HI, my question is what would be the best practices for transferring a cassette recording into a digital one? What type of files should be created? Thanks
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Converting analogue audio into digital requires a bit of planning along with some trial and error if you want to get a good result. Apart from the limitations of the original recording, quality depends on the playback setup, the digital capture software and format, and the hardware that connects the two. Playback equipment of good quality and condition will provide a more faithful reproduction. Use a tapedeck that has had the tape heads cleaned and demagnetised. Generally it is advisable to have Dolby noise reduction switched off to get the full dynamics of the tape recorded - you can clean up tape hiss once you have digitised it. As a minimum you will need a tapedeck with the red and white RCA connectors for audio out, and depending on the model it may need to be passed through an amplifier. On the computer side, you need recording software and enough RAM and free storage space to manage recording large files. Any modern computer is likely to be fine, although a desktop PC or Mac is preferable to a laptop. Desktop machines are generally more powerful, generate less electrical noise, and don't have the tendency to go into sleep mode. Audacity, http://audacity.sourceforge.net/ , is a free, open source application for sound recording and editing and is widely recommended as recording software. It works on Windows, Mac and Linux. There are two main ways to connect your tapedeck to the computer. The first is to use a cable with left and right RCA jacks on one end and a 3.5mm audio jack on the other. This should be connected to the audio out of the tapedeck and the line in of the computer soundcard. You need a well shielded cable for this, as connecting directly to computer soundcard can introduce a lot of electrical interference (noticeable with a background hum or a scratchy static sound). A second, preferred, way is to use an audio capture device such as the Griffin iMic or the Soundblaster Live! 24bit External soundcard to convert the analogue sound to digital. These devices cost around $100 new and connect via USB to the computer. They tend to provide the best sound short of a much more expensive setup. We tend to recommend two standards in our Make it Digital guides: a minimum 'safe' standard and a best practice archival standard. For audio recording formats in both cases you should aim to record in an uncompressed WAV or AIFF format. Record at a minimum of CD quality (44.1 kHz, 16 bits) or at best practice archival quality (48 kHz, 24 bits). The large files that are produced (approx 600 megabytes for an hour) will have all the detail preserved from the recording, and enable you to easily edit them. Keep a back-up of the unedited recording, and burn additional copies to CD. Then you can use software like Audacity to safely remove hiss and tweak the volumes of a copy without fear of losing the original recording. Once you have finished you can easily generate smaller compressed files from them for use on the web, but compressed files such as mp3s are not good for archival purposes. We would strongly encourage you to keep the audio cassettes once you have finished digitising them, and perhaps consider donating them to somewhere like the Alexander Turnbull Library's Oral History Centre. You can contact them to discuss this through the National Library's website http://www.natlib.govt.nz/collections/a-z-of-all-collections/oral-history-centre
We've had a follow-up question to this query from someone wanting to know why their CD-burning software won't copy the .WAV file of their oral histories that they have digitised using Audacity. There are some things you need to check before creating a CD or backing up to an optical disc. First off, if you are creating an audio CD, check that your source recording is not more than 80 minutes long. That is the maximum audio that is possible for an audio CD. Some CDs and older software will even limit you to 74 minutes. If your file is too long, you will need to break it into parts in Audacity. Second, the CD-burning software you are using may only be capable of converting 44.1kHz 16-bit WAV files to CD audio. If you have captured at 48kHz or 24 bit and you are having difficulty burning to an audio CD, you can try changing the settings in Audacity to output at this level and see if your software recognises it. If you are on Windows, one well recommended free program is CDBurnerXP http://cdburnerxp.se/en/home which works on all versions of Windows (make sure you download the correct version for your PC). If you are burning to a CD or DVD to archive or back-up your recordings rather than to play them in a conventional CD player, in order to preserve the .WAV form at the higher standard of 48khz or 24-bit you need to create a data disc, not an audio disc. In your burning software you should be able to drag and drop, or point to, the file to be copied without doing any further reformatting or converting. You are then only limited to the amount of data a disc holds - most CDs hold 700MB of data, while single-sided DVDs hold 4.7GB. Note that no digital media is currently considered to be genuinely archival. You can read about back-up and archiving strategies in our Preserving Digital Content guide http://makeit.digitalnz.org/guidelines/preserving-digital-content/ .