gr-pipe GNU Radio blocks

gr-pipe is a set GNU Radio block for using any program as a source, sink or filter by using standard I/O pipes.

Introduction

The main goals of these blocks are:

Fast development of new experimental blocks (no need to dig into C++ / GNU Radio internals / SWIG / Python).
Ability to use any programming language able to deal with standard input and output (code a block in your preferred language: C, Java, MatLab, Perl, Ruby...).

Simple interface:

The gr-pipe blocks read and write samples sequentially in their GNU Radio internal representation. The format is the same as for gr_file_source and gr_file_sink:

GNU Radio type name	C Type	size
Complex	two C floats (I,Q)	sizeof(float)*2, generally 8 bytes
Float	float	sizeof(float), generaly 4 bytes
Int	int	sizeof(int), generally 4 bytes
Short	short	sizeof(short), generally 2 bytes
Byte	unsigned char	sizeof(unsigned char), 1 byte

Since the actual size of some objects may depend on the host platform, it is recommended to use the available language definitions to get correct sizes. Most languages are also providing routines to read/write native machine C types. See examples provided in this package for some languages.

A typical source block command will produce data "forever" on its standard output, until a SIGTERM is sent by the pipe.source block to ask for normal termination. Also, in case of an exception, the pipe will be closed and a SIGPIPE will be caught.

A typical sink block command will consume data on its standard input, until end-of-file (EOF) is read, for a proper termination.

A typical filter block command will comsume data "forever" on its standard input, process it, and produce data on its standard output, until end-of-file (EOF) is read, for normal termination. Also in case of exception, SIGPIPE may be caught.

In pipe blocks, commands are executed in a /bin/sh shell, so every standard shell features are available in commands provided to blocks (variables, loops, pipes, redirection, etc...).

See examples for a "square" block implemented in C, Java, MatLab/GNU Octave, Perl and Python.

Suggestions of use:

Compression (gzip, lzma, ...)
Encryption (gpg, openssl, ...)
Encoding (ffmpeg, mencoder, gsm-tools, ...)
Debugging (od, hexdump, ...)
Interface to devices (aplay, arecord, pacat, parec, ...)
Use your own tools...

Known limitations and problems:

Small performance loss, due to pipe communications.
Small addition of latency, due to pipe buffers. (On Linux, pipe buffer capacity can be changed. See fcntl(2) F_SETPIPE_SZ).
Not compatible with stream tags
Limited to only one input and one output maximum per block (but you may use an interleaver or multiple blocks).

Building and installing gr-pipe

Installing manually

This procedure assumes you have development tools and GNU Radio already already installed.

git clone https://github.com/3dfxuser/gr-pipe.git
mkdir gr-pipe/build
cd gr-pipe/build
cmake ..
make
sudo make install
sudo ldconfig