SeedanceContentItem

{
    "type": "image_url",
    "image_url": {
        "url": "https://example.com/reference.mp4"
    },
    "video_url": {
        "url": "https://example.com/reference.mp4"
    },
    "audio_url": {
        "url": "https://example.com/reference.mp4"
    },
    "role": "first_frame"
}