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Apple TV 4K cannot handle ALAC with 8 channels

Hello,


Movie has ALAC audio stream (8 channels):

© WARNER BROS.


But is playing back with 6 channels:


De facto Apple TV 4K does this downmix:

ALAC 7.1 --> PCM 5.1: L:L R:R C:C LFE:LFE BL:BL BR:BR SL:L+C SR:R+C



Same movie now has AAC audio stream (8 channels):

© WARNER BROS.


Is playing back with 8 channels:




Same procedure with iTunes:


Movie has ALAC audio stream (8 channels) and is playing back with 8 channels:


Same movie now has AAC audio stream (8 channels) and is also playing back with 8 channels:




Apple TV audio settings:



ALAC audio stream:

Audio #1
ID                                       : 2
Format                                   : ALAC
Codec ID                                 : alac
Codec ID/Info                            : Apple Lossless Audio Codec
Duration                                 : 2 h 56 min
Duration_LastFrame                       : -49 ms
Bit rate mode                            : Variable
Bit rate                                 : 4 650 kb/s
Nominal bit rate                         : 9 216 kb/s
Channel(s)                               : 8 channels
Sampling rate                            : 48.0 kHz
Bit depth                                : 24 bits
Stream size                              : 5.72 GiB (16%)
Language                                 : English
Default                                  : No
Alternate group                          : 1


AAC audio stream:

Audio #1
ID                                       : 2
Format                                   : AAC LC
Format/Info                              : Advanced Audio Codec Low Complexity
Codec ID                                 : mp4a-40-2
Duration                                 : 2 h 56 min
Source duration                          : 2 h 56 min
Source_Duration_LastFrame                : -6 ms
Bit rate mode                            : Variable
Bit rate                                 : 724 kb/s
Maximum bit rate                         : 1 102 kb/s
Channel(s)                               : 8 channels
Channel layout                           : C L R Ls Rs Lb Rb LFE
Sampling rate                            : 48.0 kHz
Frame rate                               : 46.875 FPS (1024 SPF)
Compression mode                         : Lossy
Stream size                              : 912 MiB (3%)
Source stream size                       : 912 MiB (3%)
Language                                 : English
Default                                  : No
Alternate group                          : 1
Menus                                    : 4
mdhd_Duration                            : 10570874



Sample files to reproduce:



Hardware used:

  • Apple TV 4K (2021)


Software used:

  • tvOS v16.5
  • iTunes v12.12.9.4




Fix this please.


Best

Felix

Apple TV 4K (2nd generation)

Posted on Jun 8, 2023 10:29 AM

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Apple TV 4K cannot handle ALAC with 8 channels

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