Rpi 3 HDMI Audio Passthru

**zomboided** · December 10, 2022 at 11:12 PM

Before I dig deeper, should I expect that EAC3/Dolby Digital+ gets passed through HDMI? It’s received as stereo when the receiver is definitely capable of decoding EAC3 streams. And DTS and DD are working just fine.

I thought there was an option for this in LE9 that seems to not be there in LE10 on my RPi3.

**HiassofT** · December 10, 2022 at 11:27 PM

EAC3 passthrough should work on RPi2/3 - you have to enable expert mode in settings to see the option.

Note though that EAC3 support in Kodi is very buggy - see eg https://github.com/xbmc/xbmc/issues/19182 - so you're better off not enabling it because it won't really work.

TrueHD is another thing, due to bugs in RPi0-3 hardware they can't output 192kHz 8ch (which is required for TrueHD and DTS-X).

so long,

Hias

**zomboided** · December 11, 2022 at 10:40 AM

Thanks, was a skin issue, flipped back to Estuary and the EAC3 transcode option appeared.

What I did notice is that one of my boxes connected directly to a tv recognised a DD+ stream no problem (accepting the issues in the GitHub you linked), but the box connected to my new Denon amp did not, with the same file. Nor did it display HD options (again, accepting they don’t work here). Is there some smarts related to maybe the HDMI cable version that means I’m offered limited options in Settings? I’m loathed to try changing the cable because it’s such a rats nest of cables I’d need to deal with!

**popcornmix** · December 12, 2022 at 4:38 PM

Are you connected to the denon amp through HDMI?

The source (Pi) will read the EDID from the sink (display or AVR) and that will include audio capabilities.

A faulty HDMI cable may make it impossible to read the edid.

ssh in and run:

Code

edid-decode /sys/devices/platform/gpu/drm/card?/card?-HDMI-A-1/edid

and you should find an "Audio Data Block" describing the capabilities.

**zomboided** · December 12, 2022 at 10:49 PM

Thanks for the reply, edid-decode threw an error, so I had to change it to this:

Code

edid-decode /sys/devices/platform/soc/soc:gpu/drm/card?/card?-HDMI-A-1/edid

but that then yielded this:

Code

  Audio Data Block:
    Linear PCM:
      Max channels: 8
      Supported sample rates (kHz): 192 176.4 96 88.2 48 44.1 32
      Supported sample sizes (bits): 24 20 16
    DTS:
      Max channels: 6
      Supported sample rates (kHz): 96 88.2 48 44.1
      Maximum bit rate: 1536 kb/s
    AC-3:
      Max channels: 6
      Supported sample rates (kHz): 48 44.1 32
      Maximum bit rate: 640 kb/s
    DTS-HD:
      Max channels: 8
      Supported sample rates (kHz): 192 176.4 96 88.2 48 44.1
      Audio Format Code dependent value: 0x03
    Enhanced AC-3 (DD+):
      Max channels: 8
      Supported sample rates (kHz): 48 44.1
      Supports Joint Object Coding
      Supports Joint Object Coding with ACMOD28
    MAT (MLP):
      Max channels: 8
      Supported sample rates (kHz): 192 176.4 96 88.2 48 44.1
      Supports Dolby TrueHD, object audio PCM and channel-based PCM
      Hash calculation not required for object audio PCM or channel-based PCM
    One Bit Audio:
      Max channels: 6
      Supported sample rates (kHz): 44.1
      Audio Format Code dependent value: 0x00
    DTS-HD:
      Max channels: 8
      Supported sample rates (kHz): 192 176.4 96 88.2 48 44.1
      Audio Format Code dependent value: 0x01

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which maybe matches this in the log and certainly matches my expectations on what the amp can support:

Quote

2022-12-11 18:17:56.151 T:590 INFO <general>: m_deviceName : hdmi:CARD=vc4hdmi,DEV=0
2022-12-11 18:17:56.151 T:590 INFO <general>: m_displayName : vc4-hdmi (vc4hdmi)
2022-12-11 18:17:56.152 T:590 INFO <general>: m_displayNameExtra: DON DENON-AVR on HDMI
2022-12-11 18:17:56.152 T:590 INFO <general>: m_deviceType : AE_DEVTYPE_HDMI
2022-12-11 18:17:56.152 T:590 INFO <general>: m_channels : FL, FR, LFE, FC, BL, BR, BC, BLOC, BROC
2022-12-11 18:17:56.152 T:590 INFO <general>: m_sampleRates : 32000,44100,48000,88200,96000,176400,192000
2022-12-11 18:17:56.152 T:590 INFO <general>: m_dataFormats : AE_FMT_RAW,AE_FMT_S24NE3,AE_FMT_S24NE4,AE_FMT_S32NE,AE_FMT_S16NE,AE_FMT_S16LE,AE_FMT_S16BE,AE_FMT_U8,AE_FMT_RAW
2022-12-11 18:17:56.152 T:590 INFO <general>: m_streamTypes : STREAM_TYPE_AC3,STREAM_TYPE_DTSHD,STREAM_TYPE_DTSHD_MA,STREAM_TYPE_DTSHD_CORE,STREAM_TYPE_DTS_1024,STREAM_TYPE_DTS_2048,STREAM_TYPE_DTS_512,STREAM_TYPE_EAC3,STREAM_TYPE_TRUEHD

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I'm assuming the next step is to get a full log of me playing one of the EAC3 files and share here. Do I need to enable any particular level of debug?

**HiassofT** · December 12, 2022 at 11:02 PM

Standard pastekodi log (with kodi debug logging enabled) would do fine for the next step. Edid and sound device info look like it should work (from driver and kodi side).

so long,

Hias

**zomboided** · December 14, 2022 at 1:48 PM

Both of these are from RPi3 systems that got a fresh install with LE10 and are using the default skin. The non-working system, 'KodiLounge' got a restore of a config backup I took in 'KodiBedroom'. Turned on logging, did a reboot and played the same file on both boxes.

Here are the results from 'KodiLounge', where the amp did not pick up an EAC3 signal via HDMI

http://ix.io/4iA2

Here are the results from 'KodiBedroom', where the TV did detect it as a DD+ signal via HDMI.

http://ix.io/4iA3

Also on this box I'm offered 'TrueHD' and 'DTSHD' options in System/Audio settings (I'm not offered these on 'KodiLounge') which is more unexplained weirdness.

subrata310 · January 12, 2025 at 1:35 PM

In my case with LibreELEC 12.01 on pi5/8gb it's found at:

edid-decode /sys/class/drm/card1-HDMI-A-1/edid

Rpi 3 HDMI Audio Passthru

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