Audio modelOpen weights
Index-Echo-S2TT-2B
Bilibili Index Team
- Released
- -
- Data date
- October 7, 2026
Index-Echo-S2TT-2B translates speech into subtitles. Its package uses a 2B text decoder, accepts audio or video, and returns a transcript plus translated, timestamped text segments for Chinese to English, Japanese, or Spanish.
Specifications and access
| Specification | Value and source |
|---|---|
| Model type | Open weightsSource |
| Model ID | IndexTeam/Index-Echo-S2TT-2BSource |
| Model task | Speech translation into timestamped subtitlesSource |
| Access | Public Hugging Face weights for local executionSource |
| Input modalities | Audio or video containing speechSource |
| Output modalities | Transcript and translated subtitles with timestampsSource |
| License | Apache 2.0 according to the Hugging Face model cardSource |
| Translation directions | Chinese to English, Japanese, or SpanishSource |
| Decoder size | 2 billion parameters in the text decoder; not the total audio-package sizeSource |
Measurements without matching peer values
These measurements have no matching peer values under the same test conditions. Their original values and sources remain available here.
Index-Echo S2TT in-house video translation: MT judge (Show measurement, test conditions, and source)
- Source value
- 0.825
- Score
- 0.825
- Metric
- Gemini-3.1-Pro per-line translation quality rating on 0 / 0.5 / 1 scale
- Unit
- ratio
- Benchmark version
- arXiv:2609.40181v1, Table 7
- Category
- audio
- Direction
- Higher is better
- Sample
- 140
- Source type
- vendor-reported
- Evaluator
- Index-Translate paper v1, Table 7
- Status
- active
- Retrieved at
- 2026-10-07
- Methodology
- Vendor-reported result. Index-Echo-S2TT-2B text decoder; 140 in-house video-translation windows of 50–60 seconds, 20 in each of seven directions (Chinese to English/Japanese/Korean/Spanish/Portuguese/Arabic, plus English to Chinese).
- Context
- Model-team in-house test; no external replication or per-direction sample breakdown is provided in the table row.
Index-Echo S2TT in-house video translation: median ASR error (Show measurement, test conditions, and source)
- Source value
- 0.088
- Score
- 0.088
- Metric
- median rate of source-audio transcript errors versus reference
- Unit
- ratio
- Benchmark version
- arXiv:2609.40181v1, Table 7
- Category
- audio
- Direction
- Lower is better
- Sample
- 140
- Source type
- vendor-reported
- Evaluator
- Index-Translate paper v1, Table 7
- Status
- active
- Retrieved at
- 2026-10-07
- Methodology
- Vendor-reported result. Index-Echo-S2TT-2B text decoder; 140 in-house video-translation windows of 50–60 seconds, 20 in each of seven directions (Chinese to English/Japanese/Korean/Spanish/Portuguese/Arabic, plus English to Chinese).
- Context
- Model-team in-house test; no external replication or per-direction sample breakdown is provided in the table row.
Index-Echo S2TT in-house video translation: sentence start-time MAE (Show measurement, test conditions, and source)
- Source value
- 0.395
- Score
- 0.395
- Metric
- mean absolute sentence start-time error
- Unit
- seconds
- Benchmark version
- arXiv:2609.40181v1, Table 7
- Category
- audio
- Direction
- Lower is better
- Sample
- 140
- Source type
- vendor-reported
- Evaluator
- Index-Translate paper v1, Table 7
- Status
- active
- Retrieved at
- 2026-10-07
- Methodology
- Vendor-reported result. Index-Echo-S2TT-2B text decoder; 140 in-house video-translation windows of 50–60 seconds, 20 in each of seven directions (Chinese to English/Japanese/Korean/Spanish/Portuguese/Arabic, plus English to Chinese).
- Context
- Model-team in-house test; no external replication or per-direction sample breakdown is provided in the table row.
Sources and data date
| Type | Evidence and data date |
|---|---|
| Research status | Research date October 7, 2026. 1 source URLs checked. This documents the inspected sources, not an exhaustive inventory of every publication. |
| Not found in the inspected sources | independent-s2tt-replication Original wording The S2TT scores come from the model team's in-house video test; no independent repetition for this checkpoint was found in the sources read. |
| Additional source | Index-Echo-S2TT-2B Hugging Face model card (retrieved October 7, 2026) · Index-Echo-S2TT-2B model card · Editorial description reviewed October 7, 2026 |
| Additional source | Bilibili Index-Translate repository (retrieved October 7, 2026) · Bilibili Index-Translate repository · Editorial description reviewed October 7, 2026 |
| Additional source | Index-Translate paper v1, Table 7 (retrieved October 7, 2026) |