[Freeswitch-users] codec negotiation weirdness

Brian J. Tarricone

2013-02-16 11:40:07 UTC

Sorry about the self reply, but I figured out something new: if I
don't specify the codec params in inbound-codec-prefs, and instead
just specify:

opus,isac,speex at ***@20i,speex at ***@20i,PCMU

... then isac does get selected when opus isn't advertised by the client:

2013-02-16 03:23:53.045715 [DEBUG] sofia_glue.c:5139 Audio Codec
Compare [ISAC:103:16000:30:0]/[opus:116:48000:40:32000]
2013-02-16 03:23:53.045715 [DEBUG] sofia_glue.c:5139 Audio Codec
Compare [ISAC:104:32000:30:0]/[opus:116:48000:40:32000]
2013-02-16 03:23:53.045715 [DEBUG] sofia_glue.c:5139 Audio Codec
Compare [PCMU:0:8000:20:64000]/[opus:116:48000:40:32000]
2013-02-16 03:23:53.045715 [DEBUG] sofia_glue.c:5139 Audio Codec
Compare [PCMA:8:8000:20:64000]/[opus:116:48000:40:32000]
2013-02-16 03:23:53.045715 [DEBUG] sofia_glue.c:5139 Audio Codec
Compare [CN:106:32000:20:0]/[opus:116:48000:40:32000]
2013-02-16 03:23:53.045715 [DEBUG] sofia_glue.c:5139 Audio Codec
Compare [CN:105:16000:20:0]/[opus:116:48000:40:32000]
2013-02-16 03:23:53.045715 [DEBUG] sofia_glue.c:5139 Audio Codec
Compare [CN:13:8000:20:0]/[opus:116:48000:40:32000]
2013-02-16 03:23:53.045715 [DEBUG] sofia_glue.c:5139 Audio Codec
Compare [telephone-event:126:8000:20:0]/[opus:116:48000:40:32000]
2013-02-16 03:23:53.045715 [DEBUG] sofia_glue.c:5268 Set 2833 dtmf
send/recv payload to 126
2013-02-16 03:23:53.045715 [DEBUG] sofia_glue.c:5139 Audio Codec
Compare [ISAC:103:16000:30:0]/[isac:99:32000:60:160000]
2013-02-16 03:23:53.045715 [DEBUG] sofia_glue.c:5161 Bah HUMBUG!
Sticking with isac at ***@60i

However, in that case it picks a 60ms ptime, which is not what I want.
FS startup messages seem to indicate the isac version I'm using does
support 30ms:

2013-02-16 03:21:49.163553 [NOTICE] switch_loadable_module.c:187
Adding Codec isac 99 isac 32000hz 60ms 160000bps
2013-02-16 03:21:49.163562 [NOTICE] switch_loadable_module.c:187
Adding Codec isac 99 isac 32000hz 30ms 160000bps
2013-02-16 03:21:49.163567 [NOTICE] switch_loadable_module.c:187
Adding Codec isac 99 isac 16000hz 60ms 53400bps
2013-02-16 03:21:49.163572 [NOTICE] switch_loadable_module.c:187
Adding Codec isac 99 isac 16000hz 30ms 53400bps

Why won't it let me select 30ms? Why does FS auto-select 60ms when I
don't specify a preference?

Forgot to mention before: I'm using current git master, rev 9733740.

