Best way to set up audio/midi devices

[thejiggers]

Can anyone help me understand the audio/midi setup window?

Summary:
I want to understand how various applications decide which audio output to use, based on the setup I have. I'd also like to know the best way to take control of that, and ensure that it's set up optimally.

Details:
I've been using my imac (osx 10.6.4) for a few years now in my studio with my external soundcard Prism Orpheus soundcard, which is wired directly into external speakers.

I still like to use the mac's onboard speakers and microphone, because I like system sounds to come directly from the computer, not through the studio speakers (they can sometimes be turned up quite loud!). I also like to use the mac's own hardware for skype, rather than having to ensure I've got a mic plugged into the soundcard.

I also don't always have the soundcard/speakers switched on. Typically, this means that OSX reverts the speaker output to the imac's own speakers.

It gets complicated though when I want to use skype when I've got my soundcard on, like if I'm discussing a Logic pro project with someone over skype. I'd like to know how to override the default choice of sound input/output, without resorting to switching the soundcard on/off.

Other side issues:
Keyboard volume control disabled:
I'm not sure if this is a connected issue, but recently, the keyboard volume controls which adjusted the volume/mute of the onboard speakers stopped working. It used to be that this worked until I switched on the soundcard, at which point it would come up with the Ø symbol if I tried to use those keys.

Firefox videos judder:
Also, now, when I play videos on firefox, there's a judder as the audio stops, and then catches up with the video...

Record audio output of e.g. browser
I'd also like to be able to record the audio output of e.g. firefox or some other app.

Latency settings etc...
I'm using Logic 9 as my main recording software, too. I'm not convinced that my current setup is optimal.

Occasional distorted audio
Sometimes the output of logic gets really nasty and distorted and I have to reset the soundcard to make it work right again. (this might be more a tech support issue with Prismsound, though!?)

Here's what the audio midi setup panel looks like with the external soundcard switched off (i.e. not plugged in at the wall)

And here it is once the soundcard is switched on.

Note: I used Soundflower once, many months ago, but have since been told that it's no longer necessary because of "aggregate devices". I don't really understand aggregate devices, though...

I'm not an expert with audio hardware: I just tinker til it seems to work, and leave it be...but if anyone can advise on any of the above issues, and help me understand how it all works, I'd be very grateful!

Many thanks
Greg

 

[thejiggers]

I guess that was a bit full-on with the questions, and the diagrams and everything...Anyone not scared off?!

 

[Boyd01]

I can only provide a couple insights from my own use. Seems odd to use the term "soundcard" when "firewire interface" would convey more information about what you have (I had to do a google search to see what you were talking about).

An aggregate device allows you to combine different physical input devices into a virtual device that may be selected in programs like Logic and Garageband. In the past I have created an aggregate device for using a USB microphone along with a two channel USB audio interface. With this setup, for example, my audio interface might appear as inputs 1 and 2 in Logic and the USB mic appear as inputs 3 and 4.

Logic can be a little buggy with this sometimes and won't recognize the aggregate device. The solution was deleting the device and creating a new one. I have also seen the problem with distorted audio from Logic, but quitting and restarting Logic always cured it. I no longer use an aggregate device in Logic and have not seen this problem since then, so I suspect it's related. The ability to combine things into an aggregate devices is dependent on driver software. I now have an EIE Pro 4 channel interface and it does not support aggregate devices so I can't use my USB mic with it.

I don't know of a way to do what you want with Skype - and would be interested if somebody else has a solution. I have always gone into the System Preferences and switched to the built-in mic and speakers on my MacBook Air when using Skype.

Regarding latency, in the Logic Audio Preferences it will tell you what the round trip latency is. You can decrease this by using a smaller buffer but it will probably take some trial and error to see how low you can go without creating a problem. Logic also has a low latency mode (one of the buttons next to the transport controls at the bottom of the screen). As I understand it, enabling this just temporarily reduces your buffer size.

 

[ChrisA]

I guess that was a bit full-on with the questions, and the diagrams and everything...Anyone not scared off?!

Make it easy for people to answer and they will. Ask ONE well defined question at a time. For example the latency one. Say how yu are set up and what mix you have in the headphones and that you hear a "lag" and peole then can explain about buffer size and or using the zero lantany feature of the audio interface

 

[thejiggers]

I can only provide a couple insights from my own use. Seems odd to use the term "soundcard" when "firewire interface" would convey more information about what you have (I had to do a google search to see what you were talking about).

Ha ha, I must be such a grandad...I use the terms interchangeably, but will be more accurate in the future!

Thanks very much for your help on this. I will experiment by removing the aggregate devices, so that the software has fewer options about which device to use, and see if I can manually switch between them without the software struggling to keep track.

----------

Ask ONE well defined question at a time.

Another fair point
Here's one...How do I record the audio output of e.g. firefox? Or, to put it another way... Does OSX have an internal mixer that you can access which identifies every application which is generating sound?

 

[Sackvillenb]

Ha ha, I must be such a grandad...I use the terms interchangeably, but will be more accurate in the future!

Well to be fair, those terms really are pretty much interchangeable Semantics perhaps, but anyway, I knew what you were talking about.

Like someone mentioned, adjusting your buffer can help with latency, but it can be tricky to find the sweet spot (because a smaller buffer reduces latency, which is good, but a smaller buffer also makes your cpu work hard, which can be bad (might give you performance issues, audio drop-outs, etc.), so you have to find the right balance point between these extremes).

As for recording audio from firefox (or any audio source on your computer), there are some different apps to do that, one that I like (because it's partly free ) is called audio hijack pro. It's partly free because you can record a max of 10 minutes with it for free. If you need it for longer projects you can buy it. It's worked great for me.

 

[thejiggers]

As for recording audio from firefox (or any audio source on your computer), there are some different apps to do that, one that I like (because it's partly free ) is called audio hijack pro. .

That's very cool, thanks! Have downloaded it and will check it out. Looks like just the thing, and $32 is not the end of the world!