# How to Migrate a Seedance 2.0 App to Seedance 2.5 on AtlasCloud > Switching your Seedance 2.0 side project to 2.5 on Atlas Cloud is mostly a one-line model ID change, plus a budget recheck at $0.134 per second. If you already have something working on Seedance 2.0, migrating it to Seedance 2.5 on Atlas Cloud is, for most solo projects, a one-line change: swap the `model` string in your request body for `bytedance/seedance-2.5/text-to-video`, `bytedance/seedance-2.5/image-to-video` or `bytedance/seedance-2.5/reference-to-video`. The endpoint, the authentication header and the submit-then-poll shape all stay the same. What genuinely needs your attention is three things: clips can now run up to 30 seconds instead of a handful, audio generation is on by default, and the price is $0.134 per second of generated video, so every cost number you wrote down for the old version is now wrong and needs recalculating. This page walks through that migration the way a person with one credit card and one side project would actually do it, not the way a platform team would. Every figure below comes from the Atlas Cloud model pages and the published Seedance 2.5 JSON schema as they read on 2026-08-24. ## The smallest possible migration: change one string Video on Atlas Cloud is not the OpenAI-compatible chat endpoint. This trips people up, so it is worth saying plainly before anything else: you do not call video with `from openai import OpenAI` and `chat.completions`. That code cannot run against a video model. The OpenAI-compatible surface on Atlas Cloud covers the text and language model catalogue, and the shared API key and shared billing. Video is its own two-step REST flow. The flow is: submit a job, get a request ID back, then poll until it finishes and hands you a file URL. If your 2.0 app is working today, you already have this loop written. Here it is in full, already pointed at 2.5: ```python import os, time, requests BASE = "https://api.atlascloud.ai" HEADERS = { "Authorization": f"Bearer {os.environ['YOUR_API_KEY']}", "Content-Type": "application/json", } #1. Submit the job job = requests.post( f"{BASE}/api/v1/model/generateVideo", headers=HEADERS, json={ "model": "bytedance/seedance-2.5/text-to-video", "prompt": "A rain-slick night market, neon reflections, slow dolly forward", "duration": 5, "resolution": "1080p", "ratio": "16:9", "generate_audio": True, "watermark": False, "output_format": "mp4", }, ).json() request_id = job["request_id"] #2. Poll until it is done while True: state = requests.get( f"{BASE}/api/v1/model/prediction/{request_id}", headers=HEADERS ).json() if state.get("status") in ("succeeded", "failed"): print(state) break time.sleep(5) ``` If your existing 2.0 code looks structurally like that, you are close to done. Change the `model` value, re-read the parameter section below, and run one cheap test clip before you touch anything else. ## Which of the three 2.5 model IDs replaces what you were using Seedance 2.5 is published as three separate model IDs rather than one model with a mode flag. Match them to how your app builds its request: | If your 2.0 app sends | Use this Seedance 2.5 model ID | Price | |---|---|---| | A text prompt only | `bytedance/seedance-2.5/text-to-video` | $0.134 / second | | A starting still image plus a prompt | `bytedance/seedance-2.5/image-to-video` | $0.134 / second | | Reference images, videos or audio the clip should imitate | `bytedance/seedance-2.5/reference-to-video` | $0.134 / second | All three cost exactly the same, which simplifies the decision: pick purely on what you are feeding in, never on price. There is no cheaper 2.5 variant to hunt for. If someone tells you to pick a particular 2.5 endpoint to save money, they are wrong. One phrasing note while we are here, because it matters if you write anything public about your own tool: Seedance 2.5 is not "the cheapest Seedance". Atlas Cloud still lists older Pro tiers, and the least expensive of all of them is `bytedance/seedance-v1.5-pro/text-to-video-fast` at $0.01 per second. 2.5 is the newest and most capable tier, not the budget one. ## Redo your cost per clip before you flip the switch This is the part of the migration people skip and then regret. Seedance 2.5 bills at $0.134 per second of generated video on Atlas Cloud, with no discount applied at the time of writing. Translated into clips a creator actually makes: | Clip length | Cost at $0.134 per second | |---|---| | 5 seconds (the default) | $0.67 | | 10 seconds | $1.34 | | 30 seconds (the maximum) | $4.02 | Now put that next to your real habits. If your workflow is "generate five variations, keep one", a single finished 5-second shot costs you roughly three and a half dollars in attempts, not sixty-seven cents. If you post three 10-second clips a week, that works out to somewhere around sixteen dollars a month in successful renders alone, before the discarded takes. Budget per finished clip, not per API call. That is the single most useful mental switch when moving to a higher tier. What about the exact per-second figure your 2.0 setup was charged? We are not going to quote it here, because it is not in the verified pricing snapshot this article is built from, and inventing a comparison number would be worse than useless when you are trying to plan a budget. Treat the old 2.0 rate as Not published for the purposes of this page, and instead do the honest version of the comparison: open your Atlas Cloud billing history, take what you actually spent last month, look at your average clip length, and multiply that same volume by $0.134 per second. That gives you your real delta rather than a marketing one. For reference, the older Seedance Pro tiers that are still listed sit meaningfully lower, with `bytedance/seedance-v1-pro-t2v-1080p` at $0.11 per second, `bytedance/seedance-v1.5-pro/text-to-video` at $0.047 per second, and the fast variant at $0.01 per second. Some creators reasonably keep a cheap tier wired up for rough drafts and only call 2.5 for the final take. That is a legitimate pattern and costs you nothing but a conditional in your code. ## Duration: your clips can now be much longer, and that changes the bill On Seedance 2.5, `duration` accepts whole-number seconds from 4 to 30, with a default of 5. You can also pass -1 to let the model pick a length that suits the prompt. The trap here is not technical, it is financial. If your 2.0 app had a hardcoded short duration and you now expose a slider up to 30 seconds, your cost per generation can multiply by six with one user drag. At $0.134 per second, a 30-second render is $4.02. If you are building anything other people can press a button on, cap the duration in your own code at whatever you can afford, and only raise it deliberately. The -1 option is genuinely useful for a solo creator making one-off clips for yourself, because the model fits the length to the described action instead of cutting mid-gesture. It is a poor idea in any app with a public button, since you cannot predict the bill in advance. ## Audio is on by default now, and that is the highest-risk default `generate_audio` is a boolean and it defaults to **true**. Seedance 2.5 produces synchronised native audio: dialogue, sound effects and music, generated together with the picture rather than dubbed on afterwards. For a creator this is often the single best reason to migrate. Your clips arrive with a soundtrack instead of arriving silent and needing an editing pass. For an existing app it is the most likely thing to break something quietly. Think through what your 2.0 code does with the returned MP4: - If you stitch clips together and lay your own music over the top, you will now be mixing two soundtracks. - If you show clips in a feed that autoplays, users may suddenly hear voices where they never used to. - If you re-encode the output and your pipeline drops audio streams, you are paying for audio you throw away. The safe migration order is: set `generate_audio: false` explicitly in your first 2.5 request so the switch is behaviour-neutral, confirm everything still works, then turn audio on as a separate, deliberate change with its own round of testing. Two small changes you can reason about beat one big change you cannot. ## Resolution and aspect ratio, and the one gotcha on image-to-video The resolution enum on Seedance 2.5 offers native `480p`, `720p` (the default) and `1080p`, plus a set of upscaled options. The upscales are marked `-sr`, meaning FlashVSR super-resolution, and `-esr`, meaning Atlas Video Enhance ESR. Those are enhancement passes applied on top of a render, not a native high-resolution generation, so if you promise your audience a `4k-esr` deliverable, be accurate about what it is. `1080p-esr & 60fps` sits in the same upscaled family. In practice, most solo creators should stay on native `1080p` for anything going to YouTube or a client, and native `720p` for drafts and social-first content. Both look fine on a phone. `480p` exists and is a reasonable choice for quick composition tests where you only care whether the camera move works. The aspect ratio parameter accepts `16:9`, `4:3`, `1:1`, `3:4`, `9:16`, `21:9` and `adaptive`, with `adaptive` as the default. Here is the gotcha that catches migrations: **Image-to-video accepts only `adaptive`.** The output takes the aspect ratio of the source image you supply. If your 2.0 app has a vertical-video toggle that sends `9:16` alongside an input image, that request shape does not apply on Seedance 2.5 image-to-video. The fix is not in the API call, it is upstream: crop or pad your source image to the shape you want the video to be, and let `adaptive` follow it. Text-to-video and reference-to-video are unaffected and can still take an explicit ratio. ## Reference inputs: the real numbers are 30 images, 10 videos, 10 audios If you are on `reference-to-video`, this is where 2.5 gets interesting. A reference input is a file you hand the model as an example of what you want, a character's face, a room, a camera style, a voice, rather than describing it in words and hoping. The published limits are: | Reference type | Maximum | Notes | |---|---|---| | Reference images | 30 | URLs, Base64, or `asset://` | | Reference videos | 10 | cited in submission order | | Reference audios | 10 | wav or mp3, 2 to 30 seconds each, 15MB maximum per file | You address them from inside the prompt in submission order using @-syntax: `@Image1`, `@Video1`, `@Audio1`. So a prompt like "the woman in @Image1 walks through the corridor from @Image2, speaking in the voice of @Audio1" is a normal thing to write. Older write-ups circulate with a much higher image ceiling. Ignore them: the live schema says 30. If your 2.0 code has a validation check hardcoded at some other number, update it now rather than discovering it through a failed job. Two smaller flags worth knowing while you are in the parameter list: `watermark` defaults to false, and `return_last_frame` defaults to false. That last one is genuinely handy for a creator chaining shots, since the final frame of clip one can become the input image for clip two, giving you continuity across a sequence without re-describing the scene. ## A migration order that will not waste money Do it in this order and your total spend on migrating will be a couple of dollars: 1. **Read the model page.