MP4 to FLV Converter

MP4 to FLV Converter | Online Free Tool | Elysia Tools

Tool usage guide

Learn when to use this tool, what it supports, and how real users apply it.

Key facts

Category: Media
Input types: file, select, number
Output type: file
Sample coverage: 4
API ready: Yes

Overview

The MP4 to FLV Converter allows you to easily convert MP4 video files into the FLV (Flash Video) format. This tool supports custom video codecs like H.264 and FLV1, audio codecs like AAC and MP3, and adjustable CRF quality settings to optimize your video files for legacy web players and streaming platforms.

When to use

When you need to prepare video content for legacy web players or streaming servers that require the FLV container format.
When you want to re-encode MP4 videos using specific codecs like H.264 or FLV1 to ensure compatibility with older media systems.
When you need to compress MP4 files into smaller FLV files by adjusting the Constant Rate Factor (CRF) quality settings.

How it works

1Upload your MP4 video file (up to 100MB) using the file selector.
2Select your preferred video codec (such as H.264 or FLV1) and audio codec (such as AAC or MP3).
3Optionally set a CRF quality value between 18 and 28 to control the output file size and visual fidelity.
4Click the convert button to process the video and download the resulting FLV file.

Use cases

Converting modern MP4 recordings to FLV format for integration into legacy RTMP streaming workflows.
Re-encoding high-definition MP4 videos with H.264 and AAC codecs inside an FLV container for web-based flash players.
Reducing video file sizes by converting MP4s to FLV with a custom CRF quality setting for bandwidth-constrained environments.

Examples

1. Optimizing Video for Legacy Web Player

Web Developer

Background

A developer needs to host a video on an older corporate intranet portal that only supports FLV playback via an embedded flash player.

Problem

The source video is in MP4 format and is too large for the portal's bandwidth limits.

How to use

Upload the MP4 file, select H.264 as the video codec, AAC as the audio codec, and set the CRF quality to 24.

Video Codec: H.264, Audio Codec: AAC, CRF Quality: 24

Outcome

An optimized FLV file that plays smoothly on the legacy portal with reduced bandwidth usage.

2. Converting MP4 for RTMP Streaming Test

Streaming Engineer

Background

An engineer is testing an RTMP ingest server that requires FLV formatted streams with MP3 audio.

Problem

The test source clips are saved as MP4s with AAC audio, which are incompatible with the specific test configuration.

How to use

Upload the MP4 test clip, select FLV1 as the video codec, and choose MP3 as the audio codec.

FAQ

What is the maximum file size I can upload?

You can upload MP4 video files up to 100 MB in size.

Which video codecs are supported for the FLV output?

The converter supports H.264, FLV1, H.265/HEVC, and MPEG-4 video codecs.

How does the CRF quality setting work?

The Constant Rate Factor (CRF) controls video quality during re-encoding. Values range from 18 to 28, where lower numbers yield higher quality and larger file sizes.

Can I convert the audio track to MP3?

Yes, you can select MP3, AAC, or PCM 16-bit as the audio codec for your output FLV file.

Does this tool support batch conversion?

No, this tool processes one MP4 video file at a time.

Video Codec: FLV1, Audio Codec: MP3

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Learn when to use this tool, what it supports, and how real users apply it.

Key facts

Overview

When to use

How it works

Use cases

Examples

1. Optimizing Video for Legacy Web Player

2. Converting MP4 for RTMP Streaming Test

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