[Asterisk-video] capability translation from h245 to SIP

[Sergio Garcia Murillo]

In Asterisk 1.4 the only thing that can be configured for video is de 
codec, so there is not much problem as the only one supported is 
h263-1998/2000 for sending and h263-1996 h263-1998/2000 for receiving. 
Using the videocaps branch we could map the codec parameters to the SDP 
offer.

Best regards
Sergio

Dan Julius escribió:
> Hi, Sergio,
>
> If there is no capability mapping, how does asterisk decide what 
> capabilities to put in the SDP body of the SIP Invite message?
>
>
> When I originate a call from a Nokia N73 to a SIP client, the Invite 
> message includes and SDP section for video:
> m=video 10070 RTP/AVP 34 103
> a=rtpmap:103 h263-1998/90000
> a=sendrecv
>   
>
> When I originate a call from a Nokia N95 the SDP is different and also 
> includes the h263/9000 capability:
> m=video 10120 RTP/AVP 34 103
>
> a=rtpmap:34 H263/90000
> a=rtpmap:103 h263-1998/90000
> a=sendrecv
>   
>
>
>
> Thanks,
> Dan
>
> On Tue, Sep 9, 2008 at 11:54 AM, Sergio Garcia Murillo 
> <sergio.garcia at fontventa.com <mailto:sergio.garcia at fontventa.com>> wrote:
>
>     Hi Dan,
>
>     There is no capability negotiation, or mapping between SIP and the
>     h245, I send fixed ones For H263 and AMR:
>
>
>               [0]={
>                 capabilityTableEntryNumber = 1
>                 capability = receiveAndTransmitVideoCapability
>     h263VideoCapability {
>                   qcifMPI = 2
>                   maxBitRate = 520
>                   unrestrictedVector = FALSE
>                   arithmeticCoding = FALSE
>                   advancedPrediction = FALSE
>                   pbFrames = FALSE
>                   temporalSpatialTradeOffCapability = FALSE
>                   errorCompensation = FALSE
>                 }
>               }
>               [1]={
>                 capabilityTableEntryNumber = 2
>                 capability = receiveAndTransmitAudioCapability
>     genericAudioCapability {
>                   capabilityIdentifier = standard 0.0.8.245.1.1.1
>                   maxBitRate = 122
>                   collapsing = 1 entries {
>                     [0]={
>                       parameterIdentifier = standard 0
>                       parameterValue = unsignedMin 1
>                     }
>                   }
>                 }
>               }
>     .
>
>     Best regards
>     Sergio
>
>     Dan Julius escribió:
>>     Hi,
>>
>>     I'm experiencing some issues when using Asterisk as a gateway
>>     between 3G and SIP clients.
>>     I'm trying to complete a call using h263p as the video codec on
>>     the sip client in order to avoid  video transcoding.
>>     For audio I'm using AMR on the 3G side and g711 on the SIP side
>>     since most SIP clients don't support AMR out of the box.
>>
>>     For some phones this works without a problem while other phones
>>     don't seem to show video depending on the SIP client.
>>     For example: N73 works with X-Lite, but not with OpenPhone. N95
>>     works with both.
>>     I've traced this down to an issue with the capability exchange,
>>     specifically how capabilities are translated from h245 to SIP.
>>
>>     Can someone point to which part of the code, Asterisk or libh324M
>>     does the mapping between capabilities?
>>     After reviewing some relevant RFCs and specs, it is not clear to
>>     me what the 1:1 mapping should be - is there any relevant
>>     documentation?
>>
>>     Thanks,
>>     Dan
>>
>>
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