Convert FLV files to MP4 format for compatibility with modern web browsers.

Install FFmpeg

The Wolfram Language ships with a limited version of FFmpeg, but you can expand supported codecs by installing the full FFmpeg framework:

Follow the instructions for installing FFmpeg. Once installed, the Wolfram System will attempt to use FFmpeg by default:

Convert the file

Find the FLV file you want to convert:

Use FileConvert to directly convert the file to MP4:

Alternatively, Import the file into the notebook, then Export the file to MP4 using optional parameters for more fine-tuned control, such as for changing the RasterSize: