Podcasting Tutorial

My church records all the sermons and music that occur in the main sanctuary, and I'm responsible for putting them online at our website.   This is a little tutorial and explanation of how I do it.

Step 0: Converting recordings to digital format. 

I get recordings directly on CD, so to convert them to a digital format I simply use a CD ripping program to convert them to a .wav file.  I use FreeRip, but there are many choices here.  Use whatever you are comfortable with, but the rest of this tutorial assumes you are ripping to .wav files, since that will be the easiest/quickest to deal with while editing.

If you have recordings on tape, you'll have to hook up a tape player to your computer through the line-in connection.  You can then play the tape and record it on your computer using a program like Audacity, which we will use throughout the rest of the tutorial.

It's important to note that the file name should start at this point to be something descriptive.  Naming it "recording1" won't be much help if you have to leave and come back later.  I use the following naming scheme on the recordings to make them easier to organize:


So a file I would start with might look something like:


This helps automatically sort them by name, and by not using spaces you make things a lot easier for yourself in the future when you have to link to things in HTML/XML.

 Step 1:  Convert to Mono, remove noise

After you have your recording in a digital wav file, we can begin editing it to post online.  If you notice in your file manager, the wav file you have is probably quite large (likely hundreds of megabytes), and is far too large to post online.  We're going to shrink it down quite a big, but hopefully you won't notice much of a difference between our final file and what we're starting with.

Open your file in Audacity (I open Audacity and drag-and-drop my file into it), and lets see how it looks.

The first thing you'll notice are two blue waveforms.  These represent the left and right channel of the stereo recording.  Since you probably didn't have a stereo microphone recording the presenter, we can safely remove one of the channels and convert it to mono.  I use the right channel because it's louder on the recordings I get, but it's really up to you.

To convert to mono: on the left side of the combined channels is a control box.  At the top there is an arrow pointing downwards, click that and select Split Stereo Track.  Then click the X next to whichever channel you want to remove.  On the remaining channel, click the down arrow and select Mono.  You should now have only one channel, and if you play it back, you should it hear it coming out of both your left and right speakers.

Now we need to remove the noise.  To do that we need to find a section of the recording where this isn't any talking for a couple seconds. Once you find that, highlight it.

Click on the Effect menu, and select Noise Removal...  This will bring up the noise removal dialog box.  Click Get Noise Profile to tell Audacity that any sound it hears in the selected section is actually just noise.  Then click Close.  


Now highlight your entire recording (Alt+A works well for this), and click Effect and Noise Removal... again.  This time drag the slider bar to the far left, then back to the right one notch, and click Remove Noise.  



 You can click the Preview button to hear what it will sound like.  I've experimented with the recordings I get and the "1 from the farthest left" setting works well for me. You can use whatever you like, but your results will vary depending on the quality of your recording and how much noise you have.  If you don't have much noise, feel free to skip this step.

After the noise removal process completes, we need to save our file. with no selections made (no blue highlighted areas), use the File -> Export as WAV option to create a new file. I usually add "-mono" to the end of the file name (before .wav), so it will be something like:



 If you look at the file size, it should be right around half of what the original was.  That's because it's only one channel instead of two.

Step 2: Levelating

Now that you have your mono recording, you may notice that some parts are quieter than others.  We want to amplify these quieter parts without making the louder parts any louder.  I used to do this by opening the file in Audacity, listening to the whole recording, and selecting sections to amplify using the Effect -> Amplify menu.  This is perfectly fine, but it takes a while.  I found a faster way, and that is to use The Levelator, a free (for non-commercial use) tool that does exactly what we're looking for.  After downloading The Levelator and following the installation instructions, start it up.

Drag and drop your mono recording from step 1 into the box, and it will automatically begin the conversion.

The box will change when it's done, and you'll have a new file with "-output" added to the file name.  It should be approximately the same (if not exactly the same) as the "-mono" file you created.


Step 3: Editing

This is the most time consuming part, but is also partially optional.  Open up your new file with the "-output" name into Audacity.  It should look more like the waveform below.

As you can see, the sound is a lot more consistent in it's volume.  But so far we haven't actually done any real editing, only volume adjustments and some noise removal.  To really edit it, we're going to listen to the whole recording.


So you start listening and you find a section where the speaker begins reading a passage, and then realizes it's the wrong one, so they find the right one and begin there.  There's no need to include that in the version that people download, so lets take it out.  Simply highlight the unnecessary section and press the Delete key.

With some careful editing (and some luck with what the speaker said), you can make your edits undetectable.

Lots of little pauses

Another thing you might see in the recording is a section with a lot of long pauses.  From my experience, anything longer than 2 seconds can be edited down without any affect on the impact.  Highlight enough of the recording to make the pause only about 2 seconds long, and delete it.  This will shorten your recording and lower the final filesize ever so slightly.

Extremely long pauses may have more noise in them from a combination of the recording equipment and Levelating process.  try to remove the noisiest part of the pauses, as those parts will be more noticeable to the listener later.

Step 4:  Exporting to MP3

Now that you have your edited recording,  we need to compress it to an MP3 to make it easier for people to download and listen to.  Audacity doesn't support exporting to MP3 when you first install it, but adding the capability is easy: Click here for those instructions.

We need to enter some information about the recording so people can easily read the title and who made it. Click Project and then Edit ID3 Tags... and fill in the appropriate information.

 I use ID3v1 since I'd rather be more compatible than flexible, but the choice is up to you. 

The need to choose the specific bitrates for the MP3 file we will be creating.  These specify how much data to use to represent the audio file.  Using more data means it will sound better, but it will take longer to download.  I've found that a good setting for audio of people talking is 32 kB/second.  To set it to this (and to see what your options are) Click on File and then Preferences.  Click on the File Formats tab and you'll see a section at the bottom labeled MP3 Export Setup.  The drop down menu lets you select the bitrate. Select 32 for our recording, and click OK.


One way to make this data stretch further is to lower the sampling rate for the recording.  You can do that changing the project rate from 44100 Hz to 22050 Hz.  For simple voice recordings, this sampling rate is perfectly high enough, and will probably not even be noticeable in the final mp3. To change this setting, change the drop down on the main editing screen.  The screenshot below shows it more clearly.


Then simply choose the Export as MP3... option under the File menu.  You can remove the "-mono-output" section of the file name, since the new extension will ensure you don't overwrite your original wav file.

Now take a listen and notice how it sounds almost the same as your original, with a much much smaller file size! 

Steps 5+: Posting online

From this point I'm leaving it up to you to figure out how to post your new MP3 file online.  I will probably expand this section in the future, but for now you will have to look elsewhere.