Popping sound from audio jack after silence

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ste_fan
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Popping sound from audio jack after silence

Unread post by ste_fan » Sun Apr 07, 2019 11:34 pm

Hi all,

I noticed that after some seconds of no audio output from the audio jack of the N2, there is a short medium-loud popping sound before audio is output again. Is somebody else having similar issues? What could I do to fix this?

Thanks and best regards
Stefan

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Re: Popping sound from audio jack after silence

Unread post by mad_ady » Mon Apr 08, 2019 3:18 am

If kodi is active it has a setting to keep audio active for a while. Once that time expires audio is deactivated. Maybe this is what you're hearing.

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Re: Popping sound from audio jack after silence

Unread post by ste_fan » Mon Apr 08, 2019 4:28 am

Hi mad_ady, thanks, however, at the moment I'm not using kodi, just the plain MATE desktop environment...

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Re: Popping sound from audio jack after silence

Unread post by phaseshifter » Wed Apr 10, 2019 8:31 am

which op sys image are you using...can you pls post the image file you have flashed
if it`s the early test image it may very well be the problem...

the sound has been updated in the 03/25 mate image..

other wise flash the 03/25 image

other wise what power supply are you using...????
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Re: Popping sound from audio jack after silence

Unread post by ste_fan » Thu Apr 11, 2019 2:10 am

Hi phaseshifter, thanks for your response! I used the linux image that came preflashed with the eMMC module which I ordered together with the N2. After setting it up, I did the usual apt update and apt dist-upgrade, so I assume I have the most recent version..? Or do you recommend flashing it anyway? cat /etc/os-release tells I am using Ubuntu 18.04.2 LTS now (MATE Desktop).

Power supply: I am using the 12V/2A one that was recommended by HK (also ordered together with the N2).

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Re: Popping sound from audio jack after silence

Unread post by phaseshifter » Thu Apr 11, 2019 7:24 am

if you could reflash with the latest image and see how that goes...are you completely shure that the noise is not coming from other equipment..spikes from mains powered appliances.i dont know your gear so it`s hard to put a finger on it directly..old power boards..do you have the power pack plugged directly to a gpo..mains outlet..

here is the download page link just click on it and your download will start
https://dn.odroid.com/S922X/ODROID-N2/U ... 325.img.xz
run this after the initial reboot and rootfs has been done..

Code: Select all

apt update && apt upgrade && apt dist-upgrade

Code: Select all

uname -a

Code: Select all

lsb_release -a
will tell you about your software
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Re: Popping sound from audio jack after silence

Unread post by phaseshifter » Thu Apr 11, 2019 8:02 am

maybe have a look here as well..this may be an issue if you have cheap usb amp/speakers...

viewtopic.php?f=118&t=33077

any devices that are on the same main`s circuit weather they be several meters away from your gpo mains outlet where the supply is plugged into..
can cause line spikes if the contacts are dirty ..dirty means not a good connection
or have a large load on any appliance..EG..a fridge freezer when the pump switches on it draws an huge inrush current..
also the spike may come when it stop`s if the contacts that are built into the fridge/freezer.. are not in good condition..due to age mainly..

also that kodi issue is noted by op`s..that mad_ady. spoke of...
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Re: Popping sound from audio jack after silence

Unread post by Amnezida » Tue Jun 11, 2019 9:04 pm

I'd like to resurrect this topic since the issue is there.
I replaced a Raspberry Pi 3B+ with I2S DAC with Odroid N2 as my home TTS server and now can hear loud pops every time audio playback starts after several seconds of silence.
Back to back playback prevents the popping but 5 seconds of idling is enough. N2 currently hooked up to Dayton DTA-1 mini T-class amp.

