MoviePy Video Tools

Kern MoviePyVideoTools enable an Agent to process videos, extract audio, generate SRT caption files, and embed rich, word-highlighted captions.

Prerequisites

To use MoviePyVideoTools, you need to install moviepy and its dependency ffmpeg:

1uv pip install moviepy ffmpeg

Important for Captioning Workflow: The create_srt and embed_captions tools require a transcription of the video's audio. MoviePyVideoTools itself does not perform speech-to-text. You'll typically use another tool, such as OpenAITools with its transcribe_audio function, to generate the transcription (often in SRT format) which is then used by these tools.

Example

The following example demonstrates a complete workflow where an agent uses MoviePyVideoTools in conjunction with OpenAITools to:

Extract audio from a video file
Transcribe the audio using OpenAI's speech-to-text
Generate an SRT caption file from the transcription
Embed the captions into the video with word-level highlighting

1from kern.agent import Agent
2from kern.models.openai import OpenAIResponses
3from kern.tools.moviepy_video import MoviePyVideoTools
4from kern.tools.openai import OpenAITools
5
6video_tools = MoviePyVideoTools(
7    process_video=True, generate_captions=True, embed_captions=True
8)
9
10openai_tools = OpenAITools()
11
12video_caption_agent = Agent(
13    name="Video Caption Generator Agent",
14    model=OpenAIResponses(
15        id="gpt-5.2",
16    ),
17    tools=[video_tools, openai_tools],
18    description="You are an AI agent that can generate and embed captions for videos.",
19    instructions=[
20        "When a user provides a video, process it to generate captions.",
21        "Use the video processing tools in this sequence:",
22        "1. Extract audio from the video using extract_audio",
23        "2. Transcribe the audio using transcribe_audio",
24        "3. Generate SRT captions using create_srt",
25        "4. Embed captions into the video using embed_captions",
26    ],
27    markdown=True,
28)
29
30video_caption_agent.print_response(
31    "Generate captions for {video with location} and embed them in the video"
32)

Toolkit Functions

These are the functions exposed by MoviePyVideoTools:

Function	Description
`enable_extract_audio`	Extracts the audio track from a video file and saves it to a specified output path.
`enable_create_srt`	Saves a given transcription (expected in SRT format) to a `.srt` file at the specified output path.
`enable_embed_captions`	Embeds captions from an SRT file into a video, creating a new video file with word-level highlighting.

Toolkit Params

These parameters are passed to the MoviePyVideoTools constructor:

Parameter	Type	Default	Description
`process_video`	`bool`	`True`	Enables the `extract_audio` tool.
`generate_captions`	`bool`	`True`	Enables the `create_srt` tool.
`embed_captions`	`bool`	`True`	Enables the `embed_captions` tool.

Developer Resources

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