la question des frequences est autrement plus sournoise;)
à quoi servent donc ces aigus qui volent sur nos tetes?
entre autre , Ã definir l'espace, la precision de la stereo.
et c'est là , par exemple , que tous les preamplis ne sont pas egaux .
donc, le rapport 48kHz et 24 ips, est surement un concours de circonstances , puisque le cinema se synchronise depuis 20 ans via des vitesses d'execution autres
- Compositeur .org - Forum des Compositeurs : Musique et Composition
In the early days of digital audio research, the necessary bandwidth of about 1 megabit per second per audio channel was difficult to store. Disk drives had the bandwidth but not the capacity for the long recording time, so attention turned to video recorder. In chapter 9 it will be seen that these were adapted to store audio samples by creating a
pseudo-video waveform which would convey binary as black and white
levels. The sampling rate of such a system is constrained to relate simply
to the field rate and field structure of the television standard used, so that
an integer number of samples can be stored on each usable TV line in
the field.
Such a recording can be made on a monochrome recorder, and these
recording are made in two standards, 525 lines at 60 Hz and 625 lines at
50 Hz. Thus it is possible to find a frequency which is a common multiple
of the two and is also suitable for use as a sampling rate.
The allowable sampling rates in a pseudo-video system can be deduced
by multiplying the field rate by the number of active lines in a field
(blanking lines cannot be used) and again by the number of samples in a
line. By careful choice of parameters it is possible to use either 525/60 or
625/50 video with a sampling rate of 44.1KHz.
In 60 Hz video, there are 35 blanked lines, leaving 490 lines per frame or
245 lines per field, so the sampling rate is given by :
60 X 245 X 3 = 44.1 KHz
In 50 Hz video, there are 37 lines of blanking, leaving 588 active lines per
frame, or 294 per field, so the same sampling rate is given by
50 X 294 X3 = 44.1 Khz.
The sampling rate of 44.1 KHz came to be that of the Compact Disc. Even
though CD has no video circuitry, the equipment used to make CD
masters is video based and determines the sampling rate.
Source : le grand classique "The Art of Digital Audio" de John Watkinson
Et pour le 48khz :
For landlines to FM stereo broadcast transmitters having a 15 Khz audio bandwidth, the sampling ration of 32 Khz is more than adequate [...] The professional sampling rate of 48 Khz was proposed as having a simple relationship to 32Khz, being far enough above 40 Khz for variable-speed operation
si j'ai bien compris, il demandait si pour un environnement homestudio, il etait preferable d'utiliser du hardware externe, ou si une solution informatique pouvait suffire.
moi, si je devais conseiller du hardware, je dirais à davis de trouver un bon petit studer analogique avec 70kHz (dolby sr) de BP et 110 dB de dynamique
donc pas la peine d'inventer de l'analogique , ni la roue, les outils existent depuis plus de 15 ans.
rappelez vous que si on a sorti le cd (un peu rapidement et meme si l'echantillonage etait au point en 1956) c'est uniquement pour que les maisons de disques ne perdent pas les droits de reproduction sur les oeuvres.
la remasterisation a permis de faire repartir le compteur de zero - Compositeur .org - Forum des Compositeurs : Musique et Composition
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le heral, parce que je le vaurien
