4. Broadcast WAV Extension Metadata

4.1. 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 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 description. Here also the 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.

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 WavInfoReader()

4.2. Example

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

4.3. Class Reference

class wavinfo.wave_bext_reader.WavBextReader(bext_data, encoding)

coding_history: str: A variable-length text field containing a list of processes and and conversions performed on the file.

description: str: Description. A free-text field up to 256 characters long.

loudness_range: float | None: EBU R128 Loudness range, in LUFS.

loudness_value: float | None: EBU R128 Integrated loudness, in LUFS.

max_momentary_loudness: float | None: EBU R128 Maximum momentary loudness, in LUFS

max_shortterm_loudness: float | None: EBU R128 Maximum short-term loudness, in LUFS.

max_true_peak: float | None: True peak level, in dBFS TP

originator: str: Originator. Usually the name of the encoding application, sometimes an artist name.

originator_date: str: Date of the recording, in the format YYYY-MM-DD.

originator_ref: str: A unique identifier for the file, a serial number.

originator_time: str: Time of the recording, in the format HH:MM:SS.

time_reference: int: The sample offset of the start, usually relative to midnight.

umid: bytes | None: SMPTE 330M UMID of this audio file, 64 bytes are allocated though the UMID may only be 32 bytes long.

version: int: BEXT version.