Papers › Continual 3D Convolutional Neural Networks for Real-time Processing of Videos

Continual 3D Convolutional Neural Networks for Real-time Processing of Videos

31 May 2021arXiv:2106.00050archive 2025-07-28

Lukas Hedegaard, Alexandros Iosifidis

We introduce Continual 3D Convolutional Neural Networks (Co3D CNNs), a new computational formulation of spatio-temporal 3D CNNs, in which videos are processed frame-by-frame rather than by clip. In online tasks demanding frame-wise predictions, Co3D CNNs dispense with the computational redundancies of regular 3D CNNs, namely the repeated convolutions over frames, which appear in overlapping clips. We show that Continual 3D CNNs can reuse preexisting 3D-CNN weights to reduce the per-prediction floating point operations (FLOPs) in proportion to the temporal receptive field while retaining similar memory requirements and accuracy. This is validated with multiple models on Kinetics-400 and Charades with remarkable results: CoX3D models attain state-of-the-art complexity/accuracy trade-offs on Kinetics-400 with 12.1-15.3x reductions of FLOPs and 2.3-3.8% improvements in accuracy compared to regular X3D models while reducing peak memory consumption by up to 48%. Moreover, we investigate the transient response of Co3D CNNs at start-up and perform extensive benchmarks of on-hardware processing characteristics for publicly available 3D CNNs.

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Code

LukasHedegaard/co3d officialmentioned in papermentioned on GitHubpytorchApache-2.0 report

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Tasks

Action ClassificationVideo Recognition

Results from the paper archive 2025-07-28

TaskDatasetModelMetricValueRank at snapshotLeaderboardReport
Action Classification Charades Co Slow_64 FLOPs (G) x views 6.9x1 #43 of 49 Archive leaderboard report
Action Classification Charades Co Slow_64 MAP 25.2 #43 of 49 Archive leaderboard report
Action Classification Charades Slow-8×8 FLOPs (G) x views 54.9x1 #44 of 49 Archive leaderboard report
Action Classification Charades Slow-8×8 MAP 24.1 #44 of 49 Archive leaderboard report
Action Classification Charades Co Slow_8 FLOPs (G) x views 6.9x1 #47 of 49 Archive leaderboard report
Action Classification Charades Co Slow_8 MAP 21.5 #47 of 49 Archive leaderboard report
Action Classification Kinetics-400 Co Slow_64 Acc@1 73.05 #169 of 207 Archive leaderboard report
Action Classification Kinetics-400 Co Slow_64 FLOPs (G) x views 6.90x1 #169 of 207 Archive leaderboard report
Action Classification Kinetics-400 Co Slow_64 Parameters (M) 32.45 #169 of 207 Archive leaderboard report
Action Classification Kinetics-400 Co X3D-L_64 Acc@1 71.61 #178 of 207 Archive leaderboard report
Action Classification Kinetics-400 Co X3D-L_64 FLOPs (G) x views 1.25x1 #178 of 207 Archive leaderboard report
Action Classification Kinetics-400 Co X3D-L_64 Parameters (M) 6.15 #178 of 207 Archive leaderboard report
Action Classification Kinetics-400 Co X3D-M_64 Acc@1 71.03 #180 of 207 Archive leaderboard report
Action Classification Kinetics-400 Co X3D-M_64 FLOPs (G) x views 0.33x1 #180 of 207 Archive leaderboard report
Action Classification Kinetics-400 Co X3D-M_64 Parameters (M) 3.79 #180 of 207 Archive leaderboard report
Action Classification Kinetics-400 X3D-L Acc@1 69.29 #181 of 207 Archive leaderboard report
Action Classification Kinetics-400 X3D-L FLOPs (G) x views 19.17x1 #181 of 207 Archive leaderboard report
Action Classification Kinetics-400 X3D-L Parameters (M) 6.15 #181 of 207 Archive leaderboard report
Action Classification Kinetics-400 SlowFast-8×8-R50 Acc@1 68.45 #183 of 207 Archive leaderboard report
Action Classification Kinetics-400 SlowFast-8×8-R50 FLOPs (G) x views 66.25x1 #183 of 207 Archive leaderboard report
Action Classification Kinetics-400 SlowFast-8×8-R50 Parameters (M) 66.25 #183 of 207 Archive leaderboard report
Action Classification Kinetics-400 Slow-8x8-R50 Acc@1 67.42 #186 of 207 Archive leaderboard report
Action Classification Kinetics-400 Slow-8x8-R50 FLOPs (G) x views 54.87x1 #186 of 207 Archive leaderboard report
Action Classification Kinetics-400 Slow-8x8-R50 Parameters (M) 32.45 #186 of 207 Archive leaderboard report
Action Classification Kinetics-400 Co X3D-S_64 Acc@1 67.33 #187 of 207 Archive leaderboard report
Action Classification Kinetics-400 Co X3D-S_64 FLOPs (G) x views 0.17x1 #187 of 207 Archive leaderboard report
Action Classification Kinetics-400 Co X3D-S_64 Parameters (M) 3.79 #187 of 207 Archive leaderboard report
Action Classification Kinetics-400 X3D-M Acc@1 67.24 #188 of 207 Archive leaderboard report
Action Classification Kinetics-400 X3D-M FLOPs (G) x views 4.97x1 #188 of 207 Archive leaderboard report
Action Classification Kinetics-400 X3D-M Parameters (M) 3.79 #188 of 207 Archive leaderboard report
Action Classification Kinetics-400 SlowFast-4×16-R50 Acc@1 67.06 #189 of 207 Archive leaderboard report
Action Classification Kinetics-400 SlowFast-4×16-R50 FLOPs (G) x views 36.46x1 #189 of 207 Archive leaderboard report
Action Classification Kinetics-400 SlowFast-4×16-R50 Parameters (M) 34.48 #189 of 207 Archive leaderboard report
Action Classification Kinetics-400 Co Slow_8 Acc@1 65.90 #190 of 207 Archive leaderboard report
Action Classification Kinetics-400 Co Slow_8 FLOPs (G) x views 6.90x1 #190 of 207 Archive leaderboard report
Action Classification Kinetics-400 Co Slow_8 Parameters (M) 32.45 #190 of 207 Archive leaderboard report
Action Classification Kinetics-400 X3D-S Acc@1 64.71 #192 of 207 Archive leaderboard report
Action Classification Kinetics-400 X3D-S FLOPs (G) x views 2.06x1 #192 of 207 Archive leaderboard report
Action Classification Kinetics-400 X3D-S Parameters (M) 3.79 #192 of 207 Archive leaderboard report
Action Classification Kinetics-400 I3D-R50 Acc@1 63.98 #193 of 207 Archive leaderboard report
Action Classification Kinetics-400 I3D-R50 FLOPs (G) x views 28.61x1 #193 of 207 Archive leaderboard report
Action Classification Kinetics-400 I3D-R50 Parameters (M) 28.04 #193 of 207 Archive leaderboard report
Action Classification Kinetics-400 Co X3D-L_16 Acc@1 63.03 #194 of 207 Archive leaderboard report
Action Classification Kinetics-400 Co X3D-L_16 FLOPs (G) x views 1.25x1 #194 of 207 Archive leaderboard report
Action Classification Kinetics-400 Co X3D-L_16 Parameters (M) 6.15 #194 of 207 Archive leaderboard report
Action Classification Kinetics-400 Co X3D-M_16 Acc@1 62.80 #195 of 207 Archive leaderboard report
Action Classification Kinetics-400 Co X3D-M_16 FLOPs (G) x views 0.33x1 #195 of 207 Archive leaderboard report
Action Classification Kinetics-400 Co X3D-M_16 Parameters (M) 3.79 #195 of 207 Archive leaderboard report
Action Classification Kinetics-400 Co X3D-S_13 Acc@1 60.18 #196 of 207 Archive leaderboard report
Action Classification Kinetics-400 Co X3D-S_13 FLOPs (G) x views 0.17x1 #196 of 207 Archive leaderboard report
Action Classification Kinetics-400 Co X3D-S_13 Parameters (M) 3.79 #196 of 207 Archive leaderboard report
Action Classification Kinetics-400 Co I3D_8 Acc@1 59.58 #197 of 207 Archive leaderboard report
Action Classification Kinetics-400 Co I3D_8 FLOPs (G) x views 5.68x1 #197 of 207 Archive leaderboard report
Action Classification Kinetics-400 Co I3D_8 Parameters (M) 28.04 #197 of 207 Archive leaderboard report
Action Classification Kinetics-400 R(2+1)D-18_16 Acc@1 59.52 #198 of 207 Archive leaderboard report
Action Classification Kinetics-400 R(2+1)D-18_16 FLOPs (G) x views 40.71x1 #198 of 207 Archive leaderboard report
Action Classification Kinetics-400 R(2+1)D-18_16 Parameters (M) 31.51 #198 of 207 Archive leaderboard report
Action Classification Kinetics-400 X3D-XS Acc@1 59.37 #199 of 207 Archive leaderboard report
Action Classification Kinetics-400 X3D-XS FLOPs (G) x views 0.64x1 #199 of 207 Archive leaderboard report
Action Classification Kinetics-400 X3D-XS Parameters (M) 3.79 #199 of 207 Archive leaderboard report
Action Classification Kinetics-400 Co I3D_64 Acc@1 56.86 #200 of 207 Archive leaderboard report
Action Classification Kinetics-400 Co I3D_64 FLOPs (G) x views 5.68x1 #200 of 207 Archive leaderboard report
Action Classification Kinetics-400 Co I3D_64 Parameters (M) 28.04 #200 of 207 Archive leaderboard report
Action Classification Kinetics-400 R(2+1)D-18_8 Acc@1 53.52 #201 of 207 Archive leaderboard report
Action Classification Kinetics-400 R(2+1)D-18_8 FLOPs (G) x views 20.35x1 #201 of 207 Archive leaderboard report
Action Classification Kinetics-400 R(2+1)D-18_8 Parameters (M) 31.51 #201 of 207 Archive leaderboard report
Action Classification Kinetics-400 RCU_8 Acc@1 53.40 #202 of 207 Archive leaderboard report
Action Classification Kinetics-400 RCU_8 FLOPs (G) x views 4.71x1 #202 of 207 Archive leaderboard report
Action Classification Kinetics-400 RCU_8 Parameters (M) 12.80 #202 of 207 Archive leaderboard report

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