| --- |
| license: bsd-3-clause |
| tags: |
| - executorch |
| - xnnpack |
| - pte |
| - on-device |
| - optical-flow |
| - video |
| --- |
| # raft_small — ExecuTorch |
| |
| - **Source**: torchvision raft_small (C_T_V2, FlyingChairs + FlyingThings3D) |
| - **License**: BSD-3-Clause |
| - **Input**: [[1, 3, 384, 512], [1, 3, 384, 512]] — two RGB frames, each scaled to [-1,1], 384x512 (both dimensions must stay divisible by 8) |
| - **Output**: flow [1,2,384,512] in pixels: channel 0 is horizontal displacement from frame 1 to frame 2, channel 1 vertical. Refined over 12 iterations, which are baked into the graph — the intermediate iterates are not returned. |
|
|
| ## Variants |
|
|
| All variants take and return fp32 tensors — swap the `.pte` file, keep your app code. |
|
|
| | build | file | size (MB) | parity vs fp32 eager (worst corr) | Mac median (ms)* | |
| |-----------|------|-----------|------------------------------------|------------------| |
| | fp32 | `raft_small_xnnpack_fp32.pte` | 4.4 | 1.000000 | 173.0 | |
| | Core ML (fp32, iOS) | `raft_small_coreml_all_fp32.pte` | 10.6 | 1.000000 | 12.0 | |
|
|
| \*Mac arm64, single process, median of 10 — a reference point for relative cost |
| only, not a device number (torch eager fp32 on the same machine: 140.6 ms). |
| |
| ## Verification (executorch 1.4.0, torch 2.13.0) |
| |
| Parity is measured against the fp32 eager model on real image input; `corr` is |
| the correlation over all elements of each output tensor. |
| |
| | output | shape | max_abs_diff | corr | |
| |--------|-------|--------------|------| |
| | 0 | [1, 2, 384, 512] | 4.792e-04 | 1.000000 | |
| |
| XNNPACK delegate coverage (fp32): 63.0% (1209/1920 ops); ops left on the portable kernels: `dim_order_ops._to_dim_order_copy.default` x435, `aten.split_with_sizes_copy.default` x50, `aten.grid_sampler_2d.default` x48, `aten.expand_copy.default` x30, `aten.arange.start_step` x28, `aten.lt.Scalar` x24, `aten.sub.Tensor` x24, `aten.where.self` x24, `aten._native_batch_norm_legit.no_stats` x21, `aten.alias_copy.default` x12, `aten.view_copy.default` x6, `aten.avg_pool2d.default` x3, `aten.cat.default` x2, `aten.unsqueeze_copy.default` x2, `aten.repeat.default` x2 |
| |
| ## Conversion |
| |
| torch.export -> to_edge_transform_and_lower(partitioner) -> .pte |
| (conversion scripts: [executorch-models](https://github.com/john-rocky/executorch-models)) |
| |
