Stereo Sound on 5.1 Speaker Setup (4 Viewers)

[Snoopy87]

I know that some people want to upmix the stereo signal to 5.1. For example some users don't have an AVR. They use active speakers with their sound card. So it's ok, if someone want to upmix the stereo signal to 5.1 on his PC. But this shouldn't be the only option. Because there are some users who really like to hear stereo as stereo. By the way: I also want to upmix stereo to 5.1 BUT of course with my AVR, because it is at least 1000times better than LAV, MPAR or whatever can do! Why? You have Dolby ProLogic II, DTS Neo:6, you have very, very great DSP programs by Yamaha, you have a great speaker calibration by microphone (YPAO), etc.

At the moment the PCM 2.0 signal is not upmixed to 5.1. The issue is, that the 2.0 signal is packed in a 5.1 signal. That means:

Front Left: Left signal of stereo
Front Right: Right signal of stereo
Center: Empty
Rear Left: Empty
Rear Right: Empty
Subwoofer: Empty

So the AVR is unable to play bass and unable to create a surround effect, because it already get a 5.1 signal which will be untouched and routed to the specific speakers. Which of course is correct handling of the AVR. So I want to send PCM 2.0 as PCM 2.0, because then my AVR is able to upmix (if I want, if not want I disable it, also I have programs like "Straight" and "Pure Direct" which play the signal 100% original and completly untouched!), is able to play bass and is able to route dialogs to the center speaker, while everything else is routed to the left and right front speakers.

That's the reason why you use an AVR and every AVR user want this and it is very typically that HTPC users who want to watch movies, having a little "home cinema", attaching importance to great audio and video quality, etc. are having an AVR ;-)

So what I want is the best and correct playback, which is correct for everyone! And for those 0,01% who want to upmix the stereo signal on their PCs to 5.1, there should be also an option. So 100% of the users would be happy ;-) But at the moment only those 0,01 % are happy :-(

 

[Stéphane Lenclud]

those 0,01% who want to upmix the stereo signal on their PCs to 5.1

IMHO that percentage is totally off the mark, more like 50/50 these days. It's not the 1990s anymore there are some really descent active surround solution out there, including SONOS' for instance.

At the moment the PCM 2.0 signal is not upmixed to 5.1. The issue is, that the 2.0 signal is packed in a 5.1 signal.

Ok now I understand your issue. Which use case is giving you that problem again?

 

[Snoopy87]

You are right, but those solutions are active solutions and those speaker setups also want to have the correct signal, because they know how to handle it or the user is able to set up how to handle e.g. a stereo signal. It's very simple: A player should always untouch a signal. It's up to the endpoint to handle the audio / video. Only if there are issues (old devices, no compatibility or quality issues) you should use workarounds like changing the signal (audio or video) on the devices which plays back the media. These are HiFi basics.

Here again the use case:
- I want to hear Dolby Digital, DTS, TrueHD, DTS HD Master, etc. Those signals should be sent as bitstream and untouched to the AVR
--> This is always working, no matter which speaker configuration I set up in the Windows Speaker Config

- I want to send PCM 2.0 as PCM 2.0 and PCM 5.1 as PCM 5.1 to the AVR. PCM 2.0 will be used by many TV channels in SD quality (MPEG2 Audio), or Internet Radio, MP3s, etc. PCM 5.1 will be used by some Blu-ray Discs, 5.1 FLAC, 5.1 in web video players (here is a 5.1 test: https://www2.iis.fraunhofer.de/AAC/multichannel.html)

--> This is not working. Because if I set up 5.1 in Windows Speaker Config, all PCM 2.0 signals are packed in PCM 5.1 signal (NOT upmixed!). If I set up 2.0 in Windows Speaker Setup all PCM 2.0 signals are correct, but than PCM 5.1 is downmixed to PCM 2.0.

So there should be two options:
1.) You are using an external active audio device like AVR, Soundbar, etc. In those cases ALL audio signals should be sent untouched to the device as they are
2.) Your PC is the "AVR", because you are using your internal sound card with active speakers. Those user should be able to set up how many speakers they have (2.0, 2.1, 5.1, 7.1 etc.) and whether the signal should be upmixed or not.

 

[Stéphane Lenclud]

So going back to your first post, it looks like the following is your issue on 5.1 speaker setup:

PCM is not working correct! e.g. on Internet Radio channels with RadioTime plugin (AAC or MP3 streams), on TV channels which are using default Stereo Audio (e.g. Comedy Central in Germany) or on both UHD/4K test channels on Astra 19.2. My AVR is getting a 5.1 PCM signal, where the stereo is set to Front Left and Front Right. That means, my AVR is not able to convert the original stereo signal to a 5.1 signal, because the received signal is already 5.1 PCM where the channels for center, sub and surround are empty. Also spoken words are not coming out of the center speaker. They come both from Front Left and Front Right.

