ultralytics/engine/exporter.py

# Ultralytics YOLO 🚀, AGPL-3.0 license
"""

Export a YOLO PyTorch model to other formats. TensorFlow exports authored by https://github.com/zldrobit.



Format                  | `format=argument`         | Model

---                     | ---                       | ---

PyTorch                 | -                         | yolo11n.pt

TorchScript             | `torchscript`             | yolo11n.torchscript

ONNX                    | `onnx`                    | yolo11n.onnx

OpenVINO                | `openvino`                | yolo11n_openvino_model/

TensorRT                | `engine`                  | yolo11n.engine

CoreML                  | `coreml`                  | yolo11n.mlpackage

TensorFlow SavedModel   | `saved_model`             | yolo11n_saved_model/

TensorFlow GraphDef     | `pb`                      | yolo11n.pb

TensorFlow Lite         | `tflite`                  | yolo11n.tflite

TensorFlow Edge TPU     | `edgetpu`                 | yolo11n_edgetpu.tflite

TensorFlow.js           | `tfjs`                    | yolo11n_web_model/

PaddlePaddle            | `paddle`                  | yolo11n_paddle_model/

NCNN                    | `ncnn`                    | yolo11n_ncnn_model/



Requirements:

    $ pip install "ultralytics[export]"



Python:

    from ultralytics import YOLO

    model = YOLO('yolo11n.pt')

    results = model.export(format='onnx')



CLI:

    $ yolo mode=export model=yolo11n.pt format=onnx



Inference:

    $ yolo predict model=yolo11n.pt                 # PyTorch

                         yolo11n.torchscript        # TorchScript

                         yolo11n.onnx               # ONNX Runtime or OpenCV DNN with dnn=True

                         yolo11n_openvino_model     # OpenVINO

                         yolo11n.engine             # TensorRT

                         yolo11n.mlpackage          # CoreML (macOS-only)

                         yolo11n_saved_model        # TensorFlow SavedModel

                         yolo11n.pb                 # TensorFlow GraphDef

                         yolo11n.tflite             # TensorFlow Lite

                         yolo11n_edgetpu.tflite     # TensorFlow Edge TPU

                         yolo11n_paddle_model       # PaddlePaddle

                         yolo11n_ncnn_model         # NCNN



TensorFlow.js:

    $ cd .. && git clone https://github.com/zldrobit/tfjs-yolov5-example.git && cd tfjs-yolov5-example

    $ npm install

    $ ln -s ../../yolo11n_web_model public/yolo11n_web_model

    $ npm start

"""

import gc
import json
import os
import shutil
import subprocess
import time
import warnings
from copy import deepcopy
from datetime import datetime
from pathlib import Path

import numpy as np
import torch

from ultralytics.cfg import TASK2DATA, get_cfg
from ultralytics.data import build_dataloader
from ultralytics.data.dataset import YOLODataset
from ultralytics.data.utils import check_cls_dataset, check_det_dataset
from ultralytics.nn.autobackend import check_class_names, default_class_names
from ultralytics.nn.modules import C2f, Detect, RTDETRDecoder
from ultralytics.nn.tasks import DetectionModel, SegmentationModel, WorldModel
from ultralytics.utils import (
    ARM64,
    DEFAULT_CFG,
    IS_JETSON,
    LINUX,
    LOGGER,
    MACOS,
    PYTHON_VERSION,
    ROOT,
    WINDOWS,
    __version__,
    callbacks,
    colorstr,
    get_default_args,
    yaml_save,
)
from ultralytics.utils.checks import check_imgsz, check_is_path_safe, check_requirements, check_version
from ultralytics.utils.downloads import attempt_download_asset, get_github_assets, safe_download
from ultralytics.utils.files import file_size, spaces_in_path
from ultralytics.utils.ops import Profile
from ultralytics.utils.torch_utils import TORCH_1_13, get_latest_opset, select_device, smart_inference_mode


def export_formats():
    """Ultralytics YOLO export formats."""
    x = [
        ["PyTorch", "-", ".pt", True, True],
        ["TorchScript", "torchscript", ".torchscript", True, True],
        ["ONNX", "onnx", ".onnx", True, True],
        ["OpenVINO", "openvino", "_openvino_model", True, False],
        ["TensorRT", "engine", ".engine", False, True],
        ["CoreML", "coreml", ".mlpackage", True, False],
        ["TensorFlow SavedModel", "saved_model", "_saved_model", True, True],
        ["TensorFlow GraphDef", "pb", ".pb", True, True],
        ["TensorFlow Lite", "tflite", ".tflite", True, False],
        ["TensorFlow Edge TPU", "edgetpu", "_edgetpu.tflite", True, False],
        ["TensorFlow.js", "tfjs", "_web_model", True, False],
        ["PaddlePaddle", "paddle", "_paddle_model", True, True],
        ["NCNN", "ncnn", "_ncnn_model", True, True],
    ]
    return dict(zip(["Format", "Argument", "Suffix", "CPU", "GPU"], zip(*x)))


def gd_outputs(gd):
    """TensorFlow GraphDef model output node names."""
    name_list, input_list = [], []
    for node in gd.node:  # tensorflow.core.framework.node_def_pb2.NodeDef
        name_list.append(node.name)
        input_list.extend(node.input)
    return sorted(f"{x}:0" for x in list(set(name_list) - set(input_list)) if not x.startswith("NoOp"))


def try_export(inner_func):
    """YOLO export decorator, i.e. @try_export."""
    inner_args = get_default_args(inner_func)

    def outer_func(*args, **kwargs):
        """Export a model."""
        prefix = inner_args["prefix"]
        try:
            with Profile() as dt:
                f, model = inner_func(*args, **kwargs)
            LOGGER.info(f"{prefix} export success ✅ {dt.t:.1f}s, saved as '{f}' ({file_size(f):.1f} MB)")
            return f, model
        except Exception as e:
            LOGGER.error(f"{prefix} export failure ❌ {dt.t:.1f}s: {e}")
            raise e

    return outer_func


class Exporter:
    """

    A class for exporting a model.



    Attributes:

        args (SimpleNamespace): Configuration for the exporter.

        callbacks (list, optional): List of callback functions. Defaults to None.

    """

    def __init__(self, cfg=DEFAULT_CFG, overrides=None, _callbacks=None):
        """

        Initializes the Exporter class.



        Args:

            cfg (str, optional): Path to a configuration file. Defaults to DEFAULT_CFG.

            overrides (dict, optional): Configuration overrides. Defaults to None.

            _callbacks (dict, optional): Dictionary of callback functions. Defaults to None.

