[Freeswitch-users] Distortion on approx first 200ms of G722 prompts on DECT based CPE

[Keith Laaks]

Hi All,

 

I am testing a range of G722 capable DECT based CPE.

With one range, I have noticed that the first 200ms or so of each
separate prompt file being played back is played out distorted from the
DECT handset.

When having a normal conversation, the quality is excellent, but when
accessing your vmail, all the individual audio files making up the menu
choices exhibit the distortion, which is pretty annoying.

The same unit using G729, alaw or ulaw works 100%.

 

I wonder if anybody else has uncounted this issue?

 

My guess at this point -

There may be a short break in the RTP between the separate files being
played out by FS that makes up any menu. 

During this time the DECT handset's AGC probably goes to MAX
amplification (as its not receiving any input during the short break in
RTP).

Then, when the RTP returns at the start of the next file, the AGC boosts
the audio into clipping zone and takes 200ms to dampen down back to
normal good levels.

 

Looks like in these devices the G722 encode/decode is actually done in
the DECT handset and not the voip-base unit.

 

Is there any parameter that can be set in FS to ensure that the RTP
keeps flowing, sending 'silence' between prompts ? Would be interesting
to validate the above 'guess'.

 

 

Best Regards

 

Keith

 

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