对比性语言图像预测在学习网络尺度数据的视觉文本联合表示方面取得了巨大的成功，这表明了各种图像任务的显着“零射”概括能力。但是，如何有效地将这种新的语言图像预处理方法扩展到视频域仍然是一个开放的问题。在这项工作中，我们提出了一种简单而有效的方法，该方法将预验证的语言图像模型直接适应视频识别，而不是从头开始预处理新模型。更具体地说，为了捕获沿时间维度框架的远距离依赖性，我们提出了一种跨框架注意机制，该机制明确地跨帧交换信息。这样的模块是轻量级的，可以无缝地插入验证的语言图像模型中。此外，我们提出了一个特定于视频的提示方案，该方案利用视频内容信息生成歧视性文本提示。广泛的实验表明，我们的方法是有效的，可以推广到不同的视频识别方案。特别是，在完全监督的设置下，我们的方法在Kinectics-400上获得了最高1的精度为87.1％，而与SWIN-L和Vivit-H相比，使用量少12倍。在零拍摄的实验中，我们的方法超过了当前的最新方法 +7.6％和 +14.9％，而在两个流行协议下，TOP-1的准确性。在少数拍摄的情况下，当标记的数据非常有限时，我们的方法优于先前的最佳方法 +32.1％和 +23.1％。代码和型号可在https://aka.ms/x-clip上找到

Large-scale multi-modal training with image-text pairs imparts strong generalization to CLIP model. Since training on a similar scale for videos is infeasible, recent approaches focus on the effective transfer of image-based CLIP to the video domain. In this pursuit, new parametric modules are added to learn temporal information and inter-frame relationships which require meticulous design efforts. Furthermore, when the resulting models are learned on videos, they tend to overfit on the given task distribution and lack in generalization aspect. This begs the following question: How to effectively transfer image-level CLIP representations to videos? In this work, we show that a simple Video Fine-tuned CLIP (ViFi-CLIP) baseline is generally sufficient to bridge the domain gap from images to videos. Our qualitative analysis illustrates that the frame-level processing from CLIP image-encoder followed by feature pooling and similarity matching with corresponding text embeddings helps in implicitly modeling the temporal cues within ViFi-CLIP. Such fine-tuning helps the model to focus on scene dynamics, moving objects and inter-object relationships. For low-data regimes where full fine-tuning is not viable, we propose a `bridge and prompt' approach that first uses fine-tuning to bridge the domain gap and then learns prompts on language and vision side to adapt CLIP representations. We extensively evaluate this simple yet strong baseline on zero-shot, base-to-novel generalization, few-shot and fully supervised settings across five video benchmarks. Our code is available at https://github.com/muzairkhattak/ViFi-CLIP.

Video recognition in an open and dynamic world is quite challenging, as we need to handle different settings such as close-set, long-tail, few-shot and open-set. By leveraging semantic knowledge from noisy text descriptions crawled from the Internet, we focus on the general video recognition (GVR) problem of solving different recognition tasks within a unified framework. The core contribution of this paper is twofold. First, we build a comprehensive video recognition benchmark of Kinetics-GVR, including four sub-task datasets to cover the mentioned settings. To facilitate the research of GVR, we propose to utilize external textual knowledge from the Internet and provide multi-source text descriptions for all action classes. Second, inspired by the flexibility of language representation, we present a unified visual-linguistic framework (VLG) to solve the problem of GVR by an effective two-stage training paradigm. Our VLG is first pre-trained on video and language datasets to learn a shared feature space, and then devises a flexible bi-modal attention head to collaborate high-level semantic concepts under different settings. Extensive results show that our VLG obtains the state-of-the-art performance under four settings. The superior performance demonstrates the effectiveness and generalization ability of our proposed framework. We hope our work makes a step towards the general video recognition and could serve as a baseline for future research. The code and models will be available at https://github.com/MCG-NJU/VLG.