        """
        self.args = get_cfg(cfg, overrides)
        if self.args.format.lower() in {"coreml", "mlmodel"}:  # fix attempt for protobuf<3.20.x errors
            os.environ["PROTOCOL_BUFFERS_PYTHON_IMPLEMENTATION"] = "python"  # must run before TensorBoard callback

        self.callbacks = _callbacks or callbacks.get_default_callbacks()
        callbacks.add_integration_callbacks(self)

    @smart_inference_mode()
    def __call__(self, model=None) -> str:
        """Returns list of exported files/dirs after running callbacks."""
        self.run_callbacks("on_export_start")
        t = time.time()
        fmt = self.args.format.lower()  # to lowercase
        if fmt in {"tensorrt", "trt"}:  # 'engine' aliases
            fmt = "engine"
        if fmt in {"mlmodel", "mlpackage", "mlprogram", "apple", "ios", "coreml"}:  # 'coreml' aliases
            fmt = "coreml"
        fmts = tuple(export_formats()["Argument"][1:])  # available export formats
        if fmt not in fmts:
            import difflib

            # Get the closest match if format is invalid
            matches = difflib.get_close_matches(fmt, fmts, n=1, cutoff=0.6)  # 60% similarity required to match
            if not matches:
                raise ValueError(f"Invalid export format='{fmt}'. Valid formats are {fmts}")
            LOGGER.warning(f"WARNING ⚠️ Invalid export format='{fmt}', updating to format='{matches[0]}'")
            fmt = matches[0]
        flags = [x == fmt for x in fmts]
        if sum(flags) != 1:
            raise ValueError(f"Invalid export format='{fmt}'. Valid formats are {fmts}")
        jit, onnx, xml, engine, coreml, saved_model, pb, tflite, edgetpu, tfjs, paddle, ncnn = flags  # export booleans
        is_tf_format = any((saved_model, pb, tflite, edgetpu, tfjs))

        # Device
        if fmt == "engine" and self.args.device is None:
            LOGGER.warning("WARNING ⚠️ TensorRT requires GPU export, automatically assigning device=0")
            self.args.device = "0"
        self.device = select_device("cpu" if self.args.device is None else self.args.device)

        # Checks
        if not hasattr(model, "names"):
            model.names = default_class_names()
        model.names = check_class_names(model.names)
        if self.args.half and self.args.int8:
            LOGGER.warning("WARNING ⚠️ half=True and int8=True are mutually exclusive, setting half=False.")
            self.args.half = False
        if self.args.half and onnx and self.device.type == "cpu":
            LOGGER.warning("WARNING ⚠️ half=True only compatible with GPU export, i.e. use device=0")
            self.args.half = False
            assert not self.args.dynamic, "half=True not compatible with dynamic=True, i.e. use only one."
        self.imgsz = check_imgsz(self.args.imgsz, stride=model.stride, min_dim=2)  # check image size
        if self.args.int8 and engine:
            self.args.dynamic = True  # enforce dynamic to export TensorRT INT8
        if self.args.optimize:
            assert not ncnn, "optimize=True not compatible with format='ncnn', i.e. use optimize=False"
            assert self.device.type == "cpu", "optimize=True not compatible with cuda devices, i.e. use device='cpu'"
        if edgetpu:
            if not LINUX:
                raise SystemError("Edge TPU export only supported on Linux. See https://coral.ai/docs/edgetpu/compiler")
            elif self.args.batch != 1:  # see github.com/ultralytics/ultralytics/pull/13420
                LOGGER.warning("WARNING ⚠️ Edge TPU export requires batch size 1, setting batch=1.")
                self.args.batch = 1
        if isinstance(model, WorldModel):
            LOGGER.warning(
                "WARNING ⚠️ YOLOWorld (original version) export is not supported to any format.\n"
                "WARNING ⚠️ YOLOWorldv2 models (i.e. 'yolov8s-worldv2.pt') only support export to "
                "(torchscript, onnx, openvino, engine, coreml) formats. "
                "See https://docs.ultralytics.com/models/yolo-world for details."
            )
        if self.args.int8 and not self.args.data:
            self.args.data = DEFAULT_CFG.data or TASK2DATA[getattr(model, "task", "detect")]  # assign default data
            LOGGER.warning(
                "WARNING ⚠️ INT8 export requires a missing 'data' arg for calibration. "
                f"Using default 'data={self.args.data}'."
            )
        # Input
        im = torch.zeros(self.args.batch, 3, *self.imgsz).to(self.device)
        file = Path(
            getattr(model, "pt_path", None) or getattr(model, "yaml_file", None) or model.yaml.get("yaml_file", "")
        )
        if file.suffix in {".yaml", ".yml"}:
            file = Path(file.name)

        # Update model
        model = deepcopy(model).to(self.device)
        for p in model.parameters():
            p.requires_grad = False
        model.eval()
        model.float()
        model = model.fuse()
        for m in model.modules():
            if isinstance(m, (Detect, RTDETRDecoder)):  # includes all Detect subclasses like Segment, Pose, OBB
                m.dynamic = self.args.dynamic
                m.export = True
                m.format = self.args.format
                m.max_det = self.args.max_det
            elif isinstance(m, C2f) and not is_tf_format:
                # EdgeTPU does not support FlexSplitV while split provides cleaner ONNX graph
                m.forward = m.forward_split

        y = None
        for _ in range(2):
            y = model(im)  # dry runs
        if self.args.half and onnx and self.device.type != "cpu":
            im, model = im.half(), model.half()  # to FP16

        # Filter warnings
        warnings.filterwarnings("ignore", category=torch.jit.TracerWarning)  # suppress TracerWarning
        warnings.filterwarnings("ignore", category=UserWarning)  # suppress shape prim::Constant missing ONNX warning
        warnings.filterwarnings("ignore", category=DeprecationWarning)  # suppress CoreML np.bool deprecation warning

        # Assign
        self.im = im
        self.model = model
        self.file = file
        self.output_shape = (
            tuple(y.shape)
            if isinstance(y, torch.Tensor)
            else tuple(tuple(x.shape if isinstance(x, torch.Tensor) else []) for x in y)
        )
        self.pretty_name = Path(self.model.yaml.get("yaml_file", self.file)).stem.replace("yolo", "YOLO")
        data = model.args["data"] if hasattr(model, "args") and isinstance(model.args, dict) else ""
        description = f'Ultralytics {self.pretty_name} model {f"trained on {data}" if data else ""}'
        self.metadata = {
            "description": description,
            "author": "Ultralytics",
            "date": datetime.now().isoformat(),
            "version": __version__,
            "license": "AGPL-3.0 License (https://ultralytics.com/license)",
            "docs": "https://docs.ultralytics.com",
            "stride": int(max(model.stride)),
            "task": model.task,
            "batch": self.args.batch,
            "imgsz": self.imgsz,
            "names": model.names,
        }  # model metadata
        if model.task == "pose":
            self.metadata["kpt_shape"] = model.model[-1].kpt_shape

        LOGGER.info(
            f"\n{colorstr('PyTorch:')} starting from '{file}' with input shape {tuple(im.shape)} BCHW and "
            f'output shape(s) {self.output_shape} ({file_size(file):.1f} MB)'
        )

