Hello Gene and thank you for your response. Gene Heskett ha scritto: > On Thursday 06 November 2008, OrazioPirataDelloSpazio (Lorenzo) wrote: > >> Hi all, >> I need to use a microphone input as a trigger. In other words my idea is >> to connect a switch to the microphone input. In this way, when the >> switch is turned on it generates a spike in the captured track. >> I would like to create a program that trigger an event every spike it >> receives. >> > > 1st, the switch needs to switch a voltage, otherwise there is nothing to > record. > I was thinking the same but even if the switch always open produces no signal, and the always closed produces no signal, when the switch is closing it does produce a signal! Here you can find two wave files: https://svn.ninux.org/ninuxdeveloping/browser/webradio trig.wav -> caputed when I trigger the switch notrig.wav -> the switch is always open
As you can see there is some spikes in the first. If I open with audacity, I can see the volume level that raise when I closed the switch (about 5 or 6 times in the wav file). So I cast every couple of bytes in a int16_t as you suggest, and make the program trigger after a given threshold is overwhelmed. So I write a simple program that when the captured sample overwhelm a given threshold, it triggers. The code is here: https://svn.ninux.org/ninuxdeveloping/browser/webradio/trigmic.c When I fix the treshold to 180, it does work properly, even if sometimes it exchange a "white noise" sample for my trigger. Lorenzo _______________________________________________ Linux-audio-dev mailing list [email protected] http://lists.linuxaudio.org/mailman/listinfo/linux-audio-dev
