Do I need to install anything?

Yes. The command generated here requires FFmpeg installed on your computer. FFmpeg is free and available at ffmpeg.org for Windows, macOS, and Linux. This tool generates the command — your machine does the actual conversion.

What is the difference between MPEG-4 and H.264 output?

MPEG-4 (libxvid / mpeg4 codec) produces files readable by almost any player built in the last 20 years. H.264 (libx264) offers better compression at the same quality, but requires a slightly more capable player. Both are stored inside the AVI container.

What does "stream copy" mean?

Stream copy (-c copy) remuxes the video and audio bitstreams from FLV to AVI without re-encoding. It is near-instant and lossless, but only works if the AVI container supports the codec already inside the FLV (usually H.263 or VP6).

Why does my AVI file have no sound after conversion?

Some FLV files use AAC audio, which AVI does not support well. Choose MP3 as the audio codec in this tool to transcode audio to a format AVI handles reliably.

What CRF value should I use?

CRF (Constant Rate Factor) controls quality for H.264 and MPEG-4 encoders. Lower = better quality, larger file. 18 is near-lossless, 23 is the default (good balance), 28 is smaller but visibly lossy. For archival use 18–20; for sharing use 23–26.

Can I convert multiple FLV files at once?

Yes. On Linux/macOS use a shell loop: for f in *.flv; do ffmpeg -i "$f" "${f%.flv}.avi"; done. On Windows use a batch file with a similar for loop. The generated command is for a single file to keep it clear.

FLV to AVI Converter

Generate the exact FFmpeg command to convert an FLV file to AVI with your chosen codec and quality settings.

FFmpeg Command Builder

Input filename

Output filename

Video codec

Quality (CRF) — lower = better

Best qualitySmaller file

Audio codec

Audio bitrate

Generated FFmpeg Command

ffmpeg -i input.flv -c:v libx264 -crf 23 -c:a libmp3lame -b:a 128k output.avi

How to run this command

1

Install FFmpeg

Download from ffmpeg.org and add it to your system PATH, or use a package manager: brew install ffmpeg / choco install ffmpeg
2

Open a terminal

Windows: Command Prompt or PowerShell. macOS/Linux: Terminal.
3

Navigate to your file folder

Use cd path/to/folder so FFmpeg can find the input file by name.
4

Paste and run the command

Copy the command above, paste it in the terminal, and press Enter. Conversion progress appears in real time.

Codec comparison

Codec	Size	Speed	Best for
libx264	Small	Medium	Web sharing, storage
mpeg4	Medium	Fast	Legacy players, DVDs
copy	Same	Instant	Remux only, no quality loss

Copied!

Summary

Generate the exact FFmpeg command to convert an FLV file to AVI with your chosen codec and quality settings.

How it works

Enter the name of your FLV input file (e.g. myvideo.flv).
Choose the output video codec: MPEG-4, H.264, or stream copy (no re-encode).
Select audio codec and quality (CRF) for the output.
Click "Generate Command" to get the ready-to-run FFmpeg command.
Copy the command, open your terminal, and run it in the folder containing your FLV file.
FFmpeg processes the file locally on your machine — no upload required.

Use cases

Recover old FLV recordings from screen capture or streaming tools.
Import FLV footage into video editors that do not support Flash Video.
Convert FLV files for playback on TVs, media players, or legacy devices.
Batch-convert an archive of Flash-era videos to a modern AVI container.
Re-encode FLV with H.264 to reduce file size while keeping AVI compatibility.
Stream-copy FLV content to AVI instantly without quality loss.

Frequently Asked Questions

Last updated: 2026-09-22 · Reviewed by Nham Vu