HH
VS1005 VSOS A
UDIO
S
UBSYSTEM
VS1005g
8.3
Pitch Shifter / Speed Shifter Audio Drivers
The FtPitch package offers a pitch and speed shifter that connects to stdout. The speed
shifter can nominally be controlled to speeds between 0.68x and 1.64x of realtime, and
the pitch shifter can nominally be controlled between 0.61x and 1.47x of normal pitch.
Features and limitations:
•
Speed divided by pitch (speed/pitch) must be between 0.68 and 1.64.
•
Pitch shifting alters sample rate. If the resulting sample exceeds 96 kHz, playback
will be at incorrect speed.
•
The shifter has been optimized to work best for audio where sample rate is be-
tween 32 and 48 kHz.
8.3.1
Driver FTOPITCH
The Pitch shifter driver FTOPITCH.DL3 connects to
stdaudioout
as shown in Figure 11
on page 28.
The driver may be controlled either through C ioctl() function calls as described in the
README.TXT file for the driver itself, or from the VSOS Shell using the SETPITCH.DL3
command.
8.3.2
Control Program SETPITCH
Usage: SetPitch [-i|-o] [-sx] [-px] [-h]
-i
Set stdaudioin
-o
Set stdaudioout (default)
-sx
Set speed to x times normal (0.68 - 1.64 if pitch=1.0)
-px
Set pitch to x times normal (0.61 - 1.47 if speed=1.0)
-h
Show this help
Note:
Correct playback requires that 0.68 <= speed/pitch <= 1.644.
Sets/Prints Pitch and Speed Shifter parameters. Example:
S:>ftopitch
S:>setpitch
Pitch 1.000
Speed 1.000
S:>setpitch -p1.1 -s0.9
S:>setpitch
Pitch 1.100
Speed 0.900
Rev. 3.57
2019-04-10
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