Add support for VIDEO as a built-in type (#7844)

* Add basic support for videos as types

This PR adds support for VIDEO as first-class types. In order to avoid
unnecessary costs, VIDEO outputs must implement the `VideoInput` ABC,
but their implementation details can vary. Included are two
implementations of this type which can be returned by other nodes:

* `VideoFromFile` - Created with either a path on disk (as a string) or
  a `io.BytesIO` containing the contents of a file in a supported format
  (like .mp4). This implementation won't actually load the video unless
  necessary. It will also avoid re-encoding when saving if possible.
* `VideoFromComponents` - Created from an image tensor and an optional
  audio tensor.

Currently, only h264 encoded videos in .mp4 containers are supported for
saving, but the plan is to add additional encodings/containers in the
near future (particularly .webm).

* Add optimization to avoid parsing entire video

* Improve type declarations to reduce warnings

* Make sure bytesIO objects can be read many times

* Fix a potential issue when saving long videos

* Fix incorrect type annotation

* Add a `LoadVideo` node to make testing easier

* Refactor new types out of the base comfy folder

I've created a new `comfy_api` top-level module. The intention is that
anything within this folder would be covered by semver-style versioning
that would allow custom nodes to rely on them not introducing breaking
changes.

* Fix linting issue

comfy_api/input/__init__.py

@@ -0,0 +1,8 @@
+from .basic_types import ImageInput, AudioInput
+from .video_types import VideoInput
+
+__all__ = [
+    "ImageInput",
+    "AudioInput",
+    "VideoInput",
+]

comfy_api/input/basic_types.py

@@ -0,0 +1,20 @@
+import torch
+from typing import TypedDict
+
+ImageInput = torch.Tensor
+"""
+An image in format [B, H, W, C] where B is the batch size, C is the number of channels,
+"""
+
+class AudioInput(TypedDict):
+    """
+    TypedDict representing audio input.
+    """
+
+    waveform: torch.Tensor
+    """
+    Tensor in the format [B, C, T] where B is the batch size, C is the number of channels,
+    """
+
+    sample_rate: int
+

comfy_api/input/video_types.py

@@ -0,0 +1,45 @@
+from __future__ import annotations
+from abc import ABC, abstractmethod
+from typing import Optional
+from comfy_api.util import VideoContainer, VideoCodec, VideoComponents
+
+class VideoInput(ABC):
+    """
+    Abstract base class for video input types.
+    """
+
+    @abstractmethod
+    def get_components(self) -> VideoComponents:
+        """
+        Abstract method to get the video components (images, audio, and frame rate).
+
+        Returns:
+            VideoComponents containing images, audio, and frame rate
+        """
+        pass
+
+    @abstractmethod
+    def save_to(
+        self,
+        path: str,
+        format: VideoContainer = VideoContainer.AUTO,
+        codec: VideoCodec = VideoCodec.AUTO,
+        metadata: Optional[dict] = None
+    ):
+        """
+        Abstract method to save the video input to a file.
+        """
+        pass
+
+    # Provide a default implementation, but subclasses can provide optimized versions
+    # if possible.
+    def get_dimensions(self) -> tuple[int, int]:
+        """
+        Returns the dimensions of the video input.
+
+        Returns:
+            Tuple of (width, height)
+        """
+        components = self.get_components()
+        return components.images.shape[2], components.images.shape[1]
+