# File Meta Sink Endianness?

**URL:** <https://www.ruby-forum.com/t/file-meta-sink-endianness/234140>\
**Category:** GNU Radio\
**Created:** [February 9, 2015, 6:55pm UTC](https://www.ruby-forum.com/t/file-meta-sink-endianness/234140 "2015-02-09T18:55:59Z")\
**Posts on this page:** 4\
**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:** [February 9, 2015, 6:55pm UTC](https://www.ruby-forum.com/t/file-meta-sink-endianness/234140/1 "2015-02-09T18:55:59Z")

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Hello,

Can someone tell me what byte order (i.e. little endian or big endian)  
is  
used in file meta sink (i.e. what is the byte order of the resulting  
file)? I’m seeing something strange, and I’m wondering if the header  
(metadata portion) is big endian while the samples are little endian.  
Does  
this change based on the endianness of the host machine?

Thanks in advance for the help.

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**Author:** ![woodzer](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/w/f08c70/32.png) [@woodzer](https://www.ruby-forum.com/u/woodzer)\
**Post date:** [February 9, 2015, 7:14pm UTC](https://www.ruby-forum.com/t/file-meta-sink-endianness/234140/2 "2015-02-09T19:14:53Z")

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On 02/09/2015 12:54 PM, Peter W. wrote:

> –  
> Peter W.  
> [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) [mailto:removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid)
> 
> * * *
> 
> 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)  
> Everything is, as far as I know, written in the native host order.

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**Author:** ![woodzer](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/w/f08c70/32.png) [@woodzer](https://www.ruby-forum.com/u/woodzer)\
**Post date:** [February 9, 2015, 7:55pm UTC](https://www.ruby-forum.com/t/file-meta-sink-endianness/234140/3 "2015-02-09T19:55:47Z")

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Hi Marcus,

That explains it. Thanks for the help.

On Mon, Feb 9, 2015 at 1:27 PM, Marcus Müller [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid)

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**Author:** ![woodzer](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/w/f08c70/32.png) [@woodzer](https://www.ruby-forum.com/u/woodzer)\
**Post date:** [February 9, 2015, 7:29pm UTC](https://www.ruby-forum.com/t/file-meta-sink-endianness/234140/4 "2015-02-09T19:29:31Z")

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Hi Peter,

the metadata is stuffed into PMT dicts, which get serialized by pmt’s  
serialization routines.  
Now, these are a bit peculiar on serializing multibyte things. They  
generally ensure big-endianness, if I understand the code [1] correctly.

The sample portion would have the same endianness as your host  
architecture, so that would explain differences.

Greetings,  
Marcus

[1] gnuradio-runtime/lib/pmt/pmt\_serialize.cc: