I wanted to share my experience using the latest OSMC Kodi 16.1 RC3 and my HiFiBerry Digi+.
Summary of issue is that while watching a movie (avi or mp4) that has the audio saved as DTS or AC3 5.1 and while using the audio passthru option enabled , the audio will cut out and go to a static noise randomly in 2 to 5 minute intervals lasting a few minutes. I know my Digi+ is working OK because:
1-If I turn off audio pass thru then the audio is fine as OSMC will send a DPL2 data stream. Plus other sources like mp3 music work fine too using the same interface.
2-More importantly, if during the audio pass thru static noise I enter the System->Audio Output menu and change something like the ākeep aliveā from 1 min to always (or vice versa) the sound will come back for a period. Or if I change the audio mode from Fixed to Optimized or if I change the sample rate limit the sound will also come back for a few seconds to minutes.
I did experiment using many OSMC settings and media files and came to the conclusion that the OSMC is losing the synchronization of the SPIDF output as the receiver will go to PCM input status during the static noise. No combination of settings (other than disabling passthru) will resolve issue for good.
My setup is using the Composite Video out and the SPIDF audio out. I am using a Yamaha RX-V800 reciever for the audio. The analog audio does work fine also.
I run NOOBS as the base OS and I also had similar issues (actually worse) with OPEN-ELEC.
I plan on capturing some scope traces of the digital audio output to confirm my suspicions that something is happening to the data stream to cause the issue. I also will try running the HDMI video instead of the composite video to see if that changes anything with regards to the audio out.
Taking a look at the system resources i see the CPUs and memory are all less than 20% used so I do not see any issues there. Also I have the RPi as a WIRED connection to reduce any network issues.
I would like to hear if anyone has similar issue.
edit:I added logs here: http://paste.osmc.io/oqimiruhiq
edit: new log after disabling cec : http://paste.osmc.io/ukupurucot
Update: I did an install using OSMC installer (to eliminate NOOBS) and issue still present in the April and the Feb release (I tried both). Feb release seemed to be worse.
Update2:I also removed my switch from ethernet path and issue still seen. I did confirm that with the keep alive set to none, then pausing and resuming video will eliminate the static. Could be a clue as to root cause here with the keep alive signals.
Update3:I did looks at the SPDIF voltage traces for the good and failed states and the signal seems to look fine in both as a 1vpp signal. SO my conclusion is there is a bit error being introduced.
Update4:I compared the Digi+ outputs vs my working (but ancient) DSM320 that was able to pass the AC3/DTS audio . I did not notice any obvious differences in these waveforms, but I do not know the SPDIF waveform requirements. Also enabled buffering in the advancedsettings.xml and no change noted.
Related issues:
Thanks!