        # Exports
        f = [""] * len(fmts)  # exported filenames
        if jit or ncnn:  # TorchScript
            f[0], _ = self.export_torchscript()
        if engine:  # TensorRT required before ONNX
            f[1], _ = self.export_engine()
        if onnx:  # ONNX
            f[2], _ = self.export_onnx()
        if xml:  # OpenVINO
            f[3], _ = self.export_openvino()
        if coreml:  # CoreML
            f[4], _ = self.export_coreml()
        if is_tf_format:  # TensorFlow formats
            self.args.int8 |= edgetpu
            f[5], keras_model = self.export_saved_model()
            if pb or tfjs:  # pb prerequisite to tfjs
                f[6], _ = self.export_pb(keras_model=keras_model)
            if tflite:
                f[7], _ = self.export_tflite(keras_model=keras_model, nms=False, agnostic_nms=self.args.agnostic_nms)
            if edgetpu:
                f[8], _ = self.export_edgetpu(tflite_model=Path(f[5]) / f"{self.file.stem}_full_integer_quant.tflite")
            if tfjs:
                f[9], _ = self.export_tfjs()
        if paddle:  # PaddlePaddle
            f[10], _ = self.export_paddle()
        if ncnn:  # NCNN
            f[11], _ = self.export_ncnn()

        # Finish
        f = [str(x) for x in f if x]  # filter out '' and None
        if any(f):
            f = str(Path(f[-1]))
            square = self.imgsz[0] == self.imgsz[1]
            s = (
                ""
                if square
                else f"WARNING ⚠️ non-PyTorch val requires square images, 'imgsz={self.imgsz}' will not "
                f"work. Use export 'imgsz={max(self.imgsz)}' if val is required."
            )
            imgsz = self.imgsz[0] if square else str(self.imgsz)[1:-1].replace(" ", "")
            predict_data = f"data={data}" if model.task == "segment" and fmt == "pb" else ""
            q = "int8" if self.args.int8 else "half" if self.args.half else ""  # quantization
            LOGGER.info(
                f'\nExport complete ({time.time() - t:.1f}s)'
                f"\nResults saved to {colorstr('bold', file.parent.resolve())}"
                f'\nPredict:         yolo predict task={model.task} model={f} imgsz={imgsz} {q} {predict_data}'
                f'\nValidate:        yolo val task={model.task} model={f} imgsz={imgsz} data={data} {q} {s}'
                f'\nVisualize:       https://netron.app'
            )

        self.run_callbacks("on_export_end")
        return f  # return list of exported files/dirs

    def get_int8_calibration_dataloader(self, prefix=""):
        """Build and return a dataloader suitable for calibration of INT8 models."""
        LOGGER.info(f"{prefix} collecting INT8 calibration images from 'data={self.args.data}'")
        data = (check_cls_dataset if self.model.task == "classify" else check_det_dataset)(self.args.data)
        # TensorRT INT8 calibration should use 2x batch size
        batch = self.args.batch * (2 if self.args.format == "engine" else 1)
        dataset = YOLODataset(
            data[self.args.split or "val"],
            data=data,
            task=self.model.task,
            imgsz=self.imgsz[0],
            augment=False,
            batch_size=batch,
        )
        n = len(dataset)
        if n < 300:
            LOGGER.warning(f"{prefix} WARNING ⚠️ >300 images recommended for INT8 calibration, found {n} images.")
        return build_dataloader(dataset, batch=batch, workers=0)  # required for batch loading

    @try_export
    def export_torchscript(self, prefix=colorstr("TorchScript:")):
        """YOLO TorchScript model export."""
        LOGGER.info(f"\n{prefix} starting export with torch {torch.__version__}...")
        f = self.file.with_suffix(".torchscript")

        ts = torch.jit.trace(self.model, self.im, strict=False)
        extra_files = {"config.txt": json.dumps(self.metadata)}  # torch._C.ExtraFilesMap()
        if self.args.optimize:  # https://pytorch.org/tutorials/recipes/mobile_interpreter.html
            LOGGER.info(f"{prefix} optimizing for mobile...")
            from torch.utils.mobile_optimizer import optimize_for_mobile

            optimize_for_mobile(ts)._save_for_lite_interpreter(str(f), _extra_files=extra_files)
        else:
            ts.save(str(f), _extra_files=extra_files)
        return f, None

    @try_export
    def export_onnx(self, prefix=colorstr("ONNX:")):
        """YOLO ONNX export."""
        requirements = ["onnx>=1.12.0"]
        if self.args.simplify:
            requirements += ["onnxslim==0.1.34", "onnxruntime" + ("-gpu" if torch.cuda.is_available() else "")]
        check_requirements(requirements)
        import onnx  # noqa

        opset_version = self.args.opset or get_latest_opset()
        LOGGER.info(f"\n{prefix} starting export with onnx {onnx.__version__} opset {opset_version}...")
        f = str(self.file.with_suffix(".onnx"))

        output_names = ["output0", "output1"] if isinstance(self.model, SegmentationModel) else ["output0"]
        dynamic = self.args.dynamic
        if dynamic:
            dynamic = {"images": {0: "batch", 2: "height", 3: "width"}}  # shape(1,3,640,640)
            if isinstance(self.model, SegmentationModel):
                dynamic["output0"] = {0: "batch", 2: "anchors"}  # shape(1, 116, 8400)
                dynamic["output1"] = {0: "batch", 2: "mask_height", 3: "mask_width"}  # shape(1,32,160,160)
            elif isinstance(self.model, DetectionModel):
                dynamic["output0"] = {0: "batch", 2: "anchors"}  # shape(1, 84, 8400)

        torch.onnx.export(
            self.model.cpu() if dynamic else self.model,  # dynamic=True only compatible with cpu
            self.im.cpu() if dynamic else self.im,
            f,
            verbose=False,
            opset_version=opset_version,
            do_constant_folding=True,  # WARNING: DNN inference with torch>=1.12 may require do_constant_folding=False
            input_names=["images"],
            output_names=output_names,
            dynamic_axes=dynamic or None,
        )

        # Checks
        model_onnx = onnx.load(f)  # load onnx model

        # Simplify
        if self.args.simplify:
            try:
                import onnxslim

                LOGGER.info(f"{prefix} slimming with onnxslim {onnxslim.__version__}...")
                model_onnx = onnxslim.slim(model_onnx)

            except Exception as e:
                LOGGER.warning(f"{prefix} simplifier failure: {e}")

        # Metadata
        for k, v in self.metadata.items():
            meta = model_onnx.metadata_props.add()
            meta.key, meta.value = k, str(v)

        onnx.save(model_onnx, f)
        return f, model_onnx

    @try_export
    def export_openvino(self, prefix=colorstr("OpenVINO:")):
        """YOLO OpenVINO export."""
        check_requirements(f'openvino{"<=2024.0.0" if ARM64 else ">=2024.0.0"}')  # fix OpenVINO issue on ARM64
        import openvino as ov

