# Buffer size

**URL:** <https://www.ruby-forum.com/t/buffer-size/231526>\
**Category:** GNU Radio\
**Created:** [August 13, 2014, 2:01pm UTC](https://www.ruby-forum.com/t/buffer-size/231526 "2014-08-13T14:01:56Z")\
**Posts on this page:** 2\
**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 13, 2014, 2:01pm UTC](https://www.ruby-forum.com/t/buffer-size/231526/1 "2014-08-13T14:01:56Z")

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Hi

I ran OFDM transmitter in the grc example using 1024 point fft.  
following error was raised after running the grc. Please help to get out  
of this error…

thread[thread-per-block[7]: \<block tagged\_stream\_mux (47)\>]: Buffer too  
small for min\_noutput\_items

Thanks in advance

Regards

Sreena

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<div class="post-metadata">

**Author:** ![sreena\_p\_h](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/47e85d/32.png) [@sreena\_p\_h](https://www.ruby-forum.com/u/sreena_p_h)\
**Post date:** [August 13, 2014, 2:12pm UTC](https://www.ruby-forum.com/t/buffer-size/231526/2 "2014-08-13T14:12:41Z")

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Hi Sreena,

a quick search in the subjects of the mailing list yielded this thread:  
[http://lists.gnu.org/archive/html/discuss-gnuradio/2014-01/msg00439.html](http://lists.gnu.org/archive/html/discuss-gnuradio/2014-01/msg00439.html)

The problem is that the complete PDU has to fit into the buffer, and it  
seems that doesn’t work.  
Now, with the moderate length of 64, this works out of the box, but 1024  
will lead to packets that are just too long.  
That being said, it’s not impossible to implement OFDM with larger FFT  
lengths in GNU Radio, but you’d have to change the architecture of the  
example drastically.

Greetings,  
Marcus