[asterisk-dev] AST_FRAME_DIGITAL

[Mikael Magnusson]

Klaus Darilion wrote:
> 
> 
>>>> klaus
>>>>
>>> Have you considered CLEARMODE as defined in RFC 4040?
>>> I found a pcap sample in Wireshark wikipedia:
>>>
>>>     A sample of H.223 running over RTP, following negotiation over SIP.
>>>     http://wiki.wireshark.org/SampleCaptures
>>
>> By the way... very interesting.. 
>>
>> H.223
>> h223-over-iax.pcap.gz (libpcap) A sample of H.223 running over IAX.
>> h223-over-tcp.pcap.gz (libpcap) A sample of H.223 running over TCP. You'll need to select 'Decode as... H.223'.
>> h223-over-rtp.pcap.gz (libpcap) A sample of H.223 running over RTP, following negotiation over SIP.
> 
> indeed - this is very interesting. I wonder how wireshark knows that the 
> CLEARMODE payload is H.223? Is there somewhere an indication or it it 
> just hardcoded in the wireshark decoder?
> 

Yes, it's looks hardcoded in epan/dissectors/packet-h223.c, which 
registers the h223 dissector to handle "CLEARMODE".

Wireshark also has support for an IAX IE called "Data call format" 
IAX_IE_DATAFORMAT (255) which is defined as an enum, and is used to 
signal for example H.223 data.

   /* data format for IAX_IE_DATAFORMAT ie */
   /* suitable for use in iax2.dataformat dissector table */
   typedef enum {
       AST_DATAFORMAT_NULL,        /* N/A: analogue call etc */
       AST_DATAFORMAT_V110,        /* ITU-T V.110 rate adaption */
       AST_DATAFORMAT_H223_H245    /* ITU-T H.223/H.245 */
   } iax_dataformat_t;

Mikael