        LOGGER.info(f"\n{prefix} starting export with openvino {ov.__version__}...")
        assert TORCH_1_13, f"OpenVINO export requires torch>=1.13.0 but torch=={torch.__version__} is installed"
        ov_model = ov.convert_model(
            self.model,
            input=None if self.args.dynamic else [self.im.shape],
            example_input=self.im,
        )

        def serialize(ov_model, file):
            """Set RT info, serialize and save metadata YAML."""
            ov_model.set_rt_info("YOLO", ["model_info", "model_type"])
            ov_model.set_rt_info(True, ["model_info", "reverse_input_channels"])
            ov_model.set_rt_info(114, ["model_info", "pad_value"])
            ov_model.set_rt_info([255.0], ["model_info", "scale_values"])
            ov_model.set_rt_info(self.args.iou, ["model_info", "iou_threshold"])
            ov_model.set_rt_info([v.replace(" ", "_") for v in self.model.names.values()], ["model_info", "labels"])
            if self.model.task != "classify":
                ov_model.set_rt_info("fit_to_window_letterbox", ["model_info", "resize_type"])

            ov.runtime.save_model(ov_model, file, compress_to_fp16=self.args.half)
            yaml_save(Path(file).parent / "metadata.yaml", self.metadata)  # add metadata.yaml

        if self.args.int8:
            fq = str(self.file).replace(self.file.suffix, f"_int8_openvino_model{os.sep}")
            fq_ov = str(Path(fq) / self.file.with_suffix(".xml").name)
            check_requirements("nncf>=2.8.0")
            import nncf

            def transform_fn(data_item) -> np.ndarray:
                """Quantization transform function."""
                data_item: torch.Tensor = data_item["img"] if isinstance(data_item, dict) else data_item
                assert data_item.dtype == torch.uint8, "Input image must be uint8 for the quantization preprocessing"
                im = data_item.numpy().astype(np.float32) / 255.0  # uint8 to fp16/32 and 0 - 255 to 0.0 - 1.0
                return np.expand_dims(im, 0) if im.ndim == 3 else im

            # Generate calibration data for integer quantization
            ignored_scope = None
            if isinstance(self.model.model[-1], Detect):
                # Includes all Detect subclasses like Segment, Pose, OBB, WorldDetect
                head_module_name = ".".join(list(self.model.named_modules())[-1][0].split(".")[:2])
                ignored_scope = nncf.IgnoredScope(  # ignore operations
                    patterns=[
                        f".*{head_module_name}/.*/Add",
                        f".*{head_module_name}/.*/Sub*",
                        f".*{head_module_name}/.*/Mul*",
                        f".*{head_module_name}/.*/Div*",
                        f".*{head_module_name}\\.dfl.*",
                    ],
                    types=["Sigmoid"],
                )

            quantized_ov_model = nncf.quantize(
                model=ov_model,
                calibration_dataset=nncf.Dataset(self.get_int8_calibration_dataloader(prefix), transform_fn),
                preset=nncf.QuantizationPreset.MIXED,
                ignored_scope=ignored_scope,
            )
            serialize(quantized_ov_model, fq_ov)
            return fq, None

        f = str(self.file).replace(self.file.suffix, f"_openvino_model{os.sep}")
        f_ov = str(Path(f) / self.file.with_suffix(".xml").name)

        serialize(ov_model, f_ov)
        return f, None

    @try_export
    def export_paddle(self, prefix=colorstr("PaddlePaddle:")):
        """YOLO Paddle export."""
        check_requirements(("paddlepaddle", "x2paddle"))
        import x2paddle  # noqa
        from x2paddle.convert import pytorch2paddle  # noqa

        LOGGER.info(f"\n{prefix} starting export with X2Paddle {x2paddle.__version__}...")
        f = str(self.file).replace(self.file.suffix, f"_paddle_model{os.sep}")

        pytorch2paddle(module=self.model, save_dir=f, jit_type="trace", input_examples=[self.im])  # export
        yaml_save(Path(f) / "metadata.yaml", self.metadata)  # add metadata.yaml
        return f, None

    @try_export
    def export_ncnn(self, prefix=colorstr("NCNN:")):
        """YOLO NCNN export using PNNX https://github.com/pnnx/pnnx."""
        check_requirements("ncnn")
        import ncnn  # noqa

        LOGGER.info(f"\n{prefix} starting export with NCNN {ncnn.__version__}...")
        f = Path(str(self.file).replace(self.file.suffix, f"_ncnn_model{os.sep}"))
        f_ts = self.file.with_suffix(".torchscript")

        name = Path("pnnx.exe" if WINDOWS else "pnnx")  # PNNX filename
        pnnx = name if name.is_file() else (ROOT / name)
        if not pnnx.is_file():
            LOGGER.warning(
                f"{prefix} WARNING ⚠️ PNNX not found. Attempting to download binary file from "
                "https://github.com/pnnx/pnnx/.\nNote PNNX Binary file must be placed in current working directory "
                f"or in {ROOT}. See PNNX repo for full installation instructions."
            )
            system = "macos" if MACOS else "windows" if WINDOWS else "linux-aarch64" if ARM64 else "linux"
            try:
                release, assets = get_github_assets(repo="pnnx/pnnx")
                asset = [x for x in assets if f"{system}.zip" in x][0]
                assert isinstance(asset, str), "Unable to retrieve PNNX repo assets"  # i.e. pnnx-20240410-macos.zip
                LOGGER.info(f"{prefix} successfully found latest PNNX asset file {asset}")
            except Exception as e:
                release = "20240410"
                asset = f"pnnx-{release}-{system}.zip"
                LOGGER.warning(f"{prefix} WARNING ⚠️ PNNX GitHub assets not found: {e}, using default {asset}")
            unzip_dir = safe_download(f"https://github.com/pnnx/pnnx/releases/download/{release}/{asset}", delete=True)
            if check_is_path_safe(Path.cwd(), unzip_dir):  # avoid path traversal security vulnerability
                shutil.move(src=unzip_dir / name, dst=pnnx)  # move binary to ROOT
                pnnx.chmod(0o777)  # set read, write, and execute permissions for everyone
                shutil.rmtree(unzip_dir)  # delete unzip dir

        ncnn_args = [
            f'ncnnparam={f / "model.ncnn.param"}',
            f'ncnnbin={f / "model.ncnn.bin"}',
            f'ncnnpy={f / "model_ncnn.py"}',
        ]

        pnnx_args = [
            f'pnnxparam={f / "model.pnnx.param"}',
            f'pnnxbin={f / "model.pnnx.bin"}',
            f'pnnxpy={f / "model_pnnx.py"}',
            f'pnnxonnx={f / "model.pnnx.onnx"}',
        ]

        cmd = [
            str(pnnx),
            str(f_ts),
            *ncnn_args,
            *pnnx_args,
            f"fp16={int(self.args.half)}",
            f"device={self.device.type}",
            f'inputshape="{[self.args.batch, 3, *self.imgsz]}"',
        ]
        f.mkdir(exist_ok=True)  # make ncnn_model directory
        LOGGER.info(f"{prefix} running '{' '.join(cmd)}'")
        subprocess.run(cmd, check=True)

        # Remove debug files
        pnnx_files = [x.split("=")[-1] for x in pnnx_args]
        for f_debug in ("debug.bin", "debug.param", "debug2.bin", "debug2.param", *pnnx_files):
            Path(f_debug).unlink(missing_ok=True)

        yaml_save(f / "metadata.yaml", self.metadata)  # add metadata.yaml
        return str(f), None

    @try_export
    def export_coreml(self, prefix=colorstr("CoreML:")):
        """YOLO CoreML export."""
        mlmodel = self.args.format.lower() == "mlmodel"  # legacy *.mlmodel export format requested
        check_requirements("coremltools>=6.0,<=6.2" if mlmodel else "coremltools>=7.0")
        import coremltools as ct  # noqa

