BgmItem(BgmItem)

{
    "bgm_file_id": "file_bgm_abc123",
    "demo_url": "https://cdn.example.com/bgm/demo_501.mp3",
    "description": "节奏轻快，适合日常Vlog、美食、旅行类视频配乐",
    "id": 501,
    "name": "轻快活泼BGM",
    "tags": "轻快,活泼,正能量",
    "type": "轻音乐"
}