Tag Archives: record

First “public” release for alsa-backup

For a long time, we’re using continuous recording tools to record our radio broadcasts. Many of these tools were homemade and alsa-backup is the latest project of this “serie” (after jack-backup and just-record).

alsa-backup can :

  • record several channels,
  • change record file according your naming policy (… without a blank),
  • run as daemon,
  • log into syslog,
  • stop record and retry after errors

And many other features are coming :) This piece of Ruby code is more flexible than just-record. It uses the awesome ruby-ffi library which allows to use C libraries with few lines of ruby code.

alsa-backup is available as debian/ubuntu packages on Tryphon’s debian repository. Source files are available in GitHub alsa-backup repository.

Jack Capture : record jackd from a command line

Jack Capture is a small jack application created by Kjetil S. Matheussen. I wanted to flag it into my del.icio.us but I didn’t find a clean web page which presents the project.

You capture several channels from your jack server. It’s simple, it starts from a command line, it displays the capture level for each channel into the console :

In a X environment, it can start meterbridge for you.

For the moment, you need to download the jack capture sources (the latest release is 0.9.17).

In my mind, the standalone console level meter could be another smart jack tool :-) We need a such tool when we’re performing live or conference recordings to check levels via an ssh connection.

Don’t record “noise” with your Audiophile USB

If you load the snd-usb-audio without option with the current (2.6.24) linux kernel, your Audiophile USB will send you a nice “noise”.

$ arecord -vvv -D hw:2,1 -c2 -t raw -r48000 -fS24_3BE /tmp/test.raw
Recording raw data '/tmp/test.raw' :
Signed 24 bit Big Endian in 3bytes, Rate 48000 Hz, Stereo
Hardware PCM card 2 'Audiophile USB (tm)' device 1 subdevice 0
Its setup is:
[...]
Max peak (12000 samples): 0x007ff202 #################### 99%

But if you take look, it isn’t a noise, it’s a swapped endian stream.

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JustRecord : a tool to record

For many years, we’re using various tools to perform long recordings : record (from xawtools), an home-patched jack-record, arecord+split, rotter, etc.

To record Esperanzah lives or Forum PHP 2007 conferences, we used our ugly (but efficient) arecord+split script. But it’s really a tool which can be shared with other teams.

So we’ve just started a dedicated tool to perform long recordings : JustRecord. These few lines of python can record in loop via alsa, run as daemon, log with syslog and execute an external script when a file is ended, etc. Tiny but usefull ;-) And many features will follow.

Setup for recording 30 hours of concerts

For 4 years, Radio Esperanzah! capture about 30 hours of live each year for the Esperanzah! festival. Until the 2007 edition, we used various recorders (from Archos Gemini to Tascam Compact Flash recorder). But recording something like 20 concerts with a mobile device consumes a lot of time. Lives at Esperanzah! are performed sequentially on two stages. You need to plug and unplug everything 80 minutes and move the capture system to the other stage. It’s painful.

For this 2007 edition, we betted on a new system : install a computer on each stage for the whole festival. The idea is simple : each “satellite” records continuously and recorded files are retrieved periodically by our NAS server via wifi. No (or less) useless movement, the same setup installed for the three days of festival, no cable to plug/unplug, …

A great idea … but it required a lot of preparation. Here are some of the problems we had to solve.

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