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I hate not having at least a base level of understanding for something, and currently I don't before researching for this post I don't think that I understand understood bitstreaming lossless audio within sandy bridge or ivy bridge processors.


I'll start with what I know, and for the purposes of my description I'm going to constantly refer to an "audio chip." This might be were my understanding is wrong, but bear with me. For over a decade there has been dedicated and integrated audio.


Here is a picture of a CreativeLabs PCI sound card. I'm nearly 100% certain that the XFi logo is printed on the "audio chip"


Here is a picture of an integrated "audio chip" Here is what I thought was a picture of an integrated "audio chip" on the Asus P5k (Turns out to be the ALC codec)



Here is a picture of the integrated audio chip found in Radeon graphics cards



So how do the new Intel processors get audio to the HDMI output? If they were to make use of the ALC codec, then there lossless audio support would be limited by this chipset and only ALC 885, 889, and 892 would support lossless BD audio.



As Assassin and others have pointed out in build suggestions, the ALC codec number in your motherboard doesn't matter if you are planning to bitstream audio over HDMI, because the Intel's "audio chip" is now a part of the chipset. There isn't a separate audio chip, and there hadn't been one for a while I just didn't realize that. Also the pictures below were in the days of North bridge / south bridge which are now replaced by the combined PCH.

If I'm correct, the diagram would effectively just include one arrow showing HDMI directly from the PCH and another arrow from the PCH to ALC to Analog audio ports






Couldn't find this within Panther Point chipset discussions or any other normal google searches like "how audio hdmi sandy bridge", so I'm basically making the assumption that what I've described is correct.

If not, how does it really work?
 

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Windows adopts Universal Audio Architecture (UAA), under which there are three classes of audio devices:

 

- USB

- IEEE 1394

- Intel High Definition (HD) Audio

 

Here we are concerned with audio devices of the last class, that includes all onboard audio codecs and all HDMI audio devices in modern GPUs. An "Intel HD Audio" device consists of

 

- HD Audio Controller: controlling audio streams and transferring an audio stream from the system memory to the HD audio codec (or vice versa)

- HD Audio Codec: getting an audio stream from the controller and outputting it via HDMI, S/PDIF, or analog

 

See the block diagram below (from this PDF ). "Codec" is "(en)coder and decoder" such as DAC and ADC, but should be considered in a wider sense, including S/PDIF and HDMI transmitters. Usually you will have two "Intel HD Audio" devices in your system, which are totally independent of each other:

 

- Onboard audio codec in MB such as Realtek ALC892, the most popular audio codec right now.

- HDMI audio device in GPU such as "Intel Display Audio" and "AMD High Definition Audio Device".

 

In the case of an onboard audio cocdec,

 

- HD Audio Controller = a block integrated in the motherboard chipset such as H77/Z77/Z68 (PCH, Platform Controller Hub) or A55/A75 (FCH, Fusion Controller Hub)

- HD Audio Codec = the onboard audio codec (a small chip on the MB connected to the chipset via "HD Audio" bus, copper wires in the PCB)

 

In the case of GPU,

 

- HD Audio Controller = a block integrated in the GPU. (Note that this has nothing to do with "HD Audio Controller" in PCH/FCH !)

- HD Audio Codec = HDMI transmitter integrated in the GPU

 
Intel HD Audio deviceOnboard audio codecHDMI
HD Audio ControllerBuilt in the chipset on MBBuilt in GPU
HD Audio CodecDAC/ADC/SPDIF transmitter in the audio chip on MBHDMI transmitter built in GPU
 

 

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Discussion Starter #3

Quote:
Originally Posted by renethx  /t/1417640/audio-over-hdmi-was-a-question-but-now-a-clarification/0_50#post_22170506


An "Intel HD Audio" device consists of


- HD Audio Controller: controlling audio streams and transferring an audio stream from the system memory to the HD audio codec (or vice versa)

- HD Audio Codec: getting an audio stream from the controller and outputting it via HDMI, S/PDIF, or analog


In the case of GPU,


- HD Audio Controller = a block integrated in the GPU. (Note that this has nothing to do with "HD Audio Controller" in PCH/FCH !)

- HD Audio Codec = HDMI transmitter integrated in the GPU

I was wrong, thanks renethx. It's nice to have see some non-subjective discussions here. Used to find a lot of answers that way before joining, because the forums are indexed in google


I was headed down the right path, but knowing that it's integrated in the GPU makes a difference. All the information I've seen on Intel's newest HD 4000 focuses primarily on graphics performance, and there's plenty of pictures like this



Somewhere in that top left block, a portion is reserved as a dedicated HD Audio Controller?


Just in the most common case I can think of, would this processing (high level) be correct?



MKV -> CPU (per Gabest/Haali/etc) -> Splits Audio/Video and writes to RAM



Then



Audio stream -> From RAM -> HD4000 Audio Controller -> Codec (transmitter) -> re-paired with gpu-processed video stream -> HDMI
 
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