So recently, we had this weird problem with one of our YouTube videos (it’s fixed now). The audio on YouTube played on stereo speaker devices like laptops, smartphones, headphones, and earphones. However, it would just go mute on mono speaker devices.
Finally, we were able to troubleshoot and fix the issue. Don’t worry if you are in the same shoes as the fix is super easy. But understanding the problem is a bit tricky.
Stereo vs Mono Audio
If you are in a hurry, you can directly jump to the steps below. However, I would recommend reading a bit about stereo and mono audio for a better understanding of the problem.
Theoretically, mono audio has 1 audio channel while stereo audio has 2 audio channels i.e. Left and Right channels. Generally, you need only 1 speaker and 1 microphone to listen and record mono audio but for stereo audio, you need 2 speakers and 2 microphones.
That’s why when you are recording or editing video, you would see that mono audio has only 1 audio waveform whereas stereo has 2 audio waveforms. These 2 audio waveforms are for the left and right speakers.
Generally, most of us record audio in mono mode. And when you drop in your audio recording, the video editing software splits it into stereo. This makes the audio playable on both mono as well as stereo speakers.
In our case, an audio portion of the video was glitched during the conversion process. Our video editing software converted the mono audio recording to stereo but inverted one of the waveforms. So, the left audio waveform was the opposite of the right audio waveform. This is also known as an out-of-phase waveform.
Hence, when the audio is played on stereo devices, it plays perfectly fine. But, when you play it on mono devices, the left and right channels are clubbed. And since the audio waveforms are out-of-phase, they cancel out each other. Hence on mono devices, there is no audio in the clip.
The easiest way to fix this is by using audio editing software. For this example, I am using Audacity. If you are using a different audio editing software, the options might differ. All you have to do is invert one of the audio waveforms and that’s it.
Detecting the Problem
Now that we have the theoretical explanation out of the way. Here’s how you can detect the problem with your audio clip in Audacity. Foremost, open the audio file in Audacity. In case you don’t have Audacity, you can download it from the official website.
Once you have your audio imported in audacity, you can zoom in on the audio waveform. As you can see in the below screenshot, both the audio waveforms are out-of-phase. Next, play the audio file by pressing the space bar. If you can hear it, your audio is in the stereo modem as of now.
In order to replicate this audio on mono devices, click on the dropdown menu at the top-right corner, and select Split Stereo to Mono option. Next, hit the space bar to play the audio track and see if you can hear any sound.
In case you want to go back to Stereo mode, select Make Stereo Track from the same dropdown menu.
Now, if the audio file is audible in stereo mode but not in mono mode, we are heading in the right direction. Let’s go to the next step and fix it.
How to Fix the Audio
1. Export the audio file from your video.
2. Open the audio file in Audacity. Once done, click on the dropdown menu at the top-right corner and select the Split Stereo Track option.
3. Next, select one of the audio tracks by clicking on the left side of the audio waveform.
4. Once the audio wave is selected, go to Effect at the top menu bar and click on Invert. This will invert your audio waveform.
You will notice that both your audio waveforms have the same structure now. You can test it by listening to the audio in mono as well as stereo mode from the drop-down menu.
Closing Words: Fix YouTube Videos With No Sound
This is how you solve the stereo vs mono audio channel problem. I would recommend that you find an old smartphone or laptop that has a mono speaker and listen to your audio once before uploading.
I am still not able to replicate the same problem again but it seems to be a Final Cut Pro glitch. Let me know on Twitter if you can figure out the cause of the problem.