Audio Compression, Total Recorder - captures any audio from the Internet, records audio from CD, microphone, line-in, converts any sound formats to WAVE file, phone call recording system. Record audio from telephone calls. Ideal for agent monitoring in call center environments.

This page provides information about High Criteria's use of various compression algorithms. Issues discussed include:

wav File Compression and High Criteria,
mp3 File Compression and High Criteria,
A Comparison Chart of Compression Algorithms available to our products and
Changing Compression Options in Total Recorder and Dictation Buddy

wav File Compression and High Criteria

Both Total Recorder and Dictation Buddy support the industry standard "wav" file format for saving audio recordings. wav files are identified by the extension wav, just as Word files are identified by the extension doc. The wav files have a wav extension and consist of a fixed length header and a body. Wav files might be either compressed or uncompressed. The compression algorithm used (if any) is specified within the header. Within the wav format, a large number of compression algorithms are available. Quite a number of these algorithms are standard components within the Windows operating system. High Criteria does not produce any compression algorithms, but instead, its products make use of the algorithms supplied in Windows to provide a wide selection of compression options.

The different algorithms are designed and written for different applications. One algorithm may be best for high quality music reproduction, while another may be best for recording dictation or radio news broadcasts. Please keep in mind that any form of compression will usually have some affect on the quality of the reproduced sound. Users must balance the desire for high quality sound with the need to minimize the size of the recorded file.

mp3 File Compression and High Criteria

Users wishing to record large volumes of music should consider the mp3 recording format. mp3 was designed to retain high quality musical sound, while at the same time, provide very good compression. The mp3 compression algorithm can be used within a wav file or on its own, making an mp3 file with an mp3 extension. mp3 files with an mp3 extension do not contain a header.

Both Total Recorder and Dictation Buddy support the "mp3 compression within wav" file format that is provided as part of some Windows operating systems or may be purchased by the user. Go to the recording settings within Total Recorder or Dictation Buddy and look for MPEG Layer - 3 format option. If this option is available, then you can record in "mp3 within a wav" file format.

Total Recorder (but not Dictation Buddy) can use third-party software to create mp3 files with an mp3 extension. This software is not available from High Criteria and does not come with your Total Recorder download. Please follow this link for more information about obtaining and using this software with Total Recorder.

A Comparison Chart of Compression Algorithms

This comparison chart is meant to assist users in determining the compression algorithm that best addresses their requirements. Any assessments within the chart are purely subjective and should not be taken as endorsements of one algorithm over another. Users should test various algorithms to determine the one that best suits their needs.

Note that all of the algorithms described in the chart come with the Windows operating system and are always available to users of High Criteria products. Also, the chart is not a complete listing of the compression algorithms available within Windows. Other algorithms may be better suited to a specific purpose.

DSP Group Truespeech
General Application	DSP Truespeech is a highly compressed recording format generally used for recordings of conversations or dictations.
Approx MB per hour	3.5MB per hour
Possible Attributes	8,000kHz, 1 bit mono
Application	Used to provide compression for conversations and dictations. Not suitable for music.
GSM
General Application	GSM is a highly compressed recording format that is most often used to record dictation or conversations. At 8,000kHz 1 bit mono, it will record in a fashion similar to DSP Truespeech. At 44,100kHz mono, it will retain more sound quality than a DSP recording.
Approx MB per hour	Varies from 3.5MB per hour up to 28MB per hour, depending upon the attributes selected by the user.
Possible Attributes	8,000kHz, mono (voice quality) to 44,100kHz 16 bit stereo (CD quality)
Application	Use when high quality sound reproduction is required for conversations and dictation. Not suitable for music.
Microsoft ADPCM
General Application	Microsoft ADPCM is a general purpose algorithm that provides some compression while at the same time retaining a good quality of sound recording.
Approx MB per hour	Varies from 14.0MB per hour up to 151.2MB per hour, depending upon the attributes selected by the user.
Possible Attributes	8,000kHz, 4 bit mono (voice quality) to 44,100kHz 4 bit stereo (CD quality)
Application	Good general purpose algorithm with limited compression.
PCM
General Application	PCM is an uncompressed recording format that may be used for any application.
Approx MB per hour	Varies from 24.6MB per hour up to 657MB per hour, depending upon the attributes selected by the user.
Possible Attributes	8,000kHz, 8 bit mono (voice quality) to 48,000kHz 16 bit stereo (DVD quality)
Application	Use when high quality sound reproduction is required and recording space is unlimited.
IMA ADPCM
General Application	High quality, multi-purpose compression algorithm.
Approx MB per hour	Varies from 10.5MB per hour up to 151MB per hour, depending upon the attributes selected by the user.
Possible Attributes	8,000kHz, 4 bit mono (voice quality) to 44,100kHz 4 bit stereo (CD quality)
Application	Use when high quality sound reproduction is required and recording space is not an issue.
Lernout & Hauspie
General Application	Only suitable for voice recordings.
Approx MB per hour	Varies from 3.5MB per hour up to 7.0MB per hour, depending upon the attributes selected by the user.
Possible Attributes	8,000kHz, 8 bit mono (voice quality) for all selections.
Application	Use for voice and speech applications.
CCITT A-Law
General Application	Provides compatibility with European TAPI standards.
Approx MB per hour	Varies from 24.6MB per hour up to 302MB per hour, depending upon the attributes selected by the user.
Possible Attributes	8,000kHz, 8 bit mono to 41,100kHz, 8 bit stereo (CD quality)
Application	For TAPI devices.
CCITT u-Law
General Application	Provides compatibility with North American TAPI standards.
Approx MB per hour	Varies from 24.6MB per hour up to 302MB per hour, depending upon the attributes selected by the user.
Possible Attributes	8,000kHz, 8 bit mono to 41,100kHz, 8 bit stereo (CD quality)
Application	For TAPI devices.

Changing Compression Options in Total Recorder and Dictation Buddy

To change Compression Options within Total Recorder, select "Recording Source and Parameters" on the Total Recorder main menu. At the bottom of the box that appears, you will see the current parameter settings. You may alter these settings by selecting the "Change" button, next to the current settings. A drop down box then allows users to select the appropriate compression algorithm and attributes.

To change Compression Options within Dictation Buddy, select View==>Options==>Recording from the Dictation Buddy main menu. At the bottom of the box that appears, you will see the current parameter settings. You may alter these settings by selecting the "Change" button next to the current settings. A drop down box then allows users to select the appropriate compression algorithm and attributes.