When we talk, we create sounds. If we were to record them, these sounds are sent in analogue format. Analogue is term used to describe a continuous electrical signal. This signal can be degraded by noise. Most modern computers convert analogue signals into digital signals. This improves the quality of the signal and makes it easier to work with, if you wish to make changes to it.
Digital audio technology will allow you, to record, play and edit digital sound. Most of you will have heard digitally stored audio files on your mobile music players, whether it is an iPod or some other make. We can download these sounds in various different digital formats and use software like Windows Media Player or iTunes to allow us to play them. Audio files can be quite large, so using digital audio allows us to compress the files into much smaller ones. This makes it much easier to transfer or download files to our computers or music devices, even our mobile phones.
There are three main types of digital audio files:
- Wave (WAV) store files in a wave audio format. It is an older audio standard now, but you may still find some digital audio files stored in this format. The quality was good, but the files sizes were much larger than the next two.
- MPEG (MP3) stands for Motion Picture Expert Group and is the common standard for digital audio files today. Most music files come in this format when you download them from the Internet or when you listen to them on your mobile music device.
- Windows Media Audio (WMA) was developed by Microsoft and is used by Windows Media Player software to play music.
Using audio software allows you to save your audio files in different formats. So if you want to play your Compact Disc music on a portable music device, you would use the software on your computer to convert the music into the format you need for your portable device.
Our computers can even convert our sounds when we are speaking into digital format and play it back to us with Speech Recognition software and Speech Synthesis.
Speech recognition software allows the computer to listen to your voice and convert it to text or commands on your computer. You will need an audio input device like a microphone to record your voice and audio conversion software to convert your voice into a digital signal the computer recognises. It can then carry out your commands, like entering text in a word processor – you tell it what to write.
In order to record audio, you will need a microphone. Most modern laptops, tablets and smartphones will have a built in microphone allowing you to record audio. If your computer system does not have a built in microphone, you can purchase a microphone that will plug into the mic-in socket. This would be the simplest method. To get better quality audio you can purchase an external professional -quality hardware sound card with a professional-quality microphone, however this is beyond the scope of this course.
The simplest way to record video would be to use the built-in webcam on your computer system. Most modern laptops, tablets and smartphones have a built in webcam, this can be used to record video to the hard drive. Again an inexpensive webcam can be purchased and connected to a PC via USB to facilitate video recording.
There will be instances where you want to record video away from your computer system. In this case a number of mobile phones have a simple video cameras built in. Alternatively, you can purchase a digital video camera. This records video on to a digital storage device, and the video can be copied to your computer system by means of a cable or card reader. The digital video camera has the advantage that it will also record audio.