7.3. Digital transfers from DAT If your sound materials have been digitised onto DAT tape (or any other digital tape format) then all that needs to be done is to transfer them to computer. Digital transfers are much easier than analogue transfers, as no recording levels need be set and there are no potential sources of background noise. However, it is important to be aware that digital errors can occur in such transfers, for a variety of reasons, which could result in clicks, dropouts or other noises occurring in the audio file. Making a digital transfer from a DAT machine to a computer's audio hardware is simply a case of connecting an appropriate cable from the S/PDIF or AES/EBU output of the DAT, to the digital input of the computer. Using cables of high quality and avoiding excessive length (a few metres maximum) should help to avoid errors. In established sound studios or editing suites such connections should already be in place (as should analogue connections). When making the recording, you will need to select the 'Digital' input of the computer's audio hardware. This may be found in the mixer panel, or in an audio options menu in the audio recording software you are using. There may be other settings which you need to make, and you should consult the manuals for your particular software and hardware. 7.4. Digital extraction from audio CD Some audio CD players have a digital signal output, in which case sound can be transferred digitally to the computer in the same way as for DAT above. In addition, most modern computer CD-ROM drives are capable of extracting audio tracks from CDs and placing them straight into audio files, using data transfer which is completely internal to the computer. There are many software products capable of doing this, including many CD-burning programmes. 7.5. Post-digitisation tasks Once you have digitised your sounds, you will almost certainly need to do some post-digitisation processing. The most common operations will be: Editing out unwanted segments of sound, such as silence at the beginning and end. 'Zooming in' on the sound can assist in finding appropriate points at which to make edits. You may also wish to apply a short fade to avoid clicks at these points, or your sound editor may be configured to do this automatically. Removing hiss, clicks and pops, rumble, and pitched hum. Advanced sound editors sometimes have functions for doing this, either built in or as optional plug-ins which can be purchased separately. Refer to user manuals and help files for information on how to use them. Some will be more useful than others for particular sounds, and bear in mind that they will result in changing the spectral content of the sound, possibly significantly. For instance, de-clicking may lead to some loss of clarity of attack transients in musical material. For very noisy sources, a significant degree of trial and error and careful listening will be required; it may be that in extreme cases, so much processing is required to make a sound seem 'clean' that much of the desired sound has been eradicated. If this happens, it may be better just to leave the sound in its noisy state. The intended use of the digitised sound will also have a bearing on how much cleaning up is necessary or desirable. Converting sound files into compressed or streamable formats. As they stand your sound files are good copies of the originals, but are cumbersome for delivery over the internet. In order to reduce the time taken to download them, the sound file data can be compressed. Alternatively, they may be converted into a format which can be streamed in real-time over the internet. This area is covered in more detail in chapter 9. Top of Page
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