I have a new Mac Pro and decided to convert some video to check how fast it could do it. I used Toast 12.1, running Yosemite 10.10.2. I first converted about 9GB MKV to DVD. I was pleased at the speed (an hour and 15 minutes) but the DVD didn't play sound at all. It shows that there is supposed to be 5.1 surround sound, both in Toast and when I put the DVD into 2 different players, the sound shows under Audio, but sound will not play with software on my Mac or on a Blu-ray or DVD player I used.
Today, I converted an mp4 video that has stereo sound to DVD using Toast again. The result was that I got sound to play, but the video was jerky.
Right now, this type of conversion is not a big deal to me. I only did it to test my new Mac Pro's speed. However, I think it would be nice if Toast could do a better job at converting video if they have the features included.