Digital File Formats Used for Transcription Services
Transcription service providers usually advise clients to use digital audio and video recordings whenever possible. The superior quality of digital recordings makes it easier, faster, and more cost-effective to obtain better-quality transcripts than those produced from traditional analogue tape transcription.
With all digital files, there is a tradeoff between recording quality and file size. Digital sound files can be extremely large if they are not compressed, but then compression is 'lossy.' In other words, if you compress an original 'lossless' audio file to a smaller size, this removes redundant data, but may also result in a reduction in audio quality, and create problems with the transcription. For transcription purposes, it is best not to compress digital recordings of multiple speakers where there is much background noise (conference transcription, focus group transcription, etc.). On the other hand, where the audio recording is of a lecture, one-to-one interview, or dictation, compressing the sound file normally will not affect its quality.
The multiple digital file formats available can be confusing when considering the recording device to buy and the transcription issues involved. Below is a list of some of the most common digital file formats:
- Digital Speech Standard (DSS): This file format has a high compression rate and uses less disk space for storing. It makes it possible to record many dictations on one devise, and allows high-speed transmission on the Internet. Using this file format allows you to save information such as, date, time and dictation length, too.
- MP3 Format: One of the most popular digital audio formats; it falls under the category of ‘lossy’ compression, but it produces very clear recordings. It is small in size, can be quickly uploaded, and needs less transmission time over the Internet.
- Waveform or WAV files: In a wave file, unprocessed data is stored in a raw form (‘lossless’), ensuring superb audio quality. The wave file format is not suitable for transmission over the Internet and uses a lot of disk space because WAV files are uncompressed.
- MP4 Format: Very similar to MP3 files, but also has the ability to compress video files.
- AIFF (Audio Interchange File Format) is a file format used by Macintosh computers and Silicon Graphics Inc. to store and transmit high-quality audio data such as music. AIFF files are uncompressed, making the files quite large compared to the MP3 format, for example.
- FLAC (Free Lossless Audio Codec) is a compression technique that preserves original audio quality while reducing file size. Compression techniques take large files such as .wav files and reduce the data bits while preserving as much of the audio quality as possible.
- APE is a lossless audio compression format. It is a fast and easy way to compress digital music, but its decompression speeds are slow compared to other lossless audio codecs, and one of its main competitors is FLAC.
- TAK is a lossless audio compressor, similar to FLAC and APE. Its compression efficiency matches that of APE and it can achieve decompression speeds similar to FLAC.
- TTA (The True Audio) is a free real-time lossless audio compressor that offers adequate compression levels while maintaining high operation speeds. Having no loss in data or quality, TTA compresses files to as little as 30% of their original size.
- WMA (Windows Media Audio) is an audio file format developed by Microsoft, the maker of Windows Media Player, for encoding digital audio files similar to MP3 though it can compress files at a higher rate than MP3.
- Ogg Vorbis is an audio compression format, comparable to other formats used to store digital sound. It is free, open and unpatented.
- AAC (Advanced Audio Coding) is one of the audio compression formats defined by the MPEG-2 standard. It is not compatible with theMPEG-1 coding scheme.
- Mpeg4: includes many of the features of Mpeg1 and Mpeg2 with added new features. Apart from supporting audio and video, Mpeg4 can also support text, 3D objects and other media types. The Mpeg4 file format can deliver high-quality video at a smaller size.
Transcriptionsouthcarolina.com recommends that its transcription clients use digital recording formats whenever possible. However, it is important not to compromise on the quality of recordings for the sake of file size. For first rate transcription services and best turnaround times, we recommend that clients send us the original, full-sized digital file. |
