This is a call to cut through the fog.
I’m trying to do something extremely basic: get 5.1 LPCM audio over HDMI from a Raspberry Pi 3B, running Raspberry Pi OS Lite. Not Dolby, not DTS passthrough—just raw 6-channel PCM, which my AVR fully supports (confirmed via decoded EDID showing 8-channel LPCM, proper speaker mask, full sample rate range).
I've now spent days trying every supposed “supported” method:
- Configuring PulseAudio with 6-channel settings
- Forcing module-alsa-sink to hw:1,0 with an explicit 6-channel channel_map
- Manually editing default.pa
- Restarting clean headless sessions
- Using verified EDID blocks that show 8-channel support
Result: PulseAudio still exposes only the stereo-fallback sink tied to the onboard audio. The HDMI path (vc4-hdmi, hw:1,0) is ignored. ALSA does not enumerate a usable multichannel HDMI PCM device.
This isn’t “doing it wrong.” This is following the scattered advice of RPL forum posts and PulseAudio documentation to the letter—and still getting nowhere.
So I’m done asking what might work. Here’s what I need from someone who actually knows:
- Has anyone successfully achieved 5.1+ LPCM output over HDMI on a headless Raspberry Pi OS Lite install (no desktop GUI, no pavucontrol) using PulseAudio or ALSA?
- If so, what exact combination of:
- ALSA device string
- PulseAudio sink or module
- .asoundrc, default.pa, or kernel parameters
- Profile override or mapping patches
got the job done?
- Does Raspberry Pi Ltd. officially support multichannel LPCM over HDMI on Pi 3/4/5 platforms, and if so, where is the tested working documentation?
- If the system cannot expose 5.1 HDMI output under Lite or headless conditions without a full desktop environment: why? What’s missing, what’s blocking it, and why is none of this documented?
This is not an EDID issue. This is not a sink misconfiguration. This is a fundamental failure to expose standard HDMI LPCM capability that works on every other device in my setup.
So please: either show the path, or own up that there isn’t one. But let’s stop treating stereo fallback as an acceptable default for an HDMI stack claiming modern multichannel support.
I’m trying to do something extremely basic: get 5.1 LPCM audio over HDMI from a Raspberry Pi 3B, running Raspberry Pi OS Lite. Not Dolby, not DTS passthrough—just raw 6-channel PCM, which my AVR fully supports (confirmed via decoded EDID showing 8-channel LPCM, proper speaker mask, full sample rate range).
I've now spent days trying every supposed “supported” method:
- Configuring PulseAudio with 6-channel settings
- Forcing module-alsa-sink to hw:1,0 with an explicit 6-channel channel_map
- Manually editing default.pa
- Restarting clean headless sessions
- Using verified EDID blocks that show 8-channel support
Result: PulseAudio still exposes only the stereo-fallback sink tied to the onboard audio. The HDMI path (vc4-hdmi, hw:1,0) is ignored. ALSA does not enumerate a usable multichannel HDMI PCM device.
This isn’t “doing it wrong.” This is following the scattered advice of RPL forum posts and PulseAudio documentation to the letter—and still getting nowhere.
So I’m done asking what might work. Here’s what I need from someone who actually knows:
- Has anyone successfully achieved 5.1+ LPCM output over HDMI on a headless Raspberry Pi OS Lite install (no desktop GUI, no pavucontrol) using PulseAudio or ALSA?
- If so, what exact combination of:
- ALSA device string
- PulseAudio sink or module
- .asoundrc, default.pa, or kernel parameters
- Profile override or mapping patches
got the job done?
- Does Raspberry Pi Ltd. officially support multichannel LPCM over HDMI on Pi 3/4/5 platforms, and if so, where is the tested working documentation?
- If the system cannot expose 5.1 HDMI output under Lite or headless conditions without a full desktop environment: why? What’s missing, what’s blocking it, and why is none of this documented?
This is not an EDID issue. This is not a sink misconfiguration. This is a fundamental failure to expose standard HDMI LPCM capability that works on every other device in my setup.
So please: either show the path, or own up that there isn’t one. But let’s stop treating stereo fallback as an acceptable default for an HDMI stack claiming modern multichannel support.
Statistics: Posted by ArmyOfQuad — Fri Jun 27, 2025 5:31 pm — Replies 0 — Views 47