        LOGGER.info(f"\n{prefix} starting export with coremltools {ct.__version__}...")
        assert not WINDOWS, "CoreML export is not supported on Windows, please run on macOS or Linux."
        assert self.args.batch == 1, "CoreML batch sizes > 1 are not supported. Please retry at 'batch=1'."
        f = self.file.with_suffix(".mlmodel" if mlmodel else ".mlpackage")
        if f.is_dir():
            shutil.rmtree(f)
        if self.args.nms and getattr(self.model, "end2end", False):
            LOGGER.warning(f"{prefix} WARNING ⚠️ 'nms=True' is not available for end2end models. Forcing 'nms=False'.")
            self.args.nms = False

        bias = [0.0, 0.0, 0.0]
        scale = 1 / 255
        classifier_config = None
        if self.model.task == "classify":
            classifier_config = ct.ClassifierConfig(list(self.model.names.values())) if self.args.nms else None
            model = self.model
        elif self.model.task == "detect":
            model = IOSDetectModel(self.model, self.im) if self.args.nms else self.model
        else:
            if self.args.nms:
                LOGGER.warning(f"{prefix} WARNING ⚠️ 'nms=True' is only available for Detect models like 'yolov8n.pt'.")
                # TODO CoreML Segment and Pose model pipelining
            model = self.model

        ts = torch.jit.trace(model.eval(), self.im, strict=False)  # TorchScript model
        ct_model = ct.convert(
            ts,
            inputs=[ct.ImageType("image", shape=self.im.shape, scale=scale, bias=bias)],
            classifier_config=classifier_config,
            convert_to="neuralnetwork" if mlmodel else "mlprogram",
        )
        bits, mode = (8, "kmeans") if self.args.int8 else (16, "linear") if self.args.half else (32, None)
        if bits < 32:
            if "kmeans" in mode:
                check_requirements("scikit-learn")  # scikit-learn package required for k-means quantization
            if mlmodel:
                ct_model = ct.models.neural_network.quantization_utils.quantize_weights(ct_model, bits, mode)
            elif bits == 8:  # mlprogram already quantized to FP16
                import coremltools.optimize.coreml as cto

                op_config = cto.OpPalettizerConfig(mode="kmeans", nbits=bits, weight_threshold=512)
                config = cto.OptimizationConfig(global_config=op_config)
                ct_model = cto.palettize_weights(ct_model, config=config)
        if self.args.nms and self.model.task == "detect":
            if mlmodel:
                # coremltools<=6.2 NMS export requires Python<3.11
                check_version(PYTHON_VERSION, "<3.11", name="Python ", hard=True)
                weights_dir = None
            else:
                ct_model.save(str(f))  # save otherwise weights_dir does not exist
                weights_dir = str(f / "Data/com.apple.CoreML/weights")
            ct_model = self._pipeline_coreml(ct_model, weights_dir=weights_dir)

        m = self.metadata  # metadata dict
        ct_model.short_description = m.pop("description")
        ct_model.author = m.pop("author")
        ct_model.license = m.pop("license")
        ct_model.version = m.pop("version")
        ct_model.user_defined_metadata.update({k: str(v) for k, v in m.items()})
        try:
            ct_model.save(str(f))  # save *.mlpackage
        except Exception as e:
            LOGGER.warning(
                f"{prefix} WARNING ⚠️ CoreML export to *.mlpackage failed ({e}), reverting to *.mlmodel export. "
                f"Known coremltools Python 3.11 and Windows bugs https://github.com/apple/coremltools/issues/1928."
            )
            f = f.with_suffix(".mlmodel")
            ct_model.save(str(f))
        return f, ct_model

    @try_export
    def export_engine(self, prefix=colorstr("TensorRT:")):
        """YOLO TensorRT export https://developer.nvidia.com/tensorrt."""
        assert self.im.device.type != "cpu", "export running on CPU but must be on GPU, i.e. use 'device=0'"
        f_onnx, _ = self.export_onnx()  # run before TRT import https://github.com/ultralytics/ultralytics/issues/7016

        try:
            import tensorrt as trt  # noqa
        except ImportError:
            if LINUX:
                check_requirements("tensorrt>7.0.0,<=10.1.0")
            import tensorrt as trt  # noqa
        check_version(trt.__version__, ">=7.0.0", hard=True)
        check_version(trt.__version__, "<=10.1.0", msg="https://github.com/ultralytics/ultralytics/pull/14239")

        # Setup and checks
        LOGGER.info(f"\n{prefix} starting export with TensorRT {trt.__version__}...")
        is_trt10 = int(trt.__version__.split(".")[0]) >= 10  # is TensorRT >= 10
        assert Path(f_onnx).exists(), f"failed to export ONNX file: {f_onnx}"
        f = self.file.with_suffix(".engine")  # TensorRT engine file
        logger = trt.Logger(trt.Logger.INFO)
        if self.args.verbose:
            logger.min_severity = trt.Logger.Severity.VERBOSE

        # Engine builder
        builder = trt.Builder(logger)
        config = builder.create_builder_config()
        workspace = int(self.args.workspace * (1 << 30))
        if is_trt10:
            config.set_memory_pool_limit(trt.MemoryPoolType.WORKSPACE, workspace)
        else:  # TensorRT versions 7, 8
            config.max_workspace_size = workspace
        flag = 1 << int(trt.NetworkDefinitionCreationFlag.EXPLICIT_BATCH)
        network = builder.create_network(flag)
        half = builder.platform_has_fast_fp16 and self.args.half
        int8 = builder.platform_has_fast_int8 and self.args.int8
        # Read ONNX file
        parser = trt.OnnxParser(network, logger)
        if not parser.parse_from_file(f_onnx):
            raise RuntimeError(f"failed to load ONNX file: {f_onnx}")

        # Network inputs
        inputs = [network.get_input(i) for i in range(network.num_inputs)]
        outputs = [network.get_output(i) for i in range(network.num_outputs)]
        for inp in inputs:
            LOGGER.info(f'{prefix} input "{inp.name}" with shape{inp.shape} {inp.dtype}')
        for out in outputs:
            LOGGER.info(f'{prefix} output "{out.name}" with shape{out.shape} {out.dtype}')

        if self.args.dynamic:
            shape = self.im.shape
            if shape[0] <= 1:
                LOGGER.warning(f"{prefix} WARNING ⚠️ 'dynamic=True' model requires max batch size, i.e. 'batch=16'")
            profile = builder.create_optimization_profile()
            min_shape = (1, shape[1], 32, 32)  # minimum input shape
            max_shape = (*shape[:2], *(max(1, self.args.workspace) * d for d in shape[2:]))  # max input shape
            for inp in inputs:
                profile.set_shape(inp.name, min=min_shape, opt=shape, max=max_shape)
            config.add_optimization_profile(profile)

