Here is my concern:
Sometimes I watch videos downloaded or directly from a browser on my TV.
For that I connect with an HDMI cable this one on a PC Lenovo Z70 80FG which is under Linux Mint 21 (since yesterday
==> The problem was exactly the same under Mint 20.3...).Then I choose the audio output: HDMI /DisplayPort and I launch my video with a player (Smplayer or VLC): no sound.
From there I have all these tests:
1 - I stop playing and I do a "sound test" in the sound settings and after a certain number of tests, I have sound, I restart the video with my player: I have to his.
2 - If I use Google Chrome to go to Youtube: no sound. Changing the hardware acceleration option doesn't change anything.
3 - If I use Firefox to go to Youtube: no sound. But if I cut the sound in the Youtube player, then put it back, I have sound.
4 - If I use QuodLibet or another music player (Rythmbox): no sound.
If I turn off the computer with cable TV in HDMI, to have sound in my video player, I have to redo step 1. The other steps give the same result: no sound.
I looked everywhere, under Mint 20.3, I even tried kernel recompilations with smoky drivers... Thank you Timeshift
Finally under Linux Mint 21, although on this side, nothing seems to have changed, I went to tickle in the alsamixer terminal:
The status of the HDMI audio output (S/PDIF) is "00" (open/unmute) by default.
While reading the alsamixer manual I used the mute/unmute command which is done with the "m" key. in order to change the state of the S/PDIF output from "00" to "MM" then "00" (the others S/PDIF are useless, because whatever I do it doesn't matter).
By doing this mute/unmute on S/PDIF in alsamixer the HDMI audio output works with Chrome/Youtube!!!
I launch QuodLibet, mute/unmute with alsamixer: I have sound.
In short, I have not tried all the combinations but the result is that:
If I have no sound with the TV's HDMI audio output in a program, I run alsamixer => mute/unmute, it's fixed.
The thing that "drives me crazy" is that with Firefox and only Firefox, I solve the problem without going through alsamixer, simply by cutting the sound in the Youtube player, then putting it back...
For example, I don't have this sound problem with a Fedora live which also uses pulseaudio...
Any ideas ???
Thank you very much for your attention,
Herve.
P.S.: I have no problem with an other laptop with the exact same system, it is on a Lenovo Z70 80FG PC I have this issue of which here is the config:
[EDIT]:
Always with the TV's HDMI audio output:
If I launch a Youtube video in firefox, I have sound without going through alsamixer.
If while the video is running in Firefox I launch QuodLibet, I have sound in QuodLibet, I can change songs, albums, etc... I still have sound.
If I close Firefox, I still have sound in QuodLibet.
If I change songs in QuodLibet after closing Firefox, I have no sound.