In this morning’s service, the sound quality at the beginning of the service wasn’t up to our usual standard. This blog post takes a quick look at what happened, why it happened, why we didn’t catch it sooner, what we did to fix it, and how we’re making sure it doesn’t happen again.

What happened?

Just after the service started, some of our viewers reported that the sound was “choppy” or “bumpy”. Thanks to those who let us know – as you’ll read later without this feedback we wouldn’t have known there was a problem.

This problem only affected the service when we were using our wide-angle camera; when we switched to the lectern camera the problem disappeared.

Why did this happen?

As part of making recordings for our Ash Wednesday service we unplugged our wide-angle camera, and didn’t properly reconnect it before we started the pre-service checklist this morning.

When we power up various pieces of equipment along the chain they sometimes rely on other things being available first. In this case, the box we use to capture the camera couldn’t detect a video stream, which meant our broadcasting software switched to using some defaults for both the video and audio. The audio stream it switched to caused some interference in the encoded output from the software, but only whilst the wide-angle camera input was selected.

Why didn’t we notice it?

Although we spotted the missing video feed and reset this, we didn’t spot the unusual audio behaviour. This is because we don’t actually use any of the audio from the cameras themselves as part of our broadcasts, instead using an output from the church’s sound system.

We do listen in to the audio stream as part of our streaming process to make sure we’re broadcasting a good mix and volume, but we listen in to the audio stream from before it’s encoded and sent to the internet. The problem with the wide-angle camera audio interfering with the output happened further along the chain than we were listening to, so we didn’t hear anything wrong.

What did we to do fix it?

We were able to switch to use the lectern camera whilst we reset the audio input for the wide-angle camera to the one we normally use. Switching this input removed the interference.

How are we stopping it from happening again?

We’ve added a couple of new points to our service streaming preflight checklist to make sure we test our audio at more points along the chain, including listening in to the audio after it’s completed the entire process, been encoded and been streamed back to us.