Re: [Audacity-devel] R: Questions from Argentina

[Federico M. <fm...@fc...>]

Dear Simone,

>I'm Simone from University of Parma (Italy) and we use Audacity for acoustical
>measurement purposes, too; also we developed a set of modules to do this kind
>of tasks, maybe you are interested about them...we need testers...:)

OK, please send me the link.

>I don't know so deeply the Audacity code, but when you try to save your
>project as aup, a message warns you about the fact that this format 
>is readable only
>by audacity;

But that could change easily if someone writes the appropriate code :)

>if I have understood the code correctly, the .au files are the same
>that the program uses for the periodic data backup: when you save 
>everything as an
>aup, simply these files - if updated to the current status - were 
>copied where
>you've found them. Maybe this is a format optimized for audacity and 
>I don't know if
>it's suitable for data export.

It does contain audio data in a recognizable format. I've been doing 
some reverse engineering from several cases and these are my findigs so far:

It starts with sdn. (short for "sound"?), then comes the length of 
the header (it may be quite long), then some information about 
Audacity, then the samplig rate, then the IEEE 754 32 bit floating 
point representation of min, max and rms declared in the .aup (rms 
doesn't seem to be actually rms, I'm afraid). Then the same 
information is repeated except that rms is shifted 4 bits (multiplied 
by 16). Then there comes some unrecognized content that may be rather 
long (about 3 kb) and, finally, the audio data in IEEE 754 format. 
There is no footer.

>I think it's best to export (File->Export menu item) what you need  to one of
>the more useful/common file formats - Audacity support tons of them 
>(wav float 32 is
>the format we use more commonly for example) - and use the aup 
>feature only to
>store the workspace, not the datas. For us it works very well.

This is a possibility, but consider this scenario: You want to 
generate, read or analyze an Audacity project using Matlab, Scilab or 
Octave. You could export/import to/from wav format, but metadata is 
not compatible. For instance, cues, labels, etc. are not read by 
Audacity. In field measurement applications it is very useful to add 
some parsable information (i.e., that some code can extract and 
classify automatically).

>PS: I don't know if the audacity-devel discussion is the best place to post
>this kind of questions, but I thinke that all the people around us 
>can suggests a better
>place..:)

I am currently posting in two lists (users and developers) and in a 
forum. I have no definitive resposes so far.

Thank you for your comments.

Best regards,

Federico Moiyara