Onboard HDMI vs Audio Interface

[lfm]

I think here we are getting a bit closer, raising concerns about the syncing - however, just to clarify, I have no external audio streams going "in" - everything is sound libraries (VE-Pro, 99% Kontakt) or are you talking about a different kind of input when mentioning core audio, some some internal process?

HDMI out is usually related to graphics card, since it carries video if you want too.
On PC you get HD Audio drivers installed handling audio on HDMI - so in my case NVIDIA driver of some sort.

Not sure how audio is set up on Mac - but thinking using the right driver from Logic may inflict somehow.

The output from samplers and VST instruments may be considered as input stream on tracks - and might be related to the setup input for the daw in use. So when recording midi it might be handled that way. I used a daw at some time that started crackling on VST instruments much earlier than normal audio input.

So have a look at if Logic is having sync setting set for syncing recording on same device as you output. Cakewalk Sonar on PC had two such separate settings - to select what device to sync to for recording and one for playback.

Is there a setting in Logic or Mac OS for this kind of sync source?

When using ASIO it might be implied that input and output are the same device - not sure how Mac works, if audio is Core Audio always or ASIO related.

I also used other software like for notation that use other playback devices - that become "emulated ASIO" and similar and they start crackling real early. Others that support MME work better. What I'm after - OS seems to create emulated bridges sometimes where the protocol itself is not supported. Mac is more built for multimedia from start compared to PC so may be other things in there.

Just trying to put some ideas...if not hi cpu so computer cannot handle data stream without interrupt there is some sync issue. Software emulation also takes more power to keep up.

[MelloProg]

Thanks for all the thoughts on this topic.

I guess I got myself into this mess when I was looking for a clean and digital way to get multi-channel audio out of Logic and into my sound system. HDMI looked like an obvious solution, the Mac Pro has a HDMI out and my processor has several HDMI as input.
Maybe it was a misconception on my part believing that this would be a viable solution for music creation. After all it may not be.

I also didn't want to constantly having to switch between audio devices for pure listening vs. working in Logic, preferring to have one audio device where everything from the computer goes through to the processor/amp, regardless of being stereo or multi-channel. Especially switching to and from HDMI as audio source causes nothing short of chaos with a multi-screen setup because I cannot prevent the HDMI input device to be appearing as another screen which of course does not exist. So now, I am thinking of going out of the MOTU with analog audio cables into the processor. I just have to get a different processor/preamp model because mine doesn't have the analog multi channel inputs anymore. Maybe this will be a good thing after all because my monitors going crazy when switching HDMI drove me nuts (Part of that is an unstable handling of multiple screens by Apple which I read a lot of people have issues with).

In Logic a setting concerning separate clock source can only be found in the Project Settings - both there and in the MOTU driver preferences it is set to "internal" other choices in Logic are MTC and Manual, the MOTU driver adds options (aside the matching "internal") for SMPTE, S/PDIF and other audio devices.

[Kaine]

Well, now you do. Well, sort of, really, there's no "special chip" so much as there is no chip at all until the data has to be transferred or played. Digital audio, like video, is just a stream of numbers so until it gets converted to analog there is seldom a need for a "chipset." That said, modern soundsets do more than just convert digital to analog, but that's outside of this conversation. Whatever those features might be are handled by the HDMI endpoint. The Graphics hardware is what handles this stream of data when using the HDMI connection.

Aye, it still requires some kind of driver hook into the OS for it to function correctly, although it'll be the external amp that does the decoding to the digital signal as you say. But, yes, the GPU will have a specific driver designed for handling audio routing within the system. It won't have any kind of ASIO support, however, making it largely useless for audio production duties.

[Kaine]

*Double post*

[ghettosynth]

Well, now you do. Well, sort of, really, there's no "special chip" so much as there is no chip at all until the data has to be transferred or played. Digital audio, like video, is just a stream of numbers so until it gets converted to analog there is seldom a need for a "chipset." That said, modern soundsets do more than just convert digital to analog, but that's outside of this conversation. Whatever those features might be are handled by the HDMI endpoint. The Graphics hardware is what handles this stream of data when using the HDMI connection.

Aye, it still requires some kind of driver hook into the OS for it to function correctly, although it'll be the external amp that does the decoding to the digital signal as you say. But, yes, the GPU will have a specific driver designed for handling audio routing within the system. It won't have any kind of ASIO support, however, making it largely useless for audio production duties.

Yes, of course, there is a driver. And since we're talking OS/X, there's no ASIO anyway. It's a core audio driver.

[xenofungus]

To the original poster: are you using some sort of HDMI switch box? In my experience, those things cause all sort of problems. I have an older AV receiver that doesn't do HDMI, so I had to use one. I had to go through 4 to find one that works.... mostly. No pops or crackles, but once in a while audio signal just disappears, and I have to cold boot the receiver to fix it.

[MelloProg]

No, I had a direct connection between computer and preamp.

[Tj Shredder]

I am not sure, but the audio might have to be converted into some sort of dolby/dts format. That might be as well in a different sample rate. Both could create performance/conversion problems... Maybe someone with more knowledge about HDMI formats might chime in.
I bet its along those lines, maybe try with a 48 khz session, just out of curiosity...