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En
Glossary
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PCM (Linear PCM)
Linear PCM is a signal format under which an analog
audio signal is digitized, recorded and transmitted without
using any compression. This is used as a method of
recording CDs and DVD audio. The PCM system uses a
technique for sampling the size of the analog signal per
very small unit of time. Standing for “Pulse Code
Modulation”, the analog signal is encoded as pulses and
then modulated for recording.
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Sampling frequency and number of
quantized bits
When digitizing an analog audio signal, the number of
times the signal is sampled per second is called the
sampling frequency, while the degree of fineness when
converting the sound level into a numeric value is called
the number of quantized bits. The range of rates that can
be played back is determined based on the sampling rate,
while the dynamic range representing the sound level
difference is determined by the number of quantized bits.
In principle, the higher the sampling frequency, the wider
the range of frequencies that can be played back, and the
higher the number of quantized bits, the more finely the
sound level can be reproduced.
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S-video signal
With the S-video signal system, the video signal normally
transmitted using a pin cable is separated and transmitted
as the Y signal for the luminance and the C signal for the
chrominance through the S-video cable. Using the
S VIDEO jack eliminates video signal transmission loss
and allows recording and playback of even more beautiful
images.
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WAV
Windows standard audio file format, which defines the
method of recording the digital data obtained by
converting audio signals. It does not specify the
compression (coding) method so a desired compression
method can be used with it. By default, it is compatible
with the PCM method (no compression) and some
compression methods including the ADPCM method.
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WMA
An audio compression method developed by Microsoft
Corporation. It employs the irreversible compression
method, which achieves a high compression rate by
thinning out the data of hardly audible part to the human
ears. It is said to be capable of compressing the data
quantity by about 1/22 (64 kbps) while maintaining a
similar audio quality to music CD.
