that show you how to connect an IR receiver diode to the Microphone port of your sound card. You need to get +5V from somewhere and there is a suggestion to wire a 0.6V diode across the output to limit the voltage swing. I did all that, but had a lot of trouble working out how to get it to go. Most of the examples on this page did not work. I'm using the internal sound card of a T40 laptop (well its the base of a T40). I tried
arecord -D hw:# -c1 -r8000 -f U8I could not seem to find a hw:# or hw:#,# number that would work at all. If I left off the -D hw:# entirely it would work. Since I couldn't seem to work out the hardware number, attempting the next bit:
irrecord -d hw:1,0 file
was futile. After a lot of going round in circles, I discovered that plughw:0,0 would work as a device name:
irrecord -d plughw:0,0 file
But there was still something else wrong, and I ended up applying this patch that makes sampling take place in 16 bit mode rather than 8 bit mode. The only mention of it is here. The patch as it is on that web page would not apply cleanly to the current hw_audi_alsa.c file, so I ended up working out the changes by hand.
Now I had versions of irrecord and lircd that actually seemed to work. Initially I left off the 0.6V diode across the IR diode output, but I had a lot better results with it connected. Still there are certain brands of remotes that are virtually impossible to learn from.
One big thing I learned is that if you use lirc with the audio_alsa (ie. Microphone input) you don't need any special kernel modules ... as are mentioned in the instructions for other IR adapters. lircd will create that /dev/lircd socket and then other programs communicate through it.... such as irw.
I also played around with different sample rates:
lircd -d plughw:0,0@48000 /etc/lircd.conf
lircd -d plughw:0,0@11024 /etc/lircd.conf
48000 probably works better. But trying to work out the ideal capture volume is difficult (NB: I found that the Mic volume control in alsamixer didn't actually do much. Had to press Tab to get to the capture volume and control that). And also, certain remotes seemed to work better. Sony remotes were definately more understandable. The xbox remote was one of the hardest.
So far, I'm still experimenting with this as it doesn't seem to work very reliably.
