Troubleshooting Audio Issues in IBM Video Streaming

There are a variety of audio issues that can occur during a stream. In case you aren't familiar with the terms, "audio" and "sound" mean roughly the same thing and can be used interchangeably. This article covers several different audio issues and their resolutions.

Audio Topics

• No audio/sound
• Audio volume too quiet
• Audio too loud
• Audio echo or double
• Buzz, hum, or other artifacts in the audio
• Audio and video out of sync

No Audio/Sound

Check your computer audio output. 

First, verify that the computer you're watching your broadcast on has the sound turned on and the volume up. You can test this by going to your computer's audio settings and pressing the test sounds, or navigating to another video on the web to ensure you can hear audio through your computer speakers or headphones.

If you hear audio on other videos but not on IBM Video Streaming, check the volume in the player and make sure it is turned up.

If you've established that both the IBM Video Streaming player and your computer have the volume turned up but you still aren't hearing any audio on your broadcast, check the audio settings in your encoding/broadcasting software. Every encoding software has slightly different controls. We will cover the issue in the IBM Video Streaming Web Broadcaster and Producer. If you're using different software, try to find the audio controls in your encoder.

Audio Too Quiet

• Make sure you're using a microphone as close to your sound source as possible. Most microphones can only pick up sound within a few inches. A microphone that is 20 feet away from the person speaking will not pick them up well, and your levels will be too quiet.
• Check your gain (also sometimes called "level") on your microphone, audio mixer, camera, and encoding software. Make sure your levels are adequately turned up at every step of the way.

Audio Too Loud

You'll know your levels are too loud if you hear distortion on your audio signal. Distortion will sound like an unpleasant degradation of the sound, particularly when someone is speaking loudly or during loud music sections.

Check Mic/Line Input Sensitivity and Camera Input Gain

One of the most common causes of distortion in your audio signal is when you feed a mic-level input a line-level signal. If you're routing the signal from an audio mixer through your camera, make sure you set the camera to accept a line-level signal and not a mic-level signal.

Additionally, most cameras have a gain control for the incoming audio. This might be either physical dials/switches on the body of the camera or a setting inside a menu in the digital display. Locate these settings and adjust accordingly.

Check Gain Staging on Every Device in Your Audio Signal Path

Check your gain (also sometimes called "level") on your microphone, audio mixer, camera, and encoding software. Each piece of gear you're using should have a meter. If the level is too loud, it will clip or hit red on the meter. If your meters show clipping, turn your volume down immediately.

Audio Echo or Double

Echo or feedback while broadcasting - if you're using your built-in microphone, or if your microphone or camera is located close to a computer that you're also using to monitor or listen to the broadcast, you might experience audio feedback. Audio feedback starts out sounding like an echo but can also sound like a "robot voice" or a repeat, and it can escalate into a loud, piercing screeching noise. 

It's very easy to prevent audio feedback by using headphones to listen to the broadcast and making sure your headphones are not turned up too loud.

Secondary Audio or Echo While Watching a Broadcast

If you're viewing a broadcast and hear secondary audio, you may be hearing audio from another source on your computer. For example, you might have the same broadcast playing on another website while also watching it on your IBM Video Streaming channel page, or you might be watching another video on the web that is playing simultaneously. 

Make sure that all other open internet browser windows and tabs on your computer are closed or muted prior to viewing your desired IBM Video Streaming broadcast.

Buzz, Hum, or Other Artifacts in the Audio

There is a buzz or hum in the audio signal - buzzes and hums are generally analog audio problems, which means they are not caused by anything in your encoder or anything on the IBM Video Streaming platform. Two common causes of buzzes and hums are grounding issues or radio frequency interference (RFI). When RFI is really bad, sometimes you can hear radio stations or people talking through your audio wires.

These problems can be difficult to solve since sometimes they're caused by the electrical wiring of the building you're in. Here are some potential solutions to fix a buzz or hum in your audio:

Try Switching Your Cables

If you're experiencing a hum or buzz, it's worth trying to switch which kinds of cables you're using to see if you can reduce the hum or noise you're hearing. Buzzes and hums can be caused by a faulty cable with loose connections or by using the wrong type of cables.

XLR Balanced Audio Cables: XLR or mic cables are generally balanced cables because they have three connections: positive, negative, and ground. These types of connections are used in most professional productions and are more resistant to hum and other noises.

RCA Cables: RCA cables are unbalanced connections and are more likely to introduce hum or noise, particularly if they travel a longer distance. RCA connections are usually used on the cheapest consumer-grade gear.

1/4 Inch Cables: 1/4 inch cables can be either balanced or unbalanced. If you see one line on the end of the cable, it means it is unbalanced; two lines means it is balanced. Balanced 1/4 inch cables have three connections, similar to an XLR cable: positive, negative, and ground.

If you're experiencing hums or buzzes, try swapping around cables and consider investing in gear that uses balanced and not unbalanced connections.

Adjust Your Lighting

Sometimes lighting circuits can introduce hums or buzzes into your audio. Try plugging your lights into a separate circuit or turn off any overhead fluorescent lights that are not essential to your video production.

Try a Hum Eliminator

Hum eliminators are boxes that you plug into your audio signal path which can sometimes eliminate a hum or buzz.

Other Audio Artifacts: Clicks, 'Glitches,' Strange Noises

A clicking sound, glitchy sounds, or other inexplicable noises are typically caused by something wrong in the digital signal path.

Check for Sample Rate Mismatches: If you notice clicking sounds or have no audio at all, check your audio sample rate settings in your encoding software. If you have two digital audio components, the sample rate between the two must match. The most common sample rates are 44.1k and 48k. Typical video workflows have a 48k sample rate. Make sure you set the sample rates so they match.

Use High-Quality AAC Audio Encoding at at Least 96Kbps: The other potential cause is poor-quality audio encoding or too low of a bitrate on your audio encoding. We recommend AAC audio encoding at 96-160kbps.

Audio and Video Out of Sync

Most audio/video sync problems are caused by your audio and video traveling down two different paths and having a difference in the processing time between the two.

Embed Your Audio into Your Video Signal

One way to fix audio sync issues is to route your audio through your camera's audio input so that it gets embedded into the video signal and processed the same way in the encoder, rather than going into a separate interface.

Use an Audio Sync Delay

Another way to fix audio sync issues is to utilize an audio sync delay. Audio sync delays usually allow you to set in milliseconds the amount of delay you want to add to the audio signal. You watch someone speaking while adjusting the control and stop when it looks like the audio and video are in sync. Some virtual or hardware encoders have built-in audio sync delay for this purpose.

You can also use a hardware audio delay unit, such as B&H: Datavideo Audio Delay Box.

Restart the Encoder or Viewer Application

It is much less common, but occasionally there can be audio/video sync issues caused by the video encoder, in the stream itself, or audio and video can get out of sync for a single viewer. The most common way to resolve these issues is to restart the encoder or restart the viewing application.