vllm.multimodal.video ¶

@VIDEO_LOADER_REGISTRY.register("molmo2")
class Molmo2VideoBackend(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 get_candidate_target_fps(
        cls,
        video_fps: float,
        sampling_fps: float,
        max_fps: float = 8.0,
    ) -> list[float]:
        """
        Return the subset of `video_fps` factors that remain multiples
        of `sampling_fps`.

        Examples:
            >>> get_candidate_target_fps(video_fps=6, sampling_fps=2)
            [2, 6]
            >>> get_candidate_target_fps(video_fps=5, sampling_fps=1)
            [1, 5]
            >>> get_candidate_target_fps(video_fps=2, sampling_fps=2)
            [2]
            >>> get_candidate_target_fps(video_fps=5, sampling_fps=2)
            Traceback (most recent call last):
                ...
            ValueError: sampling_fps=2 must divide video_fps=5 to produce
                consistent frame steps.
        """
        video_fps = int(video_fps)
        sampling_fps = int(sampling_fps)
        max_fps = int(max_fps)

        if sampling_fps is None:
            raise ValueError("sampling_fps must be provided")
        if video_fps <= 0 or sampling_fps <= 0:
            raise ValueError(
                "video_fps and sampling_fps must be positive "
                f"(got {video_fps}, {sampling_fps})"
            )
        if video_fps % sampling_fps != 0:
            raise ValueError(
                f"sampling_fps={sampling_fps} must divide video_fps={video_fps}."
            )

        candidates = []
        for candidate in range(sampling_fps, video_fps + 1, sampling_fps):
            if candidate > max_fps:
                break
            if video_fps % candidate == 0:
                candidates.append(float(candidate))

        return candidates

    @classmethod
    def get_target_fps(
        cls,
        video_fps: float,
        max_frames: int,
        total_frames: int,
        frame_sample_mode: str,
        candidate_target_fps: list[float],
    ) -> float | None:
        """
        Get the target fps that best spans the videoand has the most frames sampled
        """
        num_frames_sampled = 0
        selected_target_fps = None
        for target_fps in candidate_target_fps:
            step_size = max(int(video_fps / target_fps), 1)
            num_frames_sampled_at_fps = int(total_frames / step_size)
            if num_frames_sampled == 0:
                if (
                    "uniform" in frame_sample_mode
                    and num_frames_sampled_at_fps > max_frames
                ):
                    break
                selected_target_fps = target_fps
                num_frames_sampled = num_frames_sampled_at_fps

            else:
                # the candidate sampling fps increases so frame count can't decrease
                assert num_frames_sampled <= num_frames_sampled_at_fps
                if num_frames_sampled_at_fps > max_frames:
                    # choose the sampling fps that spans the video
                    continue

                elif num_frames_sampled_at_fps > num_frames_sampled:
                    # both are less than max_frames; choose the one with higher
                    # density of frames sampled
                    selected_target_fps = target_fps
                    num_frames_sampled = num_frames_sampled_at_fps
        return selected_target_fps

    @classmethod
    def get_frame_times_and_chosen_fps(
        cls,
        selected_target_fps: float | None,
        total_frames: int,
        max_frames: int,
        video_fps: float,
    ) -> tuple[float | None, npt.NDArray]:
        if selected_target_fps is None:
            frame_indices = np.linspace(
                0, total_frames, max_frames, endpoint=False, dtype=int
            )
        else:
            step_size = max(int(video_fps / selected_target_fps), 1)
            frame_indices = np.arange(0, total_frames, step_size)
        if len(frame_indices) > max_frames:
            frame_indices = frame_indices[:max_frames]
        return selected_target_fps, frame_indices

    @classmethod
    def sample_times(
        cls,
        duration: float,
        max_frames: int,
        frame_sample_mode: str,
        max_fps: int | None,
        candidate_target_fps: list[float] | None = None,
        **kwargs,
    ) -> npt.NDArray:
        if frame_sample_mode == "fps":
            assert candidate_target_fps is not None
            # Try larger and larger FPSs until we hit one that can't span the video
            sampling_fps = candidate_target_fps[0]
            for candidate_fps in candidate_target_fps[1:]:
                if max_frames / candidate_fps < duration:
                    break
                sampling_fps = candidate_fps
            times = np.arange(0, max_frames) / sampling_fps
            times = times[times < duration]
            return times
        elif frame_sample_mode == "uniform_last_frame":
            if max_fps is not None:
                max_duration = (
                    max_frames - 1
                ) / max_fps  # -1 to include the last frame
                if max_duration < duration:
                    times = np.linspace(
                        0, duration, num=max_frames, endpoint=True, dtype=np.float64
                    )
                else:
                    times = np.arange(0.0, stop=duration, step=1 / max_fps)
                    times = np.concatenate([times, [duration]], axis=0)
                    assert len(times) <= max_frames
            else:
                times = np.linspace(
                    0, duration, num=max_frames, endpoint=True, dtype=np.float64
                )
            return times
        else:
            raise NotImplementedError(frame_sample_mode)

