ultralytics 8.1.26 LoadImagesAndVideos batched inference (#8817)

Signed-off-by: Glenn Jocher <glenn.jocher@ultralytics.com>

.gitignore

@@ -29,7 +29,7 @@ MANIFEST
 
 # PyInstaller
 #  Usually these files are written by a python script from a template
-#  before PyInstaller builds the exe, so as to inject date/other infos into it.
+#  before PyInstaller builds the exe, so as to inject date/other info into it.
 *.manifest
 *.spec
 

docs/en/reference/data/loaders.md

@@ -23,7 +23,7 @@ keywords: Ultralytics, data loaders, LoadStreams, LoadImages, LoadTensor, YOLO,
 
 <br><br>
 
-## ::: ultralytics.data.loaders.LoadImages
+## ::: ultralytics.data.loaders.LoadImagesAndVideos
 
 <br><br>
 

docs/en/reference/utils/files.md

@@ -38,3 +38,7 @@ keywords: Ultralytics, utility functions, file operations, working directory, fi
 ## ::: ultralytics.utils.files.get_latest_run
 
 <br><br>
+
+## ::: ultralytics.utils.files.update_models
+
+<br><br>

tests/test_python.py

@@ -8,6 +8,7 @@ import cv2
 import numpy as np
 import pytest
 import torch
+import yaml
 from PIL import Image
 from torchvision.transforms import ToTensor
 
@@ -169,8 +170,6 @@ def test_track_stream():
 
     Note imgsz=160 required for tracking for higher confidence and better matches
     """
-    import yaml
-
     video_url = "https://ultralytics.com/assets/decelera_portrait_min.mov"
     model = YOLO(MODEL)
     model.track(video_url, imgsz=160, tracker="bytetrack.yaml")

ultralytics/__init__.py

@@ -1,6 +1,6 @@
 # Ultralytics YOLO 🚀, AGPL-3.0 license
 
-__version__ = "8.1.25"
+__version__ = "8.1.26"
 
 from ultralytics.data.explorer.explorer import Explorer
 from ultralytics.models import RTDETR, SAM, YOLO, YOLOWorld

ultralytics/cfg/__init__.py

@@ -396,7 +396,7 @@ def handle_yolo_settings(args: List[str]) -> None:
 def handle_explorer():
     """Open the Ultralytics Explorer GUI."""
     checks.check_requirements("streamlit")
-    LOGGER.info(f"💡 Loading Explorer dashboard...")
+    LOGGER.info("💡 Loading Explorer dashboard...")
     subprocess.run(["streamlit", "run", ROOT / "data/explorer/gui/dash.py", "--server.maxMessageSize", "2048"])
 
 

ultralytics/data/build.py

@@ -11,7 +11,7 @@ from torch.utils.data import dataloader, distributed
 
 from ultralytics.data.loaders import (
     LOADERS,
-    LoadImages,
+    LoadImagesAndVideos,
     LoadPilAndNumpy,
     LoadScreenshots,
     LoadStreams,
@@ -150,34 +150,35 @@ def check_source(source):
     return source, webcam, screenshot, from_img, in_memory, tensor
 
 
-def load_inference_source(source=None, vid_stride=1, buffer=False):
+def load_inference_source(source=None, batch=1, vid_stride=1, buffer=False):
     """
     Loads an inference source for object detection and applies necessary transformations.
 
     Args:
         source (str, Path, Tensor, PIL.Image, np.ndarray): The input source for inference.
+        batch (int, optional): Batch size for dataloaders. Default is 1.
         vid_stride (int, optional): The frame interval for video sources. Default is 1.
         buffer (bool, optional): Determined whether stream frames will be buffered. Default is False.
 
