March 29, 2009

436 words 3 mins read

Audio Endeavours

I blogged about my funny audio problems before. In the end I got the Ubuntu-related problems figured out, but still I got weird noise in the recordings; the recording process even picked up radio. Some friends told me that their guitar amplifiers in some cases picked up radio too, others thought I was kidding. You could imagine: Drum’n’Bass mixtapes with radio announcements and classical music in them would suck slightly. :-)

After talking to a bunch of people, I knew I had to fix my hardware setup and buy an external soundcard for my laptop which was well-guarded against stray pick-up. I did not dive into the topic too much, but I learned about balanced input/output too and knew what I’d need to look out for.

I asked Ubuntu Studio and lots of other people about suggestions for a good model as Google quickly told me that there’s a variety of unsupported hardware out there.

Yesterday I went to a Sound equipment store in Berlin. I bought a E-MU Tracker Pre for 149€ and some new cables. The other cards that had similar features (external sound card, balanced input, not hilariously expensive) were Edirol UA-25EX (partly supported, 222€) and Echo AudioFire2 (can’t remember the price, but cheaper as the Edirol, no reports of it working with Linux). Luckily support for the E-MU Tracker Pre was just added to the kernel (2.6.28 in Ubuntu 9.04), so when I plugged it in, I could select it in the GNOME mixer.

A few things worth noting:

  • I tried recording with 192 KHz in the beginning, but that gave me only garbled noise. (I know that 44.1 KHz is CD quality and probably good enough for me - just wanted to try it!)
  • After playing around with the huge amount of audio / mixer settings and recording apps, just using audacity worked out for me.
  • Our audio world still is confusing!
  • Anyway, expect more mixtapes coming up soon.

Quick plea for help… nomally I use a quick script for recording, that automatically names the file, records to .ogg and tags it afterwards with some default info I give it and embeds the playlist into a comment. Unfortunately I do not know how to explicitly specify which sound card to record from in a gstreamer pipeline. Can somebody of the Gstreamer world please enlighten me?

gst-launch-0.10 pulsesrc ! queue ! audioconvert ! vorbisenc ! oggmux ! filesink location=%s

Thanks everybody who helped me out on the way to fixing my audio problems. :-)))

Update: This is it: gst-launch-0.10 alsasrc device=hw:USB,0 ! queue ! audioconvert ! vorbisenc ! oggmux ! filesink location=%s

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