Dolby Pro Logic II & Bitstreaming

[Gir]

They are many Gamecube & Wii games that support Dolby Pro Logic II and it does work over HDMI connected to an AV Receiver,   by making sure the audio device is set to Stereo,  the Audio Backend should be WASAPI (Exclusive Mode) and Pro Logic is set on the AV Receiver.  

Star Wars Rogue Squadron II as a Dolby Pro Logic demo for testing. 

I noticed that the Xbox One and PS3 have the ability to bitstream audio to the receiver from games and videos, this is also possible on the PC using the AC3 Filter with video files, is this possible with Dolphin?  

[Gir]

I was wondering, does anyone still use a dedicated Sound Card, I used to purchase them back in the day but now i use HDMI Audio, so does this mean the GPU does the audio processing or is it all on the CPU, thus HDMI Audio uses up CPU Cycle and is this
inferior to dedicated Sound cards?

Does Bitsteaming mean the AV Receiver does all the audio processing freeing up CPU Cycles?

[AnyOldName3]

Basically everything uses CPU audio these days - back when Vista was new, Microsoft realised a huge percentage of random BSODs were caused by badly written sound card drivers, and so made all the Windows sound APIs use a software implementation by default.

[skid]

(10-13-2018, 08:10 AM)Gir Wrote: does this mean the GPU does the audio processing or is it all on the CPU,  thus HDMI Audio uses up CPU Cycle and is this inferior to dedicated Sound cards?

HDMI Audio is bitstreaming, so it is the AV Receiver that is performing the audio processing, not the GPU nor the CPU.

(10-13-2018, 08:10 AM)Gir Wrote: Does Bitsteaming mean the AV Receiver does all the audio processing freeing up CPU Cycles?

Yes. Remember also that the GameCube has a DSP which performs audio processing before the audio passes through HDMI Audio. This is emulated by Dolphin using the CPU and cannot be disabled.

(10-13-2018, 08:10 AM)Gir Wrote: on the PC using the AC3 Filter with video files, is this possible with Dolphin?

The equivalent of the AC3 Filter is always on in Dolphin.

If you enable the "Dolby Pro Logic II" option in Dolphin, this turns off Bitstreaming and performs the audio processing on your CPU. You would not want this option enabled with your set-up.

[Gir]

I noticed many PS3 titles have the DTS Logo, so all the game audio is encoded into DTS on the console in real time then 'bit-streamed' to the receiver, that displays the DTS Logo, so it's the opposite to PCM?

AC3 Filter as a SPDIF option that supports various output formats, such as Dolby ProLogic II and this will display on the receiver when selected, this mean audio contains metadata that tells the receiver what content it is, so is it possible to create an Audio Backend that does this?

[skid]

PCM is the decoded audio from DTS.

There is a licence involved with DTS, DD and DPL2 encoding which means $$$ and so it is not possible to create such a backend for free.

[Paul17041993]

(10-18-2018, 10:41 AM)Gir Wrote: I noticed many PS3 titles have the DTS Logo,   so all the game audio is encoded into DTS on the console in real time then 'bit-streamed' to the receiver,   that displays the DTS Logo, so it's the opposite to PCM?  

AC3 Filter as a SPDIF option that supports various output formats,  such as Dolby ProLogic II and this will display on the receiver when selected,  this mean audio contains metadata that tells the receiver what content it is,  so is it possible to create an Audio Backend that does this?

The GC and Wii *only* have a PLII encoder in their DSP's, and are only supported by select titles. But for anything that provides an audio option for 'surround' (and also headphones), said encoder is what's used.

The PLII mix is actually incredibly easy to decode either on the CPU (simple matrix pass), or via a dedicated receiver. The later at least works really well on original hardware, but as of late however, Dolphin's DSP re-writes have completely broken the encoder (read, not the *decoder*) and thus surround and headphone modes just flat-out don't work currently...

Edit; tell a lie, the *encoder* side does in fact work via cubeb, using LLE recompiler and PLII decoding *off*. The Decoder doesn't work and you'll need to have your receiver set to PLII decoding, in my case I use a dedicated toslink link for this as the receiver doesn't support 'analogue' decoding over HDMI (it's a rather old model).

Edit2; turns out the decoder does in fact work, cubeb is just breaks if you use a 7.1 device instead of 5.1...