     Returns:
         dataset (Dataset): A dataset object for the specified input source.
     """
-    source, webcam, screenshot, from_img, in_memory, tensor = check_source(source)
-    source_type = source.source_type if in_memory else SourceTypes(webcam, screenshot, from_img, tensor)
+    source, stream, screenshot, from_img, in_memory, tensor = check_source(source)
+    source_type = source.source_type if in_memory else SourceTypes(stream, screenshot, from_img, tensor)
 
     # Dataloader
     if tensor:
         dataset = LoadTensor(source)
     elif in_memory:
         dataset = source
-    elif webcam:
+    elif stream:
         dataset = LoadStreams(source, vid_stride=vid_stride, buffer=buffer)
     elif screenshot:
         dataset = LoadScreenshots(source)
     elif from_img:
         dataset = LoadPilAndNumpy(source)
     else:
-        dataset = LoadImages(source, vid_stride=vid_stride)
+        dataset = LoadImagesAndVideos(source, batch=batch, vid_stride=vid_stride)
 
     # Attach source types to the dataset
     setattr(dataset, "source_type", source_type)

ultralytics/data/loaders.py

@@ -24,7 +24,7 @@ from ultralytics.utils.checks import check_requirements
 class SourceTypes:
     """Class to represent various types of input sources for predictions."""
 
-    webcam: bool = False
+    stream: bool = False
     screenshot: bool = False
     from_img: bool = False
     tensor: bool = False
@@ -32,9 +32,7 @@ class SourceTypes:
 
 class LoadStreams:
     """
-    Stream Loader for various types of video streams.
-
-    Suitable for use with `yolo predict source='rtsp://example.com/media.mp4'`, supports RTSP, RTMP, HTTP, and TCP streams.
+    Stream Loader for various types of video streams, Supports RTSP, RTMP, HTTP, and TCP streams.
 
     Attributes:
         sources (str): The source input paths or URLs for the video streams.
@@ -57,6 +55,11 @@ class LoadStreams:
         __iter__: Returns an iterator object for the class.
         __next__: Returns source paths, transformed, and original images for processing.
         __len__: Return the length of the sources object.
+
+    Example:
+         ```bash
+         yolo predict source='rtsp://example.com/media.mp4'
+         ```
     """
 
     def __init__(self, sources="file.streams", vid_stride=1, buffer=False):
@@ -69,6 +72,7 @@ class LoadStreams:
 
         sources = Path(sources).read_text().rsplit() if os.path.isfile(sources) else [sources]
         n = len(sources)
+        self.bs = n
         self.fps = [0] * n  # frames per second
         self.frames = [0] * n
         self.threads = [None] * n
@@ -76,6 +80,8 @@ class LoadStreams:
         self.imgs = [[] for _ in range(n)]  # images
         self.shape = [[] for _ in range(n)]  # image shapes
         self.sources = [ops.clean_str(x) for x in sources]  # clean source names for later
+        self.info = [""] * n
+        self.is_video = [True] * n
         for i, s in enumerate(sources):  # index, source
             # Start thread to read frames from video stream
             st = f"{i + 1}/{n}: {s}... "
@@ -109,9 +115,6 @@ class LoadStreams:
             self.threads[i].start()
         LOGGER.info("")  # newline
 
-        # Check for common shapes
-        self.bs = self.__len__()
-
     def update(self, i, cap, stream):
         """Read stream `i` frames in daemon thread."""
         n, f = 0, self.frames[i]  # frame number, frame array
@@ -175,11 +178,11 @@ class LoadStreams:
                 images.append(x.pop(-1) if x else np.zeros(self.shape[i], dtype=np.uint8))
                 x.clear()
 
-        return self.sources, images, None, ""
+        return self.sources, images, self.is_video, self.info
 
     def __len__(self):
         """Return the length of the sources object."""
-        return len(self.sources)  # 1E12 frames = 32 streams at 30 FPS for 30 years
+        return self.bs  # 1E12 frames = 32 streams at 30 FPS for 30 years
 
 
 class LoadScreenshots:
@@ -243,10 +246,10 @@ class LoadScreenshots:
         s = f"screen {self.screen} (LTWH): {self.left},{self.top},{self.width},{self.height}: "
 
         self.frame += 1
-        return [str(self.screen)], [im0], None, s  # screen, img, vid_cap, string
+        return [str(self.screen)], [im0], [True], [s]  # screen, img, is_video, string
 
 
-class LoadImages:
+class LoadImagesAndVideos:
     """
     YOLOv8 image/video dataloader.
 
