SDP attribute "source-filter" should not be included by default in SAP announcements
After [16564] which was backported into 0.8.6 in [16774] SAP announcements generated by VLC always contain the SDP attribute
a:source-filter IN IPx * source.ip.addr
This has bad sideeffects in several ways:
- it breaks backwards compatibility - VLC 0.8.4a and VLC 0.8.5 will be unable to play multicast streams if the OS does not support IGMPv3
- it will break if some form of address translation happens (forwarding proxy, NAT, etc).
- it will always trigger IGMPv3 source-specific joins if IGMPv3 is available
- it might break on hosts with multiple interfaces
- it might break if the user is using another application than VLC on the client side
This SDP attribute is primarily targeted for source-specific multicast streams, which need to be aware about both the group address and the source address. Adding this attribute to all streams just because courmisch is lazy is not a way to go, since it can cause severe troubles to the users.
Much more sensible approach would be to add this via new option e.g.
:sout=#std{access=rtp,mux=ts,dst=232.1.2.3:1234,sap,group="Test",name="kkk", sfilter}
by which the user could control whether he wants to include this SDP attribute.
Activity
Replying to [ticket:826 md]:
- it breaks backwards compatibility - VLC 0.8.4a and VLC 0.8.5 will be unable to play multicast streams if the OS does not support IGMPv3
I'm not buying the bug-to-bug compatibility argument for empirical reasons.
- it will break if some form of address translation happens (forwarding proxy, NAT, etc).
It's NAT that's broken. Or SDP if you like.
- it will always trigger IGMPv3 source-specific joins if IGMPv3 is available
So what?
- it might break on hosts with multiple interfaces
And have a different route for the SAP group and the stream group. If that happens the host is broken. Besides, if it were actually a problem, it could be fixed by passing the stream source address explicitly from the stream output to the SAP announce code.
- it might break if the user is using another application than VLC on the client side
We don't want to support THAT BADLY BROKEN applications. Ignore SDP parameters you don't understand.
This SDP attribute is primarily targeted for source-specific multicast streams, which need to be aware about both the group address and the source address. Adding this attribute to all streams just because courmisch is lazy is not a way to go, since it can cause severe troubles to the users.
I tend to be even less receptive to people who get close to insulting me. That wins you an invalid. Congratulations.
added Status::invalid label
Even though NAT is broken, still a lot of people use it.
Telling everyone he MUST immediately upgrade to 0.8.6, well...
And regarding IGMPv3 - you apparently haven't debugged multiple IGMPv3 bugs in multicast routers from biggest vendors. I did. One as an example - stream working fine with IGMPv2 interrupts every 5 minutes with IGMPv3.
I'm reopening this ticket one more time. If you close it again as invalid I don't care anymore.
removed Status::invalid label
added Status::fixed label
