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<H1>[99s-extend] Newbie, Cowboy + Websocket + Audio Recording</H1>
<B>Eduardo Gurgel</B>
<A HREF="mailto:extend%40lists.ninenines.eu?Subject=Re%3A%20%5B99s-extend%5D%20Newbie%2C%20Cowboy%20%2B%20Websocket%20%2B%20Audio%20Recording&In-Reply-To=%3CCAKAMJXghRnTZ1CTPkTBapOgh7BnFLUnvL%2B%2BVVedyXuAzWT6HSQ%40mail.gmail.com%3E"
TITLE="[99s-extend] Newbie, Cowboy + Websocket + Audio Recording">edgurgel at gmail.com
</A><BR>
<I>Tue Sep 30 00:53:26 CEST 2014</I>
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<PRE>Looking on the output it says:
*{reason,badarith} *on this line:
RecorderPid ! {rec, _Frame/binary},
This may help you somehow.
BTW, variables starting with _ are usually used to show unused variables
and stop warnings from the compiler.
On 30 September 2014 05:52, Juan Matías <<A HREF="https://lists.ninenines.eu/listinfo/extend">jmrepetti at gmail.com</A>> wrote:
><i> Hello list, I hope this is the right place to ask this.
</I>><i>
</I>><i> I'm learning Erlang, and I wanted to create a Cowboy app to record audio
</I>><i> from a web browser.
</I>><i>
</I>><i> Based on the websocket example in the Cowboy source code, I get the user
</I>><i> mic input and send this input to the websocket.
</I>><i>
</I>><i> I created a "recorder" module, which functionality is to save the data to
</I>><i> the a file.
</I>><i>
</I>><i>
</I>><i> *#rawe_handler.erl*-module(rawec_handler).
</I>><i> -behaviour(cowboy_websocket_handler).
</I>><i> ......
</I>><i> init(_, _, _) ->
</I>><i> case whereis(recorder) of
</I>><i> undefined ->
</I>><i> RecorderPid = recorder:start(),
</I>><i> register(recorder, RecorderPid);
</I>><i> _ -> ok
</I>><i> end,
</I>><i> {upgrade, protocol, cowboy_websocket}.
</I>><i> .....
</I>><i> websocket_handle(_Frame, Req, State) ->
</I>><i> RecorderPid = whereis(recorder),
</I>><i> RecorderPid ! {rec, _Frame/binary},
</I>><i> {ok, Req, State}.
</I>><i>
</I>><i> *#recorder.erl*
</I>><i> -module(recorder).
</I>><i>
</I>><i> -export([start/0, recorder_fun/1]).
</I>><i> -compile([debug_info]).
</I>><i>
</I>><i> recorder_fun(IoDevice) ->
</I>><i> receive
</I>><i> {rec, Data} ->
</I>><i> ok = file:write(IoDevice, Data),
</I>><i> io:format(Data),
</I>><i> recorder_fun(IoDevice);
</I>><i> {stop, _} ->
</I>><i> %%Close file
</I>><i> file:close(IoDevice)
</I>><i> end.
</I>><i>
</I>><i> start() ->
</I>><i> {ok, IoDevice} = file:open("/tmp/test_binary.wav", [write,
</I>><i> binary]),
</I>><i> spawn(recorder, recorder_fun, [IoDevice]).
</I>><i>
</I>><i>
</I>><i> When I start the console, and allow the microphone on the browser, I see
</I>><i> this error on the console:
</I>><i>
</I>><i> =ERROR REPORT==== 29-Sep-2014::18:13:03 ===
</I>><i> Ranch listener http had connection process started with
</I>><i> cowboy_protocol:start_link/4 at <0.178.0> exit with reason:
</I>><i> *{[{reason,badarith},{mfa,{rawec_handler,websocket_handle,3*}},{stacktrace,[{rawec_handler,websocket_handle,3,[{file,"src/rawec_handler.erl"},{line,35}]},{cowboy_websocket,handler_call,7,[{file,"src/cowboy_websocket.erl"},{line,588}]},{cowboy_protocol,execute,4,[{file,"src/cowboy_protocol.erl"},{line,435}]}]},{msg,{binary,<<0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0....(ETC,
</I>><i> DATA STREAM CONTINUES)
</I>><i>
</I>><i> Probably my approach to do this is totally wrong. I there any obvious
</I>><i> problem here?
</I>><i> Can someone point me to a right direction?. Maybe I should write directly
</I>><i> to a file in the *websocket_handle *funcion, but how can I keep a file
</I>><i> opened during the streaming?
</I>><i>
</I>><i> The github repo is here: <A HREF="https://github.com/jmrepetti/rawec">https://github.com/jmrepetti/rawec</A> with the
</I>><i> whole source code if you want to take a look.
</I>><i>
</I>><i>
</I>><i> Thanks in advance,
</I>><i> Matias.
</I>><i>
</I>><i> _______________________________________________
</I>><i> Extend mailing list
</I>><i> <A HREF="https://lists.ninenines.eu/listinfo/extend">Extend at lists.ninenines.eu</A>
</I>><i> <A HREF="https://lists.ninenines.eu/listinfo/extend">https://lists.ninenines.eu/listinfo/extend</A>
</I>><i>
</I>><i>
</I>
--
Eduardo
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