I checked and it is pretty ordinary windows home 32bit. Also I read before, that firefox relies on OS to play mp3 files too, but it somehow works there.

I've installed other chromium based browser - Vivaldi and it has the same problem. I think the problem may be connected to my laptop being atom based netbook or to chromium itself.

[5] To avoid patent issues, support for MP3 is not built directly into Firefox. Instead it relies on support from the OS. Firefox supports this format on the following platforms: Windows Vista+ since Firefox 22.0, Android since Firefox 20.0, Firefox OS since Firefox 15.0, Linux since Firefox 26.0 (relies on GStreamer codecs) and OS X 10.7 since Firefox 35.0.

Hi @buleczka19, if your Windows 10 is "N", or "KN" edition, you can try to download and install the Media Feature Pack: click the "Download" button, select the checkbox on the left of "Microsoft-Windows-MediaFeaturePack-OOB-Package.msu", and click "Next". After you install it, restart the Windows, and see if this helps in your case.

It didn't help. I tried it before.

Nah, they do not pay and also rely on OS. Thats why I am almost sure I encounter some kind of persistent bug. It has something with me using netbook. On a thread I found about opera and codecs, the OP had similar problem with codecs and similar error. The thing we have in common is using of netbook.

If we can find root of problem, we can report it and it can get fixed one day.

further details
Sound was playing? The status in the image is 'stopped'.

The sound wasn't playing.

I understand that opera can't play what OS can't play natively but firefox somehow plays MP3 files, even though it has the same policy.

further details

I tried using this, the part with ffmpegsumo downloading and pasting into the opera folder, then adding "patch-html5-media" extension but it didn't work

When I use duolingo it changes to:

screen of "players" when using duolingo

screen of "audio" when using duolingo

When I try to open mp3 file (http://www.niemiecki.ang.pl/sound/de/grammar/konnen.mp3 ) it changes to:

screen of "players" when trying to use mp3

screen of "audio" when trying to use mp3

Of coure in those two examples it doesn't play the sound.

But it plays OGG files perfectly. Example of ogg file

players with ogg file

audio with ogg file

It shows "none" everywhere.

video

Players: none

audio:

Input Controllers: none

Output Controllers: none

Output Streams: none"

I'm using native ad blocking of opera and "ghostery" addon.

Can you hear the pronunciation here?
http://www.dictionary.com/browse/test

I couldn't hear the sound there, until I disabled "ghostery" addon. Then I was able to hear the pronunciation.

But this didn't work with duolingo or mp3s. I couldn't hear anything on duolingo even after disabling all of my addons, native ad-blocking and using private window.

Also the play button is greyed out when I open mp3 file at a tab.

(example of mp3 file: http://www.niemiecki.ang.pl/sound/de/grammar/konnen.mp3 )

Like in topic. Opera doesn't play any sounds on duolingo website or mp3 files. Youtube, twitch are working perfectly.

Opera version: 39.0.2256.48

Windows version: Windows 10 Home 32 bit

Computer model: HP mini 210-3000EW

Forgot to mention: I have PC, where everything works perfectly.
The difference is the pc is 64 bit and has windws 10 64bit professional.
I do not have any external codecs nor flash installed on both computers.