Cleaning up recordings / recording formats
fartwell2000 at y...
Wed Feb 27 15:29:49 GMT 2002
--- In bellhistorians at y..., "oakcroft13" <bill at h...> wrote:
> In answer to Alan's question: the software package I use for sound
> editing is Syntrillion's Cool Edit, which I have found very
> It is shareware, but you can download a trial version and use it
> 30 days (with restrictions) before you have to purchase it. It is
> available from www.syntrillion.com. Its most useful facilities are:
> * it can record via the PC soundcard from whatever recorder you use
> * it can record from a directly attached microphone, especially
> useful for laptops
> * it can translate between all the standard formats,
> and .mp3
> * it has extensive capabilties for editing, transformation,
> amplification, enveloping, noise removal etc.
> There are other packages too, I'm only recommending this one
> I use it and it works. If you only wish to digitise recordings, not
> edit them, Windows Sound Recorder (free!) will work fine, but there
> are some tricks not covered in the documentation required to make
> use the file format you want. Also, you may have to download a
> seperate mp3 codec.
> (I apologise to Macintosh users that I am only covering PC work
> perhaps someone who understands Macs better could join in!)
> As regards recording formats, I always record at 44,100 samples per
> second, 16 bit data, mono. This can lead to very large files
> (fortunately I have a big hard-drive!). When I add recordings to my
> database I reformat them as mp3, which gives a reduction in file-
> of over ten times. I also edit out initial silence, trim the
> recordings to length, etc. I archive the big .wav files off to CD
> case I ever need them again.
> Here are some thoughts on recording formats.
> Sampling rate: the Nyquist theorem, grossly summarised, says that
> need to sample at double the maximum frequency present in the
> In practice I find with recordings you need to go higher than that.
> To sample at 22,050 runs the risk of losing frequencies somewhat
> below 10 kHz. Therefore, I always use 44,100. Do NOT digitise at
> 48,000 as some Windows drivers have bugs at this sampling rate.
> Number of bits: 8 bit data gives disappointing results, 32 bit data
> is complete overkill and is not universally supported. Use 16 bit.
> Number of channels: except for recordings in exceptional
> circumstances (e.g. recording a swinging bell close up) I do not
> believe stereo adds any value - save the disc space and use mono.
> File format: .wav files using PCM format are guaranteed to give you
> back exactly what went in, but at the expense of large amounts of
> disc (over 5 Mbyte per minute).
> .wav files using the ADPCM format are also guaranteed to give you
> back almost exactly what went in, and are 25% of the size of PCM
> format files. In trials I conducted last year, I could detect no
> difference in the sound of PCM and ADPCM recordings. Disc usage is
> 1.3 Mbyte / minute.
> .mp3 files are very compressed. The format I use (56k bits/sec on
> Cool Edit menu) reduces file sizes by a factor of 12. If the
> recording is high quality then this mp3 format gives moderately
> reproduction. However, if the original recording is distorted (i.e.
> the bells were too loud for microphone or recorder), or there is a
> big wash of background harmonics, mp3 gives a very poor result.
> usage is about 420 kByte / minute.
> The only exception to the above rules, of course, is if the
> recording is of such poor quality (e.g. severely bandwidth limited)
> that digitising at 44,100 is not warranted.
> I've written enough now, more (if people think it is useful) in a
> follow-up post on recorders, microphones, loudness, distortion, and
> how to get Windows Sound Recorder to record and save in your chosen
> file format.
> Bill H
Please continue Bill,it is very interesting.
I am sure that many of us have tried making analogue recordings of
bells and have at times been dissapointed with the results.
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