1 To start converting, select one or more .mp4 videos on your device. 2 Next, use the conversion settings, click the "Convert" button and wait for the conversion to complete. 3 Now you can download your GIF images individually or in a single archive. Needless to download or install anything on macOS, just follow the below instructions to re-format MKV to MP4: Step 1. Run Permute on your MacBook or iMac. Navigate to File > Open under the menu bar. Step 2. Load your MKV files from Mac to this MKV to MP4 converting software. .