feat: Add VideoSlice node with lazy operations on VideoInput

- Add VideoOp base class and SliceOp in _input/video_types.py
- Add sliced() method to VideoInput that returns a copy with operation appended
- Each subclass applies operations in get_components() and get_frame_count()
- After materialization, VideoFromFile delegates to internal VideoFromComponents
- Add VideoSlice node that uses video.sliced(start_frame, frame_count)
- Add tests for SliceOp, sliced() behavior, and materialization
This commit is contained in:
bymyself
2026-01-23 20:32:57 -08:00
parent d7f3241bf6
commit e4f3d335dc
6 changed files with 263 additions and 13 deletions

View File

@@ -1,7 +1,8 @@
from .video_types import VideoFromFile, VideoFromComponents
from .._input import SliceOp
__all__ = [
# Implementations
"VideoFromFile",
"VideoFromComponents",
"SliceOp",
]

View File

@@ -3,7 +3,7 @@ from av.container import InputContainer
from av.subtitles.stream import SubtitleStream
from fractions import Fraction
from typing import Optional
from .._input import AudioInput, VideoInput
from .._input import AudioInput, VideoInput, VideoOp
import av
import io
import json
@@ -63,6 +63,8 @@ class VideoFromFile(VideoInput):
containing the file contents.
"""
self.__file = file
self._operations: list[VideoOp] = []
self.__materialized: Optional[VideoFromComponents] = None
def get_stream_source(self) -> str | io.BytesIO:
"""
@@ -161,6 +163,10 @@ class VideoFromFile(VideoInput):
if frame_count == 0:
raise ValueError(f"Could not determine frame count for file '{self.__file}'")
# Apply operations to get final frame count
for op in self._operations:
frame_count = op.compute_frame_count(frame_count)
return frame_count
def get_frame_rate(self) -> Fraction:
@@ -239,10 +245,18 @@ class VideoFromFile(VideoInput):
return VideoComponents(images=images, audio=audio, frame_rate=frame_rate, metadata=metadata)
def get_components(self) -> VideoComponents:
if self.__materialized is not None:
return self.__materialized.get_components()
if isinstance(self.__file, io.BytesIO):
self.__file.seek(0) # Reset the BytesIO object to the beginning
with av.open(self.__file, mode='r') as container:
return self.get_components_internal(container)
components = self.get_components_internal(container)
for op in self._operations:
components = op.apply(components)
self.__materialized = VideoFromComponents(components)
self._operations = []
return components
raise ValueError(f"No video stream found in file '{self.__file}'")
def save_to(
@@ -317,14 +331,27 @@ class VideoFromComponents(VideoInput):
def __init__(self, components: VideoComponents):
self.__components = components
self._operations: list[VideoOp] = []
def get_components(self) -> VideoComponents:
if self._operations:
components = self.__components
for op in self._operations:
components = op.apply(components)
self.__components = components
self._operations = []
return VideoComponents(
images=self.__components.images,
audio=self.__components.audio,
frame_rate=self.__components.frame_rate
)
def get_frame_count(self) -> int:
count = int(self.__components.images.shape[0])
for op in self._operations:
count = op.compute_frame_count(count)
return count
def save_to(
self,
path: str,
@@ -332,6 +359,9 @@ class VideoFromComponents(VideoInput):
codec: VideoCodec = VideoCodec.AUTO,
metadata: Optional[dict] = None
):
# Materialize ops before saving
components = self.get_components()
if format != VideoContainer.AUTO and format != VideoContainer.MP4:
raise ValueError("Only MP4 format is supported for now")
if codec != VideoCodec.AUTO and codec != VideoCodec.H264:
@@ -345,22 +375,22 @@ class VideoFromComponents(VideoInput):
for key, value in metadata.items():
output.metadata[key] = json.dumps(value)
frame_rate = Fraction(round(self.__components.frame_rate * 1000), 1000)
frame_rate = Fraction(round(components.frame_rate * 1000), 1000)
# Create a video stream
video_stream = output.add_stream('h264', rate=frame_rate)
video_stream.width = self.__components.images.shape[2]
video_stream.height = self.__components.images.shape[1]
video_stream.width = components.images.shape[2]
video_stream.height = components.images.shape[1]
video_stream.pix_fmt = 'yuv420p'
# Create an audio stream
audio_sample_rate = 1
audio_stream: Optional[av.AudioStream] = None
if self.__components.audio:
audio_sample_rate = int(self.__components.audio['sample_rate'])
if components.audio:
audio_sample_rate = int(components.audio['sample_rate'])
audio_stream = output.add_stream('aac', rate=audio_sample_rate)
# Encode video
for i, frame in enumerate(self.__components.images):
for i, frame in enumerate(components.images):
img = (frame * 255).clamp(0, 255).byte().cpu().numpy() # shape: (H, W, 3)
frame = av.VideoFrame.from_ndarray(img, format='rgb24')
frame = frame.reformat(format='yuv420p') # Convert to YUV420P as required by h264
@@ -371,9 +401,9 @@ class VideoFromComponents(VideoInput):
packet = video_stream.encode(None)
output.mux(packet)
if audio_stream and self.__components.audio:
waveform = self.__components.audio['waveform']
waveform = waveform[:, :, :math.ceil((audio_sample_rate / frame_rate) * self.__components.images.shape[0])]
if audio_stream and components.audio:
waveform = components.audio['waveform']
waveform = waveform[:, :, :math.ceil((audio_sample_rate / frame_rate) * components.images.shape[0])]
frame = av.AudioFrame.from_ndarray(waveform.movedim(2, 1).reshape(1, -1).float().cpu().numpy(), format='flt', layout='mono' if waveform.shape[1] == 1 else 'stereo')
frame.sample_rate = audio_sample_rate
frame.pts = 0