Category Archives: diy

Dual Fade Nyquist Plugin for Audacity

On my hard drive a couple of wav recordings of classical concerts are waiting eagerly being split into the individual pieces and to be saved as ogg respectively mp3 files.

I’m using Audacity for the task, a famous open source audio editing software.

The tasks requires the following steps:

  1. Remove audio in front of the first piece.
  2. Remove audio past the final applause of the audience.
  3. Fade out the applause.
  4. Normalize both channels independently due to mike differences.
  5. Add silence between the pieces.
  6. Fade in the hum caused by the audience in front of each piece.
  7. Fade out the hum at the end of each piece.
  8. Create text markers for each piece containing the name of the compser, the name of the piece and the like.
  9. Let Audacity do the job by splitting and exporting the audio material based on the text markers.

I searched a possibility to ease steps 5 through 7. I found a code snippet by edgar-rft. He politely granted the permission to reuse the Nyquist plugin code, so I slightly modified it to get my job done.

Installation and Usage

  • Download dual-fade.ny.zip and extract it.
  • Move the resulting file dual-fade.ny to the plug-ins folder of your Audacity installation.
  • (Re)start Audacity and load some audio data.
  • Select some of the audio.
  • From the menu effects, choose the command »Dual-Fade«.

That’s it. The first third of the selected audio will be faded out, the second third will appear as silence, and the last third will be faded in. The complete fade follows a three-stage envelope with linear segments (using pwl, »piece-wise linear functions«):

BTW: I also found the Fade+ plugin by Steve Daulton which uses bezier curves to apply some smoother fading curves instead of the usual linear one. In case you do not only want to fade noise but real audio pieces, I’d recommend to check whether it gives you pleasant results.

Edit: Obviously I didn’t search hard enough before writing a plug-in of my own, since I got a reply that a similar plug-in already exists.

Recent MoNav Additions

Displaying a tracklog using openstreetmap.org data (CC-by-SA)

Displaying a tracklog using openstreetmap.org data (CC-by-SA)

Since the last post, I spent a couple of hours writing code for MoNav. The follwing list provides an overview over the lastest additions of mine:

  • There are three map widgets in MoNav, the main map, the place chooser map, and the street choser map. As there was no central instance to control the zoom level, some nasty effects occured in case the user used the various zoom controls (F-keys, mouse wheel, zoom bar, zoom buttons). The zoom levels now are stored persistently for each individual map, and managed by one central method, setZoom(int). The code now provides reasonable default zoom values instead of using the maximum possible zoom at each startup.
  • On the N900, the backlight now remains switched on as long as there is GPS data. Of course the user can still switch off the backlight using the hardware switch.
  • MoNav centered the map only in routing mode. In the map view mode, the GPS position left the viewport without the map following its position. As a cyclist, it may well be that you don’t want to use routing, but want the map to follow the GPS position anyway. There is no preference option for this new feature. The map link to the GPS position gets lost as soon as the user pans the map. It gets set during application startup, when loading another map data set, the user selects “Goto Departure”, or the user selects “Goto Gps-Location”.
  • In routing mode, the auto rotation now is optional. In case you are used to maps which always show north up, this option is for you.
  • MoNav got GPS updates by the GPS subsystem every 5 seconds or so. Though the documentation of QGeoPositionInfoSource states that a default object gets updates each time there are any, calling setUpdateInterval(1000) clearly boosts the GPS performance of MoNav.
  • The user can now switch track logging on and off via the preferences.
  • The tracklog files created by MoNav now are proper UTF-8 encoded files, which JOSM no longer denies to consume.
  • MoNav now is capable of rendering the tracklog in red colour (see screenshot), which is a much sought-after feature for pedestrians, hikers and cyclists.

Case for the Nokia N810

For this year’s biking trips, I want to replace my worthy Garmin GPSMap 60Cx with my Nokia N810. But unlike the GPSMap, the Nokia is neither water- nor shock-resistant. I searched the web for a bike mount, but that led me nowhere. So I came up with a rather DIY’ish solution, which I started today:

otterbox_animation.gif

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