从任务不足的预训练的深层模型中转移知识以进行下游任务是计算机视觉研究中的一个重要主题。随着计算能力的增长，我们现在拥有大规模的模型体系结构和数据量的开源视觉语言预培训模型。在这项研究中，我们专注于转移视力分类任务的知识。传统方法随机初始化线性分类器头进行视觉分类，但是它们将文本编码器的用法留为未发现的下游视觉识别任务。在本文中，我们修改了线性分类器的角色，并用对象类别的嵌入式语言表示替换分类器。这些语言表示是从视觉语言预训练模型的文本编码器初始化的，以进一步利用其良好的语言模型参数。实证研究表明，我们的方法提高了视频分类的性能和训练速度，模型的变化微不足道。特别是，我们的范式在动力学400上实现了87.3％的最新准确性。

This work explores an efficient approach to establish a foundational video-text model for tasks including open-vocabulary video classification, text-to-video retrieval, video captioning and video question-answering. We present VideoCoCa that reuses a pretrained image-text contrastive captioner (CoCa) model and adapt it to video-text tasks with minimal extra training. While previous works adapt image-text models with various cross-frame fusion modules (for example, cross-frame attention layer or perceiver resampler) and finetune the modified architecture on video-text data, we surprisingly find that the generative attentional pooling and contrastive attentional pooling layers in the image-text CoCa design are instantly adaptable to ``flattened frame embeddings'', yielding a strong zero-shot transfer baseline for many video-text tasks. Specifically, the frozen image encoder of a pretrained image-text CoCa takes each video frame as inputs and generates \(N\) token embeddings per frame for totally \(T\) video frames. We flatten \(N \times T\) token embeddings as a long sequence of frozen video representation and apply CoCa's generative attentional pooling and contrastive attentional pooling on top. All model weights including pooling layers are directly loaded from an image-text CoCa pretrained model. Without any video or video-text data, VideoCoCa's zero-shot transfer baseline already achieves state-of-the-art results on zero-shot video classification on Kinetics 400/600/700, UCF101, HMDB51, and Charades, as well as zero-shot text-to-video retrieval on MSR-VTT and ActivityNet Captions. We also explore lightweight finetuning on top of VideoCoCa, and achieve strong results on video question-answering (iVQA, MSRVTT-QA, MSVD-QA) and video captioning (MSR-VTT, ActivityNet, Youcook2). Our approach establishes a simple and effective video-text baseline for future research.

Vision-language models (VLMs) that are pre-trained on large-scale image-text pairs have demonstrated impressive transferability on a wide range of visual tasks. Transferring knowledge from such powerful pre-trained VLMs is emerging as a promising direction for building effective video recognition models. However, the current exploration is still limited. In our opinion, the greatest charm of pre-trained vision-language models is to build a bridge between visual and textual domains. In this paper, we present a novel framework called BIKE which utilizes the cross-modal bridge to explore bidirectional knowledge: i) We propose a Video Attribute Association mechanism which leverages the Video-to-Text knowledge to generate textual auxiliary attributes to complement video recognition. ii) We also present a Temporal Concept Spotting mechanism which uses the Text-to-Video expertise to capture temporal saliency in a parameter-free manner to yield enhanced video representation. The extensive studies on popular video datasets (ie, Kinetics-400 & 600, UCF-101, HMDB-51 and ActivityNet) show that our method achieves state-of-the-art performance in most recognition scenarios, eg, general, zero-shot, and few-shot video recognition. To the best of our knowledge, our best model achieves a state-of-the-art accuracy of 88.4% on challenging Kinetics-400 with the released CLIP pre-trained model.

视频识别是由端到端学习范式主导的 - 首先初始化具有预审预周化图像模型的视频识别模型，然后对视频进行端到端培训。这使视频网络能够受益于验证的图像模型。但是，这需要大量的计算和内存资源，以便在视频上进行填充以及直接使用预审计的图像功能的替代方案，而无需填充图像骨架会导致结果不足。幸运的是，在对比视力语言预训练（剪辑）方面的最新进展为视觉识别任务的新途径铺平了道路。这些模型在大型开放式图像文本对数据上进行了预测，以丰富的语义学习强大的视觉表示。在本文中，我们介绍了有效的视频学习（EVL） - 一种有效的框架，用于直接训练具有冷冻剪辑功能的高质量视频识别模型。具体来说，我们采用轻型变压器解码器并学习查询令牌，从剪辑图像编码器中动态收集帧级空间特征。此外，我们在每个解码器层中采用局部时间模块，以发现相邻帧及其注意力图的时间线索。我们表明，尽管有效地使用冷冻的骨干训练，但我们的模型在各种视频识别数据集上学习了高质量的视频表示。代码可在https://github.com/opengvlab/feld-video-rencognition上找到。