@@ -269,7 +272,7 @@ class LoadImages:
         _new_video(path): Create a new cv2.VideoCapture object for a given video path.
     """
 
-    def __init__(self, path, vid_stride=1):
+    def __init__(self, path, batch=1, vid_stride=1):
         """Initialize the Dataloader and raise FileNotFoundError if file not found."""
         parent = None
         if isinstance(path, str) and Path(path).suffix == ".txt":  # *.txt file with img/vid/dir on each line
@@ -298,7 +301,7 @@ class LoadImages:
         self.video_flag = [False] * ni + [True] * nv
         self.mode = "image"
         self.vid_stride = vid_stride  # video frame-rate stride
-        self.bs = 1
+        self.bs = batch
         if any(videos):
             self._new_video(videos[0])  # new video
         else:
@@ -315,49 +318,68 @@ class LoadImages:
         return self
 
     def __next__(self):
-        """Return next image, path and metadata from dataset."""
-        if self.count == self.nf:
-            raise StopIteration
-        path = self.files[self.count]
-
-        if self.video_flag[self.count]:
-            # Read video
-            self.mode = "video"
-            for _ in range(self.vid_stride):
-                self.cap.grab()
-            success, im0 = self.cap.retrieve()
-            while not success:
-                self.count += 1
-                self.cap.release()
-                if self.count == self.nf:  # last video
+        """Returns the next batch of images or video frames along with their paths and metadata."""
+        paths, imgs, is_video, info = [], [], [], []
+        while len(imgs) < self.bs:
+            if self.count >= self.nf:  # end of file list
+                if len(imgs) > 0:
+                    return paths, imgs, is_video, info  # return last partial batch
+                else:
                     raise StopIteration
-                path = self.files[self.count]
-                self._new_video(path)
-                success, im0 = self.cap.read()
 
-            self.frame += 1
-            # im0 = self._cv2_rotate(im0)  # for use if cv2 autorotation is False
-            s = f"video {self.count + 1}/{self.nf} ({self.frame}/{self.frames}) {path}: "
+            path = self.files[self.count]
+            if self.video_flag[self.count]:
+                self.mode = "video"
+                if not self.cap or not self.cap.isOpened():
+                    self._new_video(path)
 
-        else:
-            # Read image
-            self.count += 1
-            im0 = cv2.imread(path)  # BGR
-            if im0 is None:
-                raise FileNotFoundError(f"Image Not Found {path}")
-            s = f"image {self.count}/{self.nf} {path}: "
+                for _ in range(self.vid_stride):
+                    success = self.cap.grab()
+                    if not success:
+                        break  # end of video or failure
 
-        return [path], [im0], self.cap, s
+                if success:
+                    success, im0 = self.cap.retrieve()
+                    if success:
+                        self.frame += 1
+                        paths.append(path)
+                        imgs.append(im0)
+                        is_video.append(True)
+                        info.append(f"video {self.count + 1}/{self.nf} (frame {self.frame}/{self.frames}) {path}: ")
+                        if self.frame == self.frames:  # end of video
+                            self.count += 1
+                            self.cap.release()
+                else:
+                    # Move to the next file if the current video ended or failed to open
+                    self.count += 1
+                    if self.cap:
+                        self.cap.release()
+                    if self.count < self.nf:
+                        self._new_video(self.files[self.count])
+            else:
+                self.mode = "image"
+                im0 = cv2.imread(path)  # BGR
+                if im0 is None:
+                    raise FileNotFoundError(f"Image Not Found {path}")
+                paths.append(path)
+                imgs.append(im0)
+                is_video.append(False)  # no capture object for images
+                info.append(f"image {self.count + 1}/{self.nf} {path}: ")
+                self.count += 1  # move to the next file
+
+        return paths, imgs, is_video, info
 
     def _new_video(self, path):
-        """Create a new video capture object."""
+        """Creates a new video capture object for the given path."""
         self.frame = 0
         self.cap = cv2.VideoCapture(path)
+        if not self.cap.isOpened():
+            raise FileNotFoundError(f"Failed to open video {path}")
         self.frames = int(self.cap.get(cv2.CAP_PROP_FRAME_COUNT) / self.vid_stride)
 
     def __len__(self):
-        """Returns the number of files in the object."""
-        return self.nf  # number of files
+        """Returns the number of batches in the object."""
+        return math.ceil(self.nf / self.bs)  # number of files
 
 
 class LoadPilAndNumpy:
@@ -373,7 +395,6 @@ class LoadPilAndNumpy:
         im0 (list): List of images stored as Numpy arrays.
         mode (str): Type of data being processed, defaults to 'image'.
         bs (int): Batch size, equivalent to the length of `im0`.
-        count (int): Counter for iteration, initialized at 0 during `__iter__()`.
 
