Audio setup and information

Wiki
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Notice: There’s a new audio wiki article now. See here: Audio hardware and software configuration

This one is now deprecated and will be locked.

This wiki entry should give you an overview over recommended audio settings in different scenarios of using your OSMC device… Other than that there’s some explanation of the different audio settings available as well as some related audio information (FAQ).

Recommended audio settings when using your AVR/soundbar/TV’s HDMI input

Go to Settings/System/Audio… Select the following settings:

  • Audio device:
    • Vero 2, 4K/4K +: PCM or HDMI
    • Vero 1: HDMI
    • Raspberry Pi: HDMI
  • Number of channels: 7.1 (so your AVR/soundbar/TV can do the processing of LPCM according to your speaker setup)
    • Some HDMI devices can only process 2-channel LPCM! Please check your AVR/soundbar/TV’s manual for a list of supported HDMI audio formats… If your AVR/soundbar/TV only supports 2-channel LPCM, please set Number of channels to 2.0 and enable AC3 transcoding, if you don’t want all HD audio down-mixed to 2.0 LPCM (also see the explanation of AC3 transcoding a bit further down)
  • Output configuration: Best match
  • Passthrough: enabled (on Raspberry Pi select Passthrough device: HDMI)
  • DTS/AC3 passthrough: enabled
  • DTS-HD passthrough: enabled* (if your AVR/soundbar/TV supports it)
  • TrueHD passthrough: enabled* (if your AVR/soundbar/TV supports it)
  • E-AC3 passthrough: enabled (if your AVR/soundbar/TV supports it)

* Vero 2 and all Raspberry Pis do not support DTS-HD or Dolby TrueHD

Keep in mind to disable “Sync playback to display” under Settings/Player/Videos for passthrough to work!

Recommended audio settings when connecting your OSMC device to your AVR/soundbar’s S/PDIF input

Go to Settings/System/Audio… Select the following settings:

  • Audio device:
    • Vero 2, 4K/4K +: PCM or HDMI
    • Vero 1: S/PDIF
    • Raspberry Pi: your S/PDIF soundcard
  • Number of channels: 2.0 (S/PDIF only supports 2-channel LPCM)
  • Output configuration: Best match
  • Passthrough: enabled (on Raspberry Pi select Passthrough device: your S/PDIF soundcard)
  • DTS/AC3 passthrough: enabled
  • DTS-HD passthrough: disabled (only present on Vero 1 and Vero 4K/4K +)
  • TrueHD passthrough: disabled (only present on Vero 1 and Vero 4K/4K +)
  • E-AC3 passthrough: disabled
  • AC3 transcoding: enabled (enable this if you don’t want multi-channel LPCM and HD audio down-mixed to 2.0 LPCM, also see the explanation of AC3 transcoding a bit further down)

Keep in mind to disable “Sync playback to display” under Settings/Player/Videos for passthrough to work!

Recommended audio settings when connecting your OSMC device to your AVR/soundbar’s analogue input

Go to Settings/System/Audio… Select the following settings:

  • Audio device:
    • Vero 2, 4K/4K +: PCM or HDMI
    • Vero 1: HDMI
    • Raspberry Pi: Analogue
  • Number of channels: 2.0
  • Output configuration: Best match
  • Passthrough: disabled

Keep in mind that the analogue port is not amplified to power low sensitivity headphones at a satisfactory volume level!

Some of the audio settings explained in more detail

Output configuration:

The Kodi wiki states the following concerning this setting (AudioEngine, under 5.3 ActiveAE):

ActiveAE has three build-in profiles: Best Match, Optimized and Fixed.

  • Fixed takes care that all audio you will play is play in the very same data format. Your receiver does not need to switch modes.
  • Best Match is what previously existed as the “audiophile” mode. Whenever a new video or music playback starts, the audio engine will select the best sink for that stream. By design Best Match and gapless playback are not compatible. If you rely on gapless playback, consider using Optimized instead.
  • Optimized is something special, as it tries to reduce the reopening of sinks a lot. One example is live-TV where it switches between 5.1 to 2.0 during commercials. In order to not open the device anew and loosing some (milliseconds of) audio, the 2.0 commercials are played with the already open 5.1 sink by muting the non existent channels.

We recommend using Best match all the time for these reasons:

  • Fixed resamples everything (that doesn’t match the selected output samplerate), but most audio hardware can process all audio samplerates anyway.
  • Optimized may produce very weird results when queuing different audio files for playback. Especially when files with different channel layouts are mixed in a queued playback (e.g. 2.0 and 5.1 files), sound may be played from wrong/unexpected speakers.
  • Also, both fixed and optimized are not recommended, if you’re interested in bit-perfect playback (which the Vero 4K/4K+ supports, see here: Can Vero do bit-perfect playback?). Those two settings will resample your audio files often or most of the time (optimized resamples, if the samplerate of a queued files is not the same as the samplerate of the file before that in your queue).

If you’re interested in bit-perfect playback, set the output configuration to Best match and set the Kodi volume to 100% (using a Kodi remote app e.g.)!

AC3 transcoding:

This setting is only available if you set the Number of channels to 2.0. In this case, surround LPCM channels will normally be downmixed and HD passthrough formats will be decoded and down-mixed to LPCM 2.0. If you want to retain surround audio also with those formats in this scenario, AC3 transcoding will do the trick: It transcodes all LPCM and HD audio stream’s surround audio into a lossy 5.1 Dolby Digital (AC3) stream on-the-fly to give you the best surround sound possible with your setup.
Just keep in mind: Same as decoding of lossless tracks to LPCM, transcoding won’t preserve any 3D audio information of DTS:X, Dolby Atmos or AURO-3D - the 3D metadata can only be streamed to a capable receiver when the audio stream is transported untouched!

Keep audio device alive:

This setting is not needed in the normal use case of your OSMC device. It’s meant for systems where more than one audio application wants to use the audio sink. The keep alive setting will force Kodi to always retain control of the audio sink thus making it impossible for other audio applications to take over. As the normal use case of your OSMC device only has one application that will make use of the audio sink (Kodi), this setting can be ignored and it basically doesn’t matter what you set it to.

Send low volume noise:

This setting helps with two issues, if you’re sensitive about them:

  1. The audio sink of the Vero takes a very short time to open which leads to a short period of silence before the actual audio is audible (this mostly affects PCM playback, not so much passthrough).
  2. Some audio receiving equipment falls into a standby mode when no audio information is received through its input. This setting may help preventing an audio receiving device from going into standby. It has also been reported that some audio receiving devices make strange “plop” noises when the state of the input changes. So, this setting may help to prevent too many changes from happening (by keeping the Vero’s audio sink open all the time).

Mute HDMI audio (Vero 4K/4K + only)

This setting is audio related, but it is to be found in a different settings window: Settings/System/Video. Enable this setting, if you’re e.g. connecting your Vero 4K/4K + to your TV via HDMI and to your AVR/soundbar via S/PDIF/analogue and you don’t want the TV to receive any audio via HDMI. The setting will mute audio on HDMI only - S/PDIF and analogue will still output audio.

Some FAQs (if any other common questions pop up, we’ll add the answers here)

What is HD audio?

HD audio files are considered audio formats that can be passed through via HDMI by our Vero 1 and Vero 4K/4K + (not the Vero 2 or any Raspberry Pi). These include: Dolby TrueHD, Dolby Atmos, DTS-HD MA, DTS:X and AURO-3D.
Dolby Digital Plus (or DD+/E-AC3) and DTS-HD HRA are special cases as they sit somewhere between HD and non-HD audio (for more explanation see under one of the next questions).

Why can’t I passthrough HD audio via S/PDIF?

S/PDIF’s maximum supported bandwidth equals the audio bandwidth needed for 2-channel 24 bit 192 kHz PCM audio. The bandwidth needed for HD audio to be passed through is a lot higher - which is only supported by the HDMI interface. Be aware: some older and even today’s equipment only supports a maximum of 2-channel 24 bit 96 kHz PCM audio via S/PDIF!

