[Freeswitch-users] issue with ilbc and ptime between a call between webrtc client and freeswitch

[Dragos Oancea]

Hi,

I see in SDP "a=fmtp:102 mode=30" - which means 30 ms ptime for ILBC ,
but you also have the line "a=ptime:20". As you said, perhaps that's
what's confusing. Not sure which setting should prevail . Try iLBC at 30i
in the codec_string .

Dragos

On 03/10/2016 18:02, Michael Jerris wrote:
> libc at 20 is a totally valid rate for libc.  If they are rejecting that, you should file a bug with them.  Depending on how you are negotiating codecs you could force it by our normal codec negotiation settings.
> 
> 
>> On Oct 3, 2016, at 5:40 AM, Caragea Silviu <silviu.cpp at gmail.com> wrote:
>>
>> Hello,
>>
>> I have a call coming from FS and going via sip to a webrtc compliant client. 
>> Works fine as time the codec is not ILBC. If codec is ILBC is failing because 
>> Webrtc consider the codec as being invalid because of the ptime line. 
>>
>> Inside their code:
>>
>> bool IsILBCRateValid(int rate, int frame_size_samples) {
>>   if (((frame_size_samples == 240) || (frame_size_samples == 480)) &&
>>       (rate == 13300)) {
>>     return true;
>>   } else if (((frame_size_samples == 160) || (frame_size_samples == 320)) &&
>>       (rate == 15200)) {
>>     return true;
>>   } else {
>>     return false;
>>   }
>> }
>>
>> This is failing because rate will be 13300 and frame_size_samples will be 160.
>>
>> frame_size_samples = (8000 / 1000) * 20 which is 160. 
>>
>> How I can make fs to advertise correctly that the codec ILBC is 30 ms one and not 20 ?
>>
>> Here is the sdp that's generated:
>>
>> v=0
>> o=FreeSWITCH 1475470534 1475470535 IN IP4 91.231.138.218
>> s=FreeSWITCH
>> c=IN IP4 91.XXX.XXX.XXX
>> t=0 0
>> a=msid-semantic: WMS 5K3pT3kGUXTisXNhdMYGtMP1VGBmzT0v
>> a=end-of-candidates
>> m=audio 16430 RTP/SAVPF 102 0 103 101 104
>> a=rtpmap:102 iLBC/8000
>> a=fmtp:102 mode=30
>> a=rtpmap:0 PCMU/8000
>> a=rtpmap:103 isac/16000
>> a=fmtp:103 ibitrate=32000;maxbitrate=53400
>> a=rtpmap:101 telephone-event/8000
>> a=rtpmap:104 telephone-event/16000
>> a=fingerprint:sha-256 B9:24:01:90:AD:E6:43:60:10:F9:CA:3A:85:86:26:91:A6:41:A8:77:3B:F0:39:20:3C:50:0F:A3:5E:1F:48:03
>> a=setup:actpass
>> a=rtcp-mux
>> a=rtcp:16430 IN IP4 91.xxx.xxxx.xxx
>> a=ssrc:4159978388 cname:tTLcMVJxIsF1gi8j
>> a=ssrc:4159978388 msid:5K3pT3kGUXTisXNhdMYGtMP1VGBmzT0v a0
>> a=ssrc:4159978388 mslabel:5K3pT3kGUXTisXNhdMYGtMP1VGBmzT0v
>> a=ssrc:4159978388 label:5K3pT3kGUXTisXNhdMYGtMP1VGBmzT0va0
>> a=ice-ufrag:VWQeyw6k2xxshnNB
>> a=ice-pwd:6oDJad6JwBACKzMvlsAKOwUH
>> a=candidate:8788212768 1 udp 659136 91.XXX.XXX.XXX16430 typ host generation 0
>> a=candidate:8788212768 2 udp 659136 91.XXX.XXX.XXX16430 typ host generation 0
>> a=silenceSupp:off - - - -
>> a=ptime:20
>>
>> Silviu
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> 
> 
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