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Global Call IP Technology Guide — November 2007 127
Dialogic Corporation
IP-Specific Operations
See the reference page for IP_CAPABILITY on page 543 for more information.
Table 2 shows the coders that are supported when using the Dialogic
®
Global Call API with
Dialogic
®
Host Media Processing (HMP) Software.
Note: When using low bit-rate (LBR) coders, reliable in-band transmission of DTMF tones is not
possible.
4.3.2.1 Specifying Media Capabilities Before Connection
Applications can only specify media capabilities before initial call connection. For an outbound
call, capabilities must be set before or with the gc_MakeCall( ). For inbound calls, capabilities
must be set before or with the gc_AnswerCall( ), but it is recommended that they be set before
Table 2. Coders Supported for Dialogic
®
Host Media Processing (HMP) Software
Coder
and Rate
Dialogic
®
Global Call API #
Define
Frames Per Packet (fpp)
and Frame Size (ms)
VAD Support
G.711 A-law GCCAP_AUDIO_g711Alaw64k Frame size
1
: 10, 20, or 30 ms
Frames per Packet: fixed at 1 fpp
Not supported;
must be explicitly
disabled
G.711 mu-law GCCAP_AUDIO_g711Ulaw64k Frame size
1
: 10, 20, or 30 ms
Frames per packet: fixed at 1 fpp
Not supported;
must be explicitly
disabled
G.723.1
5.3 kbps
GCCAP_AUDIO_g7231_5_3k Frames per packet: 2 or 3
Frame size: fixed at 30 ms
Supported
G.723.1,
6.3 kbps
GCCAP_AUDIO_g7231_6_3k Frames per packet: 2 or 3
Frame size: fixed at 30 ms
Supported
G.726,
16 kbps
GCCAP_AUDIO_g726_16k Frames per packet: 1, 2, or 3
Frame size: fixed at 20 ms
Not supported;
must be explicitly
disabled
G.726,
24 kbps
GCCAP_AUDIO_g726_24k Frames per packet: 1, 2, or 3
Frame size: fixed at 20 ms
Not supported;
must be explicitly
disabled
G.726,
32 kbps
GCCAP_AUDIO_g726_32k Frames per packet: 1, 2, or 3
Frame size: fixed at 20 ms
Not supported;
must be explicitly
disabled
G.726,
40 kbps
GCCAP_AUDIO_g726_40k Frames per packet: 1, 2, or 3
Frame size: fixed at 20 ms
Not supported;
must be explicitly
disabled
G.729a GCCAP_AUDIO_g729AnnexA Frames per packet: 2, 3, or 4
Frame size: fixed at 10 ms
Not supported;
must be explicitly
disabled
G.729a+b GCCAP_AUDIO_g729AnnexA
wAnnexB
Frames per packet: 2, 3, or 4
Frame Size: fixed at 10 ms
Must be enabled
2
T.38 GCCAP_DATA_t38UDPFax Not applicable Not applicable
Note:
1. For G.711 coders, the frames_per_pkt field of the IP_AUDIO_CAPABILITY structure is actually used to specify the frame
size rather than the fpp. See the reference page for IP_AUDIO_CAPABILITY on page 541 for more information.
2. Applications must explicitly specify VAD support even though G.729a+b implicitly supports VAD.