Increment rtx rtp packet sequence number only when trasmitted

[oto313]

Fix for wrong sequence numbers

Currently the nack responder (responder_interceptor.go) generates RTX RTP packet which has not right sequence numbers. It does not increment the sequence number by one according to RFC rfc4588

For either multiplexing scheme, the sequence number has the standard definition; i.e., it MUST be one higher than the sequence number of the preceding packet sent in the retransmission stream.

I am proposing fix for it and appreciate any feedback as this is my first pull request in GO lang.

[Sean-Der]

Nice find @oto313! How did you find this, I am really impressed! If you run go test -v locally you have some build/test failures.

• Maybe we make this part of Get? Auto-increments (if needed)
• We should write some tests that it does the auto increment as expected

[oto313]

Hi @Sean-Der. Thanks. I was investigating why retransmission not worked in my use case and I was investigating it with wireshark and I compared retransmission packets with google webrtc implementation.

If you run go test -v locally you have some build/test failures.

Sorry the build/tests are fixed

Maybe we make this part of Get? Auto-increments (if needed)

part of which Get?

[oto313]

Hi @Sean-Der, so now i fixed the tests. Hopefully now we can merge it. Thanks

[aalekseevx]

m.rtxSequencer seems unused now, maybe delete it?