     Methods:
         _single_check(im): Validate and format a single image to a Numpy array.
@@ -386,7 +407,6 @@ class LoadPilAndNumpy:
         self.paths = [getattr(im, "filename", f"image{i}.jpg") for i, im in enumerate(im0)]
         self.im0 = [self._single_check(im) for im in im0]
         self.mode = "image"
-        # Generate fake paths
         self.bs = len(self.im0)
 
     @staticmethod
@@ -409,7 +429,7 @@ class LoadPilAndNumpy:
         if self.count == 1:  # loop only once as it's batch inference
             raise StopIteration
         self.count += 1
-        return self.paths, self.im0, None, ""
+        return self.paths, self.im0, [False] * self.bs, [""] * self.bs
 
     def __iter__(self):
         """Enables iteration for class LoadPilAndNumpy."""
@@ -474,7 +494,7 @@ class LoadTensor:
         if self.count == 1:
             raise StopIteration
         self.count += 1
-        return self.paths, self.im0, None, ""
+        return self.paths, self.im0, [False] * self.bs, [""] * self.bs
 
     def __len__(self):
         """Returns the batch size."""
@@ -498,9 +518,6 @@ def autocast_list(source):
     return files
 
 
-LOADERS = LoadStreams, LoadPilAndNumpy, LoadImages, LoadScreenshots  # tuple
-
-
 def get_best_youtube_url(url, use_pafy=True):
     """
     Retrieves the URL of the best quality MP4 video stream from a given YouTube video.
@@ -531,3 +548,7 @@ def get_best_youtube_url(url, use_pafy=True):
             good_size = (f.get("width") or 0) >= 1920 or (f.get("height") or 0) >= 1080
             if good_size and f["vcodec"] != "none" and f["acodec"] == "none" and f["ext"] == "mp4":
                 return f.get("url")
+
+
+# Define constants
+LOADERS = (LoadStreams, LoadPilAndNumpy, LoadImagesAndVideos, LoadScreenshots)

ultralytics/engine/model.py

@@ -423,7 +423,7 @@ class Model(nn.Module):
             x in sys.argv for x in ("predict", "track", "mode=predict", "mode=track")
         )
 
-        custom = {"conf": 0.25, "save": is_cli, "mode": "predict"}  # method defaults
+        custom = {"conf": 0.25, "batch": 1, "save": is_cli, "mode": "predict"}  # method defaults
         args = {**self.overrides, **custom, **kwargs}  # highest priority args on the right
         prompts = args.pop("prompts", None)  # for SAM-type models
 
@@ -474,6 +474,7 @@ class Model(nn.Module):
 
             register_tracker(self, persist)
         kwargs["conf"] = kwargs.get("conf") or 0.1  # ByteTrack-based method needs low confidence predictions as input
+        kwargs["batch"] = kwargs.get("batch") or 1  # batch-size 1 for tracking in videos
         kwargs["mode"] = "track"
         return self.predict(source=source, stream=stream, **kwargs)
 

ultralytics/engine/predictor.py

@@ -73,9 +73,7 @@ class BasePredictor:
         data (dict): Data configuration.
         device (torch.device): Device used for prediction.
         dataset (Dataset): Dataset used for prediction.
-        vid_path (str): Path to video file.
-        vid_writer (cv2.VideoWriter): Video writer for saving video output.
-        data_path (str): Path to data.
+        vid_writer (dict): Dictionary of {save_path: video_writer, ...} writer for saving video output.
     """
 
     def __init__(self, cfg=DEFAULT_CFG, overrides=None, _callbacks=None):
@@ -100,10 +98,11 @@ class BasePredictor:
         self.imgsz = None
         self.device = None
         self.dataset = None
-        self.vid_path, self.vid_writer, self.vid_frame = None, None, None
+        self.vid_writer = {}  # dict of {save_path: video_writer, ...}
         self.plotted_img = None
-        self.data_path = None
         self.source_type = None
+        self.seen = 0
+        self.windows = []
         self.batch = None
         self.results = None
         self.transforms = None
@@ -155,44 +154,6 @@ class BasePredictor:
         letterbox = LetterBox(self.imgsz, auto=same_shapes and self.model.pt, stride=self.model.stride)
         return [letterbox(image=x) for x in im]
 
