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[Discuss-gnuradio] Piped Video Streaming Crash

From: Alexander Buckley
Subject: [Discuss-gnuradio] Piped Video Streaming Crash
Date: Fri, 28 Feb 2014 17:24:53 +0000

Hi Marcus 

Hopefully your seeing this, for some reason that other thread is no long in my mail inbox or trash..

My problem was:

VLC - Named Pipe 1 - File Source GRC - OFDM MOD - USRP Sink- USRP -Source - OFDM DEMOD - File Sink GRC - Named Pipe 2 - Mplayer 
> (FAILS!!). Reports: Segfault (core dumped).  GRC file is running, VLC is streaming. Fail occurs as soon as I open Named Pipe 2 with Mplayer

cvlc v4l2:///dev/video0 :v4l2-width=160 :v4l2-height=120 :v4l2-aspect-ratio=4/3 --noaudio --sout="#transcode{vcodec=h264,vb=1024}:file{dst=./txPIPE.ts}" :sout-keep
 and reading with mplayer, where the error only occurs when I introduce the USRP N210 to the circuit.

You had asked what was crashing, the play or the grc produced python set up.

It is the python/GNU radio that is crashing.

I have also had it report the following:
*** glibc detected *** python: realloc(): invalid pointer: 0x0a9c9450 ***
*** glibc detected *** python: malloc(): smallbin double linked list corrupted: 0x0a9efcb8 ***

I have trouble seeing how this should be failing like this as I have used the same set up to send a text file, with the only difference being that the file read is set to repeat.

I have been thinking there could be trouble with data rates, though I had expected that would all be taken care of by back pressure if nothing is really specified.

I really am following the set up Alexandru Csete's. The only differences being is that he is using a mac book, older usrp1 and gstreamer.
But i don't any of that should be the difference, the commands are quite straight forward.

I had to try quite a few combinations of streamers/players to get it to work initially without GRC stuff in the loop. The errors presented along the way getting to that point were very different. But now that I have that part sorted, the players don't complain or crash with what I am trying to do.

It is the GRC-python file when the USRP is added. I am using my USRP for all sorts of other things just fine though.
So again I keep coming back to data rates, buffers etc.

I do have this always displayed when i run my USRP, I have just always been ignoring it:

UHD Warning:
    The send buffer could not be resized sufficiently.
    Target sock buff size: 1048576 bytes.
    Actual sock buff size: 131071 bytes.
    See the transport application notes on buffer resizing.
    Please run: sudo sysctl -w net.core.wmem_max=1048576

Running sudo sysctl -w net.core.wmem_max=1048576 doesn't stop this warning.

But if I do have USRP buffer size problem, that does relate to segfaults, malloc etc...
This is rather beyond my USRP knowledge level though....

Alexander Buckley

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