# Producer RTCP-RR, packet sender ssrc problem.

**URL:** <https://mediasoup.discourse.group/t/producer-rtcp-rr-packet-sender-ssrc-problem/2786>\
**Category:** mediasoup libraries\
**Created:** [May 13, 2021, 12:32pm UTC](https://mediasoup.discourse.group/t/producer-rtcp-rr-packet-sender-ssrc-problem/2786 "2021-05-13T12:32:18Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![WangHoi](https://yyz2.discourse-cdn.com/free1/user_avatar/mediasoup.discourse.group/wanghoi/32/958_2.png) [@WangHoi](https://mediasoup.discourse.group/u/WangHoi)\
**Post date:** [May 13, 2021, 12:32pm UTC](https://mediasoup.discourse.group/t/producer-rtcp-rr-packet-sender-ssrc-problem/2786/1 "2021-05-13T12:32:18Z")

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Producer sent receiver report, local ssrc(packet sender ssrc) is zero.

It should defaults to 1, the same with webrtc magic default recvonly ssrc.  
And chromium’s webrtc code, will update receiver\_report\_local\_ssrc\_ to first sender’s ssrc.  
Related chromium discussion:  
[Issue 51099004: Set local SSRCs on receivers added before senders. - Code Review (webrtc.org)](https://review.webrtc.org/51099004/)  
[Receiver SSRC in RR packets (google.com)](https://groups.google.com/g/discuss-webrtc/c/5yuZjV7lkNc)

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**Author:** ![ibc](https://yyz2.discourse-cdn.com/free1/user_avatar/mediasoup.discourse.group/ibc/32/1540_2.png) [@ibc](https://mediasoup.discourse.group/u/ibc)\
**Post date:** [May 13, 2021, 12:43pm UTC](https://mediasoup.discourse.group/t/producer-rtcp-rr-packet-sender-ssrc-problem/2786/2 "2021-05-13T12:43:33Z")

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Please. Specify how this affects to mediasoup. We are not gonna change 0 to 1 just because libwebrtc does it. BTW the issue you referenced is super old and we are not aware of any related issue when using Chrome and mediasoup together.

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**Author:** ![WangHoi](https://yyz2.discourse-cdn.com/free1/user_avatar/mediasoup.discourse.group/wanghoi/32/958_2.png) [@WangHoi](https://mediasoup.discourse.group/u/WangHoi)\
**Post date:** [May 13, 2021, 12:52pm UTC](https://mediasoup.discourse.group/t/producer-rtcp-rr-packet-sender-ssrc-problem/2786/3 "2021-05-13T12:52:14Z")

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I’m testing with Linphone client, it will ignore this RTCP-RR, so RTT computation and other RTP stats is broken.  
And this RTCP-RR will be silently skipped by current webrtc code.

> **Hide wrong comments.**
>
> See line 414, it compares the sender ssrc.  
> [webrtc/modules/rtp\_rtcp/source/rtcp\_receiver.cc - external/webrtc - Git at Google (googlesource.com)](https://chromium.googlesource.com/external/webrtc/+/a49f1105eb7d5169588ac2876bf59fba2dd06125/webrtc/modules/rtp_rtcp/source/rtcp_receiver.cc)

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SORRY, the actual RR process line is 456, RTCPReceiver::HandleReportBlock(), remote\_ssrc arg is zero.

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<div class="post-metadata">

**Author:** ![ibc](https://yyz2.discourse-cdn.com/free1/user_avatar/mediasoup.discourse.group/ibc/32/1540_2.png) [@ibc](https://mediasoup.discourse.group/u/ibc)\
**Post date:** [May 13, 2021, 1:01pm UTC](https://mediasoup.discourse.group/t/producer-rtcp-rr-packet-sender-ssrc-problem/2786/4 "2021-05-13T13:01:47Z")

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If RTCP generated by mediasoup was ignored by libwebrtc we would have noticed it already. That doesn’t happen.

Regarding Liphone, that seems to be a bug in Liphone. mediasoup follows the standards here.

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<div class="post-metadata">

**Author:** ![WangHoi](https://yyz2.discourse-cdn.com/free1/user_avatar/mediasoup.discourse.group/wanghoi/32/958_2.png) [@WangHoi](https://mediasoup.discourse.group/u/WangHoi)\
**Post date:** [May 13, 2021, 1:05pm UTC](https://mediasoup.discourse.group/t/producer-rtcp-rr-packet-sender-ssrc-problem/2786/5 "2021-05-13T13:05:12Z")

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Thanks, though i already fix it in forked linphone and mediasoup repo.  
I will revert the mediasoup fix and re-test it.