vllm.multimodal.video ¶

@VIDEO_LOADER_REGISTRY.register("opencv_dynamic")
class OpenCVDynamicVideoBackend(OpenCVVideoBackend):
    @classmethod
    def load_bytes(
        cls,
        data: bytes,
        num_frames: int = -1,
        fps: int = 2,
        max_duration: int = 300,
        **kwargs,
    ) -> tuple[npt.NDArray, dict[str, Any]]:
        import cv2

        backend = cls().get_cv2_video_api()
        cap = cv2.VideoCapture(BytesIO(data), backend, [])
        if not cap.isOpened():
            raise ValueError("Could not open video stream")

        total_frames_num = int(cap.get(cv2.CAP_PROP_FRAME_COUNT))
        original_fps = cap.get(cv2.CAP_PROP_FPS)
        duration = total_frames_num / original_fps if original_fps > 0 else 0

        # resample video to target num_frames
        max_frame_idx = total_frames_num - 1
        duration = duration or round(max_frame_idx / original_fps) + 1

        # Refer to:
        # https://github.com/huggingface/transformers/blob/v4.55.4/src/transformers/models/glm4v/video_processing_glm4v.py#L103-L140
        frame_indices_list: list[int]
        if duration <= max_duration:
            n = int(math.floor(duration * fps))
            frame_indices_list = sorted(
                {
                    min(max_frame_idx, int(math.ceil(i * original_fps / fps)))
                    for i in range(n)
                }
            )
        else:
            num_samples = int(max_duration * fps)
            if num_samples >= total_frames_num:
                frame_indices_list = list(range(total_frames_num))
            else:
                target_seconds = np.linspace(0, duration, num_samples, endpoint=True)
                frame_indices_list = sorted(
                    {
                        min(max_frame_idx, int(math.ceil(t * original_fps)))
                        for t in target_seconds
                    }
                )

        # Convert to set for O(1) lookup performance
        frame_indices_set = set(frame_indices_list)
        frames, valid_num_frames, valid_frame_indices = cls._read_frames(
            cap,
            frame_indices_set,
            len(frame_indices_list),
            total_frames_num - 1,
        )

        # Use transformers transformers.video_utils.VideoMetadata format
        metadata = {
            "total_num_frames": total_frames_num,
            "fps": original_fps,
            "duration": duration,
            "video_backend": "opencv_dynamic",
            "frames_indices": valid_frame_indices,
            "do_sample_frames": False,
        }

        return frames, metadata

@VIDEO_LOADER_REGISTRY.register("opencv")
class OpenCVVideoBackend(VideoLoader):
    def get_cv2_video_api(self):
        import cv2.videoio_registry as vr

        api_pref = None
        for backend in vr.getStreamBufferedBackends():
            if not vr.hasBackend(backend):
                continue
            if not vr.isBackendBuiltIn(backend):
                _, abi, api = vr.getStreamBufferedBackendPluginVersion(backend)
                if abi < 1 or (abi == 1 and api < 2):
                    continue
            api_pref = backend
            break
        return api_pref

    @classmethod
    def load_bytes(
        cls,
        data: bytes,
        num_frames: int = -1,
        fps: int = -1,
        **kwargs,
    ) -> tuple[npt.NDArray, dict[str, Any]]:
        import cv2

        backend = cls().get_cv2_video_api()
        cap = cv2.VideoCapture(BytesIO(data), backend, [])
        if not cap.isOpened():
            raise ValueError("Could not open video stream")

        total_frames_num = int(cap.get(cv2.CAP_PROP_FRAME_COUNT))
        original_fps = cap.get(cv2.CAP_PROP_FPS)
        duration = total_frames_num / original_fps if original_fps > 0 else 0

        # resample video to target num_frames and fps
        # - the minimum of the two will be used
        num_frames_to_sample = total_frames_num
        if num_frames > 0:
            num_frames_to_sample = min(num_frames, total_frames_num)
        if fps > 0:
            num_frames_to_sample = min(num_frames_to_sample, math.floor(duration * fps))
        num_frames_to_sample = max(1, num_frames_to_sample)  # at least one sample

        if num_frames_to_sample == total_frames_num:
            frame_idx = list(range(0, num_frames_to_sample))
        else:
            uniform_sampled_frames = np.linspace(
                0, total_frames_num - 1, num_frames_to_sample, dtype=int
            )
            frame_idx = uniform_sampled_frames.tolist()

        # Convert to set for O(1) lookup performance
        frame_idx_set = set(frame_idx)
        frames, valid_num_frames, valid_frame_indices = cls._read_frames(
            cap, frame_idx_set, num_frames_to_sample, max(frame_idx)
        )

