Simplify the process of "muxing" MP4 and similar video files. Add subtitles or remove data inside containers and simple tracks. Generate custom copies compatible with iOS devices, work with MOV and MKV files, manage AAC and AC3 formats, separate SCC sets, etc.
Subler is an open-source MP4 muxer and editor for the Mac. It allows you to do a variety of things with your multimedia files. For example, you can use it to remux a video file that has an MP4 video track, but it is saved in as an extension other than MP4. This happens a lot with MKV files. They have MPEG-4 or H.264 video tracks, but since the format is MKV, QuickTime won't play those files. You can add those files to Subler and save them in MP4 very quickly. Another interesting thing you can do with Subler is to make video files with multiple audio tracks. You simply have to add a second audio track and Subler lets you save the file with both of them. Then, when you open the file on QuickTime, you can choose which one you want to listen to. I tested the app by doing yet another interesting thing. I added a subtitle track to an MP4 video. This process was really easy. All I had to do is to add the video file and then import the SRT subtitle file. Then, I saved the file and QuickTime was able to display the subtitles natively. I was using a video file converter for this, and the process took longer than I wanted. With Subler, this was done almost instantly.