I have some MP4-Files with 3 Audio-Tracks, the first is a two channel stereo and the second and third tracks are 6 channel 5.1 Sourround sound in two seperate languages, VLC shows these Codec-Informations:
Stream 1: AAC, Stereo 48000Hz, german
Stream 2: AAC, 6-Channel 48000Hz, german
Stream 2: AAC, 6-Channel 48000Hz, english
Only the first stereo Audio track plays (Output on S/PDIF), a change to one of the other tracks is ignored - why?