Stereo Downmix not working in Jellyfin media player

[DenSilent]

I'm trying to give access to my jellyfin library to my parents (my server is accessible from internet and we have 200+ Mbit/s between our places). They have only stereo audio setup.
They far from advanced pc users but like to watch movies. So I installed Jellyfin media player - here is your shortcut, press here and that's it, have fun.

Problem is, for whatever reason, Jellyfin media player ignores Stereo Downmix server settings - nothing happens at all. So parents do not hear dialogs in movies, and that's making all this unusable.

Strangely enough - if I open the same movie on the same PC but in a web browser - downmix works just fine. Dialogs are loud and clear and I can hear differences in downmix algorithms. At the same time video stream is NOT being transcoded, only audio. Unfortunately, using a browser is a bad option - some movies are streamed "as is" but many videos are playing only with video transcoding (when parents pc can easily hardware decode them "as is") that means ruined picture quality, slow performance and unnecessary load on server hardware. Also, this is more difficult for parents to use.
I can force downmix in media player by forcing a video transcoding with low quality settings, but this is obviously not a solution. With all the problems mentioned above, the main thing is that video should not be transcoded just so audio downmix can work. That makes no sense.

So, why this even a thing? Why have a dedicated downmix server settings when your own player just ignores it?

Firstly I don't undestand why downmix is a server-side feature. This must be done on a client. But ok, fine. It is a server-side.
Then why server don't downmix audio? There is a setting in media player where you can set, that your audio is stereo only - why this is ignored? Why it works in a browser but not in a media player?
Is there any workaround, maybe an alternative client application?

As it should work - client must downmix the audio request server to downmix audio if audio output in a client set to whatever setting that do not match the original audio stream while requesting video to be send "as is" (if bandwidth and server settings allows it, of course)

[DenSilent]

Ok, I found a workaround. It is not perfect, so I hope JMP can use server-side downmix someday.

As it turns out, you can force a client-side downmix. In client settings, "Manual MPV Configuration". I'm still experimenting, but for now this is what I use:
af=lavfi=[lowpass=c=LFE:f=120,lowshelf=frequency=100:gain=-2.5,pan=stereo|FL=.3FL+.6FC+.3FLC+.3SL+.3BL+.21BC+.21LFE|FR=.3FR+.6FC+.3FRC+.3SR+.3BR+.21BC+.21LFE,dynaudnorm=compress=24.0:gausssize=45]

I much prefer built-in Jellyfin algorithms, but at least you can hear people talking now.

[TheDreadPirate]

I'm assuming you are talking about the downmix algorithm settings in Dashboard > Playback > Transcoding. The menu context should hint that they are only applied when transcoding occurs. In JMP, if you are setting the max audio channels to stereo, it will locally downmix and does NOT apply any audio boost or downmix algorithms in a default configuration.

[motolly3]

For what it's worth I noticed that suddenly anything that needed to be down-mixed to stereo was barely audible. For me at least down mixing is a purely client-side operation so long as the player can make sense of the supplied audio.

Changing audio output from "default" to "Pipewire" and changing audio channels from stereo to "auto" then restarting playback seems to have solved the issue.

[DenSilent]

Yes

I'm assuming you are talking about the downmix algorithm settings in Dashboard > Playback > Transcoding.  The menu context should hint that they are only applied when transcoding occurs.  In JMP, if you are setting the max audio channels to stereo, it will locally downmix and does NOT apply any audio boost or downmix algorithms in a default configuration.

Yes, I understand that server-side downmix applies only to transcoding. You can not downmix without transcoding anyway. My problem is that server doesn't switch to transcoding audio when the client is set to stereo.

You say that JMP locally downmix the audio. But one of these is true: 1) it doesn't or 2) it does a VERY poor job at it. It is literally unusable.
Anybody here even use JMP with normal stereo PC speakers?

At home, I have a normal 5.1 system and I don't use JMP. So, when I installed it at my parent's house (they have 2.0 system with monitor audio br2) and tested out I was like "What?! I barely hear people talking". You cannot just volume up - next time music starts playing or something blows up you become deaf.

BUT - If you force transcoding in JMP, then audio becomes normal. That means JMP downmix doesn't work or is very bad and server-side downmix is working well.

I see two paths out of it:

1) Transcode audio stream on server when client sets output to "stereo" and remux video stream untouched. (looks like it is how it works right now when you use a web browser instead of JMP)
or
2) Fix JMP downmix - implement the same algorithms (with ability to choose) that server already uses. [I prefer this. I think downmixing is a client-side job. But it must be done well. This is why even in Windows 98 I used sasami2k with ac3filter. Downmixing multich to stereo is always was and will be a problem]

Right now, JMP on normal stereo systems is unusable when watching movies.  (If you think it sounds OK, you just don't compare how it really should.)

[TheDreadPirate]

My PC has a stereo setup.  USB DAC -> stereo headphone amp + pre-amp -> 2.0 studio monitor speakers.  JMP is set to stereo for max audio channels.  For clarification, I have stereo set in both the "playback" settings and the "client settings" with pipewire as the output device (my desktop is Linux).

This results in a proper client side downmix.

   

[Paulo_les_Gaz]

The reason I registered is that I wanted to report the same problem!

I have deployed jellyfin server in a docker container on a synology nas. For the client part, I use Jellyfin AndroidTV installed on a Nvidia Shield (itself connected to a 4K TV).

I use Jellyfin's built-in player, not an external player like VLC.

Also, I use the sound of my TV: I don't have a 5.1 audio system etc.... To have more audible voices, I used to select the “downmix to stereo” option. It worked by the past.

But recently, I've noticed major problems seeing certain new films. The film starts, after many seconds of waiting, and ends up stopping with a message indicating too many errors.

What all these films have in common is that they are 4k films with a “Dolby Digital Plus” soundtrack.

I noticed that as soon as I activated the “downmix in stereo” option, files appeared in the transcoding folder. This suggests that transcoding at server level was taking place! (confirmed by the logs).

The only way to avoid transcoding is to set the sound output to direct, and activate Dolby Digital audio streams. No transcoding, the video starts immediatly. But now the voices are less loud than the other sounds

Is there a way, to have a "normal" sound with clear voices easily. (without reencoding the video )

[DenSilent]

My PC has a stereo setup.  USB DAC -> stereo headphone amp + pre-amp -> 2.0 studio monitor speakers.  JMP is set to stereo for max audio channels.  For clarification, I have stereo set in both the "playback" settings and the "client settings" with pipewire as the output device (my desktop is Linux).

This results in a proper client side downmix.

Well, it is good that you have great results with Pipewire and a Linux client.

My parent's PC works under Windows with stereo analogue output to an amplifier and perceived loudness of the centre channel audio (where usually all the dialogues are) with mostly default JMP settings (output set to "stereo", not "auto") about 2 to 3 times lower than at my home with a multichannel audio system. And because other sounds have about the same loudness (=much louder), you cannot fix this just by turning up the volume.

These downmix settings in Jellyfin server with a selection of different algorithms—they exist for a reason. And they work really well. If we could use them with JMP - this will fix the problem. But we cannot



>>No transcoding, the video starts immediatly. But now the voices are less loud than the other sounds
Yes. JMP bult-in downmix produces very quiet voices. When transcoding, downmix is done by server, not JMP, and it is much better.

>>Is there a way, to have a "normal" sound with clear voices easily. (without reencoding the video
Never used JMP on Android, maybe someone here can provide better assistance. But if android client allows custom MPV settings like a desktop client, you can use my settings from earlier posts. If not, I think you have to use some external player with better downmix algorithms.

[TheDreadPirate]

Is it set to stereo in both playback and in client settings? There shouldn't be much, if any, difference in how JMP downmixes between Linux and Windows clients when the settings are the same.

[DenSilent]

Is it set to stereo in both playback and in client settings?  There shouldn't be much, if any, difference in how JMP downmixes between Linux and Windows clients when the settings are the same.

No, only in "client settings".
But I just tried at my place on a PC with stereo speakers (changed in "playback" from auto to 2.0) - no audible difference.