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UMID Implementation

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This commit is contained in:
Jamie Hardt
2020-01-06 08:27:34 -08:00
parent 1b9547e8c2
commit 5a30ce3afc
4 changed files with 185 additions and 203 deletions
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82
wavinfo/wave_bext_reader.py
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@@ -1,21 +1,22 @@
import struct
import binascii
from .umid_parser import UMIDParser
class WavBextReader:
def __init__(self,bext_data,encoding):
def __init__(self, bext_data, encoding):
"""
Read Broadcast-WAV extended metadata.
:param best_data: The bytes-like data.
"param encoding: The encoding to use when decoding the text fields of the
BEXT metadata scope. According to EBU Rec 3285 this shall be ASCII.
"""
packstring = "<256s"+ "32s" + "32s" + "10s" + "8s" + "QH" + "64s" + "hhhhh" + "180s"
packstring = "<256s" + "32s" + "32s" + "10s" + "8s" + "QH" + "64s" + "hhhhh" + "180s"
rest_starts = struct.calcsize(packstring)
unpacked = struct.unpack(packstring, bext_data[:rest_starts])
def sanatize_bytes(bytes):
first_null = next( (index for index, byte in enumerate(bytes) if byte == 0 ), None )
first_null = next((index for index, byte in enumerate(bytes) if byte == 0), None)
if first_null is not None:
trimmed = bytes[:first_null]
else:
@@ -25,68 +26,67 @@ class WavBextReader:
return decoded
#: Description. A free-text field up to 256 characters long.
self.description = sanatize_bytes(unpacked[0])
self.description = sanatize_bytes(unpacked[0])
#: Originator. Usually the name of the encoding application, sometimes
#: a artist name.
self.originator = sanatize_bytes(unpacked[1])
self.originator = sanatize_bytes(unpacked[1])
#: A unique identifer for the file, a serial number.
self.originator_ref = sanatize_bytes(unpacked[2])
self.originator_ref = sanatize_bytes(unpacked[2])
#: Date of the recording, in the format YYY-MM-DD
self.originator_date = sanatize_bytes(unpacked[3])
#: Time of the recording, in the format HH:MM:SS.
self.originator_time = sanatize_bytes(unpacked[4])
#: The sample offset of the start of the file relative to an
#: epoch, usually midnight the day of the recording.
self.time_reference = unpacked[5]
self.time_reference = unpacked[5]
#: A variable-length text field containing a list of processes and
#: and conversions performed on the file.
self.coding_history = sanatize_bytes(bext_data[rest_starts:])
self.coding_history = sanatize_bytes(bext_data[rest_starts:])
#: BEXT version.
self.version = unpacked[6]
self.version = unpacked[6]
#: SMPTE 330M UMID of this audio file, 64 bytes are allocated though the UMID
#: may only be 32 bytes long.
self.umid = None
self.umid = None
#: EBU R128 Integrated loudness, in LUFS.
self.loudness_value = None
self.loudness_value = None
#: EBU R128 Loudness rante, in LUFS.
self.loudness_range = None
self.loudness_range = None
#: True peak level, in dBFS TP
self.max_true_peak = None
self.max_true_peak = None
#: EBU R128 Maximum momentary loudness, in LUFS
self.max_momentary_loudness = None
self.max_momentary_loudness = None
#: EBU R128 Maximum short-term loudness, in LUFS.
self.max_shortterm_loudness = None
self.max_shortterm_loudness = None
if self.version > 0:
self.umid = unpacked[7]
if self.version > 1:
self.loudness_value = unpacked[8] / 100.0
self.loudness_range = unpacked[9] / 100.0
self.max_true_peak = unpacked[10] / 100.0
self.max_momentary_loudness = unpacked[11] / 100.0
self.max_shortterm_loudness = unpacked[12] / 100.0
def umid_to_str(self):
if self.umid:
return str(binascii.hexlify(self.umid), encoding='ascii')
else:
return None
self.loudness_value = unpacked[8] / 100.0
self.loudness_range = unpacked[9] / 100.0
self.max_true_peak = unpacked[10] / 100.0
self.max_momentary_loudness = unpacked[11] / 100.0
self.max_shortterm_loudness = unpacked[12] / 100.0
def to_dict(self):
return {'description': self.description,
'originator': self.originator,
'originator_ref': self.originator_ref,
'originator_date': self.originator_date,
'originator_time': self.originator_time,
'time_reference': self.time_reference,
'version': self.version,
'umid': self.umid_to_str(),
'coding_history': self.coding_history,
'loudness_value': self.loudness_value,
'loudness_range': self.loudness_range,
'max_true_peak': self.max_true_peak,
'max_momentary_loudness': self.max_momentary_loudness,
'max_shortterm_loudness': self.max_shortterm_loudness
}
if self.umid is not None:
umid_parsed = UMIDParser(self.umid)
umid_str = umid_parsed.basic_umid_to_str()
else:
umid_str = None
return {'description': self.description,
'originator': self.originator,
'originator_ref': self.originator_ref,
'originator_date': self.originator_date,
'originator_time': self.originator_time,
'time_reference': self.time_reference,
'version': self.version,
'umid': umid_str,
'coding_history': self.coding_history,
'loudness_value': self.loudness_value,
'loudness_range': self.loudness_range,
'max_true_peak': self.max_true_peak,
'max_momentary_loudness': self.max_momentary_loudness,
'max_shortterm_loudness': self.max_shortterm_loudness
}