Reading the posts from @mm1352000 it seems like both MP1 audio paths are causing you trouble, the music audio path which is using BASS by default, and the TV audio path which is using LAV by default. Therefore I wonder if the issue could be at the Windows driver level, though you mentioned it works from Edge...

As a workaround and until some developer takes a closer look at that you could do the following:

• For your music issue you should consider doing the BASS upmix to 5.1. As explained above there is no reason why the result should be worst than with your AVR upmix. Upmixing stereo to 5.1 is no rocket science really, I believe you can even set the low frequency cut off threshold. Then again I'm not sure how this is implemented.
• For your TV issue you could also do some upmixing using AC3Filter which probably offers more settings and fine tuning options than you would want.

Note that those solutions will still let you benefit from your AVR/Speakers setup calibration even though upmixing is done by the PC.
However I do understand your point and frustration. With your setup you should be able to delegate all upmixing tasks to your AVR.

 

[ajs]

This is not working. Because if I set up 5.1 in Windows Speaker Config, all PCM 2.0 signals are packed in PCM 5.1 signal (NOT upmixed!)

WASAPI Exclusive for Music (mp3, flac,tunein etc)? Without upmixing?
LAV Audio with bitstream and turning off option - Convert output to standard channel layouts ? For Video etc ...

 

[Stéphane Lenclud]

Also spoken words are not coming out of the center speaker. They come both from Front Left and Front Right.

Somehow I doubt your AVR would be able to achieve that from a stereo signal. Like any other DSP algorithm it's probably just going to try isolate dialogues based on frequency and redirecting them to the dedicated speaker, giving you at best mixed results. Then again I'm no DSP expert, far from it. Also for music you are probably best not trying to isolate voices and just duplicate the stereo to the surround speakers, play the mix on the central and redirect the low frequency to the subwoofer. It's probably worth noting that different upmix approach for music and movies can't be taken automatically by your AVR, you would need to switch between modes, whereas you can do that with MP1. Then again as stated above I'm no DSP expert nor a proper audiophile.

 

[Snoopy87]

As explained above there is no reason why the result should be worst than with your AVR upmix. Upmixing stereo to 5.1 is no rocket science really, I believe you can even set the low frequency cut off threshold. Then again I'm not sure how this is implemented.

The reason is really simple: There are millions ways of upmixing a 2.0 signal to 5.1 signal. The simpliest one would be to copy the front signal to the rear speakers. That's what my AVR also supports, but that sounds not good, it's just the same signal from all speakers. Yamaha, Denon, Onkyo, etc. have decades of knowledge. Those DSP programs are able to investigate the stereo signal. Finding voices which will be send to the center speaker. Locating musical instruments which will be then placed at the correct position in your room, etc. Hope you understand what I mean. Upmixing != Upmixing. So a good AVR is able to create a 5.1 sound from a 2.0 source which sounds exactly if the source have been recorded in 5.1 ;-) I can't belive that a few open source developers included such high quality audio upmixing without studying audio many years, writing thousands of algorithms, etc. in LAV Filter, BASS, MPAR, etc. Never! This is too complex and if it would be possible no one would ever need a AVR from Yamaha, Denon, etc. anymore

 

[Snoopy87]

Somehow I doubt your AVR would be able to achieve that from a stereo signal. Like any other DSP algorithm it's probably just going to try isolate dialogues based on frequency and redirecting them to the dedicated speaker

This is working if you have a 2.0 signal. If you have a 5.1 signal the dialogs are already set to the correct speakers in the signal. So if my AVR gets a PCM 5.1 signal it doesn't understand why 3 of 5 channels are empty/muted and that it is not a 5.1 signal and should upmix the 2.0 signal. Because if the AVR got a 5.1 signal everything is already fine. Only qualizer, DSP, etc. are improving the audio playback, but not changing the location of speaker signal.

 

[Vasilich]

have you tried to set windows speaker count to 5.1 so browser players will work, and use WASAPI over MPAR?

 

[Stéphane Lenclud]

Yamaha, Denon, Onkyo, etc. have decades of knowledge

That's what they want you to believe In fact they are mostly brands. Somehow I doubt any engineer that was developing amplifier/AVR 30 years ago at Yamaha is still doing it today. If that guy was successful in the company he most certainly moved on to some management position.

I can't belive that a few open source developers included such high quality audio upmixing without studying audio many years

You would be surprised, and some of them most certainly have years of domain expertise.