Files
wavinfo/docs/source/scopes/bext.rst
2023-11-06 17:34:10 -08:00

78 lines
2.5 KiB
ReStructuredText

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.
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>`
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 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
Example
-------
.. code:: python
print(info.bext.description)
print("----------")
print("Originator:", info.bext.originator)
print("Originator Ref:", info.bext.originator_ref)
print("Originator Date:", info.bext.originator_date)
print("Originator Time:", info.bext.originator_time)
print("Time Reference:", info.bext.time_reference)
print(info.bext.coding_history)
Result:
::
sSPEED=023.976-ND
sTAKE=1
sUBITS=$12311801
sSWVER=2.67
sPROJECT=BMH
sSCENE=A101
sFILENAME=A101_1.WAV
sTAPE=18Y12M31
sTRK1=MKH516 A
sTRK2=Boom
sNOTE=
----------
Originator: Sound Dev: 702T S#GR1112089007
Originator Ref: USSDVGR1112089007124001008206301
Originator Date: 2018-12-31
Originator Time: 12:40:00
Time Reference: 2190940753
A=PCM,F=48000,W=24,M=stereo,R=48000,T=2 Ch
Class Reference
---------------
.. autoclass:: wavinfo.wave_bext_reader.WavBextReader
:members: