Some MPEG-4 codecs produce encrypted content that cannot be converted. Others such as Apple, Real Media and DivX require proprietary software. Free and open source MPEG-4 codecs such Microsoft's MPEG-4 codecs and XviD will decode the source file correctly but you must have the same codec that was used to create the file.

In this example we will convert a DivX movie to MPEG-1.

There may also be a long delay while the file is being parsed depending upon file size. When loading a very large file, if Windows is busy it may seem that the program is hung simply because Windows is keeping the processor for itself and not permitting Fx MPEG Writer to update progress.

Many DivX files are non-standard sizes. The example we used was 640X300. To match your MPEG-1 file to the source file size, remove the check from the option labeled "Use MPEG Presets" then select the MPEG Settings tab.

On the MPEG Settings tab, click the button to "Set Aspect = Source".

Once you have all the properties set as you wish, click the Start button to begin your conversion. With some version of the DivX codec, the main Fx MPEG Writer window may flash periodically as the DivX codec interface tries to take focus and Fx MPEG Writer takes it back.

Progress and estimated time during conversion is displayed at the bottom of the main window. Conversion time depends upon your system resources, the file size and complexity. You can speed up conversion significantly by defragmenting your hard drive.

There may be a significant delay after the file has been converted and Windows is cleaning up the temp files. That is, the Fx MPEG Writer progress bar might show 100% converted but the mouse pointer and interface will still show busy. Wait until the button text changes to Start for Stop before trying to close the application.