Create README.md
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README.md
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---
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license: apache-2.0
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tags:
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- video-classification
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- timesformer
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- retnet
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- action-recognition
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- hmdb51
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- efficient-models
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- transformers
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datasets:
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- hmdb51
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---
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# π¬ RetFormer: Efficient TimeSformer + RetNet for Video Action Recognition
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RetFormer is a hybrid video classification model that replaces the **temporal attention** in TimeSformer with **RetNet**, achieving:
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- β‘ Lower memory usage
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- π Faster training
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- π― Competitive accuracy
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---
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## π§ Model Architecture
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### πΉ RetFormer (Proposed)
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- Spatial Modeling β TimeSformer
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- Temporal Modeling β **RetNet**
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π This replaces quadratic attention with **linear-time temporal modeling (O(n))**
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---
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## π Dataset
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- **HMDB51**
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- 51 human action classes
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- Complex motion patterns
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- Smaller and more challenging than UCF101
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---
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## π Training Strategy
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Training was performed in multiple stages due to runtime limits:
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- Initial training (Epoch 1β10)
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- Checkpoint saving
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- Resumed training (Epoch 11β14)
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- Early stopping applied
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---
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## π Training Results (Epoch 1β14)
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| Epoch | Train Loss | Train Acc | Val Loss | Val Acc | F1 |
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|------|------------|-----------|----------|---------|-----|
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| 1 | 3.9312 | 0.0350 | 3.8099 | 0.0967 | 0.0855 |
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| 2 | 3.6330 | 0.1791 | 3.2948 | 0.3654 | 0.3149 |
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| 3 | 3.0989 | 0.3691 | 2.6927 | 0.5150 | 0.4579 |
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| 4 | 2.6278 | 0.5048 | 2.2879 | 0.5869 | 0.5503 |
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| 5 | 2.3198 | 0.5782 | 2.0438 | 0.6255 | 0.5961 |
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| 6 | 2.1387 | 0.6194 | 1.9152 | 0.6242 | 0.6074 |
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| 7 | 1.9876 | 0.6657 | 1.8369 | 0.6418 | 0.6308 |
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| 8 | 1.9140 | 0.6936 | 1.7966 | 0.6359 | 0.6188 |
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| 9 | 1.8539 | 0.7041 | 1.7619 | 0.6556 | 0.6426 |
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| 10 | 1.8149 | 0.7244 | 1.7523 | 0.6614 | 0.6512 |
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| 11 | 1.7325 | 0.7524 | 1.7315 | **0.6699** | **0.6614** |
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| 12 | 1.7036 | 0.7584 | 1.7469 | 0.6621 | 0.6515 |
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| 13 | 1.6682 | 0.7717 | 1.7504 | 0.6595 | 0.6496 |
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| 14 | 1.6344 | 0.7785 | 1.7488 | 0.6588 | 0.6494 |
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---
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## π Best Performance
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- **Validation Accuracy:** **66.99%**
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- **F1 Score:** 0.6614
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- Achieved at **Epoch 11**
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---
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## βοΈ Training Details
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- Peak GPU Memory: **~7.2 GB**
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- Training Time per Epoch: ~52 minutes
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- Evaluation Time: ~8 minutes
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- Mixed Precision Training (`torch.cuda.amp`)
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- Early stopping triggered after Epoch 14
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---
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## π Observations
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- Stable improvement until **Epoch 11**
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- Slight decline afterward β early overfitting
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- Lower accuracy than baseline (expected for hybrid trade-off)
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---
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## β‘ Efficiency Advantage
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| Metric | TimeSformer | RetFormer |
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|-------|------------|----------|
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| Peak GPU Memory | ~9.3 GB | **~7.2 GB** β
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| Complexity | O(nΒ²) | **O(n)** β
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| Speed | Slower | Faster |
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π **~25% reduction in GPU memory**
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---
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## π Key Insight
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RetFormer demonstrates that:
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- Efficient temporal modeling can **significantly reduce memory usage**
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- Performance remains **competitive with baseline models**
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- Trade-off exists between **efficiency and maximum accuracy**
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---
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## π Usage
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```bash
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pip install torch torchvision transformers
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