Two incompatible delivery pipelines
| Field | Volcano Ark family (native / BeeNex / VideoFee / Apimart) | Tencent family (Tencent VOD / YesToken) |
|---|---|---|
| Container encoder | Lavf58.76.100 | Lavf58.29.100 |
| Video time_base | 1/12288 | 1/24000 |
| has_b_frames | 2 | 3 |
| moov position | after mdat | before mdat (faststart) |
| x264 SEI options | present (core 164) | absent |
| Samples | 114 | 34 |
Tencent-family files are re-encoded and lose every Ark-side fingerprint; the method returns “cannot determine” for them.
Model-version fingerprint (core finding)
| Native baseline | x264 preset | CRF | 480p size | Samples |
|---|---|---|---|---|
| doubao-seedance-2-0-260128 | superfast (me=dia subme=1) | 20.0 | 864×496 (inferred across relays) | 11/11 |
| doubao-seedance-2-5-260628 | veryfast (me=hex subme=2) | 11.0 | 854×480 | 23/23 |
Shared: keyint=250, bframes=3, ref=1, aq=1:1.00, weightp=1. No sample crosses between the two groups.
Relay observations
- Apimart: 8/8 requests for 2.0 landed in the 2.0 pipeline, 10/10 requests for 2.5 in the 2.5 pipeline; two 1080p HEVC Main10 files without SEI are of unknown origin.
- BeeNex: 10/10 in the 2.5 pipeline, but all 9 clips requested with generate_audio=false carry a low-level audio track, so parameters are not passed through verbatim.
- VideoFee: 23/23 mainline clips in the 2.5 pipeline. In the alias probe,
doubao-seedance-2-5-260628(the official 2.5 ID),-hy,-proand five more strings fell back to the 2.0 pipeline; onlydoubao-seedance-2.5,doubao-seedance-2-5andseedance-2.5reached 2.5. One clip per alias — a strong lead pending re-test.
Evidence strength
| Criterion | Support | Limit |
|---|---|---|
| Container family | Strong (148/148 split) | Fails after remux; pipeline only |
| x264 preset + CRF | Strong (34/34, zero overlap) | Upstream may change; forgeable by re-encoding with the same parameters |
| 480p size rounding | Medium | No native 2.0 480p baseline |
| Reference-video output similarity | Medium (same input PSNR 41–44 dB) | 2.5 samples only |
| Bitrate / sharpness / high-frequency | Unusable | Confounded by CRF |
| Seed reproduction | Disproved | — |
Decision flow and rejection rules
- Container family is not Volcano Ark → cannot determine.
- x264 preset + CRF hits the 2.0 or 2.5 baseline → report the pipeline; anything else, HEVC, or no SEI → cannot determine.
- 480p size and frame count (4s=97 / 5s=121) are consistency cross-checks; conflicts are flagged.
- Compare with the seller's claim → match / mismatch.
- Baseline older than 30 days without fresh native samples → the page shows a stale-baseline warning.
Limits
This proves which delivery pipeline encoded the file, not which model generated the pixels. If Volcano routes a model ID to an older model, this method cannot see it. The baseline covers 720p / 480p, 4–5 s, 24 fps only. Tool page: Seedance 2.5 / 2.0 check.