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Open weightsGoogle Research/10 trustVerified

Vid2Seq

Google's single-stage dense video captioner: special time tokens let one model emit event boundaries and captions as a single sequence, pretrained on millions of narrated YouTube videos — the CVPR 2023 approach the field still builds on.

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About

Vid2Seq (CVPR 2023, arXiv 2302.14115) from Google Research with Inria reframed dense video captioning. Instead of separate proposal and captioning stages, it augments a language model with special time tokens, so the model generates event boundaries and their textual descriptions in one output sequence. The key enabler is scale without annotation cost: pretraining reformulates transcribed-speech sentence boundaries from narrated videos as pseudo event boundaries, using the YT-Temporal-1B collection of millions of narrated videos, with generative plus denoising objectives. The resulting model set the state of the art on ActivityNet-Captions, YouCook2 and ViTT dense-captioning benchmarks at publication (author-reported), and also generalized to video paragraph captioning and few-shot settings. Code is Apache 2.0 in google-research/scenic; the README initially said checkpoints were coming, and later work confirms a public pretrained checkpoint exists and is reused by follow-up research. No hosted API.

Specs

Context window

Minutes-long untrimmed videos (frames plus transcribed speech as input); the paper publishes no single max-duration figure.

Pricing

Free / open source — Apache 2.0

Free quota

Fully open — code in the Scenic repo; pretrained checkpoint publicly released and reused by later work

API access

No hosted API — self-host via the Scenic repo and public checkpoint

Weights

Open weights

Released

Not disclosed

Benchmarks

  • State of the art on ActivityNet-Captions, YouCook2 and ViTT dense event captioning at publication (author-reported)\n- Generalized to video paragraph captioning and few-shot settings (author-reported)\n- A later paper (Streaming Dense Video Captioning) confirms using the publicly released pretrained checkpoint\n- All original figures author-reported; the field has since moved to LLM-based captioners

Provider-reported unless a source says otherwise. Benchmarks are marketing-adjacent by nature — treat them as directional.

Use cases

dense-video-captioningvideo-summarizationvideo-paragraph-captioninglecture-indexingvideo-search

Trust score — 8/10

/10 trustVerified

Scored 8/10 (TIER verified, metrics-v1). Evidence: peer-reviewed at CVPR 2023; Apache 2.0 code in the maintained Scenic repo; the time-token idea became foundational and the public checkpoint is still reused by later research. Strengths: a landmark reframing of dense captioning with an elegant weak-supervision trick (narrated video as free labels). Docked for: (1) benchmark figures are author-reported and from 2023, before LLM-based captioners took over; (2) the checkpoint release was delayed and poorly documented, though later confirmed public. License: Apache 2.0.

How the trust score is built

Full methodology →
Adoption · stars/downloads, log-scaled vs peers
8.0/10
Maintenance · recency, releases, issue load
7.0/10
Openness · license + docs
9.0/10
Manual review · sanity read + red-flag check
8.0/10
  • · CVPR 2023 landmark: single-stage dense captioning with time tokens, pretrained on YT-Temporal-1B narrated videos.
  • · SOTA on ActivityNet-Captions, YouCook2, ViTT at publication (author-reported).
  • · Public checkpoint confirmed in use by later research; maintained inside Google Scenic.

Sources