aaron wrote:
> > of the artifical test signal from 44.1 to 48 kHz and then
>> transferred the data. The resulting spectrogram shows incredible
>> artifacts:
>
>FWIW in the studio world, one can spend many thousands of dollars on
>dedicated hardware to do high-quality resampling; the software I use
>(Samplitude) has a 'high quality' mode that can take an *extremely* long
>time to do best-quality (nearly artifact-free) conversion...
>
>...the received wisdom is, if you're ever going to deliver on CD, record
>at 44.1. There's a running debate about whether 88.2 is a better choice
>for high-sample rate recording than 96, specifically because it's easier
>to drop every other sample than resample...
>
>...since I record on MD at 44.1, it's never been an issue for me.
>
>best,
> aaron
>
>
> http://www.quietamerican.org
>
I have no clue as to why the results of sample rate changes are so
unpredictable but, because of this, I stop to consider whether
resampling is necessary and sometimes, it's not. The Header change
command in Soundhack (mac) converts a soundfile's sample rate
instantly with no processing time, resampling or quality change other
than the change in pitch and time (with 48K-->44.1K, a drop in pitch,
stretch of time of ~9%). That's considerable, but with broadband
sounds (those with low pitch formation like a waterfall or pronounced
"air" in a location recording) the result from a header change can be
more pleasant than resampling. Occasionally, two header changes can
replace the need for resampling. My DAT and DV camcorder record at
48K, most of my library of sound files were saved at 44.1 for CD
outputting but my DVD/DV aps need 48K. I change the header of the
DV/DAT sound files before importing them into my sound editing ap, do
the mix and then change the header of the mix back to 48K and pull it
into my DV ap for adding video. (Sweetening during the sound mix
does not create a problem because the overall tonal balance/pitch
relations are preserved even as the final pitch/time of the mix is
changed.)
I've never detected artifacts by ear with header changes. I wonder if
one compared two sound files, one created with a header change, if
that would test the spectrogram test?
Rob D.
--
Rob Danielson
Film Department
University of Wisconsin-Milwaukee
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