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TSM: Temporal Shift Module for Efficient Video Understanding [Website] [arXiv][Demo]

  title={TSM: Temporal Shift Module for Efficient Video Understanding},
  author={Lin, Ji and Gan, Chuang and Han, Song},
  booktitle={Proceedings of the IEEE International Conference on Computer Vision},

[NEW!] We update the environment setup for the online_demo, and should be much easier to set up. Check the folder for a try!

[NEW!] We have released the pre-trained optical flow model on Kinetics. We believe the pre-trained weight will help the training of two-stream models on other datasets.

[NEW!] We have released the code of online hand gesture recognition on NVIDIA Jeston Nano. It can achieve real-time recognition at only 8 watts. See online_demo folder for the details. [Full Video]



We release the PyTorch code of the Temporal Shift Module.




The code is built with following libraries:

For video data pre-processing, you may need ffmpeg.

Data Preparation

We need to first extract videos into frames for fast reading. Please refer to TSN repo for the detailed guide of data pre-processing.

We have successfully trained on Kinetics, UCF101, HMDB51, Something-Something-V1 and V2, Jester datasets with this codebase. Basically, the processing of video data can be summarized into 3 steps:


This code is based on the TSN codebase. The core code to implement the Temporal Shift Module is ops/ It is a plug-and-play module to enable temporal reasoning, at the cost of zero parameters and zero FLOPs.

Here we provide a naive implementation of TSM. It can be implemented with just several lines of code:

# shape of x: [N, T, C, H, W] 
out = torch.zeros_like(x)
fold = c // fold_div
out[:, :-1, :fold] = x[:, 1:, :fold]  # shift left
out[:, 1:, fold: 2 * fold] = x[:, :-1, fold: 2 * fold]  # shift right
out[:, :, 2 * fold:] = x[:, :, 2 * fold:]  # not shift
return out

Note that the naive implementation involves large data copying and increases memory consumption during training. It is suggested to use the in-place version of TSM to improve speed (see ops/ Line 12 for the details.)

Pretrained Models

Training video models is computationally expensive. Here we provide some of the pretrained models. The accuracy might vary a little bit compared to the paper, since we re-train some of the models.


Dense Sample

In the latest version of our paper, we reported the results of TSM trained and tested with I3D dense sampling (Table 1&4, 8-frame and 16-frame), using the same training and testing hyper-parameters as in Non-local Neural Networks paper to directly compare with I3D.

We compare the I3D performance reported in Non-local paper:

method n-frame Kinetics Acc.
I3D-ResNet50 32 * 10clips 73.3%
TSM-ResNet50 8 * 10clips 74.1%
I3D-ResNet50 NL 32 * 10clips 74.9%
TSM-ResNet50 NL 8 * 10clips 75.6%

TSM outperforms I3D under the same dense sampling protocol. NL TSM model also achieves better performance than NL I3D model. Non-local module itself improves the accuracy by 1.5%.

Here is a list of pre-trained models that we provide (see Table 3 of the paper). The accuracy is tested using full resolution setting following here. The list is keeping updating.

model n-frame Kinetics Acc. checkpoint test log
TSN ResNet50 (2D) 8 * 10clips 70.6% link link
TSM ResNet50 8 * 10clips 74.1% link link
TSM ResNet50 NL 8 * 10clips 75.6% link link
TSM ResNext101 8 * 10clips 76.3% TODO TODO
TSM MobileNetV2 8 * 10clips 69.5% link link

Uniform Sampling

We also provide the checkpoints of TSN and TSM models using uniform sampled frames as in Temporal Segment Networks paper, which is more sample efficient and very useful for fine-tuning on other datasets. Our TSM module improves consistently over the TSN baseline.

model n-frame acc (1-crop) acc (10-crop) checkpoint test log
TSN ResNet50 (2D) 8 * 1clip 68.8% 69.9% link link
TSM ResNet50 8 * 1clip 71.2% 72.8% link link
TSM ResNet50 16 * 1clip 72.6% 73.7% link -

Optical Flow

We provide the optical flow model pre-trained on Kinetics. The model is trained using uniform sampling. We did not carefully tune the training hyper-parameters. Therefore, the model is intended for transfer learning on other datasets but not for performance evaluation.

model n-frame top-1 acc top-5 acc checkpoint test log
TSM ResNet50 8 * 1clip 55.7% 79.5% link -


Something-Something V1&V2 datasets are highly temporal-related. TSM achieves state-of-the-art performnace on the datasets: TSM achieves the first place on V1 (50.72% test acc.) and second place on V2 (66.55% test acc.), using just ResNet-50 backbone (as of 09/28/2019).