        LOGGER.info(f"{prefix} building {'INT8' if int8 else 'FP' + ('16' if half else '32')} engine as {f}")
        if int8:
            config.set_flag(trt.BuilderFlag.INT8)
            config.set_calibration_profile(profile)
            config.profiling_verbosity = trt.ProfilingVerbosity.DETAILED

            class EngineCalibrator(trt.IInt8Calibrator):
                def __init__(

                    self,

                    dataset,  # ultralytics.data.build.InfiniteDataLoader

                    batch: int,

                    cache: str = "",

                ) -> None:
                    trt.IInt8Calibrator.__init__(self)
                    self.dataset = dataset
                    self.data_iter = iter(dataset)
                    self.algo = trt.CalibrationAlgoType.ENTROPY_CALIBRATION_2
                    self.batch = batch
                    self.cache = Path(cache)

                def get_algorithm(self) -> trt.CalibrationAlgoType:
                    """Get the calibration algorithm to use."""
                    return self.algo

                def get_batch_size(self) -> int:
                    """Get the batch size to use for calibration."""
                    return self.batch or 1

                def get_batch(self, names) -> list:
                    """Get the next batch to use for calibration, as a list of device memory pointers."""
                    try:
                        im0s = next(self.data_iter)["img"] / 255.0
                        im0s = im0s.to("cuda") if im0s.device.type == "cpu" else im0s
                        return [int(im0s.data_ptr())]
                    except StopIteration:
                        # Return [] or None, signal to TensorRT there is no calibration data remaining
                        return None

                def read_calibration_cache(self) -> bytes:
                    """Use existing cache instead of calibrating again, otherwise, implicitly return None."""
                    if self.cache.exists() and self.cache.suffix == ".cache":
                        return self.cache.read_bytes()

                def write_calibration_cache(self, cache) -> None:
                    """Write calibration cache to disk."""
                    _ = self.cache.write_bytes(cache)

            # Load dataset w/ builder (for batching) and calibrate
            config.int8_calibrator = EngineCalibrator(
                dataset=self.get_int8_calibration_dataloader(prefix),
                batch=2 * self.args.batch,  # TensorRT INT8 calibration should use 2x batch size
                cache=str(self.file.with_suffix(".cache")),
            )

        elif half:
            config.set_flag(trt.BuilderFlag.FP16)

        # Free CUDA memory
        del self.model
        gc.collect()
        torch.cuda.empty_cache()

        # Write file
        build = builder.build_serialized_network if is_trt10 else builder.build_engine
        with build(network, config) as engine, open(f, "wb") as t:
            # Metadata
            meta = json.dumps(self.metadata)
            t.write(len(meta).to_bytes(4, byteorder="little", signed=True))
            t.write(meta.encode())
            # Model
            t.write(engine if is_trt10 else engine.serialize())

        return f, None

    @try_export
    def export_saved_model(self, prefix=colorstr("TensorFlow SavedModel:")):
        """YOLO TensorFlow SavedModel export."""
        cuda = torch.cuda.is_available()
        try:
            import tensorflow as tf  # noqa
        except ImportError:
            suffix = "-macos" if MACOS else "-aarch64" if ARM64 else "" if cuda else "-cpu"
            version = ">=2.0.0"
            check_requirements(f"tensorflow{suffix}{version}")
            import tensorflow as tf  # noqa
        check_requirements(
            (
                "keras",  # required by 'onnx2tf' package
                "tf_keras",  # required by 'onnx2tf' package
                "sng4onnx>=1.0.1",  # required by 'onnx2tf' package
                "onnx_graphsurgeon>=0.3.26",  # required by 'onnx2tf' package
                "onnx>=1.12.0",
                "onnx2tf>1.17.5,<=1.22.3",
                "onnxslim>=0.1.31",
                "tflite_support<=0.4.3" if IS_JETSON else "tflite_support",  # fix ImportError 'GLIBCXX_3.4.29'
                "flatbuffers>=23.5.26,<100",  # update old 'flatbuffers' included inside tensorflow package
                "onnxruntime-gpu" if cuda else "onnxruntime",
            ),
            cmds="--extra-index-url https://pypi.ngc.nvidia.com",  # onnx_graphsurgeon only on NVIDIA
        )

        LOGGER.info(f"\n{prefix} starting export with tensorflow {tf.__version__}...")
        check_version(
            tf.__version__,
            ">=2.0.0",
            name="tensorflow",
            verbose=True,
            msg="https://github.com/ultralytics/ultralytics/issues/5161",
        )
        import onnx2tf

        f = Path(str(self.file).replace(self.file.suffix, "_saved_model"))
        if f.is_dir():
            shutil.rmtree(f)  # delete output folder

        # Pre-download calibration file to fix https://github.com/PINTO0309/onnx2tf/issues/545
        onnx2tf_file = Path("calibration_image_sample_data_20x128x128x3_float32.npy")
        if not onnx2tf_file.exists():
            attempt_download_asset(f"{onnx2tf_file}.zip", unzip=True, delete=True)

        # Export to ONNX
        self.args.simplify = True
        f_onnx, _ = self.export_onnx()

        # Export to TF
        np_data = None
        if self.args.int8:
            tmp_file = f / "tmp_tflite_int8_calibration_images.npy"  # int8 calibration images file
            if self.args.data:
                f.mkdir()
                images = [batch["img"].permute(0, 2, 3, 1) for batch in self.get_int8_calibration_dataloader(prefix)]
                images = torch.cat(images, 0).float()
                np.save(str(tmp_file), images.numpy().astype(np.float32))  # BHWC
                np_data = [["images", tmp_file, [[[[0, 0, 0]]]], [[[[255, 255, 255]]]]]]

        LOGGER.info(f"{prefix} starting TFLite export with onnx2tf {onnx2tf.__version__}...")
        keras_model = onnx2tf.convert(
            input_onnx_file_path=f_onnx,
            output_folder_path=str(f),
            not_use_onnxsim=True,
            verbosity="error",  # note INT8-FP16 activation bug https://github.com/ultralytics/ultralytics/issues/15873
            output_integer_quantized_tflite=self.args.int8,
            quant_type="per-tensor",  # "per-tensor" (faster) or "per-channel" (slower but more accurate)
            custom_input_op_name_np_data_path=np_data,
            disable_group_convolution=True,  # for end-to-end model compatibility
            enable_batchmatmul_unfold=True,  # for end-to-end model compatibility
        )
        yaml_save(f / "metadata.yaml", self.metadata)  # add metadata.yaml

        # Remove/rename TFLite models
        if self.args.int8:
            tmp_file.unlink(missing_ok=True)
            for file in f.rglob("*_dynamic_range_quant.tflite"):
                file.rename(file.with_name(file.stem.replace("_dynamic_range_quant", "_int8") + file.suffix))
            for file in f.rglob("*_integer_quant_with_int16_act.tflite"):
                file.unlink()  # delete extra fp16 activation TFLite files

        # Add TFLite metadata
        for file in f.rglob("*.tflite"):
            f.unlink() if "quant_with_int16_act.tflite" in str(f) else self._add_tflite_metadata(file)

        return str(f), keras_model  # or keras_model = tf.saved_model.load(f, tags=None, options=None)

    @try_export
    def export_pb(self, keras_model, prefix=colorstr("TensorFlow GraphDef:")):
        """YOLO TensorFlow GraphDef *.pb export https://github.com/leimao/Frozen_Graph_TensorFlow."""
        import tensorflow as tf  # noqa
        from tensorflow.python.framework.convert_to_constants import convert_variables_to_constants_v2  # noqa

