Digital Signal Processing Reference
In-Depth Information
1
0.5
0
−0.5
0
50
100
150
200
(a) Original Sequence (1st 225 Samples)
1
0.5
0
−0.5
0
50
100
150
200
(b) Upsampled Sequence; InterpFac = 2 (1st 225 Samples)
Figure 3.27:
(a) A portion of the original sequence; (b) The same number of samples of the interpolated
sequence.
ML
_
InterpAudioPOC(InterpFac)
is very similar to
LV
_
I nterpAudio
, except that
InterpFac
may assume the positive integral values 2,
3, 4, etc. Several of the windows that are opened by
ML
_
I nterpAudioP OC
have push buttons that
allow playing the input sequence at the original sample rate (11025 Hz) and the output sequence at the
original or new sample rates.
• To maintain the same apparent output frequency after interpolation, compute the necessary post-
interpolation sample rate
SR
New
as follows:
I
where
I
is the interpolation factor and the original, pre-interpolation sample rate is
SR
Orig
.
• If the sample rate is not to be changed, then the post-interpolation apparent output frequency
F
New
is computed as follows:
SR
New
=
SR
Orig
·
