Editing
Author: admin
For audio editing, the best and easiest program I have found to use is Audacity. You will need to visit their page for install files, including the LAME MP3 encoder so you can export your audio to MP3 and also the LADSPA plugins installer. I highly recommend using the most recent beta release of Audacity.
I will again walk you through my process for the Journey Church sermon podcast. First, I import the audio file that I captured during the service, the result of which is the included screen shot. Since I record our entire service from beginning to end, to keep an archive our of services. Since I record in stereo, for the podcast I split the tracks and set them both to mono and then mix the two mono tracks back together to create a single mono track. (Audacity – Mixing stereo tracks to mono in your Project)
The next step is to trip off the ends of the recorded audio. You want your sermon audio to start at the beginning of the talk and end at the end of the talk. Again, for our podcast I start the audio when the speaker gets on stage, typically when they are welcoming everyone and then at the end I will end the file after the prayer at then end of the sermon. Where you start and end your file is completely up to you, but consistency will set your podcast apart from the others that are “good enough for a church podcast”.
After triming down the audio file to the audio we want. I do some enhancing, if you want to set your podcast apart from the hundreds/thousands that are out there pay close attention to this part.
1. Noise Removal – I do this in two different ways, the first is using a high pass filter – I drop all sound frequencies that are below 120Hz, this eliminates most of the hum. The second is to use the built in Noise Removal feature of audacity. First find a section of audio that should be quiet, you will need to zoom in a bit and look for a section where there is a flat line, select that portion of audio and select “get noise profile” in the Noise Removal feature, go back to your audio and select the entire file, go back to Noise Removal and select OK. (Audacity – Noise Removal).
2. Compression & Amplification – This is the single most important thing you can do to your audio, podcasts that are not compressed and amplified properly are not a pleasure to listen to. Imagine being in your car and you want to listen to a sermon, but you have to keep adjusting the volume level so you can hear parts and not get blown away during other parts, or worse yet – you can only listen to the sermon by using headphones. I continue to be shocked by how many large churches don’t take a few simple steps to make sure that their message can be listened to.
To use the Compression feature of Audacity, first you need to find your dynamic range. Select a small portion (I believe 28 seconds is the max) of audio that has your highest and lowest level in it, you could also do this process twice. With the audio selected go to Analyze – Plot Spectrum and mouse over the high and low areas to find out what the levels are. You want to determine the dynamic range. For our recordings we usually have a range of 60 dB, in the screen shot the range was from -27.2dB to -87.3dB.
Once we know the dynamic range of the audio file we can apply compression. Select the entire audio file and go to Effect – Compressor. Set the Threshold to half of your dynamic range, in this example half of 60dB is 30dB. Set your Ratio, I used very hard compression and set this to 10:1, again this is what works for me. I also adjust the Attack Time to as fast as possible, same with Decay Time. Then hit OK and the file will be modified. Now your audio will have a more consistent volume level. But note there are still some large peaks.
The last modification to the audio is to now amplify it all to an appropriate level. Go to Effect – Amplify, in most cases the amplify tool will indicate how much amplification you can apply before the highest peak will reach 0, if you have selected all of your audio this field will most likely show 0dB and the OK box will be grayed out. To give you an idea of where to start, I suggest selecting a small portion of audio that doesn’t contain any large spikes and then see what Amplify suggests, you can then cancel and select all of your audio and go back to Amplify. What typically works best for me is to amplify all of the audio by 20dB, make sure you check the Allow Clipping box so you can click on OK to apply your setting. From a visual stand point you will notice on the main screen that your audio has two shades of blue, the dark blue section and the light blue section. I have found that you don’t want the light blue section to go past the 0.5 and -0.5 marks on the main view, and you definitely do not want the light blue area to get to 1 and -1 or your audio will sounds horrible. However you may also notice that the dark blue section may fill most of the upper and lower areas and you don’t have much gray space, that is actually OK.
Additionally, you can import additional audio files, such as an intro or outro for your podcast and then use the Time Shift Tool to move your individual files around to get everything lined up to play in the correct order.
Now we have our audio edited, we can create an MP3. (link to come)