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Looprecord
Summary
An example program that plays back audio through a PC sound card, and records at the same time (full duplex).It uses the portaudio library. The example program compiles with gcc under MinGW (Windows), and should also work on other platforms supporting portaudio (Linux, Mac, ...) if the makefile is modified.
By default, it uses one audio channel, although the number of channels can be easily changed by editing the source code.
Purpose
The program was written to support signal processing experiments without expensive hardware.Download
Starting the program
Most users will want to use looprecord.exe from a command line prompt, although it can be also started without arguments (simply double-click).By default, when started without arguments, it will play back the contents from play.float, and write recorded data into rec.float.
The generate_testtone function gives an example, how to write float numbers in binary format to disk. The format works efficiently with Matlab
Command line arguments
- rate_Hz=44100: Sample rate, must be supported by audio hardware
- playFile=play.float: Source file, binary float
- recFile=rec.float: Destination file, binary float
- testf_Hz=(disabled): Writes three seconds of sinewave at testf_Hz and exits
- offset=(one buffer size)
- gain_dB=0: Playback volume control
- dev=(system default, system default): Input / output portaudio device
- -list: Shows names of audio devices and corresponding numbers for dev argument
- -help: Print built-in help text
See also
  How to read and write data in binary float format from Matlab / Octave |
© Markus Nentwig 2007-2008
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