-    def write_results(self, idx, results, batch):
-        """Write inference results to a file or directory."""
-        p, im, _ = batch
-        log_string = ""
-        if len(im.shape) == 3:
-            im = im[None]  # expand for batch dim
-        if self.source_type.webcam or self.source_type.from_img or self.source_type.tensor:  # batch_size >= 1
-            log_string += f"{idx}: "
-            frame = self.dataset.count
-        else:
-            frame = getattr(self.dataset, "frame", 0)
-        self.data_path = p
-        self.txt_path = str(self.save_dir / "labels" / p.stem) + ("" if self.dataset.mode == "image" else f"_{frame}")
-        log_string += "%gx%g " % im.shape[2:]  # print string
-        result = results[idx]
-        log_string += result.verbose()
-
-        if self.args.save or self.args.show:  # Add bbox to image
-            plot_args = {
-                "line_width": self.args.line_width,
-                "boxes": self.args.show_boxes,
-                "conf": self.args.show_conf,
-                "labels": self.args.show_labels,
-            }
-            if not self.args.retina_masks:
-                plot_args["im_gpu"] = im[idx]
-            self.plotted_img = result.plot(**plot_args)
-        # Write
-        if self.args.save_txt:
-            result.save_txt(f"{self.txt_path}.txt", save_conf=self.args.save_conf)
-        if self.args.save_crop:
-            result.save_crop(
-                save_dir=self.save_dir / "crops",
-                file_name=self.data_path.stem + ("" if self.dataset.mode == "image" else f"_{frame}"),
-            )
-
-        return log_string
-
     def postprocess(self, preds, img, orig_imgs):
         """Post-processes predictions for an image and returns them."""
         return preds
@@ -228,18 +189,20 @@ class BasePredictor:
             else None
         )
         self.dataset = load_inference_source(
-            source=source, vid_stride=self.args.vid_stride, buffer=self.args.stream_buffer
+            source=source,
+            batch=self.args.batch,
+            vid_stride=self.args.vid_stride,
+            buffer=self.args.stream_buffer,
         )
         self.source_type = self.dataset.source_type
         if not getattr(self, "stream", True) and (
-            self.dataset.mode == "stream"  # streams
-            or len(self.dataset) > 1000  # images
+            self.source_type.stream
+            or self.source_type.screenshot
+            or len(self.dataset) > 1000  # many images
             or any(getattr(self.dataset, "video_flag", [False]))
         ):  # videos
             LOGGER.warning(STREAM_WARNING)
-        self.vid_path = [None] * self.dataset.bs
-        self.vid_writer = [None] * self.dataset.bs
-        self.vid_frame = [None] * self.dataset.bs
+        self.vid_writer = {}
 
     @smart_inference_mode()
     def stream_inference(self, source=None, model=None, *args, **kwargs):
@@ -271,10 +234,9 @@ class BasePredictor:
                 ops.Profile(device=self.device),
             )
             self.run_callbacks("on_predict_start")
-            for batch in self.dataset:
+            for self.batch in self.dataset:
                 self.run_callbacks("on_predict_batch_start")
-                self.batch = batch
-                path, im0s, vid_cap, s = batch
+                paths, im0s, is_video, s = self.batch
 
                 # Preprocess
                 with profilers[0]:
@@ -290,8 +252,8 @@ class BasePredictor:
                 # Postprocess
                 with profilers[2]:
                     self.results = self.postprocess(preds, im, im0s)
-
                 self.run_callbacks("on_predict_postprocess_end")
+
                 # Visualize, save, write results
                 n = len(im0s)
                 for i in range(n):
@@ -301,41 +263,32 @@ class BasePredictor:
                         "inference": profilers[1].dt * 1e3 / n,
                         "postprocess": profilers[2].dt * 1e3 / n,
                     }
-                    p, im0 = path[i], None if self.source_type.tensor else im0s[i].copy()
-                    p = Path(p)
-
                     if self.args.verbose or self.args.save or self.args.save_txt or self.args.show:
-                        s += self.write_results(i, self.results, (p, im, im0))
-                    if self.args.save or self.args.save_txt:
-                        self.results[i].save_dir = self.save_dir.__str__()
-                    if self.args.show and self.plotted_img is not None:
-                        self.show(p)
-                    if self.args.save and self.plotted_img is not None:
-                        self.save_preds(vid_cap, i, str(self.save_dir / p.name))
+                        s[i] += self.write_results(i, Path(paths[i]), im, is_video)
+
+                # Print batch results
+                if self.args.verbose:
+                    LOGGER.info("\n".join(s))
 
                 self.run_callbacks("on_predict_batch_end")
                 yield from self.results
 
