MKV is a special media container. Being different from other video formats, MKV could integrate various video and audio Tracks into one file as most of other formats could only handle one single video and audio Streams. For the video tracks or streams, there could be different codec, such as H.264, xvid, vc1, mpeg-1, mpeg-2, mpeg-4 and so on. Various audio tracks or streams are listed as mp3, aac, dts, ac3 and so on. The last three tracks also include different channels: stereo, 5.1, 7.1 and so on. Subtitle is also the important part of a video. General speaking, subtitle contains information about PGS, DVDsub and languages. It means that a MKV file would contain many media streams including several audios and subtitles, just like an image of DVD or Blu-ray movie, in which you can select different language which you want to hear (audio) and read (subtitle).
But it’s a pity that most of the video editors, could not recognize MKV directly, such as iMovie, Final Cut Pro, iDVD and so on. This will bring us lots of problems, especially when having to edit the videos for better effects.
Final Cut Pro, whose new version is X, has now been so widely used that I just take this as the example. FCP X couldn't read MKV as its native video format is Apple ProRes. Native format means that when using this format, one can easily import the video files into FCP X without Rendering, if not, FCP X will not be able to recognize the movies or spend too much on the process of rendering.
Generally speaking, using a video conversion tool is helpful to get correct videos from original MKV files. Such conversion tools would help transcode MKV files to get new formats. But you need to pay attention to the quality of new videos as most of them can't keep the top quality of your original videos. Sometimes, new videos will be jumpy when being broadcasted. The more important is that few converter programs will support you to choose the exact audio and subtitle you want or need to convert. So, it's necessary to choose a perfect tool.
Aunsoft MKV Converter for Mac(For Windows users, Aunsoft MKV Converter will do the same job), which is designed for MKV specially, can totally meet your demands. This software is easy to use and user-friendly, as the main functions can be summarized as Import, Select Format and Export. The following picture shows how to get Apple ProRes for FCP X:
Never worry about the quality of the new videos output. Aunsoft MKV Converter for Mac could keep high quality, even the same as your original ones. And the process can be completed in much shorter time than the other converters because it will fully utilize your CPU cores.
As MKV could contain various stream, Aunsoft MKV Converter for Mac could support the stream selection, which means you can pick your favorite tracks to export. This function has not been owned by most of such video conversion tools.