[Freeswitch-users] G722 16k or 8k?

[Stephen Dame]

Think I found my answer...

 

G.722 VoIP is typically carried in RTP
<http://en.wikipedia.org/wiki/Real-time_Transport_Protocol>  payload type 9.
<http://en.wikipedia.org/wiki/G.722#cite_note-1> [2] Note that IANA
<http://en.wikipedia.org/wiki/Internet_Assigned_Numbers_Authority>  records
the clock rate for type 9 G.722 as 8 kHz (instead of 16 kHz), RFC3551
<http://en.wikipedia.org/wiki/G.722#cite_note-2> [3] clarifies that this is
due to a historical error and is retained in order to maintain backward
compatibility. Consequently correct implementations represent the value
8,000 where required but encode and decode audio at 16 kHz.

Whilst G.722 allows for bitrates of 64, 56 and 48 kbit/s, in practice, data
is encoded at 64 kbit/s, with bits from the lower sub-band being used to
encode auxiliary data. The greater the number of bits allocated to aux data,
the lower the bit rate.

Regards,

Stephen

 

From: freeswitch-users-bounces at lists.freeswitch.org
[mailto:freeswitch-users-bounces at lists.freeswitch.org] On Behalf Of Stephen
Dame
Sent: Thursday, February 23, 2012 10:35 AM
To: 'FreeSWITCH Users Help'
Subject: [Freeswitch-users] G722 16k or 8k?

 

Question on G722,   trying to see if the quality of basic g.722 is much
better than the standard g729 or g711.

 

Looking at wiki docs.  "G722 - G722 16kHz using default 20ms ptime.
(multiples of 10)"

 

However, when I connect to freeswitch using blink client I see  G722/8000?
I thought this would be 16000.        I know when I connect using speex wb,
it shows 16000.

 

 

2012-02-23 10:20:07.116606 [DEBUG] mod_sofia.c:750 Local SDP
sofia/internal/1004 at 107.XX.XX.XX:

v=0

o=FreeSWITCH 1329993171 1329993172 IN IP4 107.XX.XXX.XXX

s=FreeSWITCH

c=IN IP4 107.XX.XXX.XXX

t=0 0

m=audio 17236 RTP/AVP 9 101

a=rtpmap:9 G722/8000

a=rtpmap:101 telephone-event/8000

a=fmtp:101 0-16

a=silenceSupp:off - - - -

a=ptime:20

a=sendrecv

 

Shouldn't this be 16000?

 

Thanks

Stephen

 

 

 

 

 

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