Whether you’re digitizing audio for archives, making mp3s of your record albums, or hoping to add taped interviews to that documentary video you’re making, converting audio from analog format (i.e., cassette tape, vinyl record, etc…) usually requires format-specific audio equipment.
For instance, if you’re trying to make a digital copy of an interview that was recorded onto a mini cassette tape. You will need a device that has the ability to play that mini cassette tape (obvious, no?). The audio device will also need some sort of output interface, usually in the form of a headphone jack (“line out” is another common term for this). Older audio devices such as record players and cassette players will often have an RCA output that interfaces with a stereo receiver via an RCA cable (also known as a phono cable), but no headphone output. In these cases, you can just connect the analog device to the receiver and use the receiver’s headphone jack as the output.
Next, you will need a digital device, such as a computer, that is capable of receiving audio through an input jack, AND is capable of converting that signal to digital. Most computers these days come with software for making digital audio recordings. Apple’s Garageband (for use on a Mac) or Audacity (either Mac or PC) are good options. Both programs allow you to directly record analog audio into a digital audio track and are enabled with a number of basic editing tools.
In order to capture the analog audio on a digital device, the most essential piece of equipment you’ll need is the appropriate hardware, such as a stereo cable or RCA cable, for interfacing the analog device output with the input of the digital device. A stereo-mini-to-stereo-mini cable (also known as a 1/8in. cable) will usually suffice, as most computers are equipped with audio inputs that use this type of interface. Some analog devices such as stereo receivers use 1/4in. cable outlets, however, whereas computers rarely do. If you’re faced with this problem, you can simply purchase an adapter that will convert a 1/4in. cable end down to 1/8in., allowing you to plug this into the computer’s audio input jack. You can find most of the necessary cables and adapters for this at Radio Shack for relatively cheap prices.
Converting from a Digital Format to Another Digital Format
Some digital audio formats are not compatible with other computers, software, or audio devices (for instance, .wma will not play on a Mac, while .aac will not play on Windows). This is particularly the case when editing audio in a specific application like Garageband or Audacity. Most audio editing applications keep audio files in an application-specific native format. This allows the user to preserve the original quality of the audio, as well as any added effects. When you’re done editing your audio file, you can usually export it in a number of sharable formats (e.g., .mp3, .aiff, .wav, .wma, etc.)
When you’re ready to export your finished audio file, keep in mind that some digital audio formats compress or reduce the size (and quality) of an audio file more than others. Simple audio programs, such as iTunes or QuickTime Pro, allow you to convert from one digital audio format to another, such as from .aiff to .mp3. Flip4Mac is a program that allows you to convert native Windows audio files (.wma) into a more universal file format (such as .mp3). Generally, the .aiff format preserves the best quality audio (at the expense of file size), but other common formats of decent quality are .mp3 and .wav.
For more information about converting analog audio to digital, and descriptions about different digital audio formats, take a look at the following links:
Converting Analog Audio to Digital on a Mac
Description of Different Audio File Formats
Image Credit: FourthFloor via Flickr, used under a Creative Commons Attribution license.