Knowledge Base/Streaming video production for Ustream

Audio

Alden
posted this on June 26, 2013 11:11

There are a variety of audio issues possible as part of 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 possible audio issues and resolutions for each.

 

No sound / audio

Check your computer audio output

First, you'll want to check that the computer you are watching your broadcast on, you actually have the sound turned on and the volume up. You can test this by going to your computers audio settings and pressing the test sounds, or navigating to another video on the web and making sure you can hear audio through your computer speakers or headphones.

If you hear audio on other videos on the web and not on Ustream, check the volume in the Ustream player and make sure it is turned up.

If you have already established that the Ustream player and your computer have the volume turned up but you still aren't hearing any audio on your broadcast, next you need to check the audio settings in your encoding / broadcasting software. Every encoding software might have slightly different controls. We will cover the issue in the Ustream Web Broadcaster and Ustream Producer and if you are using something different, try to find the audio controls in the encoder you are using.

Ustream Web Broadcaster:

If you are not hearing audio in your broadcasts from the web broadcaster, you can likely fix the issue by following these steps:

Check Flash is up to date

You can check what version of Flash you have installed on your computer quickly by going to your Broadcast Console, and right clicking on the broadcast preview window. This will bring up a small menu. This menu will show you Settings/Global/Settings/About Adobe Flash Player XX.XXX.XXX. Selecting "About Adobe Flash Player" will take you to Adobe's website, where you can update your Flash player.

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Make sure that your microphone is being recognized by the Flash Player.

You can do this the same way that you checked your Adobe Flash version- by right clicking the broadcast preview window. This time, select "settings". This will bring up a small field where you can make sure that Flash is recognizing your mic and your camera. First, you want to make sure that you are allowing the player to access your broadcast equipment; you can do so by choosing "allow".

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Once you have done so, click the small microphone icon to bring up a list of your available microphones, and choose the microphone that you would like to use for your broadcast.

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Check your audio level on the Web Broadcaster

Once you have your correct microphone recognized and selected by the broadcaster, you should make sure that you have your broadcast settings correct by clicking on the small gear icon in the bottom right corner of the broadcast window. This will open up your settings tab below the broadcaster. Here, you can make sure that both your audio and your video sources are playing in your broadcaster. You will see an audio meter below the audio settings tab where you can adjust your audio levels.

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Ustream Producer:

There are several places in the Producer interface where you can control your audio.

Check master audio output

The first thing to check is that your master audio fader is turned up and that there are sound waves coming out of the speaker icon. These are the default settings when you open up Producer, but it is possible they have been disengaged by accident.

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Add your audio source as a shot

Open Ustream Producer, and add your video source and audio source using the Add Source icon. In many cases, your audio will be automatically added to your shot selection window, but in more sophisticated setups you may have to add your audio as a separate source.

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Check your audio source is paired with each video shot

Highlight your video shot thumbnail in the shot selection window, and open the audio sources tab. Here, you can make sure that the audio source you want is properly paired to your shot. If you have multiple shots in your broadcast, you'll need to do this for each shot.

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Checking to see if your mic or audio interface is recognized by Producer:

Once you connect your audio device to your computer, you should see it show up in the Add shot menu.

If you don't see your audio device in the add shot menu, do the following:

  • Close Ustream Producer, disconnect your audio device from your computer and reconnect it. Restart your computer and reopen Ustream Producer.
  • Check your audio control panel for your Mac or Windows operating system, see if your audio device is recognized there.
  • If your audio device doesn't appear in your operating system audio control panel, you either need to install drivers for your audio device, or the audio device you have connected is not compatible with your operating system. Refer to the manufacturer's support documentation for further help in resolving this issue.

 

Audio too quiet

General tips if your audio volume is too quiet

  • Make sure you are using a microphone as close to your sound source as possible. Most microphones only can pick up sound within a few inches. A microphone that is 20 feet away from the person speaking will not pick them up very well and your levels will be too quiet.
  • Make sure you aren't accidentally using the built-in mic on your computer when you mean to be using an external mic. Follow the instructions for the Ustream Web Broadcaster and Ustream Producer above, or check the audio settings in the encoding software you are using.
  • Check your gain (gain is also sometimes called "level") on your microphone, your audio mixer, your camera and your encoding software. Make sure your levels are adequately turned up on 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 somone is speaking loudly or when there are 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 are 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 either be 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 (gain is also sometimes called "level") on your microphone, your audio mixer, your camera and your encoding software. Each piece of gear you are using should have a meter. If the level is too loud, it will clip, or hit red on the meter. If your meters look like this, this is very bad and you should turn your volume down.

MAKE SURE YOUR METERS DON'T LOOK LIKE THIS!

 

Audio echo or double

Echo or feedback while broadcasting

If you are using your built in mic or your microphone or camera is located close to a computer you are also monitoring / listening to the broadcast on, you might experience audio feedback. Audio feedback starts out like an echo, but can also sound like a "robot voice" a repeat, or can turn into a horrible loud screeching noise. Its very easy to prevent audio feedback by using headphones to listen to the broadcast and make sure your headphones are not turned up too loud.

There is secondary audio or an echo coming from my computer while I'm watching a Ustream broadcast. How can I turn it off?

If you are viewing a Ustream broadcast and hear secondary audio, you may be hearing audio from another source on your computer, for example you have the same Ustream broadcast playing on Facebook and also watching it on the Ustream channel page. Or you are watching another video on the web and that is playing at the same time as the Ustream video. Make sure that all other open internet browser windows and tabs on your computer are closed or muted prior to viewing your desired Ustream broadcast.

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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 Ustream platform. Two common causes of buzzes and hums are grounding issues or radio frequency interference (RFI). When RFI is really bad, sometimes you are hearing radio stations or people talking through your audio wires. These problems can be difficult to solve since sometimes they are caused by the electrical wiring of the building you are in. Here are some potential solutions to fix a buzz or hum in your audio.

Try switching your cables

If you are experiencing a hum or a buzz it is worth it to try to switch which kinds of cables you are using to see if you can reduce the hum or noise you are 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 in them: 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 are experiencing hums or buzzes, trying 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 flourescent 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 kill a hum or buzz. Shop for hum eliminators at B&H.

Other audio artifacts: clicks, “glitches” strange noises

A clicking sound or “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 a 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 your video travelling 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. Ustream Producer Studio has a built in audio sync delay for this purpose.

You can also utilize a hardware audio delay unit. Here is an example of a hardware audio delay unit at B&H: Datavideo AD-100 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.

 
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