concatenate_videoclips sets start to 0

[bryzgaloff]

Expected Behavior

concatenate_videoclips should preserve the first clip's start.

Actual Behavior

concatenate_videoclips sets start to 0:

moviepy/moviepy/video/compositing/CompositeVideoClip.py

Line 368 in 4dd5fe4

result.start, result.duration, result.end = 0, timings[-1], timings[-1]

Which ignores the original clip's start property.

Steps and code to Reproduce the Problem

from moviepy import concatenate_videoclips

# a random "image" just for demo purposes: the actual clip does not matter
from moviepy import ImageClip
import numpy as np
image_numpy = np.arange(1).reshape(1, 1)
image_clip = ImageClip(image_numpy)

# set to 1.0; (duration is also required for concat)
clip_with_start_at_1 = image_clip.with_start(1.0).with_duration(1.0)
concatenated = concatenate_videoclips([clip_with_start_at_1])

print(concatenated.start)  # output: 0, but should be 1.0

Used medias

Works with any clip. In my case I used a regular VideoFileClip, but for the example above it is not required.

Specifications

• Python Version: 3.13.3
• MoviePy Version: this commit, which is a small edit to v2.1.2
• Platform Name: Docker Desktop, macOS
• Platform Version: python:3.13-slim image with ffmpeg and moviepy