Files saved by Audacity

If your computer is running out of space, it could be because of all those Audacity data files that are adding up on your computer. They don't automatically delete when you finish your project and export as .wav or .mp3 (or whatever). You can find out where they are being saved by looking on the Edit pulldown menu for Preferences. The location is under the tab Directories. You can change it if you want to to a drive that has more room. If your computer has multiple users, I'm not sure yet if you have to change it for each individual log-on. The easiest way to delete them is by locating the Audacity project folder and deleting the entire folder. The files you exported will remain wherever you saved them (as long as you didn't save them in the project folder!)

Setting file defaults on Audacity-win-1.3.4

I've just downloaded the latest release of the Audacity free-and-open-source audio editing software. When you open the program, you can look on the upper left of the toolbar and find a pulldown menu called Edit. At the bottom of the list you find Preferences. From there, I found locations to set the preference for .wav file exports at 16-bit and for .mp3 exports at 128 kbps. This is what I recommend in order to generate broadcast-quality files that can nevertheless be edited and played in pretty much all other programs, including older ones. The default setting in Audacity is 32-bit, which is supposedly higher quality but can cause problems in Winamp, older SoundForge releases, etc.

File formats: Codec conversion and codec chaining

Codecs are computer programs for reducing the size of audio files, for faster transmission over the internet and for saving storage space. There are quite a few different versions of codecs, and as described in the re-posted messages below, converting from one file format to another can cause you to permanently lose different parts of the audio information.

A radio program with various contributors like WINGS receives files saved with various codecs, so in order to avoid multiple audio losses, it's best to convert all files to a lossless format like .WAV for editing, so you don't do "codec chaining" and lose information several times. (My favourite editing software only recognizes 16-bit, 44.1 mHz files, so I convert to that.)

Even codecs that are ostensibly the same - have the same name, but are programmed by different companies or people - can have different aural effects. So, it's good to use your ears to help decide not only the file format but also what computer program to use for conversion.

As an example: When I edit with Soundforge 4.5, for which I bought the mp3 plugin, I prefer to save my shows as 112 kbps mp3s, because I find the 128 kbps mp3s made on that codec sound too hissy. But now that I have Audacity (a free and open-source editing program) with a Lame mp3-type converter installed, I usually drag my edited .wav files into Audacity and export them from there as 128 kbps mp3 files. That does a nice clean job.

Here are the discussion items about codecs that I've copied from the listserve of the GRC (Grassroots Radio Conference):

dateNov 13, 2007 1:36 PM
subjectRe: [grc] Anyone using flac audio codec?

I like to second this view. Every time you import an mp3 into any editor it is converted to an approximation of the original PCM (or wav)file. Every time you save it as an mp3 it is throwing our over 3/4ths of the data, you edit again and you just threw out a different set of 3/4ths of the data. Pretty soon there is not much left of the original signal. After reading about how they make mp3's I was amazed that it
even works.

All editing should be in full PCM format, wav, flac, or whatever apple calls it. This includes segments that are being shared. You can save space by using a lossless compression like Flac (there are others such as Shorten, Monkey's Audio, and WavePack, but I think Flac is the best, at least it's the most used).

Flac is the default PCM format for my Ubuntu box at home, which is handy because it takes up less then half the space. And most of the Linux sound editors use it directly. I just wish there was a plug-in for Sound Forge to give it Flac support so you didn't have to manually convert it.

BTW there are some awesome conversion tools at: http://www.rarewares.org
I like the drop utilities Flacdrop, OggDrop, and LameDrop, it's just a panel on your desktop you drop the file into it, it converts it, and very fast too. Oggdrop even works in Linux under Wine, I haven't tried Flacdrop.

I agree that this is overkill for the final product. Last step should be to convert it to mp3 for distribution.

Any original music recording should always be archived in a LOSSLESS compressed format, such as Flac. And in case you can't tell, I'm one of those DeadHead taper dudes that Scooter mentioned.

As far as lossy formats go it should be noted that ogg files sound better and make a smaller file then mp3's or wma's. But only some players support them.

(I have a song running around in the back of my head, it's called "MX'd by baby Jesus")

Dave Willard
Pseudo-Engineer
Radio Free Moscow

Here's a reply from Brian Shirutski:

dateJan 6, 2008 1:11 PM
subjectRe: [grc] Anyone using flac audio codec?

BBC paper on cascaded codecs (september 2005):

>Broadcasters have experienced significant problems with cascaded
> audio coding in the broadcast chain following the introduction of
> digital transmission. It has been found that cascading different
> codecs can result in an overall degradation in sound that many
> listeners find objectionable. A comprehensive investigation of this
> problem has been conducted by members of the EBU project group B/
> AIM. This paper describes typical cascades of codecs found in radio
> broadcast chains, and aims to identify the most critical
> combinations. The intent is to guide broadcasters in deciding which
> codec combinations should be avoided to maximise sound quality...
>
> ...An extensive, thorough, and time-consuming investigation has been
> conducted by members of the EBU B/AIM project group into cascaded
> audio coding. A model of a broadcast chain consisting of 5 cascaded
> codecs was assumed. From the thousands of possible combinations of
> codecs, a subset of the more likely ones was tested for audio
> performance using objective and subjective methods.
>
> Objective testing using PEAQ was successfully employed to reduce the
> number of combinations to be subjectively tested. The subjective
> testing was performed using the MUSHRA test method, with the subset
> of codec combinations being divided amongst a small number of test
> laboratories. Some codecs were tested by all sites for comparison
> purposes. The results clearly show that the cumulative effect of
> cascaded audio coding can be highly detrimental to audio quality,
> even when each stage in the chain makes only a small reduction in
> quality.
>
> The comparison of objective and subjective results showed a good
> correlation between scores. Caution should be exercised here because
> the scales and descriptive terms associated with the two test
> methods used are quite different. The objective and subjective test
> results were both analysed to try to identify codec performance that
> was significantly better or significantly worse than expected. It
> was found that none of the combinations showed any unusual
> behaviour. This should simplify the selection process for users of
> low bit rate coding - it implies that choosing the best codecs will
> give the best results.


<http://www.bbc.co.uk/rd/pubs/whp/whp-pdf-files/WHP118.pdf>

What are Podcasting and Internet Radio?

A friend emailed me this question. Here's my reply:

Podcasting and internet radio are both kind of vaguely defined terms right now - there can be more than one meaning.

Internet radio can mean continuously streaming audio either coming from a broadcast station onto the internet, or generated independently just for web streaming. But internet radio can also sometimes mean making pre-recorded audio files available for listening by streaming, and/or by downloading.

Podcasting generally refers to single items of audio - for example, a radio program. It can sometimes refer to streaming audio, sometimes to downloadable files that you access online, and sometimes also to a kind of automatic downloading system that delivers the audio directly to your computer or mobile device. The best known method for this automatic syndication is RSS - which supposedly stands for Really Simple Syndication. There are a few other computer applications now that do basically the same thing. The term Podcasting was created in conjunction with Apple's iTunes/iPod application, but it has been adopted to refer to pre-existing technology for audio file downloading and streaming, and also for newer technologies like RSS.

Someone needs to begin a good taxonomy of web applications, to help people figure out what they are describing and to aid in useful naming conventions. Perhaps such exists and I just haven't found it yet.