[FFmpeg-devel] UDP multicasts mixed up on receive due to wrong bind()

Jindrich Makovicka makovick
Wed Oct 15 11:05:26 CEST 2008

On Wed, Oct 15, 2008 at 10:52, Luca Abeni <lucabe72 at email.it> wrote:
> Hi Laurent,
> Laurent wrote:
> [...]
>>>> Nevertheless, the demultiplexing of UDP packets to sockets is done
>>>> using the port, and also the destination address (the multicast
>>>> address, for instance). Thanks to that, binding to the multicast
>>>> address solves the current problem, on Linux, at least.
>>> Uhm... So, there is no standard way for an application to say
>>> "I want to receive data from port P on multicast group MC", or
>>> things like this?
>> None that I am aware of.
> Ok, thanks for the information. So, I guess the real question now is:
> what happens on windows (or on other non-linux systems) if I perform
> a bind on a multicast address (instead of INADDR_ANY)?
> Does this break multicast support? Or is it just useless (but does
> not break anything)?
> In the first case, the patch cannot be applied. In the second case,
> the patch fixes an important usage case in linux and does not affect
> windows, so maybe it can be applied.

VLC and MPlayer also bind the socket to the multicast address, which
can be seen from strace output. So this seems to be at least a
de-facto standard.

Jindrich Makovicka

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