How to Convert Your Analogue Tapes to Digital Files
1. Digitising audio: an outline
1.1. What is digitisation?
Digitisation is converting something into digital or numerical form. Usually this means taking something which exists in a physical medium and making a digital copy or representation of it; this digital copy can then be stored, manipulated and distributed electronically according to one's own job related or personal needs.
We can digitise sound recordings which might be on magnetic tape, for example. By digitising, we convert the sound into numbers which can be stored on computer. The collection of numbers represents the sound: it is a copy. We no longer need to deal with magnetic tape in order to listen to the sound.
1.2. Why digitise sound recordings?
Digital copies of recordings have some important advantages over analogue ones:
• Digital copies are infinitely repeatable: once in the digital domain, further copies can be made without loss of quality. Analogue tape-to-tape copies, for instance, degrade with each generation.
• Digital copies are easily stored: a computer can store huge quantities of digital sound obviating the need for bulky archives of tapes or disks.
• Digital copies do not degrade in a way which affects sound quality: when analogue media degrade, sound quality is lost, such as when records become scratched. Constant sound quality is maintained throughout the life of a digital copy.
• Digital data may be searched easily: a computer can be used to perform complex searches on large collections of sounds very quickly.
1.3. What resources are needed to digitise audio?
Equipment:
• The equipment you will need depends on the medium of your original recordings. In general, you will need a machine to play back the recordings and a machine to make the digital copies (usually a computer).
2. Creating digital audio files: a step-by-step guide
Before embarking on the digitisation itself, you should have planned the project thoroughly, sourced all the necessary resources, and obtained, set up and tested your equipment. You should also have familiarised yourself with any equipment or software which is new to you.
Once you are at this stage, you are ready to prepare for the recording process itself. This will involve setting up audio connections for recording and listening, and organising source materials to make the process hassle-free.
2.1. Final preparations
2.1.1. Setting up audio connections
The connections you need to make will depend on the type and combination of media you have.
For a single analogue source medium: connect the playback machine directly to the computer's audio input.
2.1.2. Monitoring
It is important to be able to hear what is going on throughout the digitisation process. You need to be able to hear the playback of your sources so that you can identify the audio segments you want to digitise; you also need to hear the output of the computer, so that you can listen back to the digitised sounds and check them.
This is called monitoring, and it can be done using either loudspeakers or headphones. Whichever is used, use good quality equipment to ensure accurate aural feedback.
In order to monitor effectively it is necessary to work in a quiet environment. One of the less desirable features of working with computer audio is the noise of computer disks and fans. Some computers are quieter than others, and individual machines of the same type can differ in the perceived intrusiveness of the noise they make. You may wish to take this into account when sourcing equipment.
To set up monitoring, the analogue line output of the computer's audio hardware is used. When you play back a sound which has already been digitised, the computer sends it out through this connector. The hardware should also be able to pass sound from its input through to this output; that means you should be able to monitor sound coming from the playback machine through this output of the computer. To do this, you may need to enable input monitor or something similar on your computer's audio mixer or sound editor programme. This will effectively send the input signal straight to the output. The advantage of this is that you only need to connect your monitor loudspeakers or headphones to the output of the computer; you need not connect them to the outputs of your playback machines at all.
The analogue line output of your audio hardware should be connected to your headphones or loudspeakers. Some soundcards (usually low-end cards) allow the direct connection of headphones to this socket, others don't. If your soundcard doesn't, you'll need to connect it to an amplifier and then use the headphone socket on the amplifier. If you are using loudspeakers, you should use a high quality pair in conjunction with any necessary amplification. A good quality domestic hi-fi amplifier and speakers should be sufficient. It is unlikely that purpose made 'PC speakers' will be of sufficient quality to provide adequate monitoring accuracy, except in the most basic of digitisation projects.
2.1.3. Organising the process
Once your playback and monitoring equipment is connected to the computer, you can organise your source materials so that the recording process flows efficiently.
Make a list of the source materials, in the order of digitisation, and with timings if necessary.
Minimise changing of media; deal with sources of a common medium consecutively.
Know what format you are going to use for digitisation: decide on sampling rate, resolution, and sound file format.
2.2. Recording from analogue sources
1. Select the Line or Analogue input on the computer's audio mixer, audio control panel, or from the audio options menu item. It may be that your hardware lets you record from more than one source at a time; many lower end soundcards have a microphone input in addition to the line input, and may have 'virtual' inputs from MIDI synthesisers etc. Make sure none of these other sources are selected, or you will be recording extra noise from these inputs along with the sound you want.