-                # Print time (inference-only)
-                if self.args.verbose:
-                    LOGGER.info(f"{s}{profilers[1].dt * 1E3:.1f}ms")
-
         # Release assets
-        if isinstance(self.vid_writer[-1], cv2.VideoWriter):
-            self.vid_writer[-1].release()  # release final video writer
+        for v in self.vid_writer.values():
+            if isinstance(v, cv2.VideoWriter):
+                v.release()
 
-        # Print results
+        # Print final results
         if self.args.verbose and self.seen:
             t = tuple(x.t / self.seen * 1e3 for x in profilers)  # speeds per image
             LOGGER.info(
                 f"Speed: %.1fms preprocess, %.1fms inference, %.1fms postprocess per image at shape "
-                f"{(1, 3, *im.shape[2:])}" % t
+                f"{(min(self.args.batch, self.seen), 3, *im.shape[2:])}" % t
             )
         if self.args.save or self.args.save_txt or self.args.save_crop:
             nl = len(list(self.save_dir.glob("labels/*.txt")))  # number of labels
             s = f"\n{nl} label{'s' * (nl > 1)} saved to {self.save_dir / 'labels'}" if self.args.save_txt else ""
             LOGGER.info(f"Results saved to {colorstr('bold', self.save_dir)}{s}")
-
         self.run_callbacks("on_predict_end")
 
     def setup_model(self, model, verbose=True):
@@ -354,48 +307,81 @@ class BasePredictor:
         self.args.half = self.model.fp16  # update half
         self.model.eval()
 
-    def show(self, p):
-        """Display an image in a window using OpenCV imshow()."""
-        im0 = self.plotted_img
-        if platform.system() == "Linux" and p not in self.windows:
-            self.windows.append(p)
-            cv2.namedWindow(str(p), cv2.WINDOW_NORMAL | cv2.WINDOW_KEEPRATIO)  # allow window resize (Linux)
-            cv2.resizeWindow(str(p), im0.shape[1], im0.shape[0])
-        cv2.imshow(str(p), im0)
-        cv2.waitKey(500 if self.batch[3].startswith("image") else 1)  # 1 millisecond
+    def write_results(self, i, p, im, is_video):
+        """Write inference results to a file or directory."""
+        string = ""  # print string
+        if len(im.shape) == 3:
+            im = im[None]  # expand for batch dim
+        if self.source_type.stream or self.source_type.from_img or self.source_type.tensor:  # batch_size >= 1
+            string += f"{i}: "
+            frame = self.dataset.count
+        else:
+            frame = getattr(self.dataset, "frame", 0) - len(self.results) + i
 