        LOGGER.info(f"\n{prefix} starting export with tensorflow {tf.__version__}...")
        f = self.file.with_suffix(".pb")

        m = tf.function(lambda x: keras_model(x))  # full model
        m = m.get_concrete_function(tf.TensorSpec(keras_model.inputs[0].shape, keras_model.inputs[0].dtype))
        frozen_func = convert_variables_to_constants_v2(m)
        frozen_func.graph.as_graph_def()
        tf.io.write_graph(graph_or_graph_def=frozen_func.graph, logdir=str(f.parent), name=f.name, as_text=False)
        return f, None

    @try_export
    def export_tflite(self, keras_model, nms, agnostic_nms, prefix=colorstr("TensorFlow Lite:")):
        """YOLO TensorFlow Lite export."""
        # BUG https://github.com/ultralytics/ultralytics/issues/13436
        import tensorflow as tf  # noqa

        LOGGER.info(f"\n{prefix} starting export with tensorflow {tf.__version__}...")
        saved_model = Path(str(self.file).replace(self.file.suffix, "_saved_model"))
        if self.args.int8:
            f = saved_model / f"{self.file.stem}_int8.tflite"  # fp32 in/out
        elif self.args.half:
            f = saved_model / f"{self.file.stem}_float16.tflite"  # fp32 in/out
        else:
            f = saved_model / f"{self.file.stem}_float32.tflite"
        return str(f), None

    @try_export
    def export_edgetpu(self, tflite_model="", prefix=colorstr("Edge TPU:")):
        """YOLO Edge TPU export https://coral.ai/docs/edgetpu/models-intro/."""
        LOGGER.warning(f"{prefix} WARNING ⚠️ Edge TPU known bug https://github.com/ultralytics/ultralytics/issues/1185")

        cmd = "edgetpu_compiler --version"
        help_url = "https://coral.ai/docs/edgetpu/compiler/"
        assert LINUX, f"export only supported on Linux. See {help_url}"
        if subprocess.run(cmd, stdout=subprocess.DEVNULL, stderr=subprocess.DEVNULL, shell=True).returncode != 0:
            LOGGER.info(f"\n{prefix} export requires Edge TPU compiler. Attempting install from {help_url}")
            sudo = subprocess.run("sudo --version >/dev/null", shell=True).returncode == 0  # sudo installed on system
            for c in (
                "curl https://packages.cloud.google.com/apt/doc/apt-key.gpg | sudo apt-key add -",
                'echo "deb https://packages.cloud.google.com/apt coral-edgetpu-stable main" | '
                "sudo tee /etc/apt/sources.list.d/coral-edgetpu.list",
                "sudo apt-get update",
                "sudo apt-get install edgetpu-compiler",
            ):
                subprocess.run(c if sudo else c.replace("sudo ", ""), shell=True, check=True)
        ver = subprocess.run(cmd, shell=True, capture_output=True, check=True).stdout.decode().split()[-1]

        LOGGER.info(f"\n{prefix} starting export with Edge TPU compiler {ver}...")
        f = str(tflite_model).replace(".tflite", "_edgetpu.tflite")  # Edge TPU model

        cmd = (
            "edgetpu_compiler "
            f'--out_dir "{Path(f).parent}" '
            "--show_operations "
            "--search_delegate "
            "--delegate_search_step 3 "
            "--timeout_sec 180 "
            f'"{tflite_model}"'
        )
        LOGGER.info(f"{prefix} running '{cmd}'")
        subprocess.run(cmd, shell=True)
        self._add_tflite_metadata(f)
        return f, None

    @try_export
    def export_tfjs(self, prefix=colorstr("TensorFlow.js:")):
        """YOLO TensorFlow.js export."""
        check_requirements("tensorflowjs")
        if ARM64:
            # Fix error: `np.object` was a deprecated alias for the builtin `object` when exporting to TF.js on ARM64
            check_requirements("numpy==1.23.5")
        import tensorflow as tf
        import tensorflowjs as tfjs  # noqa

        LOGGER.info(f"\n{prefix} starting export with tensorflowjs {tfjs.__version__}...")
        f = str(self.file).replace(self.file.suffix, "_web_model")  # js dir
        f_pb = str(self.file.with_suffix(".pb"))  # *.pb path

        gd = tf.Graph().as_graph_def()  # TF GraphDef
        with open(f_pb, "rb") as file:
            gd.ParseFromString(file.read())
        outputs = ",".join(gd_outputs(gd))
        LOGGER.info(f"\n{prefix} output node names: {outputs}")

        quantization = "--quantize_float16" if self.args.half else "--quantize_uint8" if self.args.int8 else ""
        with spaces_in_path(f_pb) as fpb_, spaces_in_path(f) as f_:  # exporter can not handle spaces in path
            cmd = (
                "tensorflowjs_converter "
                f'--input_format=tf_frozen_model {quantization} --output_node_names={outputs} "{fpb_}" "{f_}"'
            )
            LOGGER.info(f"{prefix} running '{cmd}'")
            subprocess.run(cmd, shell=True)

        if " " in f:
            LOGGER.warning(f"{prefix} WARNING ⚠️ your model may not work correctly with spaces in path '{f}'.")

        # Add metadata
        yaml_save(Path(f) / "metadata.yaml", self.metadata)  # add metadata.yaml
        return f, None

    def _add_tflite_metadata(self, file):
        """Add metadata to *.tflite models per https://www.tensorflow.org/lite/models/convert/metadata."""
        import flatbuffers

        try:
            # TFLite Support bug https://github.com/tensorflow/tflite-support/issues/954#issuecomment-2108570845
            from tensorflow_lite_support.metadata import metadata_schema_py_generated as schema  # noqa
            from tensorflow_lite_support.metadata.python import metadata  # noqa
        except ImportError:  # ARM64 systems may not have the 'tensorflow_lite_support' package available
            from tflite_support import metadata  # noqa
            from tflite_support import metadata_schema_py_generated as schema  # noqa

        # Create model info
        model_meta = schema.ModelMetadataT()
        model_meta.name = self.metadata["description"]
        model_meta.version = self.metadata["version"]
        model_meta.author = self.metadata["author"]
        model_meta.license = self.metadata["license"]

        # Label file
        tmp_file = Path(file).parent / "temp_meta.txt"
        with open(tmp_file, "w") as f:
            f.write(str(self.metadata))

        label_file = schema.AssociatedFileT()
        label_file.name = tmp_file.name
        label_file.type = schema.AssociatedFileType.TENSOR_AXIS_LABELS

        # Create input info
        input_meta = schema.TensorMetadataT()
        input_meta.name = "image"
        input_meta.description = "Input image to be detected."
        input_meta.content = schema.ContentT()
        input_meta.content.contentProperties = schema.ImagePropertiesT()
        input_meta.content.contentProperties.colorSpace = schema.ColorSpaceType.RGB
        input_meta.content.contentPropertiesType = schema.ContentProperties.ImageProperties

