Supported voice data formats

VCE format

ActiveAG supports the VCE voice data format, developed by Natural MicroSystems Corporation. VCE is an ADPCM (Adaptive Differential Pulse Code Modulation) format. Voice data can be played and recorded in this format at 4 different rates.

AagConNMS16Voice	16 kilobits per second (maximum compression)
AagConNMS24Voice	24 kilobits per second
AagConNMS32Voice	32 kilobits per second
AagConNMS64Voice	64 kilobits per second (no compression)

As you might expect, the higher the bit rate, the better the quality of the voice data played and recorded. When designing your system you must make a trade-off between the disk space needed to store your voice data and the sound quality of that data. For example, 16KBS sampling requires the least disk space but the audio quality is poor relative to lower compression rates.

While 64KBS sampling gives outstanding audio quality, it requires a great deal more storage space. Most users of ActiveAG can get acceptable fidelity for human voice recordings by using 24KBS or 32KBS – which require less storage space than 64KBS data.

VOX format

Natural MicroSystems also developed a second voice data storage format named VOX. VOX files are structured files containing voice data segments – these segments are sometimes called “messages”. The individual segments stored in an NMS VOX file are encoded using the VCE format. In short, a VOX file provides a structure for storing multiple VCE-encoded messages in a single file. VCE files, by comparison, contain only one message. ActiveAG also supports VOX files.

Do not confuse NMS structured VOX files with Dialogic’s unstructured VOX files; both use the same file extension.

Other formats

There is limited support in ActiveAG for the 11 kHz WAV format used in Microsoft’s operating systems. ActiveAG can play and record audio data in the same format used for WAV files but it does not provide a RIFF header for the WAV files it records.

What does this mean? It means that your programs can play any WAV file (ones recorded by ActiveAG or by any other source) but that WAV files recorded by ActiveAG can only be played by ActiveAG. The reason for this is that since the WAV files recorded by ActiveAG have no RIFF headers, other applications can’t tell that they are WAV files.

CoolEdit 96

There is a very useful audio editor application available for Windows NT (and Windows 95) known as CoolEdit 96. This program provides a graphical means for trimming, amplifying, and otherwise editing audio data files. One of the most useful features of CoolEdit, though, is that it supports a very large number of audio formats – and can be used to convert files from one format to another. CoolEdit 96 supports the NMS VCE format. Therefore, it can be used to convert VCE to any of a number of formats, including WAV. The WAV files produced by CoolEdit do contain RIFF headers (by default) and so can be played by both ActiveAG and by any other application that supports WAV.