|Subject:||[Discuss-gnuradio] Piping to the USRP - mkfifo issue|
|Date:||Sun, 6 Mar 2011 15:59:58 -0800 (PST)|
I am using a web camera to get an MPEG-4 rtsp stream that is set to a constant bitrate. I have a script which pipes the rtsp stream to a code in C++. The C++ code modulates the signal and writes a .WAV file to the hard disk.
I have a python script which interfaces with GNURadio/USRP which I created using GRC. This takes a file stored on the hard disk and outputs the analog waveform on the output of the USRP and I run this in a second terminal window.
Everything works on the transmitter side, except that I have a file that is constantly increasing in size, and the USRP script starts from the beginning of the file and plays for a certain time before stopping. If I restart, it does it longer and longer each time as expected since the file is increasing in size. I verified I have gotten an output on the USRP using an oscilloscope and it looked fine.
I wanted to try and use piping with mkfifo.
When I erase the file that is written/read from with the couple of scripts I have, I then use mkfifo temp.wav (where temp.wav is my .wav file).
Then I start my scripts that pipe the camera output to the temp.wav file. In a second terminal window I then run my USRP script and it seems to open the file but I don't get any output on the USRP.
Has anyone encountered this problem? I'm not sure what could be wrong, but it works with a normal file as I described above. Any suggestions?
Thanks for your help!
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