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89 lines
2.8 KiB
ReStructuredText
89 lines
2.8 KiB
ReStructuredText
Broadcast WAV Extension Metadata
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================================
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Notes
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-----
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A WAV file produced to Broadcast-WAV specifications will have the broadcast
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metadata extension, which includes a 256-character free text descrption,
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creating entity identifier (usually the recording application or equipment),
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the date and time of recording and a time reference for timecode
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synchronization.
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The :py:attr:`coding_history<wavinfo.wave_bext_reader.WavBextReader.coding_history>`
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is designed to contain a record of every conversion performed on the audio file.
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In this example (from a Sound Devices 702T) the bext metadata contains
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scene/take slating information in the
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:py:attr:`description<wavinfo.wave_bext_reader.WavBextReader.description>`.
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Here also the
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:py:attr:`originator_ref<wavinfo.wave_bext_reader.WavBextReader.originator_ref>`
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is a serial number conforming to EBU Rec 99.
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If the bext metadata conforms to `EBU 3285 v1`_, it will contain the WAV's 32
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or 64 byte `SMPTE ST 330 UMID`_. The 32-byte version of the UMID is usually
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just a random number, while the 64-byte UMID will also have information on the
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recording date and time, recording equipment and entity, and geolocation data.
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If the bext metadata conforms to `EBU 3285 v2`_, it will hold precomputed
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program loudness values as described by `EBU Rec 128`_.
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.. _EBU 3285 v1: https://tech.ebu.ch/publications/tech3285s1
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.. _SMPTE ST 330 UMID: https://standards.globalspec.com/std/1396751/smpte-st-330
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.. _EBU 3285 v2: https://tech.ebu.ch/publications/tech3285s2
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.. _EBU Rec 128: https://tech.ebu.ch/publications/r128
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.. note::
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All text fields in the Broadcast-WAV metadata structure are decoded by
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default as flat ASCII. To override this and use a different encoding, pass
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an string encoding name to the ``bext_encoding`` parameter of
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:py:meth:`WavInfoReader()<wavinfo.wave_reader.WavInfoReader.__init__>`
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Example
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-------
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.. code:: python
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print(info.bext.description)
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print("----------")
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print("Originator:", info.bext.originator)
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print("Originator Ref:", info.bext.originator_ref)
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print("Originator Date:", info.bext.originator_date)
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print("Originator Time:", info.bext.originator_time)
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print("Time Reference:", info.bext.time_reference)
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print(info.bext.coding_history)
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Result:
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::
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sSPEED=023.976-ND
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sTAKE=1
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sUBITS=$12311801
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sSWVER=2.67
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sPROJECT=BMH
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sSCENE=A101
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sFILENAME=A101_1.WAV
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sTAPE=18Y12M31
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sTRK1=MKH516 A
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sTRK2=Boom
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sNOTE=
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----------
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Originator: Sound Dev: 702T S#GR1112089007
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Originator Ref: USSDVGR1112089007124001008206301
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Originator Date: 2018-12-31
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Originator Time: 12:40:00
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Time Reference: 2190940753
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A=PCM,F=48000,W=24,M=stereo,R=48000,T=2 Ch
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Class Reference
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---------------
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.. autoclass:: wavinfo.wave_bext_reader.WavBextReader
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:members:
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