Hardcode subtitles with VLC

Open VLC

Select Media > Stream (or CTRL+S by default)

Click +Add… to add your video file

Tick the Use a subtitle file box and choose your .SRT file with Browse…

Click Stream

Verify the Source is correct on the next window and then click Next

Choose a destination file using the Add button while selecting File from the dropdown menu (add .mp4 to your file name) and click Next

Activate Transcoding should be ticked by default, choose your profile (Default H.264 + MP3).

Select the Options button of the selected profile (default icon is a wrench)

Go to the Subtitles tab and tick the Subtitles box and the Overlay subtitles on the video box

Save and then click Next

On the Option Setup page click Stream