WebM to MP4 Converter

Convert WebM video files to MP4 format

Related Tags
Files 80 FFmpeg 28 Video 27 Opus 15 MP4 13

Convert WebM videos to MP4 format for maximum compatibility. WebM is optimized for web streaming, while MP4 works universally across all devices, platforms, and media players.

Click to upload file or drag and drop file here

Maximum file size: 500MB Supported formats: video/webm

Only applies when re-encoding. 18-28 is recommended range

Key Facts

Category
Images, Audio & Video
Input Types
file, select, number
Output Type
file
Sample Coverage
4
API Ready
Yes

Overview

Easily convert your WebM video files to MP4 format for universal compatibility across all devices, media players, and platforms. This online converter allows you to customize video codecs like H.264 or H.265, adjust audio codecs, and set CRF quality levels to ensure your output MP4 meets your exact playback and file size requirements.

When to Use

  • •When you have screen recordings or web-optimized WebM videos that fail to play on Apple devices, iPhones, or legacy media players.
  • •When you need to import WebM footage into video editing software that only supports MP4 containers with H.264 or H.265 video codecs.
  • •When you want to compress or re-encode a WebM video to a specific quality level (CRF) and audio format for offline presentations.

How It Works

  • •Upload your WebM video file (up to 500MB) into the converter.
  • •Select your preferred video codec (such as H.264 or H.265), audio codec (like AAC or MP3), and optional CRF quality value.
  • •Click convert to process the video and download your compatible MP4 file.

Use Cases

Converting HTML5 WebM screen recordings to MP4 for sharing on social media platforms that do not support WebM.
Preparing web-optimized video assets for editing in software like Adobe Premiere Pro or DaVinci Resolve.
Re-encoding high-bitrate WebM files with H.265 and AAC to reduce file size while maintaining high visual fidelity.

Examples

1. Convert WebM Screen Recording for Keynote Presentation

Product Manager
Background
A product manager recorded a product demo using a browser-based screen recorder, which saved the file as a WebM video. However, Keynote on macOS does not natively support WebM playback.
Problem
The manager needs to convert the WebM video to a standard MP4 format with H.264 video and AAC audio so it plays seamlessly during a live presentation.
How to Use
Upload the WebM screen recording, select 'H.264' as the video codec, select 'AAC' as the audio codec, and leave the quality setting at default.
Example Config
Video Codec: H.264 (libx264), Audio Codec: AAC (aac)
Outcome
A highly compatible MP4 video that plays perfectly inside Apple Keynote and QuickTime Player.

2. Compress WebM Video for Mobile Distribution

Content Creator
Background
A creator has a high-resolution WebM video file that is too large to send over messaging apps and needs to be highly compressed without losing too much visual quality.
Problem
Reduce the file size of the video while converting it to a mobile-friendly MP4 format.
How to Use
Upload the WebM file, select 'H.265/HEVC' for efficient compression, choose 'AAC' for audio, and set the CRF Quality value to 24.
Example Config
Video Codec: H.265 (libx265), Audio Codec: AAC (aac), CRF Quality: 24
Outcome
A compact MP4 file with excellent visual quality that is small enough for easy mobile sharing and playback.

Try with Samples

audio, video, file
Video H.264 Samples
Sample video files encoded in H.264 (AVC) format
preferred input family video
video
Video VP9 Samples
Sample video files encoded in VP9 format
preferred input family video
video
WebRTC Real-Time Communication Samples
Comprehensive WebRTC samples for peer-to-peer audio/video communication, data channels, screen sharing, and signaling server implementation
preferred input family video
video
Video AV1 Samples
Sample video files encoded in AV1 format
preferred input family video
video

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FAQ

What video codecs can I choose for the MP4 output?

You can choose H.264 (recommended for maximum compatibility), H.265/HEVC (for better compression), MPEG-4, or copy the stream directly without re-encoding.

What is the maximum file size supported for WebM uploads?

The tool supports WebM video files up to 500 MB (524,288,000 bytes) in size.

What does the CRF Quality setting do?

Constant Rate Factor (CRF) controls the video quality during re-encoding. Values range from 0 to 51, where 18 to 28 is the recommended range for a good balance of quality and file size.

Can I convert the video without re-encoding the streams?

Yes, you can set both the video and audio codecs to 'Copy' to bypass re-encoding, which preserves original quality and speeds up the conversion process.

Which audio codecs are supported for the output MP4?

The converter supports AAC (recommended), MP3, Opus, Vorbis, or copying the original audio track directly.

API Documentation

Request Endpoint

POST /en/api/tools/webm-to-mp4

Request Parameters

Parameter Name Type Required Description
videoFile file (Upload required) Yes -
videoCodec select No -
audioCodec select No -
quality number No Only applies when re-encoding. 18-28 is recommended range

File type parameters need to be uploaded first via POST /upload/webm-to-mp4 to get filePath, then pass filePath to the corresponding file field.

Response Format

{
  "filePath": "/public/processing/randomid.ext",
  "fileName": "output.ext",
  "contentType": "application/octet-stream",
  "size": 1024,
  "metadata": {
    "key": "value"
  },
  "error": "Error message (optional)",
  "message": "Notification message (optional)"
}
File: File

AI MCP Documentation

Add this tool to your MCP server configuration: 

{
  "mcpServers": {
    "elysiatools-webm-to-mp4": {
      "name": "webm-to-mp4",
      "description": "Convert WebM video files to MP4 format",
      "baseUrl": "https://elysiatools.com/mcp/sse?toolId=webm-to-mp4",
      "command": "",
      "args": [],
      "env": {},
      "isActive": true,
      "type": "sse"
    }
  }
}

You can chain multiple tools, e.g.: `https://elysiatools.com/mcp/sse?toolId=png-to-webp,jpg-to-webp,gif-to-webp`, max 20 tools.

Supports URL file links or Base64 encoding for file parameters.

If you encounter any issues, please contact us at [email protected]