The last several years have witnessed remarkable progress in video-and-language (VidL) understanding. However, most modern VidL approaches use complex and specialized model architectures and sophisticated pretraining protocols, making the reproducibility, analysis and comparisons of these frameworks difficult. Hence, instead of proposing yet another new VidL model, this paper conducts a thorough empirical study demystifying the most important factors in the VidL model design. Among the factors that we investigate are (i) the spatiotemporal architecture design, (ii) the multimodal fusion schemes, (iii) the pretraining objectives, (iv) the choice of pretraining data, (v) pretraining and finetuning protocols, and (vi) dataset and model scaling. Our empirical study reveals that the most important design factors include: temporal modeling, video-to-text multimodal fusion, masked modeling objectives, and joint training on images and videos. Using these empirical insights, we then develop a step-by-step recipe, dubbed VindLU, for effective VidL pretraining. Our final model trained using our recipe achieves comparable or better than state-of-the-art results on several VidL tasks without relying on external CLIP pretraining. In particular, on the text-to-video retrieval task, our approach obtains 61.2% on DiDeMo, and 55.0% on ActivityNet, outperforming current SOTA by 7.8% and 6.1% respectively. Furthermore, our model also obtains state-of-the-art video question-answering results on ActivityNet-QA, MSRVTT-QA, MSRVTT-MC and TVQA. Our code and pretrained models are publicly available at: https://github.com/klauscc/VindLU.

The foundation models have recently shown excellent performance on a variety of downstream tasks in computer vision. However, most existing vision foundation models simply focus on image-level pretraining and adpation, which are limited for dynamic and complex video-level understanding tasks. To fill the gap, we present general video foundation models, InternVideo, by taking advantage of both generative and discriminative self-supervised video learning. Specifically, InternVideo efficiently explores masked video modeling and video-language contrastive learning as the pretraining objectives, and selectively coordinates video representations of these two complementary frameworks in a learnable manner to boost various video applications. Without bells and whistles, InternVideo achieves state-of-the-art performance on 39 video datasets from extensive tasks including video action recognition/detection, video-language alignment, and open-world video applications. Especially, our methods can obtain 91.1% and 77.2% top-1 accuracy on the challenging Kinetics-400 and Something-Something V2 benchmarks, respectively. All of these results effectively show the generality of our InternVideo for video understanding. The code will be released at https://github.com/OpenGVLab/InternVideo .

利用在大规模图像文本对中预先训练的视觉和语言模型（VLM）成为开放式视觉识别的有希望的范式。在这项工作中，我们通过利用视频中自然存在的运动和音频来扩展这种范式。我们提出\ textbf {mov}，这是\ textbf {m} ult-imodal \ textbf {o} pen- \ textbf {v} ocabulary视频分类的简单而有效的方法。在MOV中，我们直接使用具有最小修改的预训练VLM的视觉编码器来编码视频，光流和音频频谱图。我们设计一种跨模式融合机制来汇总免费的多模式信息。 Kinetics-700和VGGSOUND的实验表明，引入流量或音频模态会带来预先训练的VLM和现有方法的大量性能增长。具体而言，MOV极大地提高了基础类别的准确性，而在新颖的课程上则更好地概括了。 MOV在UCF和HMDB零摄像视频分类基准上实现了最新结果，从而极大地超过了基于VLMS的传统零摄像方法和最新方法。代码和模型将发布。

最近出现了有希望的表现，利用大型预训练的模型来实现各种感兴趣的下游任务。由于模型的规模不断增长，因此，在模型培训和存储方面，基于标准的完整任务适应策略的成本高昂。这导致了参数有效传输学习的新研究方向。但是，现有的尝试通常集中在预训练模型的相同模式（例如图像理解）的下游任务上。这会产生限制，因为在某些特定的方式（例如，视频理解）中，具有足够知识的强大预训练模型较少或不可用。在这项工作中，我们研究了这样一种新型的跨模式转移学习设置，即参数有效的图像到视频传输学习。为了解决此问题，我们为每个视频任务提出了一个新的时空适配器（ST-ADAPTER），以进行参数有效调整。凭借紧凑设计中的内置时空推理能力，ST-ADAPTER可以实现预训练的图像模型，而无需时间知识，以小（〜8％）的每任务参数成本来理解动态视频内容，以大约需要与以前的工作相比，更新参数少20倍。在视频动作识别任务上进行的广泛实验表明，我们的ST-ADAPTER可以匹配甚至优于强大的完整微调策略和最先进的视频模型，同时享受参数效率的优势。

