{
  "schema_name": "media",
  "schema_version": 1,
  "artifact_suffix": ".mp4",
  "format": "mp4",
  "description": "Public video/audio encoding contract for WebDataset MP4 members.",
  "encoder_policy": {
    "compatibility_contract": "The public loader contract is the MP4/H.264/AAC bitstream, not a specific encoder implementation.",
    "render_stage_default_video_encoder": "h264_nvenc",
    "wds_reencode_video_encoder": "libx264 when WebDataset packing is run with reencode_mode=optimized",
    "release_environment_source": "stats/release_environment.json records the exact final encoder, FFmpeg version, and packing mode used for the published release."
  },
  "profiles": {
    "720p": {
      "container": "mp4",
      "video_codec": "h264",
      "width": 1280,
      "height": 720,
      "fps": 32,
      "gop_size": 32,
      "closed_gop": true,
      "b_frames": 0,
      "video_quality": {
        "mode": "crf",
        "value": 20,
        "applies_to": "libx264 WebDataset re-encode path"
      },
      "pixel_format": "yuv420p",
      "faststart": true,
      "audio_codec": "aac",
      "audio_profile": "LC",
      "audio_channels": 2,
      "audio_channel_layout": "stereo",
      "audio_sample_rate_hz": 44100,
      "audio_bitrate_policy": "CSDM render sets audioBitrate=128 kbps; WebDataset packing copies source AAC audio unless audio is explicitly stripped.",
      "audio_nominal_bitrate_bps": 128000,
      "audio_validation_bitrate_bps": {
        "min": 96000,
        "max": 192000
      }
    },
    "360p": {
      "container": "mp4",
      "video_codec": "h264",
      "width": 640,
      "height": 360,
      "fps": 32,
      "gop_size": 32,
      "closed_gop": true,
      "b_frames": 0,
      "video_quality": {
        "mode": "crf",
        "value": 20,
        "applies_to": "libx264 WebDataset re-encode path"
      },
      "pixel_format": "yuv420p",
      "faststart": true,
      "audio_codec": "aac",
      "audio_profile": "LC",
      "audio_channels": 2,
      "audio_channel_layout": "stereo",
      "audio_sample_rate_hz": 44100,
      "audio_bitrate_policy": "CSDM render sets audioBitrate=128 kbps; WebDataset packing copies source AAC audio unless audio is explicitly stripped.",
      "audio_nominal_bitrate_bps": 128000,
      "audio_validation_bitrate_bps": {
        "min": 96000,
        "max": 192000
      }
    }
  },
  "notes": [
    "yuv420p is used for broad decoder, browser, OpenCV, PyAV, FFmpeg, torchcodec, and hardware-decoder compatibility.",
    "faststart places MP4 metadata at the front of the file for browser playback and HTTP range-read friendliness.",
    "The release stores a stereo game-audio mix. It does not expose multichannel audio or positional audio metadata."
  ],
  "validation": [
    "video stream is decodable",
    "video codec is H.264",
    "video resolution matches the release profile",
    "video frame rate is 32 FPS",
    "video pixel format is yuv420p",
    "audio stream exists",
    "audio codec is AAC-LC",
    "audio channel count is 2",
    "audio sample rate is 44100 Hz",
    "audio bit rate is within the profile validation range when ffprobe reports bit_rate"
  ]
}