A great project features quality audio as well as quality video. To help to get you going, here are the basics of working with the audio features that SlingStudio offers.
Types of audio inputs
How do you get audio into your SlingStudio project? Here are the ways to do that:
- Camera microphone: This is the easiest and perhaps the most common way to include audio in a SlingStudio video project. Most of the cameras that you're likely to use with your SlingStudio project have a built-in microphone that record audio in addition to video. You can also connect an external microphone to your camera, too. Whichever way that your camera obtains audio, its audio/video signals can be input to the SlingStudio unit via HDMI cable in either of two ways:
- An HDMI cable between the camera and an optional SlingStudio CameraLink wireless transmitter device (one CameraLink device is required for each HDMI camera);
- An HDMI cable between the camera and the SlingStudio hub's HDMI-In port.
Important: Some HDMI cameras do not properly transmit audio over HDMI. This is true when using these cameras with any device, not just the SlingStudio hub. Be sure to check any camera(s) for compatibility before starting a project!
- Smartphone microphone: If you're using a smartphone as a camera, the smartphone's microphone can record audio and transmit it wirelessly to the SlingStudio hub along with the video. It’s also possible to use an external microphone with the smartphone using a TRRS input device.
- Audio mixer and devices connected to the SlingStudio hub’s Line-in Audio port: You can use an audio patch cord to connect an audio device's audio-out port to the SlingStudio hub's Line-In Audio port. Such audio devices could include an audio mixer, a computer, a disc player, etc.
Using audio sources with the SlingStudio hub Line-in Audio port
To connect an audio device to the SlingStudio hub’s Line-In Audio port, you'll need a male-male cable (often called a patch cable). This cable uses the plugs most common on portable audio devices and smartphones. You'll see several terms for patch cords that use these types of plugs: 1/8", 3.5mm, or terms with mini in them, such as mini jack or mini stereo.
Just as important as the patch cord is the audio signal that is required by the SlingStudio hub. The incoming audio signal needs to be:
- Two-channel (stereo)
- Unbalanced input
Here is what these terms mean.
You'll often hear at least a couple of audio terms using the word "level": Mic-level (which is a relatively weak audio signal) and line-level (which is an audio signal that is many times stronger than mic-level).
The SlingStudio hub’s Line-In Audio port requires a line-level (stronger) audio signal. If you connect an audio source that outputs a mic-level (weaker) audio signal then it is not likely to be audible.
Line-level audio is output by audio gear such as preamplifiers, mixers, and other signal-processing equipment. Typically the headphone jacks of computers, smartphones, or tablets output line-level audio as well.
Mic-level audio is output by a few devices, including microphones. You can use a mic-level audio device with a SlingStudio hub if you first connect the mic-level audio device to a preamplifier or a mixer, and then connect the preamplifier or mixer to the SlingStudio hub's Line-In Audio port.
Two-channel audio (also known simply as stereo sound) is well-known to many people. It provides one audio channel for the left signal, and one audio channel for the right signal. The SlingStudio hub's Line-In Audio port is designed for stereo audio inputs. If your audio source is monaural (also called mono, meaning it has one audio channel) that's fine, but make sure that you're using the correct patch cord plug so that the mono audio signal is being output over two audio channels. Some non-stereo plugs only transmit audio to one stereo channel (often the left) so audio is only heard from the left channel. Again, always be sure to test your setup before you find yourself on location with things not working as expected!
Best bet: Use a 1/8" mini-stereo patch cord that works properly with an iPhone, Android phone, iPad, or computer audio output. That kind of audio patch cord—the shorter the better, to avoid interference—works well with the SlingStudio hub.
An explanation of the differences between unbalanced and balanced inputs is outside of the scope of this article, but be aware that the SlingStudio Audio-In port requires unbalanced audio, should the matter come up with an audio device that you want to connect to your SlingStudio hub.
Also be aware that unbalanced audio connections tend to be more sensitive to electrical interference, so try to keep the audio patch cord as short as possible, ideally 10 feet or less. If you hear interference (such as a buzzing sound) in the audio, either re-route the cord away from potential sources of interference (such as computers or video monitors) and/or consider using a shorter length of audio patch cable.
Using the SlingStudio Console Audio Mixer
The SlingStudio Console app (for both iPad and Mac) includes a full-featured Audio Mixer feature. It offers separate channels for each of your audio sources (each camera/smartphone audio/video source and/or a standalone audio source, such as an audio mixer, that you have connected to the SlingStudio Line-In Audio port).
For details on using the SlingStudio Console Audio Mixer feature, see the Knowledgebase links at the end of this article.
If you're having trouble with:
- Erratic audio
- No audio
- Audio from only one channel (especially the left channel)
… then first try these things:
- Physically reposition, or even jiggle, the line-in connections. If doing that improves the incoming audio, then connect the audio cables more securely.
- Check to make sure that you're using proper patch cables for unbalanced, stereo audio. Audio only in the left channel suggests that the cable's plug might not be fully inserted into the jack, or that the cable you're using is a mono-type patch cable.
Note: A useful way to identify whether a cable is mono or stereo is to look at the number of "lines" on the plug: One line is mono, two lines is stereo. Be sure to use a stereo-type cable.
Audio still not right?
Try taking a look at these things:
Sound too low?
The SlingStudio hub requires line-level input. If you've connected a microphone to your SlingStudio hub’s Line-In Audio port, the signal is likely to be extremely weak, because microphones output mic-level audio signals, which are much weaker than line-level signals. Mic-level devices must first be connected to an external audio device such as an audio pre-amplifier or an audio mixer to amplify the signal to line-level. Then connect the audio pre-amplifier or mixer to the SlingStudio hub’s Line-In Audio port.
Balanced or unbalanced?
Is the audio source that you're working with balanced or unbalanced? Remember that SlingStudio only supports line-level, two-channel, unbalanced input.
Is this new behavior?
Was there a time when these same sources worked properly? If so, then please consider: What's changed since then? You might need to reverse some recent change.
If none of these things help, then please contact SlingStudio support for more assistance.