0

Problems with Optical In sound on DAC+ DSP

Cckborg2

July 03, 2022 20:23

None

Follow

I have a Raspberry Pi 4 with DAC+ DSP board attached. My end goal is to have a music player that takes an optical input or Airplay/other internal source input and plays it through the RCA output. (I've given up on having a video player.) I tried OSMC and Raspbian but struggled to get things working. (Not even knowing where to begin troubleshooting was a problem.) I installed HiFiBerryOS last week to simplify my setup and troubleshooting. 

My RPi4 is running HiFiBerryOS 20220228 and the DSP Program is DAC+ DSP Universal Version 12.

Optical Audio In is enabled and is detected as playing when there is actual input, but I can't get it to output. I have Auto-stop Other Sources turned on, Sensitivity is high. 

The Optical Audio In is coming from a Samsung TV as Dolby Digital. Speakers are set to Optical.

Airplay audio is correctly output via the Optical Out and RCA jacks.

When I connected via Optical In to a different Samsung TV with output coming from the RCA jacks into an AudioEngine N22 amplifier I got a flutter sound. Airplay sound via RCA output was fine when the Optical In was not connected. In my current setup, I have the optical out or RCA jacks connected to a Denon A/V receiver, Media Player input. (What happens if I connect both up at the same time? Does the receiver choose one?)

The output of aplay -l is as follows. The no sound checklist hasn't been helpful because I gather /boot/config.txt should be correct in HiFiBerryOS and is read-only anyway.

# aplay -l

**** List of PLAYBACK Hardware Devices ****

card 0: sndrpihifiberry [snd_rpi_hifiberry_dac], device 0: HifiBerry DAC HiFi pcm5102a-hifi-0 [HifiBerry DAC HiFi pcm5102a-hifi-0]

  Subdevices: 1/1

  Subdevice #0: subdevice #0

Can someone please point me in the right direction? I'm sure it is an obvious fix but I am stumped.

Thanks,

Carol

• Facebook
• Twitter
• LinkedIn

3 comments

• 0
  
  HiFiBerry team July 04, 2022 06:44

  Make sure your TV outputs plain stereo sound. Dolby Digital and DTS are not supported by the DAC+ DSP. Some TVs just forward the incoming signal that might be encoded in Dolby Digital.

• 0
  
  Cckborg2 July 04, 2022 20:48

  Thanks for that huge piece of info. It was indeed the missing link. My only options on that TV (Samsung UN50RU7100) are Dolby Digital & PCM. I thought I gave PCM a try with our other TV, and it hadn't worked. I just learned that PCM is uncompressed 2-channel (a.k.a. stereo) audio, so that is the setting I need. Making the switch to PCM didn't work right away, but after fiddling a bit more I was able to get the TV optical audio in to be output via the DAC+ DSP RCA jacks and the optical out. I'm not sure if plugging and unplugging the cables activated the change or if it just needed more time to propagate through the system, but it now appears to be working. Thank you so much.

  One more question, though. What does "Auto stop other sources" mean? I have it checked, and assumed it meant the optical in audio would take precedence over any other sound sources and you wouldn't get two source playing at once. When I had the TV playing through the optical in and started playing audio via airplay from my iPad, only the airplay audio came out. 

• 0
  
  HiFiBerry team July 06, 2022 07:36

  Yes, "auto stop other sources" means that players on the Pi will be stopped if a signal is detected on SPDIF.