Audio Devices
Raspberry Pi 4 with HifiBerry Digi+ → SPDIF into Denon AVR-X3400H (optical)
(running RoPieee)
Description of Issue
Whenever the PCM format changes (eg. different sample rate), there is a gap of approximately 0.5s until the Denon AVR detects the change. I tried to enable “Resync Delay” as I thought it was exactly for this case, but the gap remains (it is now 0.5s + whatever resync delay is set to).
The AVR status display shows “PCM ZERO” during the resync delay, and then “PCM” when the actual track starts.
My guess is that the AVR tries to be clever and detects PCM with all-zero samples. I was also able to reproduce this by playing a sample WAV file containing 10s of “zero” samples.
I think this could be fixed by playing inaudible white noise (similar to what Audacity creates with “Generate” > “Silence”) during the resync delay, so the AVR won’t see an all-zero PCM stream.
Would it be possible to add this as an option in a future update?
Yes I guess this would be a feature request
Maybe you can also change the subject, something like “Add an option to play inaudible white noise during resync delay”?
This is correct. Digital silence will not work well for Resync Delay with some equipment. Many DACs mute their outputs when presented with digital silence – probably to inflate SINR. Stereophile has documented this in test bench measurements for years. Inserted dither noise would be more functional for Resync Delay.
My Bakoon DAC-21 always cuts out the beginning of the songs (1~2 seconds) when I start playback via USB and changing the Resync Delay value does not solve the issue (it just delays playback, but the issue remains).
I believe the DAC will only wake up when some signal level is reached after a (very short) period of silence.
Instead of sending silence during Resync, it would be great to let the user select the level of pink noise (or better yet, very low frequency tone) instead for DACs that behave similarly.
For example, let the user choose between, say, -120dBFS and -40dBFS.