        # Use transformers transformers.video_utils.VideoMetadata format
        # NOTE(Isotr0py): For models like Qwen3-VL/GLM4.5V, this metadata
        # can cause incorrect timestamp calculation without num_frames=-1.
        metadata = {
            "total_num_frames": total_frames_num,
            "fps": original_fps,
            "duration": duration,
            "video_backend": "opencv",
            "frames_indices": valid_frame_indices,
            # extra field used to control hf processor's video
            # sampling behavior
            "do_sample_frames": valid_num_frames == total_frames_num,
        }

        return frames, metadata

class VideoLoader:
    @classmethod
    @abstractmethod
    def load_bytes(
        cls, data: bytes, num_frames: int = -1, **kwargs
    ) -> tuple[npt.NDArray, dict[str, Any]]:
        raise NotImplementedError

    @staticmethod
    def _read_frames(
        cap,
        frame_indices: set[int],
        num_expected_frames: int,
        max_frame_idx: int,
    ) -> tuple[npt.NDArray, int, list[int]]:
        import cv2

        width = int(cap.get(cv2.CAP_PROP_FRAME_WIDTH))
        height = int(cap.get(cv2.CAP_PROP_FRAME_HEIGHT))
        frames = np.empty((num_expected_frames, height, width, 3), dtype=np.uint8)

        i = 0
        valid_frame_indices = []
        for idx in range(max_frame_idx + 1):
            ok = cap.grab()
            if not ok:
                # Frame is broken/unreadable, log warning
                if idx in frame_indices:
                    logger.warning(
                        "Failed to grab frame %d during video loading. "
                        "This frame will be skipped.",
                        idx,
                    )
                continue
            if idx in frame_indices:
                ret, frame = cap.retrieve()
                if ret:
                    frames[i] = cv2.cvtColor(frame, cv2.COLOR_BGR2RGB)
                    valid_frame_indices.append(idx)
                    i += 1
                else:
                    # retrieve() failed even though grab() succeeded
                    logger.warning(
                        "Failed to retrieve frame %d during video loading. "
                        "This frame will be skipped.",
                        idx,
                    )

        valid_num_frames = len(valid_frame_indices)
        if valid_num_frames < num_expected_frames:
            logger.warning(
                "Video loading completed with %d broken/unreadable frames. "
                "Expected %d frames but only loaded %d frames.",
                num_expected_frames - valid_num_frames,
                num_expected_frames,
                valid_num_frames,
            )

        return frames[:valid_num_frames], valid_num_frames, valid_frame_indices

class VideoMediaIO(MediaIO[npt.NDArray]):
    def __init__(
        self,
        image_io: ImageMediaIO,
        num_frames: int = 32,
        **kwargs,
    ) -> None:
        super().__init__()

        self.image_io = image_io
        self.num_frames = num_frames
        # `kwargs` contains custom arguments from
        # --media-io-kwargs for this modality.
        # They can be passed to the underlying
        # media loaders (e.g. custom implementations)
        # for flexible control.
        self.kwargs = kwargs
        video_loader_backend = envs.VLLM_VIDEO_LOADER_BACKEND
        self.video_loader = VIDEO_LOADER_REGISTRY.load(video_loader_backend)

    def load_bytes(self, data: bytes) -> tuple[npt.NDArray, dict[str, Any]]:
        return self.video_loader.load_bytes(
            data, num_frames=self.num_frames, **self.kwargs
        )

    def load_base64(
        self, media_type: str, data: str
    ) -> tuple[npt.NDArray, dict[str, Any]]:
        if media_type.lower() == "video/jpeg":
            load_frame = partial(
                self.image_io.load_base64,
                "image/jpeg",
            )

            return np.stack(
                [np.asarray(load_frame(frame_data)) for frame_data in data.split(",")]
            ), {}

        return self.load_bytes(base64.b64decode(data))

    def load_file(self, filepath: Path) -> tuple[npt.NDArray, dict[str, Any]]:
        with filepath.open("rb") as f:
            data = f.read()

        return self.load_bytes(data)

    def encode_base64(
        self,
        media: npt.NDArray,
        *,
        video_format: str = "JPEG",
    ) -> str:
        video = media

        if video_format == "JPEG":
            encode_frame = partial(
                self.image_io.encode_base64,
                image_format=video_format,
            )

            return ",".join(encode_frame(Image.fromarray(frame)) for frame in video)

        msg = "Only JPEG format is supported for now."
        raise NotImplementedError(msg)