Updated: 28 September 2026 · Applies to: AlmaLinux 9, Rocky Linux 9, Ubuntu 24.04 and Debian 12
FLVTool2 edited metadata in Flash Video (FLV) files. Flash is no longer supported by browsers, and FLVTool2 is no longer maintained.
What to use instead
Convert videos to MP4 (H.264/AAC) with FFmpeg, which also moves the metadata to the start of the file so it streams immediately:
ffmpeg -i input.flv -c:v libx264 -c:a aac -movflags +faststart output.mp4
Install FFmpeg with your distribution's packages (on AlmaLinux/Rocky from the RPM Fusion repository; on Ubuntu/Debian apt install ffmpeg).
