MP4 to FLV Converter

Convert MP4 video files to FLV format

Related Tags
Files 80 FFmpeg 28 Video 27 MP4 13

Convert MP4 videos to FLV (Flash Video) format. FLV is widely used for streaming on web platforms and provides good compression with reasonable quality.

Click to upload file or drag and drop file here

Maximum file size: 100MB Supported formats: video/mp4, video/x-m4v

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

Convert your MP4 video files to FLV (Flash Video) format quickly and securely. This online converter allows you to customize your output by selecting advanced video codecs like H.264 or H.265, choosing audio codecs like AAC or MP3, and adjusting the CRF quality to achieve the perfect balance between file size and streaming performance.

When to Use

  • •When preparing video content for legacy web platforms or media servers that specifically require the FLV container.
  • •When you need to re-encode MP4 files using specific codecs like H.264 or H.265 paired with AAC audio for optimized web delivery.
  • •When compressing large MP4 videos into smaller FLV files by adjusting the Constant Rate Factor (CRF) quality settings.

How It Works

  • •Upload your MP4 video file (up to 500 MB) into the designated file input field.
  • •Select your preferred video codec, audio codec, and optional CRF quality value (between 0 and 51).
  • •Click convert to process the video and download your newly formatted FLV file.

Use Cases

Converting modern MP4 recordings to FLV format for compatibility with legacy flash-based web players.
Re-encoding high-definition MP4 clips to highly compressed FLV streams to minimize bandwidth consumption.
Standardizing diverse MP4 uploads into a uniform FLV format with specific audio and video codecs for a streaming server.

Examples

1. Optimizing Web Video for Legacy Streaming Servers

Web Administrator
Background
A web administrator needs to upload a series of product demonstration videos to an older corporate intranet portal that only supports FLV streaming.
Problem
The source videos are in high-bitrate MP4 format, which causes buffering issues and compatibility errors on the legacy portal.
How to Use
Upload the MP4 video, select H.264 as the video codec, AAC as the audio codec, and set the CRF quality to 23 for balanced compression.
Example Config
Video Codec: H.264 (libx264), Audio Codec: AAC, CRF Quality: 23
Outcome
The video is successfully converted to a highly compatible FLV file that streams smoothly on the legacy intranet portal without buffering.

2. Compressing MP4 Screencasts to FLV

E-learning Content Creator
Background
An instructor has recorded several software tutorials in MP4 format but needs to compress them to save server storage space while maintaining readable text.
Problem
Standard MP4 files are too large, and the platform requires FLV format with optimized audio for clear voice reproduction.
How to Use
Upload the MP4 tutorial, select the FLV1 video codec, choose MP3 audio codec for voice clarity, and set the CRF quality to 20.
Example Config
Video Codec: FLV1, Audio Codec: MP3 (libmp3lame), CRF Quality: 20
Outcome
Generates a compact FLV file with crisp tutorial visuals and clear MP3 voiceover, ready for direct integration into the e-learning platform.

Try with Samples

audio, video, file
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
Video H.264 Samples
Sample video files encoded in H.264 (AVC) format
preferred input family video
video
Video H.265 Samples
Sample video files encoded in H.265 (HEVC) format
preferred input family video
video

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FAQ

What is the maximum file size supported for conversion?

You can upload and convert MP4 video files up to 500 MB.

Which video codecs can I choose for the FLV output?

You can select H.264 (libx264), FLV1, H.265/HEVC (libx265), or MPEG-4.

How does the CRF quality setting affect my video?

CRF stands for Constant Rate Factor. Values range from 0 to 51, where lower numbers yield higher quality and larger file sizes, and 18-28 is the recommended range.

Can I convert the audio track to MP3?

Yes, the converter supports AAC, MP3 (libmp3lame), and PCM 16-bit audio codecs.

Do I need to configure the codecs manually?

No, the tool uses optimized defaults (H.264 video and AAC audio) so you can convert immediately without manual configuration.

API Documentation

Request Endpoint

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

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/mp4-to-flv 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-mp4-to-flv": {
      "name": "mp4-to-flv",
      "description": "Convert MP4 video files to FLV format",
      "baseUrl": "https://elysiatools.com/mcp/sse?toolId=mp4-to-flv",
      "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]