Re: [Haskell-beginners] Problem reading sound data from mic with TChan

https://github.com/bitemyapp/blacktip/blob/master/src/Database/Blacktip.hs#L... :) On Sun, Dec 20, 2015 at 7:38 PM, Luke Iannini wrote:

Hi Martin,

On line 63 http://lpaste.net/147522#line63, when you do

let sndChan = newTChan

you're not actually creating a new TChan, but rather creating a reference to the STM action that creates new TChans.

So this means that e.g. on line 71 http://lpaste.net/147522#line71, you are creating a new channel every time with

ch <- sndChan

Instead, you want to do:

sndChan <- newTChanIO

(or,

sndChan <- atomically newTChan

)

And then pass that value to your other functions, which will just take TChan [Int32] rather than STM (TChan [Int32])

Here's what I mean:

http://lpaste.net/diff/147522/147557

Hope that helps!

On Sun, Dec 20, 2015 at 9:24 AM, Martin Vlk wrote:

...

Hi, I am working on a little toy project related to controlling graphics display based on data from the computer microphone.

I am basing the whole thing on concepts from game programming, so I have a main loop which reads inputs, updates the world state and generates outputs.

As part of inputs there is microphone. I read data from it using the pulse-simple library. The "simpleRead" function blocks if there is not enough data available so I can't use it directly in the main loop or I risk delays.

So I figured I'll use a separate thread to read from the mic and write data into a TChan. The main loop in separate thread then can read from the TChan as needed and test for availability of data to avoid delaying the main loop.

Here is my current code: http://lpaste.net/147522

The data is written into TChan in the "handleMic" function and read from the TChan on line 85.

The problem I have is that the TChan never seems to contain any data when I read from it and that confuses me. Why?

Does anyone see where is my problem?

Many Thanks Martin _______________________________________________ Beginners mailing list Beginners@haskell.org http://mail.haskell.org/cgi-bin/mailman/listinfo/beginners

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