        # Create output info
        output1 = schema.TensorMetadataT()
        output1.name = "output"
        output1.description = "Coordinates of detected objects, class labels, and confidence score"
        output1.associatedFiles = [label_file]
        if self.model.task == "segment":
            output2 = schema.TensorMetadataT()
            output2.name = "output"
            output2.description = "Mask protos"
            output2.associatedFiles = [label_file]

        # Create subgraph info
        subgraph = schema.SubGraphMetadataT()
        subgraph.inputTensorMetadata = [input_meta]
        subgraph.outputTensorMetadata = [output1, output2] if self.model.task == "segment" else [output1]
        model_meta.subgraphMetadata = [subgraph]

        b = flatbuffers.Builder(0)
        b.Finish(model_meta.Pack(b), metadata.MetadataPopulator.METADATA_FILE_IDENTIFIER)
        metadata_buf = b.Output()

        populator = metadata.MetadataPopulator.with_model_file(str(file))
        populator.load_metadata_buffer(metadata_buf)
        populator.load_associated_files([str(tmp_file)])
        populator.populate()
        tmp_file.unlink()

    def _pipeline_coreml(self, model, weights_dir=None, prefix=colorstr("CoreML Pipeline:")):
        """YOLO CoreML pipeline."""
        import coremltools as ct  # noqa

        LOGGER.info(f"{prefix} starting pipeline with coremltools {ct.__version__}...")
        _, _, h, w = list(self.im.shape)  # BCHW

        # Output shapes
        spec = model.get_spec()
        out0, out1 = iter(spec.description.output)
        if MACOS:
            from PIL import Image

            img = Image.new("RGB", (w, h))  # w=192, h=320
            out = model.predict({"image": img})
            out0_shape = out[out0.name].shape  # (3780, 80)
            out1_shape = out[out1.name].shape  # (3780, 4)
        else:  # linux and windows can not run model.predict(), get sizes from PyTorch model output y
            out0_shape = self.output_shape[2], self.output_shape[1] - 4  # (3780, 80)
            out1_shape = self.output_shape[2], 4  # (3780, 4)

        # Checks
        names = self.metadata["names"]
        nx, ny = spec.description.input[0].type.imageType.width, spec.description.input[0].type.imageType.height
        _, nc = out0_shape  # number of anchors, number of classes
        assert len(names) == nc, f"{len(names)} names found for nc={nc}"  # check

        # Define output shapes (missing)
        out0.type.multiArrayType.shape[:] = out0_shape  # (3780, 80)
        out1.type.multiArrayType.shape[:] = out1_shape  # (3780, 4)

        # Model from spec
        model = ct.models.MLModel(spec, weights_dir=weights_dir)

        # 3. Create NMS protobuf
        nms_spec = ct.proto.Model_pb2.Model()
        nms_spec.specificationVersion = 5
        for i in range(2):
            decoder_output = model._spec.description.output[i].SerializeToString()
            nms_spec.description.input.add()
            nms_spec.description.input[i].ParseFromString(decoder_output)
            nms_spec.description.output.add()
            nms_spec.description.output[i].ParseFromString(decoder_output)

        nms_spec.description.output[0].name = "confidence"
        nms_spec.description.output[1].name = "coordinates"

        output_sizes = [nc, 4]
        for i in range(2):
            ma_type = nms_spec.description.output[i].type.multiArrayType
            ma_type.shapeRange.sizeRanges.add()
            ma_type.shapeRange.sizeRanges[0].lowerBound = 0
            ma_type.shapeRange.sizeRanges[0].upperBound = -1
            ma_type.shapeRange.sizeRanges.add()
            ma_type.shapeRange.sizeRanges[1].lowerBound = output_sizes[i]
            ma_type.shapeRange.sizeRanges[1].upperBound = output_sizes[i]
            del ma_type.shape[:]

        nms = nms_spec.nonMaximumSuppression
        nms.confidenceInputFeatureName = out0.name  # 1x507x80
        nms.coordinatesInputFeatureName = out1.name  # 1x507x4
        nms.confidenceOutputFeatureName = "confidence"
        nms.coordinatesOutputFeatureName = "coordinates"
        nms.iouThresholdInputFeatureName = "iouThreshold"
        nms.confidenceThresholdInputFeatureName = "confidenceThreshold"
        nms.iouThreshold = 0.45
        nms.confidenceThreshold = 0.25
        nms.pickTop.perClass = True
        nms.stringClassLabels.vector.extend(names.values())
        nms_model = ct.models.MLModel(nms_spec)

        # 4. Pipeline models together
        pipeline = ct.models.pipeline.Pipeline(
            input_features=[
                ("image", ct.models.datatypes.Array(3, ny, nx)),
                ("iouThreshold", ct.models.datatypes.Double()),
                ("confidenceThreshold", ct.models.datatypes.Double()),
            ],
            output_features=["confidence", "coordinates"],
        )
        pipeline.add_model(model)
        pipeline.add_model(nms_model)

        # Correct datatypes
        pipeline.spec.description.input[0].ParseFromString(model._spec.description.input[0].SerializeToString())
        pipeline.spec.description.output[0].ParseFromString(nms_model._spec.description.output[0].SerializeToString())
        pipeline.spec.description.output[1].ParseFromString(nms_model._spec.description.output[1].SerializeToString())

        # Update metadata
        pipeline.spec.specificationVersion = 5
        pipeline.spec.description.metadata.userDefined.update(
            {"IoU threshold": str(nms.iouThreshold), "Confidence threshold": str(nms.confidenceThreshold)}
        )

        # Save the model
        model = ct.models.MLModel(pipeline.spec, weights_dir=weights_dir)
        model.input_description["image"] = "Input image"
        model.input_description["iouThreshold"] = f"(optional) IoU threshold override (default: {nms.iouThreshold})"
        model.input_description["confidenceThreshold"] = (
            f"(optional) Confidence threshold override (default: {nms.confidenceThreshold})"
        )
        model.output_description["confidence"] = 'Boxes × Class confidence (see user-defined metadata "classes")'
        model.output_description["coordinates"] = "Boxes × [x, y, width, height] (relative to image size)"
        LOGGER.info(f"{prefix} pipeline success")
        return model

    def add_callback(self, event: str, callback):
        """Appends the given callback."""
        self.callbacks[event].append(callback)

    def run_callbacks(self, event: str):
        """Execute all callbacks for a given event."""
        for callback in self.callbacks.get(event, []):
            callback(self)


class IOSDetectModel(torch.nn.Module):
    """Wrap an Ultralytics YOLO model for Apple iOS CoreML export."""

    def __init__(self, model, im):
        """Initialize the IOSDetectModel class with a YOLO model and example image."""
        super().__init__()
        _, _, h, w = im.shape  # batch, channel, height, width
        self.model = model
        self.nc = len(model.names)  # number of classes
        if w == h:
            self.normalize = 1.0 / w  # scalar
        else:
            self.normalize = torch.tensor([1.0 / w, 1.0 / h, 1.0 / w, 1.0 / h])  # broadcast (slower, smaller)

    def forward(self, x):
        """Normalize predictions of object detection model with input size-dependent factors."""
        xywh, cls = self.model(x)[0].transpose(0, 1).split((4, self.nc), 1)
        return cls, xywh * self.normalize  # confidence (3780, 80), coordinates (3780, 4)