Few-shot (FS) and zero-shot (ZS) learning are two different approaches for scaling temporal action detection (TAD) to new classes. The former adapts a pretrained vision model to a new task represented by as few as a single video per class, whilst the latter requires no training examples by exploiting a semantic description of the new class. In this work, we introduce a new multi-modality few-shot (MMFS) TAD problem, which can be considered as a marriage of FS-TAD and ZS-TAD by leveraging few-shot support videos and new class names jointly. To tackle this problem, we further introduce a novel MUlti-modality PromPt mETa-learning (MUPPET) method. This is enabled by efficiently bridging pretrained vision and language models whilst maximally reusing already learned capacity. Concretely, we construct multi-modal prompts by mapping support videos into the textual token space of a vision-language model using a meta-learned adapter-equipped visual semantics tokenizer. To tackle large intra-class variation, we further design a query feature regulation scheme. Extensive experiments on ActivityNetv1.3 and THUMOS14 demonstrate that our MUPPET outperforms state-of-the-art alternative methods, often by a large margin. We also show that our MUPPET can be easily extended to tackle the few-shot object detection problem and again achieves the state-of-the-art performance on MS-COCO dataset. The code will be available in https://github.com/sauradip/MUPPET

现有的时间动作检测（TAD）方法依赖于大型培训数据，包括细分级注释，仅限于在推理期间单独识别先前看到的课程。为每类兴趣收集和注释一个大型培训集是昂贵的，因此无法计算。零射TAD（ZS-TAD）通过启用预训练的模型来识别任何看不见的动作类别来解决这一障碍。同时，ZS-TAD的调查大大降低，ZS-Tad也更具挑战性。受零摄像图像分类的成功的启发，我们旨在解决更复杂的TAD任务。一种直观的方法是将现成的建议探测器与剪辑样式分类集成。但是，由于顺序定位（例如，提案生成）和分类设计，它很容易进行定位误差传播。为了克服这个问题，在本文中，我们通过视觉提示（陈旧）提出了一种新型的零射击时间动作检测模型。这种新颖的设计通过破坏介于两者之间的错误传播途径来有效地消除了定位和分类之间的依赖性。我们进一步介绍了分类和定位之间的相互作用机制，以改善优化。对标准ZS-TAD视频基准测试的广泛实验表明，我们的陈旧的表现明显优于最先进的替代方案。此外，我们的模型还与最近的强大竞争对手相比，在受到监督的TAD上还能产生卓越的成果。 Stale的Pytorch实现可从https://github.com/sauradip/stale获得。

视频理解需要在多种时空分辨率下推理 - 从短的细粒度动作到更长的持续时间。虽然变压器架构最近提出了最先进的，但它们没有明确建模不同的时空分辨率。为此，我们为视频识别（MTV）提供了多视图变压器。我们的模型由单独的编码器组成，表示输入视频的不同视图，以横向连接，以跨视图熔断信息。我们对我们的模型提供了彻底的消融研究，并表明MTV在一系列模型尺寸范围内的准确性和计算成本方面始终如一地表现优于单视对应力。此外，我们在五个标准数据集上实现最先进的结果，并通过大规模预制来进一步提高。我们将释放代码和备用检查点。

视觉语言预培训对从大规模Web数据学习联合视觉文本表示的巨大成功，展示了零拍广泛的显着能力。本文介绍了一种简单的方法，可以将一个预先训练的视觉语言模型有效地调整到具有最小培训的新型任务，以及这里，我们考虑视频了解任务。具体而言，我们建议优化几个随机向量，称为连续提示向量，将新颖任务转换为与预培训目标相同的格式。此外，为了弥合静态图像和视频之间的差距，用堆叠在框架明智的视觉特征之上的轻量压变压器编码时分信息。在实验上，我们进行广泛的消融研究，以分析关键组成部分和必需品。在9个公共基准的行动认可，行动本地化和文本 - 视频检索，跨封闭式，几次射击，开放式场景，我们为现有方法实现了竞争或最先进的性能，尽管培训显着更少的参数。

探索大规模预处理的基础模型对计算机视觉具有重大兴趣，因为这些模型可以快速转移到许多下游任务中。本文介绍了对比字幕（COCA），这是一种极简主义的设计，旨在为图像文本编码器编码器基础模型预算与对比度损失和字幕损失，从而从剪辑和诸如simvlm之类的生成方法之类的对比方法中包含模型能力。与所有解码器层都参与编码器输出的标准编码器 - 模块变压器相反，可口可乐省略了解码器层的上半部分的交叉注意，以编码单峰文本表示，并串联到剩余的解码器层，这些解码器与图像编码器相交的解码器层多模式图像文本表示。除了对多模态解码器输出的字幕损失外，我们还应用了单峰图像和文本嵌入之间的对比损失，该输出可以预测文本令牌自动加压。通过共享相同的计算图，可以用最小的开销有效地计算两个培训目标。可口可乐是端到端和从头开始的网络尺度alt-text数据和带注释的图像，通过将所有标签视为文本，无缝地统一自然语言监督以进行表示。从经验上讲，可口可乐通过零拍传输或在广泛的下游任务上进行零摄像转移或最少的特定任务适应，跨越视觉识别（Imagenet，Kinetics-400/600/700，瞬间， ），交叉模式检索（MSCOCO，FLICKR30K，MSR-VTT），多模式理解（VQA，SNLI-VE，NLVR2）和图像字幕（MSCOCO，NOCAPS）。值得注意的是，在Imagenet分类方面，COCA获得了86.3％的TOP-1准确性，带有冷冻编码器和学习的分类头90.6％，以及带有填充编码器的Imagenet上的新最先进的91.0％Top-1 Top-1精度。

