Where is 5.1 "Processing" Done?

[vincent]

Setup: Windows 7 Pro 64 bit, Motherboard Realtek ALC1150 codec connected to analog 5.1 speakers
MM: 4.1.13.1801 Gold Lifetime

I disabled 5.1 sound with Realtek Audio manger (& verified speaker properties).
With MM Output set to WASAPI-Exlusive Mode-Automatic choice of format per track, when I play a Stereo flac file, I only get stereo sound (2 speakers) as expected.
However, If I set MM Output to WASAPI-Exlusive Mode-44100 Hz, 6 Channels, 16 bits, when I play the same stereo flac file, I get 5.1 sound (all 6 speakers)

This is confusing me - I thought WASAPI sent an unmodified bit stream to the hardware, so I would only get stereo output.
Is MM creating this 5.1 output & if so, how?
or
Is there something going on in the Realtek hardware which always produces 5.1 sound & the Realtek manager setting only "shuts off" the hardware

I have no idea how Realtek actually produces 5.1 sound from a 2-channel flac file - when I tried to download the data sheet from realtek web, up pops "This download page is for Realtek development partners only. You will need to sign a Non-Disclosure Agreement (NDA)"

Thanks

Settings Details:
MediaMonkey Output Plug-In: WASAPI
Exclusive Mode: checked
Event Driven Exclusive Mode: checked

Realtek HD Audio Manager Settings:
Speaker Configuration: Stereo
SoundEffects: <None>

Realtek Speaker Properties - Advanced
Exclusive Mode: Allow Applications to take exclusive control of this device

[jiri]

MM currently supplies audio stream to all available channels. So, e.g. a stereo source results in front left channel being played not only by front left, but also back left speaker. Some users prefer it this way, but others possibly don't (as is your case). Maybe it could be configurable?

Jiri

[vincent]

Thanks for the response.
If I understand what you are saying:
1)The actual hardware in the Realtek codec always has 5 channels available so they are available to WASAPI
2)When I set MM to WASAPI 6 channels and play a stereo-encoded file, it is MM who decides to send the left channel audio to both the Front & Back and the right channel audio to both the front & back.

Can you tell who/where the center speaker sound is coming from when I play the stereo file as WASAPI 6 channel?

[jiri]

1) Depends on configuration, if 'auto', MM tries to find the best supported format for the source audio (ie. 2 channels for stereo, if available). However, if you choose 6 channels then MM will _always_ provide 6 channels to the sound card.

2) Center channels get both left and right then (i.e. an average of the both channels).

Jiri

[vincent]

To further display my lack of knowledge about Surround, and whether signal processing is being done by Media Monkey, Realtek codec, or in the Speakers themselves I have to ask:

1)How does the center channel get the "average of both left and right channels". Does MM create this average and send it to the codec as the center channel? Are both channels sent by MM to the codec which then "muxes" them and sends them to the center speaker? Or something else?

2)How/Where does the ".1" subwoofer (6th channel) get it's sound? If MM sends this 6th channel to the codec how does MM decide what is in the channel? I assume that the subwoofer is designed to only play low frequency sound regardless of what type of signal it receives.

Thanks
Vince

[jiri]

1) In case of WASAPI exclusive mode all the processing is done by MM, anything later in the chain is supposed to just play the audio samples and not to modify them in any way. When the source stream has fewer channels than the destination device expects, the missing channels are calculated from the existing channels, either as a direct copy (e.g. back left is taken from front left) or as an average of neighbors (e.g. front center as an average of front left and right).

2) If not existing in the source stream, it's calculated the same way as the front center channel.

Jiri

[vincent]

Thank you - this makes sense to me (now)
It also explains why a flac encoded as 5.1 and played in MM as WASAPI-Automatic sounds very much different from a flac encoded in stereo and played in MM as WASAPI-5.1 (both flac files have the same sample rate).

BTW, the reason I am asking all these questions about MM & 5.1 is because I was trying to get a "true" (similar to DVD-A or SACD) 5.1 sound from a stereo flac (I need to create a new thread on this question).

[xavdeman]

MM currently supplies audio stream to all available channels. So, e.g. a stereo source results in front left channel being played not only by front left, but also back left speaker. Some users prefer it this way, but others possibly don't (as is your case). Maybe it could be configurable?

Jiri

Sorry to bump this age old thread, but this is the only place where this clear of a statement can be found on this.
This was driving me crazy.

I have a 5.1 setup, when playing stereo content, why would I ever want MediaMonkey to supply information to my center speaker? This ruins the sound field (and the artistic intent, may I add).
Equally, the crossover to the .1 (subwoofer) in the 5.1 is supposed to be handled by the AVR (receiver), not by an app like MM.

For anyone reading this, change from MediaMonkey WASAPI output to MediaMonkey DirectSound output if you want MediaMonkey to stop adulterating your content with an attempt at 'upmixing'.

[Peke]

Hi,
Can you please open support ticket https://www.mediamonkey.com/support so that we can attack it more directly.

There are number of settings that can interfere with Settings and MM behavior that we can test and see the best results.