Transcribe Audio Formats
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Audio Formats
| File Types/Formats & Associated Software | |
| WAV (Windows Media Player) |
WAVEform Audio is a common file format and was one of the first audio file types developed for use with the PC. It is lossless, but generally very large. N.B. Not all .wav files are the same! Although they all end in .wav, depending on the recorder, the transcriptionist may need a special ‘codec’ to play it back. An example is the Sanyo recording system, which records specifically Sanyo .wav files. You should check that your transcriptionist has the ability to transcribe Sanyo .WAVs. If not, Sanyo may oblige by sending out the relevant codec on CD, for a charge. Alternatively, you can convert the .WAV file to an .MP3 file with mp3compr09f.zip - standard audio file format used mainly in Windows PCs. Commonly used for storing uncompressed (PCM), CD-quality sound files, which means that they can be large in size - around 10MB per minute of music. It is less well known that wave files can also be encoded with a variety of codecs to reduce the file size (for example the GSM or mp3 codecs). |
| MPEG/.MP3 (Winamp, Download Free ) winamp274_full.exe | MPEG-1 Audio Layer 3 is a compressed WAV file often used in music. Many digital recorders will also record MP3 or allow you to record WAV and then compress to MP3. The compressed files will be around a twelfth the size of WAV files. However, should you want to replay this file in >MP3 format, go to mp32wav.zip and download the converter. - the MPEG Layer-3 format is the most popular format for downloading and storing music. By eliminating portions of the audio file that are essentially inaudible, mp3 files are compressed to roughly one-tenth the size of an equivalent PCM file while maintaining good audio quality. We recommend the mp3 format for music storage. It is not that good for voice storage. |
| .WMA (Windows Media Player) |
Windows Media Audio was developed for Windows Media Player, which is bundled with all Windows-based PCs these days. It is even more compressed than an MP3 - to about one thirty-sixth the size of a .wav - and smaller to send than a .WAV file, there is a considerable loss of sound quality. - the popular Windows Media Audio format owned by Microsoft. Designed with Digital Rights Management (DRM) abilities for copy protection. |
| .DSS (Olympus Professional, Olympus Light) |
Digital Standard Speech. The .dss file format was developed by Olympus, who also provide playback software for this format via http://www.olympus-europa.com/consumer /2590_software.cfm. DSS files are usually only 1/12th to 1/20th the size of conventional WAVE files. Digital Speech Standard files are an Olympus proprietary format. It is a fairly old and poor codec. Prefer gsm or mp3 where the recorder allows. |
| .DCT | Encrypted dictation. Often used for medical transcription requiring confidentiality. The recording is encrypted at the recording end and needs to be decrypted on receipt. A wide variety of playback software will deal with these files. - A variable codec format designed for dictation. It has dictation header information and can be encrypted (often required by medical confidentiality laws). |
| True Speech | TrueSpeech, from the DSP group, was designed for personal computers and personal communications devices. It has very high compression ratios ranging from 15:1 to 27:1 and is not a good format for interview/focus group recording. |
| .CDA | CD Audio File. These files are standard recordings onto CD, and are generally the file type of music files bought on CD. Most transcription recorders will not record CDA. If you are having a professional recording made of a conference or series of lectures, for example, you may well find yourself with CDA files. Most transcription software will not play back CDA format, although it is possible to convert the audio file to a .WAV file by downloading CDEX_130.zip converter. |
ogg
- a free, open source container format supporting a variety of codecs, the most popular of which is the audio codec Vorbis. Vorbis files are often compared to MP3 files in terms of quality. But the simple fact mp3 are so much more broadly supported makes it difficult to recommend ogg files.gsm
- designed for telphony use in Europe, gsm is a very practical format for telephone quality voice. It makes a good compromise between file size and quality. We recommend this format for voice. Note that wav files can also be encoded with the gsm codec.flac
- a lossless compression codec. You can think of lossless compression as like zip but for audio. If you compress a PCM file to flac and then restore it again it will be a perfect copy of the original. (All the other codecs discussed here are lossy which means a small part of the quality is lost). The cost of this losslessness is that the compression ratio is not good. But we recommend flac for archiving PCM files where quality is important (eg. broadcast or music use).au
- the standard audio file format used by Sun, Unix and Java. The audio in au files can be PCM or compressed with the ulaw, alaw or G729 codecs.aiff
- the standard audio file format used by Apple. It is like a wav file for the Mac.vox
- the vox format most commonly uses the Dialogic ADPCM (Adaptive Differential Pulse Code Modulation) codec. Similar to other ADPCM formats, it compresses to 4-bits. Vox format files are similar to wave files except that the vox files contain no information about the file itself so the codec sample rate and number of channels must first be specified in order to play a vox file. Vox a very old file type and is pretty poor. We do not recommend it for anything except for supporting legacy systems.raw
- a raw file can contain audio in any codec but is usually used with PCM audio data. It is rarely used except for technical tests.aac-
the Advanced Audio Coding format is based on the MPEG4 audio standard owned by Dolby. A copy-protected version of this format has been developed by Apple for use in music downloaded from their iTunes Music Store.
atrac (.wav)
- the older style Sony ATRAC format. It always has a .wav file extension.ra
- a Real Audio format designed for streaming audio over the Internet. The .ra format allows files to be stored in a self-contained fashion on a computer, with all of the audio data contained inside the file itself.ram
- a text file that contains a link to the Internet address where the Real Audio file is stored. The .ram file contains no audio data itself.msv
- a Sony proprietary format for Memory Stick compressed voice files. You might need a Sony plugin to load this.dvf
- a Sony proprietary format for compressed voice files; commonly used by Sony dictation recorders. You might need a Sony plugin to load this.ape-
the .ape file format from Monkey's Audio is claimed to give about 50% compression without loss in audio quality.
atrac (.oma, .omg, .atp)
- the newer style Sony proprietary format designed for minidisc use. It always has a .oma, .omg or .atp file extension. It is similar to mp3 and probably only useful if you are reading files from minidiscs or writing for minidiscs. Note most of these files are rights managed so you cannot open them in any software programs.mid
- the midi file is not an audio file format at all. It is just a list of musical notes which a synthesizer can play.