My Guide to creating a Podcast on a mac – simply with low CPU

Thats right – low CPU – simple and with free steak knifes.

Well maybe no steak knives 🙂

I struggled with the 50,000 example configs out there that tell you how to podcast. They all pretty much use soundflower, linein, soundflowerbed and/or some combination of all of these.

Well I tried them all – got some to work (and some did’nt) and found that even when they worked it pushed my mac hard (almost 100% cpu). I could live with the but the big problem was latency.

ALL of the configs people used had bad latency on the feedback in your headphones. It started off small but got worse as the recording went on (30 mins+). Well I fixed it a different way than everyone else – getting rid of soundflower and doing some of the mixing in hardware.


Record to mp3 a podcast
I have two people talking (2 mics)
Want to play music (mp3)
Need to do phone calls (skype)
Need to wireup 2 headphones with feedback for the presenters

Hardware I used:

Griffin imic – dont argue – just go and buy one now !
external mixer (4 channel) from Tandy / Radio Shack
2 Dynamics mics
my elcheapo 1.25 Ghz emac
Audio cables to hook it all together

Software needed:

Audio Hijack pro

How to do it:

Hardware wise – connect the line out (headphone out) from the emac to channels 3/4 of the mixer. Channel 3 is left – Channel 4 is right. I use a 3.5mm to dual RCA cable.
Connect the dynamic mics to channels 1 & 2 on the mixer
Hook the output of the mixer to the input of the imic (I use a stereo RCA to stereo RCA cable and the 3.5mm to RCA cable that comes with the imic)
Hook the presenters (talent ?) headphone(s) to the imic output – use a 3.5mm splitter if you want multiple headphones (I have 3 for the 2 presenters and one for me)

Configure the system output prefs as follows: Sound Effects to imic output, output to headphones, input to imic
Skype: output to imic, input to imic
Audio Hijack Pro: Create a new session. source is audio device. input imic, output imic. select the recording tab and choose your mp3 preference. Click hijack and then record.

Guess what – thats all there is to it. How does it work ?

The emac send the output from all system events direct to the imic output (headphones) so they dont get recorded onto your show.
The emac sends the output of all audio by default (such as itunes) to the lineout (heaphones)
The mixer mixes the audio from the mac (eg: itunes) with the mics and sends it back to the mac via the imic input
Audio hijack grabs the imic input – routes it to the imic output so you can hear what is happening and when you click record – records the whole thing to a mp3 file.
Skype gets its input from the output of the mixer (imic input) and sends the other persons voice to the imic output.

It all seemed to work tonight at home. I need to do a more though test but basically my mac didnt go over 30% cpu and the whole thing worked great – no LAG !!!!


One Response to My Guide to creating a Podcast on a mac – simply with low CPU

  1. Kellen says:

    PLEASE HELP! i have a problem with the above information when trying to implement on my own computer. can you email me if you’re still around?

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