Patton electronic 07MSMARTMEDIA-SCG Universal Remote User Manual


 
Configuring Codecs and Tone Detection 64
Smart Media Software Configuration Guide 3 • Configuring an ISDN-SIP Gateway
cific parameters may be any set of parameters required to be conveyed by SDP and given unchanged to the
media tool that will use this format.
a=ptime:<packet time>
This gives the length of time in milliseconds represented by the media in a packet. This is probably only mean-
ingful for audio data. It should not be necessary to know pt
ime to decode RTP or vat audio, and it is intended
as a recommendation for the encoding/packetisation of audio. It is a media attribute, and is not dependent on
charset.
Examples. Here are some examples of the attributes found in the default profile SDP description:
a=rtpmap:97 iLBC/8000
a=fmtp:97 mode=20
The above defines iLBC codec of 8000/sec sample rate with 20ms frame size.
a=rtpmap:98 telephone-event/8000
The above defines the DTMF relay using RFC2833.
Here is another example, enabling Voice Activity Detection (VAD) for G.711 ulaw, G.711 alaw, G.723.1a
and
G.729b, in addition to telephony events:
m=audio 0 RTP/AVP 0 8 4 18 98 13
a=rtpmap:0 PCMU/8000
a=rtpmap:8 PCMA/8000
a=rtpmap:4 G723/8000
a=fmtp:4 bitrate=6300;annexa=yes
a=rtpmap:18 G729/8000
a=fmtp:18 annexb=yes
a=rtpmap:98 telephone-event/8000
a=fmtp:98 0-15
a=rtpmap:13 CN/8000
This one is for a direct SIP INVITE with T.38. This can be useful if you know this route will always be with
fax. It also doesn't require any IVR resources to detect the fax tones:
m=image 0 udptl t38
a=T38FaxVersion:0
a=T38MaxBitRate:14400
a=T38FaxFillBitRemoval:0
a=T38FaxTranscodingMMR:0
a=T38FaxTranscodingJBIG:0
a=T38FaxRateManagement:transferredTCF
a=T38FaxMaxBuffer:400
a=T38FaxMaxDatagram:400
a=T38FaxUdpEC:t38UDPRedundancy