2. Set the appropriate sampling rate, resolution etc on the computer. Some soundcards allow the adjustment of these, in which case there will usually be an option in the audio mixer or sound editor software for doing so. At the digitisation stage, it is best to choose full bandwidth and full resolution. Full bandwidth means using a sampling rate of 44.1 kHz or above, and full resolution means using at least 16-bit sampling. 24-bit sampling will result in a more dynamic and vivid reproduction, but in general only professional level audio hardware will support this. Even if the sounds are to be used in a low-bandwidth situation (such as streaming over the internet), it is worth making full bandwidth originals. Though they take up more disk space, you can downgrade them later. Low bandwidth originals can never be upgraded to produce clearer sounds.
3. Adjust the recording levels. To do this, you need to playback your source recording and check the level meters on the computer. These should be found in the mixer panel or in the audio settings control panel. The levels should be showing an average of around the -12 dB mark (usually about two-thirds of the way up the scale), and should be peaking as close as possible to the 0 dB at the top. Be aware that with a digital audio system, if the signal rises above the 0 dB mark it will distort, almost certainly resulting in audible clicks or crackling.
If you are using a professional system, the audio hardware may already be calibrated to a 'reference level'. If this is the case you should be using a mixing desk in conjunction with the computer, because if the source recording is at a non-standard level or was poorly recorded, you will need to increase its playback volume. A mixing desk will allow you to do this.
4. Create a new sound file using the sound editor. This is usually available from a 'File' menu, and at this point you may be asked to define the sampling rate, number of channels (i.e. stereo or mono), and possibly how long the file should be in seconds. The settings you choose here should correspond to those of the audio hardware made in step 2, otherwise your sound may playback at the incorrect speed and pitch.
5. Click on the record button of your sound editor, and the recording should begin. Then start the playback of your source sound. You should see some indication of fluctuating levels as the volume of your source varies.
6. When the end of your source sound is reached, stop the playback machine. Then, click on the stop button of your sound editor. Doing things this way round means you won't accidentally miss the beginning or end of your sound. The rule is: press record on the computer, then play on the other machine; press stop on the machine, then stop on the computer. There will be a silent gap at the beginning and end of the sound file, but this is ok: it can be removed later.
7. Immediately do a quick check that your sound has recorded. Return your sound editor to the beginning of the sound, and click on the playback button. If your monitoring is set up correctly, you should hear your sound playback perfectly. If not, you need to check your audio settings and connections.
8. Save your sound file to the computer's hard-disk. The 'Save' option is usually under the 'File' menu. Name your file something identifiable, and choose a file format most commonly used for the platform you are on. Under Mac OS, this will be AIFF (standard Audio Interchange File Format). Under Windows, this will be WAV (a Microsoft file format). Professional sound editors on either platform will be able to cope with both WAV and AIFF files. Other types of files may not be supported on different types of computer. Do not choose a file format with compression at this stage, because you may want to do some post-digitisation processing (see section 7.5 below), and this is best done on uncompressed sound data.
You are now ready to move on to the next sound. If your last sound was very long, it is probably best to 'Close' it from the 'File' menu. This will free up the computer memory that was holding it.
3. Practical Details
3.1 How it works
3.1.1 We present below a concrete situation, in which we will be using the following tools:
3.1.2 As far as the hardware is concerned, one has to:
• connect the cable (1) to the headphones output of the tape player/dictaphone (2),
• insert the other jack of the cable in the line in plug of the computer (3) sound card
3.1.2.1 Ancillary 1
(1)
(2)
(3)
3.1.3 The software part will require undertaking the following steps:
• open the software application (Musicmatch Jukebox) (1), (see below 3.1.3.1)
• select from the “View” menu (2) the “Recorder” pane of this programme (3)
• select from “Settings” the ”Recording source”, which has to be “Line in” and the “Recording format” desired (Windows Media Audio - .wma format) (4)
• start recording on the software application
• start playing the tape
• once the tape has reached its end, one can stop recording, but no sooner than that
3.1.3.1 Ancillary 2
(1) First picture object – Music Match
(2) Second Picture Object – Select “Recorder” from “View”
(3) Third picture object – The Recorder Pane
(4) Fourth Picture Object - From “Settings” select the “Recording source” (Line In) and the “Recording format” (Windows Media Audio - .wma)
As anyone can see, resorting to this very simple procedure one can convert one's outdated analogue audio tapes into modern digital files storable on a hard disk, files that can be easily transcribed using our online application at www.typingfactory.com. For further inquiries please don't hesitate to get in touch with us.
We hope we can be of some assistance to you in the near future.
