lightricks/ltx-2-19b/video-extend11 點數起 / 5 秒影片· 影片延伸

LTX-2 19B 是 Lightricks 開源的音影片模型:每段影片都帶按提示詞生成的立體聲,從唱歌、對白到天氣和人群聲。文生影片、圖生影片和影片續寫,5 到 20 秒,480p、720p 或 1080p,其中 720p 很快。

在 POST /jobs/createTask 把模型名稱填成 lightricks/ltx-2-19b/video-extend 就能呼叫,11 點數/ 5 秒影片起(US$0.11)。新帳戶送 30 點數,可以先在 Playground 免費試用。

  • 生成影片
  • 圖生影片
  • 影片延伸
  • 最高 1080p
  • 5–20 秒
模型名稱lightricks/ltx-2-19b/video-extend
端點POST https://api.popnow.ai/api/v1/jobs/createTask
# 1. Create the task. Keep the Idempotency-Key if you retry after a network error.
export IDEMPOTENCY_KEY="$(uuidgen)"
curl -X POST https://api.popnow.ai/api/v1/jobs/createTask \
  -H "Authorization: Bearer $POPNOW_API_KEY" \
  -H "Content-Type: application/json" \
  -H "Idempotency-Key: $IDEMPOTENCY_KEY" \
  -d '{
  "model": "lightricks/ltx-2-19b/video-extend",
  "input": {
    "prompt": "A slow aerial shot drifting over a misty pine forest at sunrise",
    "video_url": "https://media.popnow.ai/effects/flower-bloom-1abd6efb.mp4",
    "resolution": "720p",
    "duration_seconds": 5
  }
}'

# 2. Copy data.taskId from the response, then poll until state is succeeded, failed, canceled or expired.
TASK_ID="TASK_ID_FROM_RESPONSE"
curl "https://api.popnow.ai/api/v1/jobs/recordInfo?taskId=$TASK_ID" \
  -H "Authorization: Bearer $POPNOW_API_KEY"

input 依下方的 Schema 產生,原樣就能通過驗證。把提示詞和連結換成你自己的即可。

價格

選項點數 /秒≈ 美元
resolution 480p2.16US$0.022
resolution 720p2.88US$0.029
resolution 1080p4.32US$0.043

1 點數 = $0.01 · 全部選項及價格:GET /models/lightricks/ltx-2-19b/video-extend

每個任務會無條件進位到整數點數,所以最低檔跑一次是 11 點數/ 5 秒影片(US$0.11)。

限制

影片長度
5–20 s
解析度
480p · 720p · 1080p
輸入片段最長
60 s

參數

這些欄位來自我們驗證每個請求所用的同一份 Schema。沒列出的欄位會被拒絕。

  • promptstring必填

    Describe what happens next: the action that follows, the camera move and the sound on an Audio: line.

    範圍
    1 – … chars
  • video_urlstring必填

    要處理的影片。

    範圍
    1 – … chars · video/mp4, video/webm, video/quicktime
  • resolutionstring選填影響價格

    輸出尺寸。越大越清晰,價格也越高。

    預設值
    "720p"
    可用值
    "480p""720p""1080p"
  • duration_secondsinteger選填影響價格

    影片長度,按秒計費。

    預設值
    5
    範圍
    5 – 20
  • seedinteger選填

    用同一個數字,結果就能重現。

    範圍
    0 – 2147483647
原始 JSON Schema
{
  "additionalProperties": false,
  "properties": {
    "duration_seconds": {
      "default": 5,
      "description": "Length of the new segment in whole seconds, from 5 to 20. The source clip is added on top and is not billed.",
      "maximum": 20,
      "minimum": 5,
      "type": "integer"
    },
    "prompt": {
      "description": "Describe what happens next: the action that follows, the camera move and the sound on an Audio: line.",
      "minLength": 1,
      "type": "string"
    },
    "resolution": {
      "default": "720p",
      "description": "Resolution of the new segment. It sets how sharp the new part is generated; match your source clip.",
      "enum": [
        "480p",
        "720p",
        "1080p"
      ],
      "type": "string"
    },
    "seed": {
      "description": "Random seed for controlled comparisons, not a frame-identical guarantee.",
      "maximum": 2147483647,
      "minimum": 0,
      "type": "integer"
    },
    "video_url": {
      "contentMediaType": [
        "video/mp4",
        "video/webm",
        "video/quicktime"
      ],
      "description": "The clip to continue: MP4, MOV or WebM, up to 60 seconds. Its last frame opens the new segment, and the result is your clip with the new segment joined on.",
      "format": "uri",
      "minLength": 1,
      "type": "string"
    }
  },
  "required": [
    "prompt",
    "video_url"
  ],
  "type": "object"
}

