Raw File XML Header

A Generic Specification


Clem Schmidt and Jan van Katwijk

Motivation and Intent

  • Specify the necessary metadata for the recording and replay of raw I/Q data files.
  • Provide an open specification.
  • Become independent of lesser suitable means being used for this purpose, like file names, file extensions or the "wav" file format.
  • Demonstrate the usability by two popular DAB SDR receivers.


This is the first version of the xml header specification. Suggestions for improvement or changes are welcome. Please contact one of the authors if you intend to contribute in some way.

XML Header

The following shows the suggested xml format, using an example from a real-world recording of Qt-DAB. It might be noted that the format supports more than one data block with different entries. To keep the format generic, modulation specific items are not included.

  • Recorder: The raw file has been recorded with Qt-DAB, Version 3.2-Beta
  • Device: The recording device was an Airspy Model I
  • Samplerate: The I/Q data have been sampled with 2.5Msps
  • Channels: All Channels (two in the example) contain I/Q-Data sampled with 12Bits. The I/Q data are stored as interleaved data in the 16-Bit signed integer format, least significant byte first.
  • Datablock(s): The file contains one datablock, specified in its <Datablock> segment. It contains 375,783,424 Channel data, i.e. 375MChannel Units = 375M Int16 ~ 750MByte. Please not that one Channel Unit comprises two Channels, one for I-, and one for Q-Data.
  • Frequency: Recording frequency has been 227.360 MHz.
  • Modulation: The data are modulated as DAB signals.


The following screenshots show how different apps display the information of the xml header when replaying a DAB raw file.

XML header display of a Qt-DAB Recording, replayed with QIRX
XML header display of a QIRX Recording, replayed with Qt-DAB

In case you would like to "copy and paste" the xml, you could do so from the pdf file of this spec, dwonloadable here.

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