Archive for November, 2010

Play the music with your DAQ card

Friday, November 26th, 2010

These days my supervisor and I have been working on some amazing (and silly) things. Briefly, using LabVIEW to synchronize a movie, a piece of music and a Jacob’s Ladder. The goal is to demo an interesting show to the school kids. And I would like to share a piece (cause it’s not done yet) of the LabVIEW code, which loads the music and plays it.

So what you need is a data acquisition card (analog output rate greater than 44k Hz, at least 2 AO channels if you like stereo), a speaker or an earphone, LabVIEW and your music. In LabVIEW we read the music file and send the waveform file to 2 analog output channels. If you chop your earphone and connect the three (L, R and ground) lines to the corresponding AO ports, you will hear the sound.

What’s the point of doing that rather than inserting the earphone straightly to your laptop? Because WE CAN.

Note: 1. In my test, reading a block of music won’t slow down your DAQ loop, since the AO task is only 44.1k Hz. I used a Producer/Consumer loop just to make it scalable.
2. To prevent the music from section repeated, I selected  ‘Do not allow regeneration‘ mode.
3. Enable ‘auto start’ for ‘Analog write‘ VI.
4. Future work can be done on stopping the AO task automaticly once the music is over. To do this, we can simply bundle the ‘end of file?‘ state of ‘sound file read.vi‘ to the queue element, and use the state to stop the consumer loop.
5. Tell me if you really have done this. 🙂

Advertisements

Days of PhD (4)

Monday, November 15th, 2010

Entering into November, I’ll begin my final year of PhD study. There are still (and always) so many things to do. Experiments, measurements, data, figures and writings. Well, this is the realworld. Sorry for not updating the posts for quite a while, since I was back to China and spent the time with friends and family.

Anyway, this is a newer comic. Hope you’ll like it:)