "author": "Saamer Mansoor",
  "clip": {
    "start": "6:38",
    "end": "9:31",
    "seconds": 173,
    "language": "en",
    "reference_words": 562
  },
  "machine": {
    "chip": "Apple M4",
    "memory_gb": 16,
    "os": "macOS 27",
    "playback": "1x real time, 100 ms chunks"
  },
  "runs": 2,
  "engines": [
    {
      "engine": "Rapid",
      "description": "System speech service (iOS / macOS 26+)",
      "word_accuracy_pct": 95.2,
      "word_error_rate_pct": 4.8,
      "accuracy_counting_filler_sounds_pct": 94.2,
      "words_wrong": 23,
      "words_missed": 4,
      "words_extra": 0,
      "total_errors": 27,
      "error_categories": {
        "names": 6,
        "endings": 3,
        "sounds": 10,
        "small": 8
      },
      "first_caption_s": 1.14,
      "delay_mean_s": 0.05,
      "delay_p95_s": 0.07,
      "delay_max_s": 1.2,
      "caption_complete_after_speech_ends_s": 0.1,
      "model_load_s": 0.9,
      "peak_memory_mb_in_app_process": 74,
      "cpu_avg_pct_of_one_core": 7,
      "runs_out_of_process": true,
      "power_whole_machine": {
        "neural_engine_avg_mw": 7,
        "neural_engine_peak_mw": 20,
        "cpu_avg_mw": 112,
        "gpu_avg_mw": 1,
        "all_compute_avg_mw": 121,
        "energy_over_clip_j": 21
      }
    },
    {
      "engine": "Mix",
      "description": "Large on-device model + voice-activity detection",
      "word_accuracy_pct": 97.2,
      "word_error_rate_pct": 2.8,
      "accuracy_counting_filler_sounds_pct": 97.2,
      "words_wrong": 11,
      "words_missed": 4,
      "words_extra": 1,
      "total_errors": 16,
      "error_categories": {
        "names": 4,
        "endings": 3,
        "sounds": 3,
        "small": 6
      },
      "first_caption_s": 5.33,
      "delay_mean_s": 1.24,
      "delay_p95_s": 1.68,
      "delay_max_s": 1.7,
      "caption_complete_after_speech_ends_s": 0.08,
      "model_load_s": 1.0,
      "peak_memory_mb_in_app_process": 800,
      "cpu_avg_pct_of_one_core": 10,
      "runs_out_of_process": false,
      "power_whole_machine": {
        "neural_engine_avg_mw": 63,
        "neural_engine_peak_mw": 628,
        "cpu_avg_mw": 164,
        "gpu_avg_mw": 1,
        "all_compute_avg_mw": 228,
        "energy_over_clip_j": 40
      }
    }
  ],
  "notes": [
    "Rapid runs in a system service outside the app, so its in-app memory and CPU understate its real cost.",
    "Power figures are whole-machine averages from a single run and include background activity."
  ]
}