Re: new socket issue

Mark Geib <[email protected]> Thu, 4 Feb 2021 15:36:00 -0700

Newsgroups	gmane.comp.lang.erlang.general
Message-ID	<[email protected]>

Correction. The dropping of datagrams is NOT related to the Timeout, but happens at about 5 minute intervals regardless of the Timeout. Just a coincidence that my Timeout was set to 5 minutes.

Mark.

> On Feb 4, 2021, at 3:04 PM, Mark Geib <[email protected]> wrote:
> 
> In order to join a source-specific multicast group I am trying the new socket module. I am able to join the multicast and start receiving datagrams by spawning the function below. The gen_udp module does not support joining a source-specific multicast currently.
> 
> active_socket(Socket, Parent, Timeout) ->
>   case socket:recvfrom(Socket, 0, [], Timeout) of
>     {ok, {#{port := Port, addr := Addr}, Data}} ->
>       Parent ! {udp, Addr, Port, Data},
>       active_socket(Socket, Parent, Timeout);
> 
>     {error, Reason} ->
>       Parent ! {error, socket, Reason},
>       active_socket(Socket, Parent, Timeout)
> 
> end.
> 
> The multicast is a 45Mb RTP MPEG-TS stream. I am able to receive and verify the RTP sequence number successfully. However, about every Timeout period, in the function above, there are a number of datagrams dropped, that is, the RTP sequence number has a gap of about 200. This continues to happen as long as the process runs. Between the drops everything looks fine.
> 
> As you can see, my approach is to simply have a recvfrom pending at all times so when a datagram arrives the recvfrom returns, I forward the datagram and call recvfrom again. The Timeout is simply to avoid recvfrom returning with no data.
> 
> Thanks,
> 
> Mark.

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