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Jamie Hardt
2023-11-07 09:27:08 -08:00
parent f1ce4888af
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docs/source/scopes/bext.rst
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@@ -4,32 +4,43 @@ Broadcast WAV Extension Metadata
Notes
-----
A WAV file produced to Broadcast-WAV specifications will have the broadcast metadata extension,
which includes a 256-character free text descrption, creating entity identifier (usually the
recording application or equipment), the date and time of recording and a time reference for
timecode synchronization.
A WAV file produced to Broadcast-WAV specifications will have the broadcast
metadata extension, which includes a 256-character free text descrption,
creating entity identifier (usually the recording application or equipment),
the date and time of recording and a time reference for timecode
synchronization.
The :py:attr:`coding_history<wavinfo.wave_bext_reader.WavBextReader.coding_history>`
is designed to contain a record of every conversion performed on the audio file.
In this example (from a Sound Devices 702T) the bext metadata contains scene/take slating
information in the :py:attr:`description<wavinfo.wave_bext_reader.WavBextReader.description>`.
Here also the :py:attr:`originator_ref<wavinfo.wave_bext_reader.WavBextReader.originator_ref>`
In this example (from a Sound Devices 702T) the bext metadata contains
scene/take slating information in the
:py:attr:`description<wavinfo.wave_bext_reader.WavBextReader.description>`.
Here also the
:py:attr:`originator_ref<wavinfo.wave_bext_reader.WavBextReader.originator_ref>`
is a serial number conforming to EBU Rec 99.
If the bext metadata conforms to `EBU 3285 v1`_, it will contain the WAV's 32 or 64 byte `SMPTE
ST 330 UMID`_. The 32-byte version of the UMID is usually just a random number, while the 64-byte
UMID will also have information on the recording date and time, recording equipment and entity,
and geolocation data.
If the bext metadata conforms to `EBU 3285 v1`_, it will contain the WAV's 32
or 64 byte `SMPTE ST 330 UMID`_. The 32-byte version of the UMID is usually
just a random number, while the 64-byte UMID will also have information on the
recording date and time, recording equipment and entity, and geolocation data.
If the bext metadata conforms to `EBU 3285 v2`_, it will hold precomputed program loudness values
as described by `EBU Rec 128`_.
If the bext metadata conforms to `EBU 3285 v2`_, it will hold precomputed
program loudness values as described by `EBU Rec 128`_.
.. _EBU 3285 v1: https://tech.ebu.ch/publications/tech3285s1
.. _SMPTE ST 330 UMID: https://standards.globalspec.com/std/1396751/smpte-st-330
.. _EBU 3285 v2: https://tech.ebu.ch/publications/tech3285s2
.. _EBU Rec 128: https://tech.ebu.ch/publications/r128
.. note::
All text fields in the Broadcast-WAV metadata structure are decoded by
default as flat ASCII. To override this and use a different encoding, pass
an string encoding name to the ``bext_encoding`` parameter of
:py:meth:`WavInfoReader()<wavinfo.wave_reader.WavInfoReader.__init__>`
Example
-------
.. code:: python