Someone asked for this (Mac) application earlier, so here is it - released today by CFF group.

Description: Submerge makes all this possible by merging subtitle files with your existing film files. The result is a file with video, sound & subtitles happily living together.

Main Features:

• Make subtitled movies that are playable on your iPod, iPh1, Apple TV, in iTunes or in Front Row.
• Add subtitles to almost any visual format like mov, avi, mp4 etc.
• Supports the major subtitle file formats like SubRip (.srt), SubViewer 1 & 2 (.sub) and MicroDVD. More about subtitle formats…
• Support for the Elgato Turbo.264 hardware encoder for faster compression.
• Force aspect ratio to 16:9 or 4:3 to use your monitor space more efficiently.
• Watch subtitled movies in fullscreen without leaving the application.
• Merge multiple movies together using simple copy and paste.
• Localized in English, Italian, French, Finnish, Spanish, Dutch, Portuguese/Brazilian, Greek & Swedish.

Release Name: Bitfield.Submerge.v1.5.MacOSX-CFF
Size: 4.86MB
Links: Homepage, NFO
Download: Here