    @classmethod
    def _sample_frames(
        cls,
        total_num_frames: int,
        video_fps: float,
        duration: float,
        frame_sample_mode: str,
        num_frames: int,
        max_fps: int,
        sampling_fps: int,
    ) -> npt.NDArray:
        if frame_sample_mode == "uniform_last_frame" and max_fps is not None:
            if total_num_frames <= 2:
                indices = np.arange(total_num_frames).astype(int)
            elif duration > (num_frames - 1) / max_fps:  # -1 to include the last frame
                # uniform fallback
                indices = np.linspace(
                    0,
                    total_num_frames - 1,
                    num=min(num_frames, total_num_frames),
                    endpoint=True,
                ).astype(int)
            else:
                float_indices = np.arange(
                    0.0,
                    stop=total_num_frames - 1,
                    step=float(video_fps / max_fps),
                )
                if np.round(float_indices[-1]) != total_num_frames - 1:
                    float_indices = np.concatenate(
                        [float_indices, [total_num_frames - 1]], axis=0
                    )
                indices = np.round(float_indices).astype(int)
                assert indices[-1] < total_num_frames
                assert len(float_indices) <= num_frames
        elif frame_sample_mode == "uniform_last_frame":
            indices = np.linspace(
                0,
                total_num_frames - 1,
                num=min(num_frames, total_num_frames),
                endpoint=True,
            ).astype(int)
        elif frame_sample_mode == "fps":
            candidate_target_fps = cls.get_candidate_target_fps(video_fps, sampling_fps)
            selected_target_fps = cls.get_target_fps(
                video_fps,
                num_frames,
                total_num_frames,
                frame_sample_mode,
                candidate_target_fps,
            )
            _, indices = cls.get_frame_times_and_chosen_fps(
                selected_target_fps,
                total_num_frames,
                num_frames,
                video_fps,
            )
        else:
            raise NotImplementedError(frame_sample_mode)

        return indices

    @classmethod
    def load_bytes_opencv(
        cls,
        data: bytes,
        frame_sample_mode: str | None = None,
        num_frames: int = -1,
        max_fps: int = 2,
        sampling_fps: int = 2,
        **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

        if frame_sample_mode is None:
            # Use transformers transformers.video_utils.VideoMetadata format
            frame_idx = list(range(0, total_frames_num))
            frame_idx_set = set(frame_idx)
            frames, valid_num_frames, valid_frame_indices = cls._read_frames(
                cap, frame_idx_set, total_frames_num, max(frame_idx)
            )
            do_sample_frames = valid_num_frames == total_frames_num
            metadata = {
                "total_num_frames": total_frames_num,
                "fps": original_fps,
                "duration": duration,
                "video_backend": "opencv",
                "do_sample_frames": do_sample_frames,
            }
            if not do_sample_frames:
                metadata["frames_indices"] = valid_frame_indices
            return frames, metadata

        frame_idx = cls._sample_frames(
            total_frames_num,
            original_fps,
            duration,
            frame_sample_mode,
            num_frames,
            max_fps,
            sampling_fps,
        ).tolist()

        frames, valid_num_frames, valid_frame_indices = cls._read_frames(
            cap,
            set(frame_idx),
            len(frame_idx),
            total_frames_num - 1,
        )

        metadata = {
            "total_num_frames": total_frames_num,
            "fps": original_fps,
            "duration": duration,
            "video_backend": "opencv",
            "frames_indices": valid_frame_indices,
            "do_sample_frames": False,
        }

        return frames, metadata

    @classmethod
    def load_bytes(
        cls,
        data: bytes,
        num_frames: int = -1,
        **kwargs,
    ) -> tuple[npt.NDArray, dict[str, Any]]:
        frame_sample_mode = cast(str | None, kwargs.pop("frame_sample_mode", None))
        max_fps = cast(int, kwargs.pop("max_fps", 2))
        sampling_fps = cast(int, kwargs.pop("sampling_fps", 2))
        out = cls.load_bytes_opencv(
            data,
            frame_sample_mode,
            num_frames,
            max_fps,
            sampling_fps,
            **kwargs,
        )
        return out

@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,
        frame_recovery: bool = False,
        **kwargs,
    ) -> tuple[npt.NDArray, dict[str, Any]]:
        """
        Load video frames with dynamic sampling based on duration.

        Args:
            data: Raw video bytes
            num_frames: Not used in dynamic backend
            fps: Target FPS for sampling (default: 2)
            max_duration: Maximum video duration to process (default: 300s)
            frame_recovery: Enable forward-scan recovery for failed frames

        Returns:
            Tuple of (frames_array, metadata_dict)
        """
        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
                    }
                )

        if frame_recovery:
            frames, valid_frame_indices, recovered_map = cls._read_frames_with_recovery(
                cap, frame_indices_list, total_frames_num
            )
            valid_num_frames = len(valid_frame_indices)

            if recovered_map:
                logger.info(
                    "Frame recovery: %d frames recovered using forward scan.",
                    len(recovered_map),
                )
        else:
            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,
        max_duration: int = 300,
        frame_recovery: bool = False,
        **kwargs,
    ) -> tuple[npt.NDArray, dict[str, Any]]:
        """
        Load video frames from bytes.

        Args:
            data: Raw video bytes
            num_frames: Target number of frames to sample (-1 for all)
            fps: Target FPS for sampling (-1 for original)
            max_duration: Maximum duration (unused in base backend)
            frame_recovery: Enable forward-scan recovery for failed frames

        Returns:
            Tuple of (frames_array, metadata_dict)
        """
        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()

        if frame_recovery:
            frames, valid_frame_indices, recovered_map = cls._read_frames_with_recovery(
                cap, frame_idx, total_frames_num
            )
            valid_num_frames = len(valid_frame_indices)

            if recovered_map:
                logger.info(
                    "Frame recovery: %d frames recovered using forward scan.",
                    len(recovered_map),
                )
        else:
            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