UserAgent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/68.0.3440.106 Safari/537.36

Steps to reproduce the problem:
I send SDP (b=AS:60), first the bitrate is as specified in the SDP, but after 10-15 seconds it increases to 3mbps (i see graph on chrome://webrtc-internals tabs). Perhaps something in the SDP is wrong?

type: answer, sdp: v=0
o=- 5109148505774599866 4 IN IP4 127.0.0.1
s=-
t=0 0
a=group:BUNDLE audio video data
a=msid-semantic: WMS
a=rcv-remote-session:5733736437684697799
a=rcv-pc-role:main
a=rcv-remote-party:52039bc9-ff50-4726-9ed8-bc47dfebc555
a=rcv-local-party:e9d9c794-d29a-46fc-9a8f-3149dcdb26fa
m=audio 60831 UDP/TLS/RTP/SAVPF 111 103 104 9 0 8 106 105 13 110 112 113 126
c=IN IP4 192.168.0.100
a=rtcp:9 IN IP4 0.0.0.0
a=candidate:2131708102 1 udp 2113937151 192.168.0.100 60831 typ host generation 0 network-cost 50
a=ice-ufrag:xKti
a=ice-pwd:eFSHx/h+Qyuxtdp8sHV/n571
a=ice-options:trickle
a=fingerprint:sha-256 FC:D6:50:D4:D2:3E:B3:73:D7:27:90:38:FC:0D:75:27:E3:6E:3D:DB:D4:6B:18:77:4F:FF:F6:56:DC:9F:84:D1
a=mid:audio
a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-level
a=recvonly
a=rtcp-mux
a=rtpmap:111 opus/48000/2
a=rtpmap:103 ISAC/16000
a=rtpmap:104 ISAC/32000
a=rtpmap:9 G722/8000
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:110 telephone-event/48000
a=rtpmap:112 telephone-event/32000
a=rtpmap:113 telephone-event/16000
a=rtpmap:126 telephone-event/8000
a=rtcp-fb:111 transport-cc
a=fmtp:111 minptime=10;useinbandfec=1
a=setup:active
m=video 9 UDP/TLS/RTP/SAVPF 102 100 96 98 124 108 101 99 97 127 122 125 107 109 123
c=IN IP4 0.0.0.0
a=rtcp:9 IN IP4 0.0.0.0
a=ice-ufrag:xKti
a=ice-pwd:eFSHx/h+Qyuxtdp8sHV/n571
a=ice-options:trickle
a=fingerprint:sha-256 FC:D6:50:D4:D2:3E:B3:73:D7:27:90:38:FC:0D:75:27:E3:6E:3D:DB:D4:6B:18:77:4F:FF:F6:56:DC:9F:84:D1
a=mid:video
a=extmap:2 urn:ietf:params:rtp-hdrext:toffset
a=extmap:3 http://www.webrtc.org/experiments/rtp-hdrext/abs-send-time
a=extmap:4 urn:3gpp:video-orientation
a=extmap:5 http://www.ietf.org/id/draft-holmer-rmcat-transport-wide-cc-extensions-01
a=extmap:6 http://www.webrtc.org/experiments/rtp-hdrext/playout-delay
a=extmap:7 http://www.webrtc.org/experiments/rtp-hdrext/video-content-type
a=extmap:8 http://www.webrtc.org/experiments/rtp-hdrext/video-timing
a=recvonly
a=rtcp-mux
a=rtcp-rsize
a=rtpmap:102 H264/90000
a=rtpmap:100 H264/90000
a=rtpmap:96 VP8/90000
a=rtpmap:98 VP9/90000
a=rtpmap:124 ulpfec/90000
a=rtpmap:108 red/90000
a=rtpmap:101 rtx/90000
a=rtpmap:99 rtx/90000
a=rtpmap:97 rtx/90000
a=rtpmap:127 H264/90000
a=rtpmap:122 rtx/90000
a=rtpmap:125 H264/90000
a=rtpmap:107 rtx/90000
a=rtpmap:109 rtx/90000
a=rtpmap:123 rtx/90000
a=rtcp-fb:102 goog-remb
a=rtcp-fb:102 transport-cc
a=rtcp-fb:102 ccm fir
a=rtcp-fb:102 nack
a=rtcp-fb:102 nack pli
a=rtcp-fb:100 goog-remb
a=rtcp-fb:100 transport-cc
a=rtcp-fb:100 ccm fir
a=rtcp-fb:100 nack
a=rtcp-fb:100 nack pli
a=rtcp-fb:96 goog-remb
a=rtcp-fb:96 transport-cc
a=rtcp-fb:96 ccm fir
a=rtcp-fb:96 nack
a=rtcp-fb:96 nack pli
a=rtcp-fb:98 goog-remb
a=rtcp-fb:98 transport-cc
a=rtcp-fb:98 ccm fir
a=rtcp-fb:98 nack
a=rtcp-fb:98 nack pli
a=rtcp-fb:127 goog-remb
a=rtcp-fb:127 transport-cc
a=rtcp-fb:127 ccm fir
a=rtcp-fb:127 nack
a=rtcp-fb:127 nack pli
a=rtcp-fb:125 goog-remb
a=rtcp-fb:125 transport-cc
a=rtcp-fb:125 ccm fir
a=rtcp-fb:125 nack
a=rtcp-fb:125 nack pli
a=fmtp:102 level-asymmetry-allowed=1;packetization-mode=1;profile-level-id=42e01f
a=fmtp:100 level-asymmetry-allowed=1;packetization-mode=1;profile-level-id=42001f
a=fmtp:101 apt=100
a=fmtp:99 apt=98
a=fmtp:97 apt=96
a=fmtp:127 level-asymmetry-allowed=1;packetization-mode=1;profile-level-id=4d0032
a=fmtp:122 apt=127
a=fmtp:125 level-asymmetry-allowed=1;packetization-mode=1;profile-level-id=640032
a=fmtp:107 apt=125
a=fmtp:109 apt=108
a=fmtp:123 apt=102
a=setup:active
m=application 9 DTLS/SCTP 5000
c=IN IP4 0.0.0.0
b=AS:60
a=ice-ufrag:xKti
a=ice-pwd:eFSHx/h+Qyuxtdp8sHV/n571
a=ice-options:trickle
a=fingerprint:sha-256 FC:D6:50:D4:D2:3E:B3:73:D7:27:90:38:FC:0D:75:27:E3:6E:3D:DB:D4:6B:18:77:4F:FF:F6:56:DC:9F:84:D1
a=mid:data
a=sctpmap:5000 webrtc-datachannel 1024
a=setup:active

What is the expected behavior?

What went wrong?
The bitrate is not limited in SDP

Did this work before? N/A 

Does this work in other browsers? N/A

Chrome version: 68.0.3440.106  Channel: stable
OS Version: 10.0
Flash Version: Shockwave Flash 30.0 r0