# Metafile Sink Execution Time

**URL:** <https://www.ruby-forum.com/t/metafile-sink-execution-time/231713>\
**Category:** GNU Radio\
**Created:** [August 25, 2014, 9:13pm UTC](https://www.ruby-forum.com/t/metafile-sink-execution-time/231713 "2014-08-25T21:13:28Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![addis\_a](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/c4cdca/32.png) [@addis\_a](https://www.ruby-forum.com/u/addis_a)\
**Post date:** [August 25, 2014, 9:13pm UTC](https://www.ruby-forum.com/t/metafile-sink-execution-time/231713/1 "2014-08-25T21:13:28Z")

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How long it takes for the Metafile Sink to began recording data?

I have a “No GUI” script that is a simple USRP source, throttle, and  
metafile sink. All have a 1M sample rates; the metafile sink has a  
relative  
rate of change of 1, 1M segment size, and have a detached header.

I start my script up I get the usually GNU Radio feed back (e.g.  
“Opening a  
USRP2/N-Series device…”), I get the “Press Enter to quit:”, however  
post  
processing of collected meta data has shown that I can not immediately  
start my data collection as it won’t collect the leading edge of the  
signal, I need to wait several seconds before proceeding. Why does this  
happen and is it possible to get a prompt on when the metafile sink has  
started recording?

Thanks,

Jon

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**Author:** ![jfaulkenberry](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/c2a13f/32.png) [@jfaulkenberry](https://www.ruby-forum.com/u/jfaulkenberry)\
**Post date:** [August 25, 2014, 9:17pm UTC](https://www.ruby-forum.com/t/metafile-sink-execution-time/231713/2 "2014-08-25T21:17:09Z")

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First thing, get rid of the throttle. It is only needed in  
_simulations_. In graphs with real hardware, everything is “paced” by  
the hardware.

On 2014-08-25 15:12, Jonathan F. wrote:

> * * *
> 
> Discuss-gnuradio mailing list  
> [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid)  
> [Discuss-gnuradio Info Page](https://lists.gnu.org/mailman/listinfo/discuss-gnuradio) [1]

Links:

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<div class="post-metadata">

**Author:** ![jfaulkenberry](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/c2a13f/32.png) [@jfaulkenberry](https://www.ruby-forum.com/u/jfaulkenberry)\
**Post date:** [August 26, 2014, 5:29am UTC](https://www.ruby-forum.com/t/metafile-sink-execution-time/231713/3 "2014-08-26T05:29:57Z")

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Got rid of it and it sped things up considerably. I think the whole  
reason  
why I had it there in the first place was to prevent sample overruns.

Thanks for the help.

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**Author:** ![jfaulkenberry](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/c2a13f/32.png) [@jfaulkenberry](https://www.ruby-forum.com/u/jfaulkenberry)\
**Post date:** [August 26, 2014, 5:34am UTC](https://www.ruby-forum.com/t/metafile-sink-execution-time/231713/4 "2014-08-26T05:34:50Z")

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What about delays for a multiple USRP sinks and metafile sinks? I had to  
wait 10 seconds before I could start recording when I used a script like  
that.

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**Author:** ![jfaulkenberry](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/c2a13f/32.png) [@jfaulkenberry](https://www.ruby-forum.com/u/jfaulkenberry)\
**Post date:** [August 26, 2014, 5:32am UTC](https://www.ruby-forum.com/t/metafile-sink-execution-time/231713/5 "2014-08-26T05:32:23Z")

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On 08/25/2014 04:30 PM, Jonathan F. wrote:

> Got rid of it and it sped things up considerably. I think the whole  
> reason why I had it there in the first place was to prevent sample  
> overruns.
> 
> Thanks for the help.

Putting a throttle in a flow that already has rate-pacing will just make  
things worse…