Hi 

 
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!

-Tom


      
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