回應、輪詢與回呼

所有模型的用法都一樣:先建立任務,再輪詢,或等待回呼。

先報價

cURL
curl -X POST https://api.popnow.ai/api/v1/jobs/quote \
  -H "Authorization: Bearer $POPNOW_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
  "model": "lightricks/ltx-2-19b/video-extend",
  "input": {
    "prompt": "A slow aerial shot drifting over a misty pine forest at sunrise",
    "video_url": "https://media.popnow.ai/effects/flower-bloom-1abd6efb.mp4",
    "resolution": "720p",
    "duration_seconds": 5
  }
}'

請求內容和 createTask 相同。它回傳預估扣款和最高可能扣款,不會真的執行。

已受理

HTTP
HTTP/1.1 202 Accepted

{
  "code": 200,
  "msg": "success",
  "data": {
    "taskId": "task_01k3m8x9q2z4v7n5p6r8s0t1w3",
    "state": "queued"
  },
  "request_id": "req_example_create"
}

HTTP 202 代表任務已受理,點數先凍結、尚未扣除。最終扣款不會超過凍結額。

查詢狀態

cURL
curl "https://api.popnow.ai/api/v1/jobs/recordInfo?taskId=$TASK_ID" \
  -H "Authorization: Bearer $POPNOW_API_KEY"

每隔幾秒查詢一次並逐步拉長間隔,state 變成 succeeded、failed、canceled 或 expired 時停止。

完成的任務

JSON
{
  "code": 200,
  "msg": "success",
  "data": {
    "taskId": "task_01k3m8x9q2z4v7n5p6r8s0t1w3",
    "model": "lightricks/ltx-2-19b/video-extend",
    "state": "succeeded",
    "output": {
      "assets": [
        {
          "url": "https://cdn.popnow.ai/tasks/task_01k3m8x9q2z4v7n5p6r8s0t1w3/output.mp4?signature=FROM_RESPONSE",
          "expiresAt": "2026-10-17T12:20:00Z",
          "mime": "video/mp4",
          "width": 1280,
          "height": 720,
          "durationSeconds": 5
        }
      ]
    },
    "settled": true
  },
  "request_id": "req_example_record"
}

請在 expiresAt 之前從 url 下載。之後需要新連結,請呼叫 POST /common/download-url。

驗證回呼

Node.js
import { createHash, createHmac, timingSafeEqual } from "node:crypto";
import express from "express";

const app = express();
// express.raw keeps the exact bytes that were signed; express.json would not match.
app.post("/hooks/popnow", express.raw({ type: "application/json" }), (req, res) => {
  const timestamp = req.header("X-Webhook-Timestamp");
  const signature = req.header("X-Webhook-Signature") ?? "";
  const body = JSON.parse(req.body.toString("utf8"));
  const taskId = body.data?.taskId ?? body.task_id;
  const digest = createHash("sha256").update(req.body).digest("hex");
  const expected = createHmac("sha256", process.env.POPNOW_WEBHOOK_SECRET)
    .update(`${taskId}.${timestamp}.${digest}`)
    .digest("base64");
  const ok = expected.length === signature.length && timingSafeEqual(Buffer.from(expected), Buffer.from(signature));
  // Check the signature first, then reject anything older than five minutes.
  if (!ok || Math.abs(Date.now() / 1000 - Number(timestamp)) > 300) return res.status(401).end();
  res.status(200).end(); // answer fast, then fetch the task and store its files
});

設定 callBackUrl 後,我們會把完成的任務送給你。先用原始請求內容驗證簽名,再信任它。

上傳本機檔案

cURL
curl -X POST https://api.popnow.ai/api/v1/common/upload-url \
  -H "Authorization: Bearer $POPNOW_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"contentType": "image/png", "bytes": 482113}'

# PUT the file bytes to data.uploadUrl with every header in data.headers, then commit it:
curl -X POST https://api.popnow.ai/api/v1/files/$FILE_ID/commit \
  -H "Authorization: Bearer $POPNOW_API_KEY"
# The commit returns a popnow://f/... reference. Put it in any image, video or
# audio field of the task input instead of a public https URL.

公開的 https 連結可以直接用。本機檔案要先經過 upload-url 和 commit。