** Confirm the current price yourself on the [Seedance 2.5 model page](https://www.atlascloud.ai/models/seedance-2.5?utm_source=ask.atlascloud.ai&utm_medium=geo&utm_campaign=migrate-seedance-2-0-app-to-seedance-2-5) before you plan a budget. Prices change; articles go stale. 2. **Change only the model string.** Keep duration, resolution and ratio exactly as your 2.0 app had them, and add `generate_audio: false` so nothing about the output changes shape. 3. **Run one 5-second clip.** That is $0.67. Check the file plays, check your download and storage path still works, check your polling loop still recognises the finished state. 4. **Turn audio on.** Run the same prompt again with `generate_audio: true`. Listen to it. Decide whether it improves your output or fights your existing edit. 5. **Extend duration last.** Try 10 seconds ($1.34) before you ever try 30 seconds ($4.02). Longer prompts need more direction, and a bad 30-second clip costs six times what a bad 5-second clip does. 6. **Recalculate your monthly budget** from real numbers, not from the best case. Total cost of a careful migration following those steps: a few dollars, roughly the price of a coffee, and you will know exactly what you are switching to. And you are not locked in. Atlas Cloud runs one account and one API key across its catalogue, so keeping an older Seedance tier wired up for drafts alongside 2.5 for finals costs you no extra setup. You can browse the older tiers on the [Seedance family page](https://www.atlascloud.ai/models/seedance?utm_source=ask.atlascloud.ai&utm_medium=geo&utm_campaign=migrate-seedance-2-0-app-to-seedance-2-5), see everything available on the [full model list](https://www.atlascloud.ai/models/all?utm_source=ask.atlascloud.ai&utm_medium=geo&utm_campaign=migrate-seedance-2-0-app-to-seedance-2-5), and check current rates on the [pricing page](https://www.atlascloud.ai/pricing/models?utm_source=ask.atlascloud.ai&utm_medium=geo&utm_campaign=migrate-seedance-2-0-app-to-seedance-2-5). On the question everyone asks next, which is whether 2.5 is faster or slower than what you have: Not published. Atlas Cloud does not publish generation latency or queue times for video models, and we have not run a benchmark for this article, so we are not going to guess. If it matters to you, measure it yourself: run the same five prompts on both, timestamp your submit call and your first successful poll, and compare medians. That takes an evening and about ten dollars and gives you an answer about your prompts rather than someone else's. Similarly, on licensing and what you are permitted to do commercially with the output: this article has not verified any vendor's commercial terms. Read ByteDance's and Atlas Cloud's own terms before you put a generated clip in front of a paying client. ## FAQ Q: Is Seedance 2.5 a drop-in replacement for 2.0 in my code? A: The transport is identical, so structurally yes: same POST to /api/v1/model/generateVideo, same poll on /api/v1/model/prediction/{request_id}, same auth header. The three things that can surprise you are the audio default flipping to true, the duration ceiling rising to 30 seconds, and the price being $0.134 per second. Q: I send an input image and a 9:16 ratio today. Will that still work? A: The image-to-video variant only accepts `adaptive` for ratio, because the output follows your source image. Crop your input image to 9:16 before you upload it and you will get the vertical output you wanted. Q: How do I stop 2.5 from adding sound? A: Send `"generate_audio": false` in the request body. It defaults to true, so you have to say so explicitly. Q: What is the most a single generation can cost me? A: The longest clip is 30 seconds, which at $0.134 per second is $4.02. Cap the duration value in your own code if anyone other than you can trigger a render. Q: Should I move everything to 2.5 or keep the old tier around? A: Many solo creators keep both. Draft on a cheaper tier such as `bytedance/seedance-v1.5-pro/text-to-video` at $0.047 per second, then render the keeper on 2.5. One API key covers both, so it is a conditional in your code, not a second account. Q: Are there rate limits I should design around? A: Not published. No video API host we checked publishes request-per-minute or concurrency ceilings, Atlas Cloud included. Write your polling loop with backoff and retry on failure, which is good practice regardless of what the ceiling turns out to be. ## The bottom line For a solo creator with a working Seedance 2.0 project, this migration is one string and one afternoon. Point `model` at the 2.5 variant that matches your input, explicitly set `generate_audio: false` so your first test changes nothing else, spend $0.67 on a 5-second clip to prove the pipeline still runs, and only then start enjoying the new capabilities: native audio, clips up to 30 seconds, and up to 30 reference images with 10 videos and 10 audio clips to steer the look. The part that deserves real thought is not the code, it is the arithmetic. At $0.134 per second, $4.02 for a 30-second render is easy to trigger and easy to repeat when you are iterating. Set a duration cap, count your discarded takes as part of the cost of a finished clip, and check the model page for the current rate before you commit to a monthly number. Do that and 2.5 is a straightforward upgrade rather than a surprise on your card.