Does Volumio support HDMI audio passthrough? I was hoping to be able to play both my local library as well as Tidal connect lossless/Atmos from my raspberry pi 4b connected to my Onkyo TX-NR5100 which can handle any audio/dolby format through HDMI in.
For now, I only get downsampled PCM 
Hey @heggink,
Volumio does not currently support HDMI bitstream passthrough (e.g., for Dolby Atmos, DTS-HD MA, or TrueHD) on Raspberry Pi 4B. Audio is generally output as PCM stereo or multichannel, depending on ALSA and kernel-level support.
/boot/userconfig.txt:hdmi_drive=2
hdmi_force_edid_audio=1
It is not currently possible to achieve HDMI bitstream passthrough (e.g., Atmos) from Raspberry Pi 4B running Volumio, including for TIDAL Connect. All output is via PCM, and lossless is limited to what ALSA and the Pi’s HDMI interface allow. For Atmos and surround passthrough, you’ll need a dedicated streamer or HTPC with full HDMI passthrough support.
Kind Regards,
The Raspberry Pi’s Linux HDMI stack currently lacks raw audio (IEC61937) bitstream support, which is necessary for:
Although your AV receiver may support these formats, the Raspberry Pi converts all output to PCM because:
This driver is located under /drivers/gpu/drm/vc4/ in the Linux kernel tree. Development work would involve:
This would require contributing to or modifying modules such as snd_hdmi_lpe_audio or snd_soc_hdmi_codec, or creating a new module to wrap the VC4 HDMI output with proper passthrough handling.
Assuming lower-level support is in place, Volumio could be extended to:
Outside of ALSA, developers have had partial success with:
Note that Volumio deliberately avoids these stacks to preserve a minimal, low-latency ALSA pipeline, so integration would require significant adaptation or forking.
Most affordable media streamers capable of Dolby or Atmos passthrough are locked into proprietary systems. Raspberry Pi remains the most flexible open hardware platform for audio streaming.
Adding HDMI bitstream support would benefit not only Volumio but also other projects like Kodi, Moode, RuneAudio, and headless ALSA-based players. You would be enabling true multichannel and lossless audio formats on $50 hardware, which currently isn’t possible.
edid-decode, aplay -l, and alsa-info.sh to validate HDMI EDID and capabilitiesIf you are interested in building a test environment, I can help you create a minimal development image including:
Let me know your level of interest and technical scope. From kernel patching to Volumio integration, your effort could be a key contribution to bringing full HDMI audio passthrough to the open-source Raspberry Pi ecosystem.
Kind Regards,
Hey @nerd,
Many thanks for your unbelievably detailed description. I had seen bits and pieces as google searches (kodi, openelec, …) on the passthrough topic indicating there’s possibilities but an integrated conclusion like you have presented is a great summary. Many thanks for that.
You mentioned other devices that do support this (Apple TV, nvidia). The reason I tried volumio is because I just can’t seem to find a device with HDMI out that also supports bitstream and has some connect function (Tidal connext). Unfortunately, Apple does not do tidal connect. There are a few devices like zidoo UHD8000 but these are pretty expensive. One UHD8000 pays for 20 years of volumio . None of the other audio players have HDMI out and I would hate to turn on a massive flat screen just to listen to some music…
Hey @heggink,
Really appreciate the thoughtful follow-up - you’re absolutely not alone in wanting a clean, headless, HDMI-capable TIDAL Connect setup. And your summary hits the nail on the head: Volumio comes closest to offering that ideal balance between high-quality output, low complexity, and modern streaming features. That’s exactly why it’s worth investing in and refining, rather than diverting to bulky workarounds.
Volumio’s strength lies in its modular, minimal signal path - by design it avoids layered audio stacks like PulseAudio or PipeWire to maintain full control via ALSA. That’s why it shines with USB DACs, I2S hats, and bit-perfect network streaming. HDMI passthrough, especially for compressed formats like Atmos or DTS-HD, would be a valuable addition but would require foundational support at the kernel and driver level first - particularly in the Raspberry Pi VC4/KMS stack.
As of now, there is no Raspberry Pi HAT that supports HDMI bitstream audio passthrough, such as Dolby Digital, DTS, TrueHD, or Atmos. This limitation stems from both hardware and software constraints:
There is room for innovation here:
However, to date, no one has built such a HAT, likely due to the tight coupling of HDMI with GPU stacks and the high complexity of licensing audio bitstream formats legally.
No HAT exists today that provides HDMI audio passthrough from a Raspberry Pi. All current solutions either stick to analog/I2S, or digital PCM (via USB or S/PDIF), without support for compressed surround formats. This is not just a hardware issue but a systemic one: Linux on the Pi does not expose HDMI passthrough, and no third-party accessory bypasses this.
It’s a technically complex goal, not because Volumio lacks features, but because the Pi’s current audio infrastructure doesn’t expose HDMI in a way that supports passthrough. The platform simply wasn’t built with AVR-grade HDMI audio pipelines in mind.
That said, this is absolutely worth exploring as a roadmap item. Right now, the project has more immediate priorities - including architecture migration (like Debian Bookworm), multi-room synchronization refinements, and Bluetooth transport stability - but your use case is clear.
Thanks again for raising this. Getting bitstream audio via HDMI while keeping the system headless and fully integrated with services like TIDAL Connect would be a powerful next step in making Volumio a complete high-fidelity home streaming core.
Kind Regards,