Why are Dolby Digital Plus (E-AC3) and DTS-HD HRA special cases?

Dolby Digital Plus and DTS-HD HRA are using a bandwidth equal to 2-channel 24 bit 192 kHz PCM audio which is supported by some S/PDIF equipment. If your AVR/soundbar/TV supports Dolby Digital Plus, DTS-HD HRA and offers support for 2-channel 24 bit 192 kHz via S/PDIF, passthrough of Dolby Digital Plus and DTS-HD HRA may also work via S/PDIF. This is the reason why Dolby Digital Plus and DTS-HD HRA are sitting in the middle of HD and non-HD audio, so to say.

Which versions of Dolby Atmos and DTS:X are there? And how is AURO-3D different?

Dolby Atmos and DTS:X exist in two different versions each. Both 3D audio formats are additions to existing Dolby and DTS audio formats in the form of added audio metadata for 3D audio objects. Older equipment that doesn’t support Atmos and DTS:X will just ignore the metadata. Dolby Atmos can have either a Dolby TrueHD core (which would be lossless Atmos) or a Dolby Digital Plus core (which would be lossy Atmos). The same applies for DTS:X: The core can either be DTS-HD MA (lossless) or DTS-HD HRA (lossy). Lossy Atmos is quite common for streaming applications nowadays (like Netflix or Amazon Prime Video) whereas the lossy version of DTS:X is still very rare and mostly used on non-English BD or UHD BD releases for space reasons (secondary DTS:X tracks).
AURO-3D is also an addition to a core audio stream, but it doesn’t utilize 3D audio objects. It adds another layer of fixed audio channels on top of the existing 5.1 or 7.1 channels. The core audio format used for AURO-3D is one these two lossless formats: LPCM or DTS-HD MA. There is no lossy version of AURO-3D and the most used channel layout for AURO-3D is 9.1 at the moment (5.1 ear level speakers, 4 upper level speakers). It supports 11.1 and 13.1 speaker layouts as well.

Which passthrough formats are supported by OSMC devices (not all are supported by all devices) and which of them can be passed through via S/PDIF or HDMI?
Be aware: Those formats that are not supported for passthrough by some of the OSMC devices will either be decoded to a surround LPCM stream by the device (via HDMI) or it will be transcoded to Dolby Digital/AC3 (via S/PDIF).

  • By Digital Theater Systems, Inc./Xperi Corporation:

    • DTS with all channel layouts from 1.0 all the way to 5.1, at samplerates of 32, 44.1 or 48 kHz and a bit-depth of 16, 20 or 24 bit
      (supported via S/PDIF and HDMI)
    • DTS-ES (DTS Extended Surround) with either the Matrix or the Discrete extension, both offer 6.1 channels, with “Matrix” mixing the extra channel into the surround channels and “Discrete” adding an extra channel that is not mixed into the surround channels
      (supported via S/PDIF and HDMI)
    • DTS 96/24 which offers up to 5.1 channels with a samplerate of 96 kHz and a bit-depth of 24 bit
      (supported via S/PDIF and HDMI)
    • DTS-HD HRA (DTS High Defintion High Resolution Audio) or DTS-HD Hi Res, DTS’ intermediate format between HD and non-HD audio, offering a higher bitrate encoding, still lossy, with up to 7.1 channels, a samplerate of up to 96 kHz and a bit-depth of up to 24 bit
      (supported via HDMI, theoretically also supported by S/PDIF, but only with HRA-capable hardware that supports 192kHz via S/PDIF)
    • DTS-HD MA (DTS High Defintion Master Audio) with lossless encoding, up to 5.1 channels at a samplerate of up to 192 kHz and a bit-depth of up to 24 bit or up to 7.1 channels at a samplerate of up to 96 kHz and a bit-depth of up to 24 bit
      (only supported on Vero 1 and Vero 4K/4K + via HDMI)
    • DTS:X, the 3D audio format of DTS, based either on DTS-HD HRA or DTS-HD MA, providing up to 9 additional 3D sound objects with a samplerate of up to 96 kHz and a bit-depth of up to 24 bit (when based on DTS-HD MA) or with a samplerate of up to 48 kHz and a bit-depth of up to 24 bit (when based on DTS-HD HRA)
      → the audio objects are mixed into the audio stream and decoded according to the metadata sent along with the audio stream - a decoder that doesn’t support DTS:X just decodes the normal audio stream ignoring any 3D information
      (supported only on Vero 1 and Vero 4K/4K + via HDMI when DTS-HD MA-based, technically also supported via S/PDIF when DTS-HD HRA-based, but only with DTS:X-capable hardware that supports 192 kHz via S/PDIF)