-    def save_preds(self, vid_cap, idx, save_path):
+        self.txt_path = self.save_dir / "labels" / (p.stem + f"_{frame}" if is_video[i] else "")
+        string += "%gx%g " % im.shape[2:]
+        result = self.results[i]
+        result.save_dir = self.save_dir.__str__()  # used in other locations
+        string += result.verbose() + f"{result.speed['inference']:.1f}ms"
+
+        # Add predictions to image
+        if self.args.save or self.args.show:
+            self.plotted_img = result.plot(
+                line_width=self.args.line_width,
+                boxes=self.args.show_boxes,
+                conf=self.args.show_conf,
+                labels=self.args.show_labels,
+                im_gpu=None if self.args.retina_masks else im[i],
+            )
+
+        # Save results
+        if self.args.save_txt:
+            result.save_txt(f"{self.txt_path}.txt", save_conf=self.args.save_conf)
+        if self.args.save_crop:
+            result.save_crop(save_dir=self.save_dir / "crops", file_name=self.txt_path.stem)
+        if self.args.show:
+            self.show(str(p), is_video[i])
+        if self.args.save:
+            self.save_predicted_images(str(self.save_dir / p.name), is_video[i], frame)
+
+        return string
+
+    def save_predicted_images(self, save_path="", is_video=False, frame=0):
         """Save video predictions as mp4 at specified path."""
-        im0 = self.plotted_img
-        # Save imgs
-        if self.dataset.mode == "image":
-            cv2.imwrite(save_path, im0)
-        else:  # 'video' or 'stream'
+        im = self.plotted_img
+
+        # Save videos and streams
+        if is_video:
             frames_path = f'{save_path.split(".", 1)[0]}_frames/'
-            if self.vid_path[idx] != save_path:  # new video
-                self.vid_path[idx] = save_path
+            if save_path not in self.vid_writer:  # new video
                 if self.args.save_frames:
                     Path(frames_path).mkdir(parents=True, exist_ok=True)
-                    self.vid_frame[idx] = 0
-                if isinstance(self.vid_writer[idx], cv2.VideoWriter):
-                    self.vid_writer[idx].release()  # release previous video writer
-                if vid_cap:  # video
-                    fps = int(vid_cap.get(cv2.CAP_PROP_FPS))  # integer required, floats produce error in MP4 codec
-                    w = int(vid_cap.get(cv2.CAP_PROP_FRAME_WIDTH))
-                    h = int(vid_cap.get(cv2.CAP_PROP_FRAME_HEIGHT))
-                else:  # stream
-                    fps, w, h = 30, im0.shape[1], im0.shape[0]
                 suffix, fourcc = (".mp4", "avc1") if MACOS else (".avi", "WMV2") if WINDOWS else (".avi", "MJPG")
-                self.vid_writer[idx] = cv2.VideoWriter(
-                    str(Path(save_path).with_suffix(suffix)), cv2.VideoWriter_fourcc(*fourcc), fps, (w, h)
+                self.vid_writer[save_path] = cv2.VideoWriter(
+                    filename=str(Path(save_path).with_suffix(suffix)),
+                    fourcc=cv2.VideoWriter_fourcc(*fourcc),
+                    fps=30,  # integer required, floats produce error in MP4 codec
+                    frameSize=(im.shape[1], im.shape[0]),  # (width, height)
                 )
-            # Write video
-            self.vid_writer[idx].write(im0)
 
-            # Write frame
+            # Save video
+            self.vid_writer[save_path].write(im)
             if self.args.save_frames:
-                cv2.imwrite(f"{frames_path}{self.vid_frame[idx]}.jpg", im0)
-                self.vid_frame[idx] += 1
+                cv2.imwrite(f"{frames_path}{frame}.jpg", im)
+
+        # Save images
+        else:
+            cv2.imwrite(save_path, im)
+
+    def show(self, p="", is_video=False):
+        """Display an image in a window using OpenCV imshow()."""
+        im = self.plotted_img
+        if platform.system() == "Linux" and p not in self.windows:
+            self.windows.append(p)
+            cv2.namedWindow(p, cv2.WINDOW_NORMAL | cv2.WINDOW_KEEPRATIO)  # allow window resize (Linux)
+            cv2.resizeWindow(p, im.shape[1], im.shape[0])  # (width, height)
+        cv2.imshow(p, im)
+        cv2.waitKey(1 if is_video else 500)  # 1 millisecond
 
     def run_callbacks(self, event: str):
         """Runs all registered callbacks for a specific event."""

ultralytics/trackers/track.py

@@ -39,6 +39,7 @@ def on_predict_start(predictor: object, persist: bool = False) -> None:
         tracker = TRACKER_MAP[cfg.tracker_type](args=cfg, frame_rate=30)
         trackers.append(tracker)
     predictor.trackers = trackers
+    predictor.vid_path = [None] * predictor.dataset.bs  # for determining when to reset tracker on new video
 
 
 def on_predict_postprocess_end(predictor: object, persist: bool = False) -> None:
@@ -54,8 +55,10 @@ def on_predict_postprocess_end(predictor: object, persist: bool = False) -> None
 
     is_obb = predictor.args.task == "obb"
     for i in range(bs):
-        if not persist and predictor.vid_path[i] != str(predictor.save_dir / Path(path[i]).name):  # new video
+        vid_path = predictor.save_dir / Path(path[i]).name
+        if not persist and predictor.vid_path[i] != vid_path:  # new video
             predictor.trackers[i].reset()
+            predictor.vid_path[i] = vid_path
 
         det = (predictor.results[i].obb if is_obb else predictor.results[i].boxes).cpu().numpy()
         if len(det) == 0: