Transcribe! Help : Audio file formats

Transcribe! reads audio sample data files. There have been dozens of formats used for audio sample data on various computer systems at one time or another and it is not our intention to support the more esoteric ones. Transcribe! currently reads :

• WAV files. This is the Microsoft standard.
• AIFF/AIFC files. This is the Apple Macintosh standard.
• MP3 - MPEG Layer III. This is a very popular compressed format.

If there is much demand then we might add to this list, but our view is that if you are using some esoteric format then you probably already have ways of converting it to standard WAV or AIFF. There are lots of tools already out there for sound file editing and conversion.

There are reasons why we don't read Windows Media Audio (WMA), mainly to do with copyright. Transcribe! allows you to copy sound files to AIFF format but this would defeat WMA's copyright protection scheme, which is not permitted by Microsoft.

Most audio file formats support a variety of sample formats and speeds. If you have a choice then 16 bit is always preferable to 8 bit. Stereo can be preferable to mono as the Stereo Mix dialog can then give you some useful options. However mono files are half the size of stereo ones so you can save disk space by using mono, and Transcribe! may then run a little faster too. High sample rates (44.1k, 48k) give better quality, especially when pitch/speed changing, but they also require larger files.

Uncompressed CD quality sound files (16 bit stereo at 44.1k) occupy about 10MB per minute.

MP3 files are much smaller (depending on the bit rate used) but decoding them in real time is hard work for Transcribe!. If Transcribe! can't keep up (likely if you have a slow machine and the MP3 file is a high bit rate, and especially if Transcribe! is doing other processing too such as EQ, speed change etc.) then the "Pre-computing audio data" dialog will appear from time to time while playing. Read about the Audio source buffer (Preferences) for solutions to this.

About MP3 versions : so called MP3 files are actually MPEG-1 (MPEG version 1) or MPEG-2 (MPEG version 2) both of which are recognised by Transcribe!. There is also a "Version 2.5" but this is not an official standard and will not be recognised by Transcribe!. Within MPEG-1 and MPEG-2, audio can be encoded as Layer I, Layer II or Layer III. Layer II is basically an update on Layer I, offering the same sound quality in a smaller file. Layer III is more sophisticated, and is usually superior when very high compression is desired. Transcribe! reads Layers II & III but not Layer I as this is seldom seen these days, having been essentially superceded by Layers II & III. So, don't tell your MP3 encoder to produce Layer I.

Sound file editing programs allow you to change sample size & sample rate, to filter and modify Sound files in many other ways. Transcribe! is not an editing program, and it is not our intention that Transcribe! should wander into this territory which is already well served by existing applications.

How to obtain audio files

If you want to transcribe a piece of music then you presumably have a recording of it in some form or other. Here are some of the possibilities.

• You have an audio recording in any format at all (cassette, vinyl, CD etc). Plug the audio signal into your computer's line-in or microphone socket and use the Record to File command (Tools menu) to "record" the audio to hard disk. There are also many other software packages available which allow you to record sound to your hard disk.
• You have a standard audio CD of the piece, and you have a CDROM drive on your computer. In this case the simplest thing to do is to use the computer's CD play function to play the CD while Transcribe! records it. See the Record to File command for more information.
• Transcribe! does not support direct digital reading of audio CD's but there are programs which do this. Recent Mac OS versions support this directly : it may surprise you to know that if you launch the "Simple Text" application and use the "File - Open" command to open a track on an audio CD then Simple Text will offer to convert the track to a "movie" on your hard disk. This is in fact an AIFF Sound file which can then be loaded by Transcribe!.
• If you are running OS 9.0.4 or later then you can use Apple's "iTunes" application to copy the track digitally to your hard disk. You can download this for free from www.apple.com/itunes if you don't already have it. Put the CD in and iTunes starts automatically (if it doesn't, you'll find it in Applications). Clear the check marks from the tracks you don't want to import, then press the Import button which will digitally copy the track(s) to hard disk.
  In iTunes - Preferences - Importing you can choose whether to import as MP3, AIFF or WAV. Transcribe! can read all of these so it's up to you.
  In iTunes - Preferences - Advanced you can choose the location folder for imported tracks. This is where you will open them from, using Transcribe!'s Open command. By default they go to "Documents:iTunes:iTunes Music".
• There are lots of shareware or free programs out there which will do CD-Ripping (digital copying from audio CD to hard disk), many offering useful features like MP3 encoding, accessing online catalogue information (CDDB) and so on.
  Check out www.mp3.com for a list of such programs. We use "Track Thief" from www.eskimo.com/%7Epristine/mp3.html#trackthief which works and is free. "SoundApp" from www.spies.com/~franke/SoundApp/ is also free and is said to be good.
• You have been given, or have downloaded, a data file containing the audio. If it isn't a format which Transcribe! can read then you must convert it, see above. Remember that files are often stored in various compressed formats (SIT, ZIP etc) and these must be uncompressed first.

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