limitations of MD

[Alexandre Enkerli]

Celso,

> In fact, I understand that spectrographic analysis works better if
> you resample audio to 8.000 or 11.500 Hz.
Not necessarily. The resampling itself changes the signal, which you may
not want to do.
But the problem with MD, is not perceived sound quality or sampling rate.
Apparently, there might be an issue of dynamic range in current
implementations of MD but that wouldn't be the main thing either.
Again, MD technology is based on a "lossy" algorithm which means that you
loose some information. In most cases, this information might not be
relevant at all, but it does have an impact on the spectrographic
analysis. It's a distortion of the data, not the sound.

> With MD, at least, you have cleaner recordings
Which, in a way, are less "true" to the original sound.

> which you can easily  digitalize directly as WAV
> through the computer's Line In, with little noise.
Which means that you depend on your computer's analog to digital
converter, therefore retransforming the signal.

> Yes, I think that the future of digital recording is MP3,
Well, that remains to be seen. It's not necessarily the best compression
mechanism, it just happens to be the most popular one on the Net.

> at least until the storage media is cheaper.
A CD-R usually costs about 2$US as opposed to a lot more for MP3 Flash
cards.

> So, I believe it is more economical still to record compressed sound and
> uncompress it only for speech analysis and other purposes.
The "uncompression" is not a perfect process either and you're loosing
further information.

> is still no audio software that works on compressed sound
Actually, AIFC (compressed AIFF) should be read directly by most programs
and any program that uses Quicktime should be able to work with MP3 and
every other sound format that Quicktime reads.

As for the limitations of uncompressed digital soundfiles, you can simply
put mono AIFF files at any sampling rate you want on a CD-R. This means
you get 148 minutes of sound (at 44.1) on a 2$US media and can then use it
in any computer that has a CD-ROM player.
Otherwise, you can burn an Audio CD (mono or stereo, doesn't matter) and
use any CD player.
Kerim's friend's use of direct-to-disk is quite interesting. The fact
that, with a large hard drive, you can actually record continuously for
hours without switching media could be quite useful in some situations.
And the availability of media surely is an issue. DATs, CDRs, and MDs can
all be quite hard to find.

Sorry to go on about this. It can be a big thing in ethnomusicology.

Alex