The fourth substream is being discarded, since its not raw audio data, but an encoded Atmos stream which needs a specialized decoder.
Fixes decoding of the true hd stream from Transformers\ -\ Age\ of\ Extinction\ 2014\ 1080P-003.mkv
dc2d0e0 mlpdec: support TrueHD streams with an Atmos substream
libavcodec/mlp.h | 2 +-
libavcodec/mlpdec.c | 4 +++-
2 files changed, 4 insertions(+), 2 deletions(-)
Upstream: git.libav.org