As you probably already know, certain LCD TV’s don’t support playback of movies with DTS sound through USB port. But you already got that big HD video and you don’t want to redownload it again. Here is some help in a form of program called PopCorn MKV Audio Converter. The trick here is that this program doesn’t transcode entire file. Instead it just copies the video stream and converts only the audio stream into lets say AC3 which everyone support. This way conversion is very quick, doesn’t make video any worse at all since it just copies it. And you won’t notice difference in audio quality either, if you use high enough settings…
PopCorn MKV Audio Converter:
Be aware that this program only supports MKV type movies. MP4 is not supported (yet).