WaveWarp 2.0 Component
      
Input ASCII Files:
Functional Description
Represents an ASCII file as a Control Signal source.
The Input ASCII Files category of the Component Library includes the filenames of
all files with the ".txt" extension located in the user-specified directory on the hard-disk.
For notational convenience, all such files are listed three times each, reflecting their intended use, i.e.
as a mono audio source, a stereo audio source, or as a control signal source.
The control signal source entry for a given file in the list can be used as a
control signal source on the DrawingBoard. Unlimited multiple copies of the same file are permitted on any number of
DrawingBoards simultaneously. It is assumed that a given ".txt" file simply contains a list
of numerical values, one number per line (see the sample ".txt" files in the \ascii\control
sub-directory of the WaveWarp root directory).
The sample rate at which the file is read can be arbitrarily set via
the "Sample-rate setting for Signal Generators and
Input ASCII files" button
(or the "Sample-Rate Setting" command under the "Edit" menu) on the toolbar, which is
activated whenever the component is selected on the DrawingBoard.
Equivalently, it can be set via the dialog box which (i) appears
when the component is initially
dragged on to the DrawingBoard or (ii) is activated using the right-mouse-button when
the component is selected on the DrawingBoard.
This procedure allows the component to either (i) enforce
a user-determined sample rate on the downstream component(s), or (ii) to inherit the sample rate from
the downstream component(s). Different ASCII files can be read with different
sample rates on a DrawingBoard, as long as the rules of connectivity
for multiple sample rates are adhered to (see the
WaveWarp Users' Guide
for more information.)
The name of any file on the DrawingBoard can be changed by double-clicking on its filename. This will
open a conventional "Save As" file dialog box which can then be used to rename the file in the usual
"Windows" manner.
When the DrawingBoard is played, the data in each ASCII file
(assumed to be simply a list of numerical values, one number per line)
is retrieved "as is",
type-cast into 32-bit floating-point representation, and streamed out sample-by-sample
at the selected sample rate for the given ASCII file.
WaveWarp does not scan for the end of ASCII files. Therefore, unlike with WAV files, the
DrawingBoard will not automatically stop when the end of an ASCII file is reached. Rather, the
DrawingBoard will continue, using the last value in the ASCII file as its persistent output. Likewise,
Loop mode has no effect on ASCII files.
Note: ASCII files are useful when prototyping a DrawingBoard or when investigating the detailed
behaviour of a component or set of components. Since the ASCII data is read "as is" without any scaling (unlike
with WAV files) the precise behaviour of a component or set of components can be ascertained from the detailed
comparison of input and output ASCII files. However, since the ASCII representation is intrinsically
inefficient, ASCII files should only be used with small "test" files, and should not be used for the
storage of material of any significant length.
Note for
MATLAB®
users:
since it is trivial to import and export ASCII files from within MATLAB (i.e.
using the "-ascii" switch with the "load" and "save" commands), it is straightforward to read ASCII files
produced by WaveWarp for off-line processing, or indeed, to create ASCII input test files for use by WaveWarp.
Algorithm
n/a
Signal Implementations
| Audio signals | Control signals | Description |
|---|
| n/a | Single output | Converts an ASCII file containing a list of numbers into a control signal |
Related components:
Example DrawingBoards illustrating usage:
|