Additional testing done on another N2 running recent image with upgrades, no exotic stuff installed or kernel recompiled:
odroid@odroid:~/Downloads$ uname -a
Linux odroid 4.9.177-28 #1 SMP PREEMPT Thu May 16 23:10:54 -03 2019 aarch64 aarch64 aarch64 GNU/Linux

I measured a voltage pulse on 3.5mm jack from 1.2 to higher than 2.2 V (see below - horizontal cursor AY at 2.23V and the pulse crosses it by at least 500mV) at the beginning of each playback.
Here's a snapshot of the signal that comes out of unloaded (to exclude any comments on cheapo amps) 3.5mm jack right channel when aplaying a test wav file after silence:
Image

Any advice will be highly appreciated, this is extremely annoying...

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Re: Popping sound from audio jack after silence

Unread post by brtsh » Wed Jun 12, 2019 8:07 am

Recently i reinstalled ubuntu on my pc (and upgraded 18 to 19) and i have same problem. After some googling seemed like its due to power saving configuration and OS automatically turning the sound card off when its not used for a while. After that, when you start playback it turns it back on with mention pop.

Didn't have time to fix it yet, so I can't say more than this.

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Re: Popping sound from audio jack after silence

Unread post by odroid » Wed Jun 12, 2019 10:45 am

@Amnezida,
Thank you for sharing the oscilloscope screen.
We will try to reproduce the issue with a 1Kohm load resistor since many external amplifier input resistance is 600~3000ohms.

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Re: Popping sound from audio jack after silence

Unread post by Amnezida » Wed Jun 12, 2019 11:48 am

I'd expect input stage impedance of a good amp to be much higher. For instance, I've got a 2-stage SET that has almost infinite input impedance as the line is feeding a tube gate.
Will measure the D-class tonight, interesting what it has.
Regardless of that, the pulse shouldn't be there, I don't think it's up to the amp to be able to filter it out and it has potential to damage high sensitivity speakers if the amp doesn't have a standby timer with soft-start circuit.

I wonder if this is a SW or HW issue.
Similar issues seem to be reported on intel platforms - like brtsh mentioned, related to power_save = N option that turns off the audio subsystem after N seconds.
I'd say that the power_save=0 hack that people do to work around this is a cover-up for the real problem.

I'd be happy to do a similar workaround though - don't care about power consumption and have full control over playback (done from my own python daemon, so I can run whatever commands needed before kicking off mplayer subprocess). Couldn't find any power save related options for N2 sound driver though.

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Re: Popping sound from audio jack after silence

Unread post by Amnezida » Fri Jun 14, 2019 12:55 pm

The following didn't work:

(as root)
echo on > /sys/devices/platform/auge_sound/power/control
echo 86400000 > /sys/devices/platform/auge_sound/TDM-C-T9015-audio-hifi/pmdown_time (-1 also doesn't make any difference)

Not sure what else can control the power down timers for this audio card, could it just be baked into the driver w/o any option of external control?

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Re: Popping sound from audio jack after silence

Unread post by Amnezida » Fri Jun 14, 2019 5:14 pm

If anyone is interested, there are no pops after the following steps:

(as root)
> echo on > /sys/devices/platform/auge_sound/power/control
> echo -1 > /sys/devices/platform/auge_sound/TDM-C-T9015-audio-hifi/pmdown_time
> gedit /etc/pulse/default.pa
comment out the following line:
#load-module module-suspend-on-idle
and add at end of file:
set-default-sink 1

And, who would've guessed, add the following to any daemon that runs via systemd and activates audio system (using UID 1000 of the default user) - otherwise the daemon/service will lock pulseaudio and normal user won't be able to connect to it:
os.environ['XDG_RUNTIME_DIR'] = "/run/user/1000/" for python, OR
setenv XDG_RUNTIME_DIR "/run/user/1000/" for csh, OR
export XDG_RUNTIME_DIR="/run/user/1000/" for bash, OR whatever needed to set this env var

Hope I've got listed everything needed here, was doing lots of experiments.
mplayer -ao pulse <whatever> is happy after this both from command line and from service / daemon.
Seems to survive reboots as well.
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