Thanks Tom, I'm a beginner still with linux/GNURadio so I couldn't really find any information that makes sense as to how gr-atsc handles the fifo piping.
I had seen an example online of someone that had done a transmission using the USRP and piping. They had piped the output of gstreamer using mkfifo like I had tried but I can't get any output on the USRP when I read from the file created by mkfifo. http://wiki.oz9aec.net/index.php/Simple_DVB_with_Gstreamer_and_GNU_Radio -Tom --- On Mon, 3/7/11, Tom Rondeau <trondeau1...@gmail.com> wrote: From: Tom Rondeau <trondeau1...@gmail.com> Subject: Re: [Discuss-gnuradio] Piping to the USRP - mkfifo issue To: "Tom Hendrick" <sdtom...@yahoo.com> Cc: discuss-gnuradio@gnu.org Date: Monday, March 7, 2011, 12:53 AM On Sun, Mar 6, 2011 at 6:59 PM, Tom Hendrick <sdtom...@yahoo.com> wrote: 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 Tom,Look how piping to fifo files is handled in the gr-atsc. That might help get you going. Tom
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