DTS-HD HRA, DTS-HD MA as well as the basis of DTS:X tracks are required to carry a lossy DTS core for backward compatability reasons. Some examples: a DTS-HD MA 6.1 track would most likely carry a DTS-ES (6.1) core, a DTS-HD HRA track (with a bit-depth of 24 bit and a samplerate of 96 kHz) would most likely carry a DTS 96/24 core, a DTS-HD MA 5.1 track would carry a DTS 5.1 core and a DTS-HD MA 7.1 based DTS:X track would include a lossy DTS 5.1 core (the same applies to AURO-3D tracks based on DTS-HD MA).
→ If your equipment can’t decode lossless HD audio, Kodi will only send the core to your equipment (if you’ve disabled DTS-HD passthrough accordingly, see above).

  • By Dolby Laboratories, Inc.:

    • Dolby Digital or AC3 with all channel layouts from 1.0 all the way to 5.1, at samplerates of 32, 44.1 or 48 kHz and a bit-depth of 16, 20 or 24 bit
      (supported via S/PDIF and HDMI)
    • Dolby Digital EX (Dolby Digital Extended Surround) which adds another one or two rear surround speakers to the Dolby Digital 5.1 layout (resulting in 6.1 or 7.1 channels), the additional information is mixed into the surround channel information of the Dolby Digital stream
      (supported via S/PDIF and HDMI)
    • Dolby Digital Plus or E-AC3, Dolby’s intermediate format between HD and non-HD audio, offering a higher bitrate encoding, still lossy, with up to 7.1 channels (up to 13.1 channels in theory), a samplerate of 32, 44.1 or 48 kHz and a bit-depth of up to 24 bit
      (supported via HDMI, theoretically also supported by S/PDIF, but only with E-AC3-capable hardware that supports 192 kHz via S/PDIF)
    • Dolby TrueHD with lossless encoding, up to 5.1 channels at a maximum samplerate of 192 kHz and a bit-depth of up to 24 bit or up to 7.1 channels (up to 15.1 channels in theory) at a samplerate of up to 96 kHz and a bit-depth of up to 24 bit
      (only supported on Vero 1 and Vero 4K/4K + via HDMI)
    • Dolby Atmos, the 3D audio format of Dolby, based either on Dolby TrueHD or Dolby Digital Plus, providing an additional maximum of 20 3D sound objects with a samplerate of up to 96 kHz and a bit-depth of up to 24 bit (when based on Dolby TrueHD) or 9 3D sound objects with a samplerate of up to 48 kHz and a bit-depth of up to 24 bit (when based on Dolby Digital Plus)
      → the audio objects are mixed into the audio stream and decoded according to the metadata sent along with the audio stream - a decoder that doesn’t support Dolby Atmos just decodes the normal audio stream ignoring any 3D information
      (supported only on Vero 1 and Vero 4K/4K + via HDMI when Dolby TrueHD-based, technically also supported via S/PDIF when Dolby Digital Plus-based, but only with Atmos-capable hardware that supports 192 kHz via S/PDIF)

Dolby TrueHD and Dolby Digital Plus don’t carry a lossy Dolby Digital core track like DTS-HD formats do carry a lossy DTS track. On the Blu-ray and UHD Blu-ray disc an additional lossy Dolby Digital track is a requirement however (mostly as a non-visible companion (not core!) Dolby Digital track).
→ If your equipment can’t decode lossless HD audio, this companion track can be selected manually in Kodi when playing back such a BD/UHD BD TrueHD track or Kodi will only send the companion track to your equipment automatically (if you’ve disabled Dolby TrueHD passthrough accordingly, see above). If there’s no additional Dolby Digital track coming with the Dolby TrueHD or Dolby Digital Plus track, the lossless track would need transcoding to Dolby Digital or decoding to LPCM by the source device.

