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ByteDance Seedance 2.5
Seedance 2.5 generates up to 30 seconds of continuous video with sound in a single pass, with capacity for up to 50 reference files: 30 images, 10 videos, 10 audio clips. In exchange, its resolution ceiling is 720p, half of what the previous unit in the same family supported.
- 30 seconds in one pass
- 50 reference inputs
- 720p ceiling
Last checked: This is a reference page. It is re-checked against the vendor sources and updated when a new version ships. Change log
The parameter the product page omits
ByteDance own Seedance 2.5 page addresses 30-second generation and precise reference control, and is silent on resolution. The answer is recorded in their API documentation: the resolution parameter for this unit accepts exactly two values, 480p and 720p, defaulting to 720p. The same documentation lists four values up to 4k for Seedance 2.0. So on that one parameter, the newer unit underperforms its own predecessor.
This finding is confirmed in a second, independent source. The Runway OpenAPI schema, for the same unit resold on their infrastructure, states in the ratio parameter description: "Seedance 2.5 supports 480p and 720p only." Two sources, one value.
What 30 seconds means precisely
The duration parameter accepts a 4-to-30-second range for this unit, and Volcano Engine own guide states the ceiling was raised from the 15 seconds of the 2.0 series to 30, with the option to extend twice thereafter. This is the longest single-pass clip among the four units logged in our table, and the gap is substantial: Veo 3.1 stops at an eight-second ceiling.
In operational terms, single-pass length is the parameter that eliminates the need for post-production editing. Three ten-second clips stitched together carry three points of potential failure for facial or lighting discontinuity; one 30-second clip carries none.
Fifty-input reference capacity, and its composition
The official guide breaks the ceiling down: 30 images plus 10 videos plus 10 audio files, 50 total. Audio alone is sufficient as a reference and need not accompany an image. For a workload requiring one consistent character or one consistent product across several scenes, this parameter carries more weight than resolution.
Editing capability, less frequently documented
The same unit edits an existing video: swapping the subject, adding or removing an element, even stripping background music. The documentation records these constraints, though poorly for error handling: the input video must run 4 to 30 seconds, the aspect ratio must remain adaptive, and duration must be set to -1. Violating any of these three constraints produces an error that does not surface at task submission — it surfaces after processing has already begun, a cost in time and processing credits for anyone who has not read the constraint documentation first.
Specifications
Every number here comes from the vendor's own page, with that page linked beside it.
- Unit identifier
- doubao-seedance-2-5-260628 Source
- Input
- text, image, video, audio Source
- Output
- video, audio Source
- Deployment surface
- Volcano Engine Ark API, Runway API Source
- Longest clip in one pass
- 30 seconds Source
- Resolution ceiling
- 720p Source
- Vertical resolution
- 720 lines of vertical resolution Source
- Native audio
- yes Source
- Reference input capacity
- 50 reference inputs Source
Using it from Iran
This column carries a date and says how it was checked, because most listicles guess it. Where we have only read a vendor policy page, the note below says exactly that.
- Reachable
- not checked
- Payment
- not checked
- Free tier
- no
- Measured on
How we checked: ByteDance publishes no supported-countries list for this unit. The official procurement route is the Chinese Volcano Engine console, which requires a minimum balance of 200 RMB before the unit can be activated, and the second route is the same unit resold on US platforms operating under US export control law. The network path has not been measured from inside Iran, and no document establishing an open or closed registration status from Iran has been identified, so this column is recorded as unknown rather than open.
Documented strengths
- Thirty seconds of continuous video in a single generation pass, the highest figure in our table today
- Reference capacity of up to fifty inputs across three data types: image, video and audio
- Audio is enabled by default and generated concurrently with the image, not in a second pass
- Edits and extends an existing video within the same unit, with no auxiliary tooling required
Room for improvement and technical considerations
- The resolution ceiling is 720p. That is insufficient for large-screen display or advertising delivery, and Seedance 2.0 supported up to 4K on the same parameter.
- The official procurement route is the Chinese Volcano Engine console, which requires a minimum balance of 200 RMB.
- The constraints on an edit task are strict, and the error surfaces after processing begins, not at submission.
- No document establishing the access route from Iran has been identified, so this unit Iran column is recorded as unknown and scores nothing in the table.
- ByteDance publishes no generation time, so the duration required to produce those 30 seconds is unknown.
Technical verdict
For a narrative-driven workload requiring a character held consistent, this unit provisions a capability the others do not today: 30 seconds and 50 reference inputs. For output destined for a billboard or television broadcast, this is not a suitable configuration — deploy Kling instead. No upscaling operation converts 720p into 4K.
Frequently raised questions, with documented answers
How long a video can Seedance 2.5 generate in one pass
Up to 30 seconds in a single pass, and the duration parameter accepts a 4-to-30-second range. Volcano Engine own guide states it can then be extended twice.
Does Seedance 2.5 output 4K
No. The API documentation permits only 480p and 720p for this unit. 4K support is active on Seedance 2.0, not on 2.5.
Is a procurement route for Seedance 2.5 available from Iran
This parameter status is unknown. ByteDance publishes no country list, and no network test has been run from inside Iran. This platform does not sell accounts and does not propose a route around this restriction.