Kofax Communication Server Line Server Model 305 Manual
How the selection of encoding scheme works:
1. Playing of the voice data (voice prompts, voice mails):
The voice application checks whether the (source) format of the voice data to be played matches
with one of the encoding schemes supported by LS1.
• If the format matches, the voice data is being played transparently via LS1.
• If the format does not match, the voice application must perform the appropriate format conversion
(via the resource engine – part of the voice application).
2. Recording of the voice data (voice mails, personal greetings): The destination format for
recorded voice messages is configured during the voice applications’ setup (refer to the TC/
VoiceAccess User Manual).
• If the configured destination format matches one of the encoding schemes supported by the LS1,
the voice data received from LS1 is being transparently stored.
• If the configured destination format does not match, voice application must perform the
appropriate format conversion.
Advantage: If all pre-recorded voice prompts and also recorded voice data would be stored/recorded in
the G.711 u-law or A-law format, the overall quality of Kofax Communication Server voice data streams
would achieve better signal-to-noise ratio (SNR) and thus subjectively better quality.
Compatibility Issues
Format conversions between A-law and u-law G.711 variants
If the G.711 variant to be used Kofax Communication Server internally differs from the one used in the
country’s telephone network, the A-law/u-law conversion is being performed by the LS1 transparently
without lost of quality. Therefore, a set of voice prompts recorded in A-law may be used in countries using
the u-law standard, and vice versa.
For example, this may occur if Kofax Communication Server voice prompts are recorded in the u-law
format but the voice server is used in Europe (using A-law format in the telephone network).
Playing of previously recorded personal greetings and voice mails
If previous messages were recorded in 8kHz 8 bit linear PCM format and they can be played via LS1
server as usual. However, if user would like to benefit from the better G.711 encoding quality, they should
re-record their own personal greetings/names.
Playing of voice messages using A-law or u-law encoding scheme
If a voice message recorded in the G.711 A-law or u-law format is to be played by TC/Player via telephone
on a workstation using TCCP older than 5.05.00, the G.711 encoded voice data stream is at first
converted to PCM 8kHz 8 bit format and played afterwards. The consequence of this conversion is a
slightly worse quality of the playback.
This drawback is caused by the resource engine (TCE_RES.DLL) older than 2.06.00 that does not
recognize all 3 audio destination formats supported by the LS1. It "sees" only the first of supported
formats, the PCM 8kHz 8 bit and therefore converts G.711 encoded data to this format at first. On the
other hand, this drawback does not occur if playing messages via TUI interface.
To reach a better G.711 quality also for the TC/Player playback, the client side should be upgraded to
TCCP 5.05.05 or later.
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