Post by Brian J. Tarricone
Hi all,
I'm experiencing some strange behavior with codec negotiation. I'm
using the default early negotiation, and I'm setting
inbound-codec-negotiation to "scrooge" so FS will always have the
final word on what codec is used. (I've also tried "greedy" with the
same results. "generous" does not meet my needs, unfortunately.)
However, I'm seeing FS select PCMU for a client that advertises both
isac/32k and PCMU. The relevant portion of the FS log is below.
v=0
o=- 1772524861 1772524861 IN IP4 10.70.209.126
s=-
c=IN IP4 10.70.209.126
t=0 0
m=audio 57178 RTP/AVP 103 104 0 8 106 105 13 126
c=IN IP4 10.70.209.126
a=rtpmap:103 ISAC/16000
a=rtpmap:104 ISAC/32000
a=rtpmap:0 PCMU/8000
a=rtpmap:8 PCMA/8000
a=rtpmap:106 CN/32000
a=rtpmap:105 CN/16000
a=rtpmap:13 CN/8000
a=rtpmap:126 telephone-event/8000
2013-02-16 01:45:06.947647 [DEBUG] sofia_glue.c:5139 Audio Codec
Compare [ISAC:103:16000:30:0]/[opus:116:48000:20:32000]
2013-02-16 01:45:06.947647 [DEBUG] sofia_glue.c:5139 Audio Codec
Compare [ISAC:104:32000:30:0]/[opus:116:48000:20:32000]
2013-02-16 01:45:06.947647 [DEBUG] sofia_glue.c:5139 Audio Codec
Compare [PCMU:0:8000:20:64000]/[opus:116:48000:20:32000]
2013-02-16 01:45:06.947647 [DEBUG] sofia_glue.c:5139 Audio Codec
Compare [PCMA:8:8000:20:64000]/[opus:116:48000:20:32000]
2013-02-16 01:45:06.947647 [DEBUG] sofia_glue.c:5139 Audio Codec
Compare [CN:106:32000:20:0]/[opus:116:48000:20:32000]
2013-02-16 01:45:06.947647 [DEBUG] sofia_glue.c:5139 Audio Codec
Compare [CN:105:16000:20:0]/[opus:116:48000:20:32000]
2013-02-16 01:45:06.947647 [DEBUG] sofia_glue.c:5139 Audio Codec
Compare [CN:13:8000:20:0]/[opus:116:48000:20:32000]
2013-02-16 01:45:06.947647 [DEBUG] sofia_glue.c:5139 Audio Codec
Compare [telephone-event:126:8000:20:0]/[opus:116:48000:20:32000]
2013-02-16 01:45:06.947647 [DEBUG] sofia_glue.c:5268 Set 2833 dtmf
send/recv payload to 126
2013-02-16 01:45:06.947647 [DEBUG] sofia_glue.c:5139 Audio Codec
Compare [ISAC:103:16000:30:0]/[SPEEX:99:16000:20:42200]
2013-02-16 01:45:06.947647 [DEBUG] sofia_glue.c:5139 Audio Codec
Compare [ISAC:104:32000:30:0]/[SPEEX:99:16000:20:42200]
2013-02-16 01:45:06.947647 [DEBUG] sofia_glue.c:5139 Audio Codec
Compare [PCMU:0:8000:20:64000]/[SPEEX:99:16000:20:42200]
2013-02-16 01:45:06.947647 [DEBUG] sofia_glue.c:5139 Audio Codec
Compare [PCMA:8:8000:20:64000]/[SPEEX:99:16000:20:42200]
2013-02-16 01:45:06.947647 [DEBUG] sofia_glue.c:5139 Audio Codec
Compare [CN:106:32000:20:0]/[SPEEX:99:16000:20:42200]
2013-02-16 01:45:06.947647 [DEBUG] sofia_glue.c:5139 Audio Codec
Compare [CN:105:16000:20:0]/[SPEEX:99:16000:20:42200]
2013-02-16 01:45:06.947647 [DEBUG] sofia_glue.c:5139 Audio Codec
Compare [CN:13:8000:20:0]/[SPEEX:99:16000:20:42200]
2013-02-16 01:45:06.947647 [DEBUG] sofia_glue.c:5139 Audio Codec
Compare [telephone-event:126:8000:20:0]/[SPEEX:99:16000:20:42200]
2013-02-16 01:45:06.947647 [DEBUG] sofia_glue.c:5268 Set 2833 dtmf
send/recv payload to 126
2013-02-16 01:45:06.947647 [DEBUG] sofia_glue.c:5139 Audio Codec
Compare [ISAC:103:16000:30:0]/[SPEEX:99:8000:20:24600]
2013-02-16 01:45:06.947647 [DEBUG] sofia_glue.c:5139 Audio Codec
Compare [ISAC:104:32000:30:0]/[SPEEX:99:8000:20:24600]
2013-02-16 01:45:06.947647 [DEBUG] sofia_glue.c:5139 Audio Codec
Compare [PCMU:0:8000:20:64000]/[SPEEX:99:8000:20:24600]
2013-02-16 01:45:06.947647 [DEBUG] sofia_glue.c:5139 Audio Codec
Compare [PCMA:8:8000:20:64000]/[SPEEX:99:8000:20:24600]
2013-02-16 01:45:06.947647 [DEBUG] sofia_glue.c:5139 Audio Codec
Compare [CN:106:32000:20:0]/[SPEEX:99:8000:20:24600]
2013-02-16 01:45:06.947647 [DEBUG] sofia_glue.c:5139 Audio Codec
Compare [CN:105:16000:20:0]/[SPEEX:99:8000:20:24600]
2013-02-16 01:45:06.947647 [DEBUG] sofia_glue.c:5139 Audio Codec
Compare [CN:13:8000:20:0]/[SPEEX:99:8000:20:24600]
2013-02-16 01:45:06.947647 [DEBUG] sofia_glue.c:5139 Audio Codec
Compare [telephone-event:126:8000:20:0]/[SPEEX:99:8000:20:24600]
2013-02-16 01:45:06.947647 [DEBUG] sofia_glue.c:5268 Set 2833 dtmf
send/recv payload to 126
2013-02-16 01:45:06.947647 [DEBUG] sofia_glue.c:5139 Audio Codec
Compare [ISAC:103:16000:30:0]/[PCMU:0:8000:20:64000]
2013-02-16 01:45:06.947647 [DEBUG] sofia_glue.c:5139 Audio Codec
Compare [ISAC:104:32000:30:0]/[PCMU:0:8000:20:64000]
2013-02-16 01:45:06.947647 [DEBUG] sofia_glue.c:5139 Audio Codec
Compare [PCMU:0:8000:20:64000]/[PCMU:0:8000:20:64000]
2013-02-16 01:45:06.947647 [DEBUG] sofia_glue.c:5161 Bah HUMBUG!
As you can see, it first compares all offered codecs against opus/48k,
next skips isac completely, then goes to speex/16k, speex/8k, and
PCMU, and eventually grudgingly accepts PCMU.
Interestingly, if I drop opus from the list, and leave the rest as-is,
2013-02-16 01:51:10.691314 [DEBUG] sofia_glue.c:5139 Audio Codec
Compare [ISAC:103:16000:30:0]/[isac:99:32000:30:160000]
2013-02-16 01:51:10.691314 [DEBUG] sofia_glue.c:5161 Bah HUMBUG!
It picks isac/32k after only examining the isac/16k line in the SDP,
before it even gets to isac/32k. (In fact those are the only 2 lines
after the SDP is printed; it makes the decision after making just one
comparison.)
Any ideas? Am I just misunderstanding how this works?
Thanks,
Brian