I'm playing back a file encoded as an MP4 with AAC5.1 audio (the media info is copied below.) If it's relevant, I'm using the latest Plex server on Synology (Version 1.3.3.3148).
When playing it with my receiver set to any of the surround modes (Dolby 5.1, neo cinema, multichannel, THX, etc), there's no speech track heard, but surround and sound effects play, as well as LFE effects. The only way I get the speech channel is to change to "all channel stereo" mode on the receiver. As soon as I enable any surround mode, I lose the speech.
On my AppleTV4, audio output mode is set to Auto. I've tried forcing the ATV settings to 5.1 audio but no help.
I can't see any way to get this to play in proper surround -- especially since ATV should play an mp4, AAC 5.1 file natively (right?). Suggestions?
=========
Media info:
Video Resolution 1080p
Duration 2:21:37
Bitrate 2731 kbps
Width 1920
Height 800
Aspect Ratio 2.35
Container MP4
Video Frame Rate 24p
Web Optimized No
Audio Profile lc
Has 64bit Offsets 0
Video Profile high
Part
Duration 2:21:37
File moviefile.mp4
Size 2.70 GB
Audio Profile lc
Container MP4
Has 64bit Offsets 0
Web Optimized No
Video Profile high
Codec H264
Bitrate 2500 kbps
Bit Depth 8
CABAC true
Chroma Subsampling 4:2:0
Duration 2:21:37
Frame Rate 23.976 fps
Frame Rate Mode cfr
Height 800
Level 4.1
Pixel Format yuv420p
Profile high
Ref Frames 4
Scan Type progressive
Stream Identifier 1
Width 1920
Codec AAC
Channels 5.1
Bitrate 224 kbps
Language English
Audio Channel Layout 5.1
Bitrate Mode CBR
Duration 2:21:37
Profile lc
Sampling Rate 48000 Hz
Stream Identifier 2