Audio Interfaces

By default, Final Cut Pro uses one of the built-in audio interfaces included with your Mac computer, such as a stereo headphone jack or a stereo speaker output. If you need to capture audio from a professional device, you may need a separate third-party interface.

Built-in Audio Interfaces

The following audio interfaces are included with your Mac computer (though some computer models may not include all interfaces).

Built-in Analog Audio

You can capture and output audio using the built-in audio ports on your computer. The built-in audio interface on your computer usually uses a stereo miniplug connector. If necessary, you can buy an adapter to connect the miniplug connector to two stereo RCA or 1/4" tip-ring-sleeve (TRS) connectors, which can then be connected to your video or audio device.

Figure. Diagram showing a computer connected to an analog audio or video device using a stereo miniplug connector and two RCA connectors.

For basic mixing, you can connect the built-in audio output on your computer to a pair of external speakers. This gives you two output channels, which can be configured for dual mono or stereo playback.

Built-in S/PDIF Digital Audio

Some computers have built-in S/PDIF optical digital ports (sometimes called TOSLINK) that you can connect to some CD players, DAT recorders, and other digital audio devices.

Figure. Diagram showing a computer connected to an audio or video device via a TOSLINK optical digital connector.

DV FireWire

If your sequence uses a DV codec, you can output audio via the FireWire port on your computer. This allows you to use a DV deck, DV camcorder, or DV-to-analog converter as an audio interface. In this case, you connect your FireWire cable to your DV device and then connect the audio outputs of the DV device to external speakers or a television monitor.

Choosing a Third-Party Audio Interface

Before you purchase a separate audio interface, consider that most third-party video interfaces may have enough audio connectors to meet your requirements. You should consider a separate audio interface when:

  • You are trying to capture or output more audio channels than your built-in audio interface or third-party video interface supports

  • You need to capture or output in a format not supported by your existing interfaces (for example, if you need to capture audio at a sample rate of 96 kHz but your video interface only supports a sample rate of 48 kHz)

Benefits of a Third-Party Audio Interface

Third-party audio interfaces can provide many more features than your computer’s built-in interfaces, such as:

  • More than 2 audio channels—8 channels is common, but some interfaces have 24 or more input and output channels

  • Professional connectors such as XLR or 1/4" TRS

  • High-quality analog-to-digital and digital-to-analog converters supporting sample rates as high as 192 kHz and 24 bits per sample

  • Support for analog and digital audio formats

  • Stable, “jitter-free” digital audio clocks

Tips for Selecting a Third-Party Audio Interface

When you select an audio interface, make sure it has the following:

  • Connectors that match your audio equipment, such as XLR, 1/4" TRS, RCA, or TOSLINK

  • Support for audio signal formats that your audio equipment uses, such as AES/EBU, S/PDIF, or ADAT Lightpipe

  • Enough audio inputs and outputs to connect your equipment

  • Sample rate and bit depth at least as high as your audio equipment. For example, if you have an audio device with a sample rate of 96 kHz and 24 bits, your audio interface should at least match this.

Important: If you are considering purchasing an interface, make sure it supports Mac OS X Core Audio. Final Cut Pro supports any audio interface that is compatible with Mac OS X Core Audio.

USB Audio Interfaces

There are a wide variety of USB audio interfaces available. Most support two or four audio channels at one time. USB audio interfaces vary in quality considerably, so take some time to research before you purchase. The connectors on USB interfaces vary; some interfaces have RCA connectors and others have both XLR and 1/4" TRS connectors. Very inexpensive USB audio interfaces may have only a stereo miniplug connector.

Figure. Diagram showng a computer connected to an audio interface connected to an analog or digital VTR.

Make sure you don’t exceed the total bandwidth of the USB bus by connecting too many devices. USB 1.1 has a fairly low data rate, so be careful not to add too many USB items to the bus. Also, USB hubs can potentially cause audio problems. If you are having audio problems with a USB interface connected to a hub, try removing USB devices and eliminating the hub from the connection.

USB 2.0 audio interfaces are also available. Because USB 2.0 devices can handle high data rates (similar to FireWire 400), you can treat them similarly to FireWire audio interfaces.

FireWire for Digital Audio

As an alternate to PCI Express cards, many manufacturers now offer audio interfaces that connect to your computer’s FireWire port. These are not DV devices, but merely devices that use FireWire as a means of transferring digital audio data. FireWire interfaces are more convenient to switch between computers than are PCI Express cards, and they can be used with both desktop and portable computers. A FireWire interface typically supports ten or more inputs, and at least eight outputs.

Figure. Diagram showing a computer connected to a digital audio device via a FireWire connection.
Figure. Diagram showing a computer connected via a FireWire cable to a breakout box connected to an analog or digital VTR via two XLR connectors.

Important: Although a FireWire bus supports a very high data rate, connecting too many devices, such as a DV video device, a FireWire hard disk, and a FireWire audio interface, could potentially exceed the bus speed, resulting in dropped video frames or audio with missing samples.

PCI Express Audio Interface Card

Of all the audio interfaces, PCI Express audio interfaces provide the maximum transfer speed and can support many channels with high sample rates. Many audio interfaces come with a separate breakout box where the audio input and output connectors are located.

Figure. Diagram showing a computer with a PCI audio interface card.

PCI Express Audio Interface Card with Built-in Connectors

Some PCI Express audio interface cards have audio connectors attached directly to the card. Because there is limited space on a PCI Express card to mount audio connectors, RCA connectors are typically used.

Figure. Diagram showing a computer with PCI card connected to an audio or video device via  RCA connectors.

PCI Express Audio Interface Card with Breakout Box

The majority of PCI Express audio interface cards have a breakout box with a large number of XLR or 1/4" TRS connectors. The breakout box is attached to the PCI Express card via a long cable with a multipin connector. The long cable allows you to place the breakout box in a convenient location, so you can easily connect and disconnect your video and audio devices without going behind your computer.

Figure. Diagram showing a computer connected to a breakout box which is connected to an analog or digital VTR.