Re: Sound head of the 'Moviola' (Steve Beet )


Subject: Re: Sound head of the 'Moviola'
From:    Steve Beet  <steve.beet@xxxxxxxx>
Date:    Wed, 29 Dec 2010 22:24:16 -0000
List-Archive:<http://lists.mcgill.ca/scripts/wa.exe?LIST=AUDITORY>

Sorry to point out the glaringly obvious, but this thread seems to be getting rather surreal. The confusion seems to have started because Wikipedia has been used as a reference point, and the respective article has used inappropriate nomenclature. The word "amplitude" was used in the original article not in the currently accepted sense, but to mean what might be phrased as "signal value, with a DC offset sufficient to ensure that that value is always positive". In other words the area of the clear part of the film represents the waveform itself (with a DC offset). There is no processing involved - no Fourier or Hilbert analysis - just a raw signal. Forget phase, frequency, etc. - just feed the output of a photodiode/phototransistor detector into an amplifier and you should get the audio you're after! I would strongly recommend never using Wikipedia alone as a source of information. Most of the articles are not written by true experts and they are not scientifically rigorous or exact. Steve Beet -----Original Message----- From: AUDITORY - Research in Auditory Perception [mailto:AUDITORY@xxxxxxxx On Behalf Of James Johnston Sent: Wednesday, December 29, 2010 9:47 PM To: AUDITORY@xxxxxxxx Subject: Re: Sound head of the 'Moviola' There is no need for "quantization". Frequency and phase are the Fourier Transform (which is a linear, energy-preserving transform) of Amplitude in the time domain. The Fourier Transform is really a complex, but it often gets converted to polar. More convenient sometimes, less so sometimes. ________________________________ From: AUDITORY - Research in Auditory Perception [AUDITORY@xxxxxxxx On Behalf Of Kevin Austin [kevin.austin@xxxxxxxx Sent: Wednesday, December 29, 2010 1:29 PM To: AUDITORY@xxxxxxxx Subject: Re: [AUDITORY] Sound head of the 'Moviola' In the time domain, as Hugh Le Caine used to say, everything is amplitude (displacement). As I understand this, frequency and phase are derived from amplitude in [quantized] time. Kevin On 2010, Dec 29, at 2:47 AM, ita katz wrote: But the amplitude does not carry all the information needed to recreate the sound. Similarly, the "Sound-on-Film" entry states: stereo variable-area <http://en.wikipedia.org/w/index.php?title=Stereo_variable-area&action=edit& redlink=1> (SVA) recording, encoding a two-channel audio signal as a pair of lines running parallel with the film's direction of travel through the projector. The lines change area (grow broader or narrower) depending on the magnitude of the signal. Again, what encodes the frequency/phase? Thank you Ita. Notice: This message and any included attachments are intended only for the use of the addressee, and may contain information that is privileged or confidential. If you are not the intended recipient, you are hereby notified that any dissemination, distribution or copying of this communication is strictly prohibited. If you have received this communication in error, please destroy the original message and any copies or printouts hereof.


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