Here we provide some of the models on the dataset. The accuracy is tested using both efficient setting (center crop * 1clip) and accuate setting (full resolution * 2clip)

model n-frame acc (center crop * 1clip) acc (full res * 2clip) checkpoint test log
TSM ResNet50 8 45.6 47.2 link link1 link2
TSM ResNet50 16 47.2 48.4 link link1 link2
TSM ResNet101 8 46.9 48.7 link link1 link2


On V2 dataset, the accuracy is reported under the accurate setting (full resolution * 2clip).

model n-frame accuracy checkpoint test log
TSM ResNet50 8 * 2clip 61.2 link link
TSM ResNet50 16 * 2lip 63.1 link link
TSM ResNet101 8 * 2clip 63.3 link link


For example, to test the downloaded pretrained models on Kinetics, you can run scripts/ The scripts will test both TSN and TSM on 8-frame setting by running:

# test TSN
python kinetics \
    --weights=pretrained/TSM_kinetics_RGB_resnet50_avg_segment5_e50.pth \
    --test_segments=8 --test_crops=1 \

# test TSM
python kinetics \
    --weights=pretrained/TSM_kinetics_RGB_resnet50_shift8_blockres_avg_segment8_e50.pth \
    --test_segments=8 --test_crops=1 \

Change to --test_crops=10 for 10-crop evaluation. With the above scripts, you should get around 68.8% and 71.2% results respectively.

To get the Kinetics performance of our dense sampling model under Non-local protocol, run:

# test TSN using non-local testing protocol
python kinetics \
    --weights=pretrained/TSM_kinetics_RGB_resnet50_avg_segment5_e50.pth \
    --test_segments=8 --test_crops=3 \
    --batch_size=8 --dense_sample --full_res

# test TSM using non-local testing protocol
python kinetics \
    --weights=pretrained/TSM_kinetics_RGB_resnet50_shift8_blockres_avg_segment8_e100_dense.pth \
    --test_segments=8 --test_crops=3 \
    --batch_size=8 --dense_sample --full_res

# test NL TSM using non-local testing protocol
python kinetics \
    --weights=pretrained/TSM_kinetics_RGB_resnet50_shift8_blockres_avg_segment8_e100_dense_nl.pth \
    --test_segments=8 --test_crops=3 \
    --batch_size=8 --dense_sample --full_res

You should get around 70.6%, 74.1%, 75.6% top-1 accuracy, as shown in Table 1.

For the efficient (center crop and 1 clip) and accurate setting (full resolution and 2 clip) on Something-Something, you can try something like this:

# efficient setting: center crop and 1 clip
python something \
    --weights=pretrained/TSM_something_RGB_resnet50_shift8_blockres_avg_segment8_e45.pth \
    --test_segments=8 --batch_size=72 -j 24 --test_crops=1

# accurate setting: full resolution and 2 clips (--twice sample)
python something \
    --weights=pretrained/TSM_something_RGB_resnet50_shift8_blockres_avg_segment8_e45.pth \
    --test_segments=8 --batch_size=72 -j 24 --test_crops=3  --twice_sample


We provided several examples to train TSM with this repo:

  • To train on Kinetics from ImageNet pretrained models, you can run scripts/, which contains:

    # You should get TSM_kinetics_RGB_resnet50_shift8_blockres_avg_segment8_e50.pth
    python kinetics RGB \
         --arch resnet50 --num_segments 8 \
         --gd 20 --lr 0.02 --wd 1e-4 --lr_steps 20 40 --epochs 50 \
         --batch-size 128 -j 16 --dropout 0.5 --consensus_type=avg --eval-freq=1 \
         --shift --shift_div=8 --shift_place=blockres --npb

    You should get TSM_kinetics_RGB_resnet50_shift8_blockres_avg_segment8_e50.pth as downloaded above. Notice that you should scale up the learning rate with batch size. For example, if you use a batch size of 256 you should set learning rate to 0.04.

  • After getting the Kinetics pretrained models, we can fine-tune on other datasets using the Kinetics pretrained models. For example, we can fine-tune 8-frame Kinetics pre-trained model on UCF-101 dataset using uniform sampling by running:

    python ucf101 RGB \
         --arch resnet50 --num_segments 8 \
         --gd 20 --lr 0.001 --lr_steps 10 20 --epochs 25 \
         --batch-size 64 -j 16 --dropout 0.8 --consensus_type=avg --eval-freq=1 \
         --shift --shift_div=8 --shift_place=blockres \
  • To train on Something-Something dataset (V1&V2), using ImageNet pre-training is usually better:

    python something RGB \
         --arch resnet50 --num_segments 8 \
         --gd 20 --lr 0.01 --lr_steps 20 40 --epochs 50 \
         --batch-size 64 -j 16 --dropout 0.5 --consensus_type=avg --eval-freq=1 \
         --shift --shift_div=8 --shift_place=blockres --npb

Live Demo on NVIDIA Jetson Nano

We have build an online hand gesture recognition demo using our TSM. The model is built with MobileNetV2 backbone and trained on Jester dataset.

  • Recorded video of the live demo [link]
  • Code of the live demo and set up tutorial: online_demo