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Viewing entries 289 to 283 [338 total entries to date]

Hmmm. Way too complicated probably, but if you can actually get the device to pair and sink it as an audio device, then you can do this:

mplayer -ao alsa:device=bluetooth

and it may or may not require ~/.asoundrc that looks like

pcm.bluetooth {
    type bluetooth

I heard audio at least one time from my headphones via mplayer that least before the batteries ran out.

Open question: Why doesn't it just show up like a normal alsa device? Meh.

Monday, December 6th 2010 11:55pm
Tags: tonight dorkbot dorkbotpdx pdx portland

Tonight I...

  • ...rode a bicycle across two bridges.
  • ...was approached by a man and a woman (both strangers) and was told "we wish to join the cult".
  • ...witnessed a man tapping a plastic pad connected to a tangle of circuits and wires and causing a drum sound to be played.
  • ...saw a pair of multicolor robot eyeballs glowing on a tabletop
  • ...witnessed a middle-aged man covered in a mass of glowing LEDs and EL wire.
  • ...listened to the sound of a cello convolved with the impulse response from a wooden door.
  • ...helped a woman field test a subversive, covert anti-television teddy bear implant prototype.
  • ...watched a slot car adjust its speed in response to a computer's system load average.
  • ...was in good company.


Ok, enough is enough. You gotta help me out.

I can't be the only person running Linux on a Lenovo Thinkpad T410 (Conexant CX20585) that has audio volume problems. How is it that I've owned this machine for 6+ months and have tried kernel upon kernel, scoured message boards, compiled alsa from trunk, tweaked endless permutations of snd-intel-hda kernel module options, yet still can't get a reasonable audio volume from this Intel HDA audio card on my T410!? It's unthinkable!

I know, I know, the driver is still relatively "new", and the good work that *has* been done has been based on hacking some undocumented codecs without support from the manufacturers...but come on! Output volume is critical!

You see, sound works just fine...but the output power is lacking. Something, somewhere, is preventing the output amplifier from being turned on or otherwise being configured correctly. I have to *crank* the alsa master and pcm output to 100% for music or movies to even be listenable, and even then it's not quiet loud enough. Thinkpads are still considered "good", Linux friendly laptops, so how is it that people are living with this problem? Certainly I can't be the only one!

I've tinkered with hda-analyzer and hda-verb, and have some vague indication that an output amplifier is muted, but there's no apparent way to enable it.

I guess its time to dig in and try and grok the source...but I kinda dread it. Don't get me wrong, I love hacking source and learning and trying things, but sometimes I just want stuff to work. I assumed 5 or 6 years ago that the "oooooh, audio on Linux is so *hard*" problem had been solved...but I guess I was wrong. After so many years of ALSA "just working" and doing what I needed, I guess it is actually a problem again...and that sucks.

If you have any insights into this issue or want to steer me down a path, please send me an email...otherwise wish me luck.

I need practice.

...but this video gives a brief demonstration of the Ghetto Drum System that I built several years ago, and I just recently added MIDI over USB.

The sounds you hear are from a pretty sizable collection of samples ripped from (mostly commodity) synthesizers and played horribly by me in real time.

The Ghetto Drum is triggering MIDI into Pure Data (Pd) in order to play the samples, and the Dickhole Keypiss controller sitting on top of it is used to do bank programming and selection. Audio is routed out of the cheap-o netbook and into an even cheaper guitar amplifier.

So Paul hooked me up with a Teensy++ with a couple bad pins a few months ago and I ended up putting it to good use by retrofitting my Ghetto Drum system in order to support MIDI over USB. The project page has been updated and provides a few more details about the Frankenstein job.

ghetto drum 2.0

I pulled open the old SyQuest case and unmounted the existing circuit board. After hacking at it with the Dremel for some time, I was able to turn the board sideways to make room for the new Teensy board. I mounted this new Teensy in the upper back and made a ghetto faceplate that allows the mini USB connector to poke through.

I mounted the Teensy on a small piece of perfboard and made some super ghetto wooden standoffs. I wired 10 pins from the Teensy over to the existing PIC board with wire-wrap wire: 2 power lines and the 8 trigger points. On the legacy side, I decided to solder the connections right to the pins on the PIC chip itself. Whatever works!

This change allows the whole mess to be powered by USB when pluged in. The legacy PIC board maintains its old function of reading the triggers and converting the data to RS232, but more importantly, the PIC toggles the trigger LED whenever a pad is hit. :)

On the software side of things, I leveraged Dean Camera's LUFA to build some firmware that allows the Ghetto Drum to show up as a USB MIDI device. When plugged in, the device will show up with a clever name and show itself to the host computer as a USB audio/MIDI interface device. When the triggers are hit, the Teensy sends note on/off MIDI events on channel 1 (zero based).

In order to make some sounds, I built a fairly involved Pd patch that receives the MIDI events and can trigger drum samples from a gigantic library of synthesizers. I used the Dickhole Keypiss with Pd to program different patches and assign samples to trigger channels. After the integration was complete, I ended up demonstrating the whole shebang one Monday night at Dorkbot in Portland.

I hope to have a demonstration video up within a few days.

Robotic baby cacophony
Friday, April 9th 2010 11:48pm
Tags: cacophony robotic babies

Recorded in Bi-Mart in Portland, OR, 2010.