Overlay a watermark on a video

Overlay a logo or image watermark onto a video at a fixed position using Rendi’s FFmpeg API. Node.js, Python, and cURL examples.

Overlay a logo or image watermark onto a video at a fixed position (corner, center, or custom coordinates).

Code

Node.js

const API_KEY = process.env.RENDI_API_KEY;

const submit = await fetch("https://api.rendi.dev/v1/run-ffmpeg-command", {
  method: "POST",
  headers: {
    "Content-Type": "application/json",
    "X-API-KEY": API_KEY,
  },
  body: JSON.stringify({
    input_files: {
      in_1: "https://storage.rendi.dev/sample/sample.avi",
      in_logo: "https://storage.rendi.dev/sample/rendi_banner_white_transparent.png",
    },
    output_files: {
      out_1: "watermarked.mp4",
    },
    ffmpeg_command:
      '-i {{in_1}} -i {{in_logo}} -ss 00:00:00 -to 00:00:10 -filter_complex "[0:v][1:v]overlay=W-w-10:10" -c:v libx264 -c:a copy {{out_1}}',
  }),
});
const { command_id } = await submit.json();

while (true) {
  const res = await fetch(`https://api.rendi.dev/v1/commands/${command_id}`, {
    headers: { "X-API-KEY": API_KEY },
  });
  const data = await res.json();
  if (data.status === "SUCCESS") {
    console.log("Watermarked URL:", data.output_files.out_1.storage_url);
    break;
  }
  if (data.status === "FAILED") throw new Error("Command failed");
  await new Promise((r) => setTimeout(r, 2000));
}

Python

import os
import time
import requests

API_KEY = os.environ["RENDI_API_KEY"]
BASE = "https://api.rendi.dev/v1"
headers = {"X-API-KEY": API_KEY}

submit = requests.post(
    f"{BASE}/run-ffmpeg-command",
    headers=headers,
    json={
        "input_files": {
            "in_1": "https://storage.rendi.dev/sample/sample.avi",
            "in_logo": "https://storage.rendi.dev/sample/bbb-splash.png",
        },
        "output_files": {"out_1": "watermarked.mp4"},
        "ffmpeg_command": '-i {{in_1}} -i {{in_logo}} -filter_complex "[0:v][1:v]overlay=W-w-10:10" -c:v libx264 -c:a copy {{out_1}}',
    },
)
command_id = submit.json()["command_id"]

while True:
    res = requests.get(f"{BASE}/commands/{command_id}", headers=headers).json()
    if res["status"] == "SUCCESS":
        print("Watermarked URL:", res["output_files"]["out_1"]["storage_url"])
        break
    if res["status"] == "FAILED":
        raise RuntimeError("Command failed")
    time.sleep(2)

cURL

curl --request POST \
  --url https://api.rendi.dev/v1/run-ffmpeg-command \
  --header 'Content-Type: application/json' \
  --header 'X-API-KEY: <api-key>' \
  --data '{
    "input_files": {
      "in_1": "https://storage.rendi.dev/sample/sample.avi",
      "in_logo": "https://storage.rendi.dev/sample/bbb-splash.png"
    },
    "output_files": {"out_1": "watermarked.mp4"},
    "ffmpeg_command": "-i {{in_1}} -i {{in_logo}} -filter_complex \"[0:v][1:v]overlay=W-w-10:10\" -c:v libx264 -c:a copy {{out_1}}"
  }'

curl --request GET \
  --url https://api.rendi.dev/v1/commands/<command_id> \
  --header 'X-API-KEY: <api-key>'

How the FFmpeg command works

• -i {{in_1}} — input video
• -i {{in_logo}} — second input: logo PNG (with transparency if desired)
• -filter_complex "[0:v][1:v]overlay=W-w-10:10" — place logo 10 px from the top-right corner
  • W-w-10 = video width − logo width − 10 px padding
  • 10 = 10 px from the top
• -c:v libx264 -c:a copy — re-encode video (needed after filter), pass audio through

Position shortcuts:

• Top-left: overlay=10:10
• Top-right: overlay=W-w-10:10
• Bottom-left: overlay=10:H-h-10
• Bottom-right: overlay=W-w-10:H-h-10
• Center: overlay=(W-w)/2:(H-h)/2

Response

{
  "output_files": {
    "out_1": {
      "file_id": "e7f8a9b0-...",
      "size_mbytes": 28.1,
      "duration": 596.459,
      "file_type": "video",
      "file_format": "mp4",
      "storage_url": "https://storage.rendi.dev/temp_files/.../watermarked.mp4",
      "width": 854,
      "height": 480,
      "codec": "h264"
    }
  },
  "status": "SUCCESS",
  "command_type": "FFMPEG_COMMAND"
}

Related

• Transcode
• Burn-in SRT subtitles
• Cheatsheet — Overlay text on video