  • By Auro Technologies:

    • AURO-3D is a special 3D audio format based on two lossless format audio streams - LPCM or DTS-HD MA with a bit-depth of 24 bit - with a samplerate of up to 96 kHz, an actual bit-depth of 20 bit per audio layer, offering 5.1 or 7.1 ear level channels, 2, 4 or 6 over-head channels and an optional VoG (Voice of God) channel on top and/or an additional center hight channel above the normal front center channel: between 9.1 and 13.1 channels in total
      → the extra channels are squeezed into the lower 4 bits of the 24 bit bit-depth and the actual bit-depth of 20 bit per audio layer is achieved by a mathematical trick interweaving the layers into one audio signal, the decoding is done according to the metadata sent with the audio data - a decoder that doesn’t support AURO-3D just decodes the normal audio stream ignoring the lower 4 bits of the 24 bit bit-depth
      (only supported on Vero 1 and Vero 4K/4K + via HDMI)

If AURO-3D is based on DTS-HD MA, it will carry a lossy DTS track.
→ If your equipment can’t decode lossless HD audio tracks, those AURO-3D tracks based on LPCM would need transcoding to Dolby Digital (the only way to compress LPCM) or decoding to LPCM by the source device. If the AURO-3D track is based on DTS-HD MA, the lossy DTS core will be sent to your equipment (if you’ve disabled DTS-HD passthrough accordingly, see above).

Which LPCM output formats are supported by OSMC devices via HDMI and S/PDIF?

  • Vero 4K/4K +
    • HDMI: a samplerate of up to 192 kHz, a bit-depth of up to 24 bit and all channel layouts from 1.0 all the way to 7.1 (the surround center channel of 6.1 is mapped equally to both 7.1 back surround channels)
    • S/PDIF (built-in TOSLINK): a samplerate of up to 192 kHz, a bit-depth of up to 24 bit and 2.0 channels
  • Vero 2
    • HDMI: a samplerate of up to 192 kHz, a bit-depth of up to 24 bit and 2.0 channels
    • S/PDIF (built-in Coax): a samplerate of up to 192 kHz, a bit-depth of up to 24 bit and 2.0 channels
  • Vero 1
    • HDMI: a samplerate of up to 192 kHz, a bit-depth of up to 24 bit and 2.0 or 7.1 channels
    • S/PDIF (built-in TOSLINK): a samplerate of up to 192 kHz, a bit-depth up to 24 bit and 2.0 channels
  • Raspberry Pi
    • HDMI: a samplerate of up to 192 kHz, a bit-depth of up to 24 bit and 2.0 channels, but only a samplerate of up to 96 kHz with more than 2.0 channels (up to 7.1 channels)
    • S/PDIF: depending on your S/PDIF capable soundcard

Is passthrough of DSD via HDMI supported?

Neither of the OSMC devices support any sort of DSD passthrough via HDMI - be it DoP (DSD over PCM) or native DSD streaming. Any DSD container that can be played back by Kodi will be decoded to 24 bit 192 kHz PCM and sent to the AVR afterwards.
Keep in mind: The DSD to PCM conversion (not just decoding!) is happening on-the-fly and puts a lot of load on the CPU. Therefore some files may play ok and others won’t (DSD64 2.0 and DSD128 2.0 are mostly fine on Vero 4K/4K +, more demanding DSD versions like surround DSD or DSD256 and more can cause stutter and heat issues, all other devices than Vero 4K/4K + will probably not play DSD fine at all).

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