我们呈现了基于纯变压器的视频分类模型，在图像分类中最近的近期成功进行了借鉴。我们的模型从输入视频中提取了时空令牌，然后由一系列变压器层编码。为了处理视频中遇到的令牌的长序列，我们提出了我们模型的几种有效的变体，它们将输入的空间和时间维构建。虽然已知基于变换器的模型只有在可用的大型训练数据集时才有效，但我们展示了我们如何在训练期间有效地规范模型，并利用预先训练的图像模型能够在相对小的数据集上训练。我们进行彻底的消融研究，并在包括动力学400和600，史诗厨房，东西的多个视频分类基准上实现最先进的结果，其中 - 基于深度3D卷积网络的现有方法表现出优先的方法。为了促进进一步的研究，我们在https://github.com/google-research/scenic/tree/main/scenic/projects/vivit发布代码

We present a simple approach which can turn a ViT encoder into an efficient video model, which can seamlessly work with both image and video inputs. By sparsely sampling the inputs, the model is able to do training and inference from both inputs. The model is easily scalable and can be adapted to large-scale pre-trained ViTs without requiring full finetuning. The model achieves SOTA results and the code will be open-sourced.

自动视觉解对我们多样化和开放的世界需要计算机视觉模型，以概括为特定任务的最小定制，类似于人类视力。计算机视觉基础型号培训，培训多样化，大型数据集，可以适应各种下游任务，对该任务来解决现实世界计算机视觉应用而言至关重要。虽然现有的视觉基础模型如剪辑，对齐和吴道2.0主要集中在映射图像和文本表示到跨模型共享表示，我们介绍了一台新的计算机视觉基础模型，佛罗伦萨，扩大粗糙的表示（现场）到精细（对象），从静态（图像）到动态（视频），以及从RGB到多个模态（标题，深度）。通过从Web级图像文本数据中纳入通用视觉语言表示，我们的佛罗伦萨模型可以很容易地适应各种计算机视觉任务，例如分类，检索，对象检测，VQA，图像标题，视频检索和动作识别。此外，佛罗伦萨在许多类型的转移学习中表现出出色的表现：全面采样的微调，线性探测，几次射击传输和用于新颖图像和物体的零拍摄传输。所有这些属性对于我们的视觉基础模型至关重要，以提供通用视觉任务。佛罗伦萨实现了新的最先进的导致44个代表性基准，例如Imagenet-1K零射击分类，最高1精度为83.74，最高5个精度为97.18，62.4地图上的Coco微调， 80.36在VQA上，动力学-600上的87.8。

本文研究了视频变压器的BERT预借鉴。考虑到近期图像变形金刚的伯爵预借鉴成功，这是一个简单但值得学习的延伸。我们介绍了Decouples将视频表示学习学习的BEVT进入空间代表学习和时间动态学习。特别地，BEVT首先在图像数据上执行屏蔽图像建模，然后在视频数据上与屏蔽视频建模联合进行屏蔽图像建模。这种设计具有两个观察的动机：1）在图像数据集上学习的变压器提供了体面的空间前沿，可以缓解视频变压器的学习，这通常是从划痕训练的计算密集型的时间。 2）鉴别的线索，即空间和时间信息，需要在不同的视频中进行正确的预测，由于阶级的阶级和阶级际变化而不同。我们对三个具有挑战性的视频基准进行了广泛的实验，其中BEVT达到了非常有前途的结果。在动力学400上，哪些识别主要依赖于歧视性空间表示，BEVT达到了强大的监督基线的可比结果。在某种东西 - V2和潜水48上，其中包含依靠时间动态的视频，BEVT优于所有替代基准，分别实现了70.6％和86.7％的最新性能。