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Implementation

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This commit is contained in:
Jamie Hardt
2018-12-31 15:56:58 -08:00
parent 37a9849b4e
commit 65add975da
2 changed files with 65 additions and 33 deletions
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11
wavinfo/wave_parser.py
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@@ -6,10 +6,8 @@ from .wave_ixml_reader import WavIXMLFormat
from collections import namedtuple
ListChunkDescriptor = namedtuple('ListChunk' , 'signature children')
class ChunkDescriptor(namedtuple('Chunk', 'ident start length') ):
def read_data(self, from_stream):
from_stream.seek(self.start)
@@ -50,15 +48,6 @@ def parse_chunk(stream):
WavInfoFormat = namedtuple("WavInfoFormat",'audio_format channel_count sample_rate byte_rate block_align bits_per_sample')
WavBextFormat = namedtuple("WavBextFormat",'description originator originator_ref ' +
'originator_date originator_time time_reference version umid ' +
'loudness_value loudness_range max_true_peak max_momentary_loudness max_shortterm_loudness ' +
'coding_history')

87
wavinfo/wave_reader.py
View File

@@ -1,5 +1,18 @@
import struct
from collections import namedtuple
WavDataDescriptor = namedtuple('WavDataDescriptor','byte_count frame_count')
WavInfoFormat = namedtuple("WavInfoFormat",'audio_format channel_count sample_rate byte_rate block_align bits_per_sample')
WavBextFormat = namedtuple("WavBextFormat",'description originator originator_ref ' +
'originator_date originator_time time_reference version umid ' +
'loudness_value loudness_range max_true_peak max_momentary_loudness max_shortterm_loudness ' +
'coding_history')
class WavInfoReader():
"""
format : WAV format
@@ -11,17 +24,37 @@ class WavInfoReader():
with open(path, 'rb') as f:
chunks = parse_chunk(f)
main_list = chunks.children
self.main_list = chunks.children
f.seek(0)
self.fmt = self._get_format(main_list,f)
self.info = self._get_bext(main_list,f)
self.ixml = self._get_ixml(main_list,f)
self.fmt = self._get_format(self.main_list,f)
self.bext = self._get_bext(self.main_list,f)
self.ixml = self._get_ixml(self.main_list,f)
self.data = delf._describe_data(self.main_list,f)
def _find_chunk_data(self, ident, from_stream, default_none=False):
chunk_descriptor = None
if default_none:
chunk_descriptor =next((chunk for chunk in self.main_list if chunk.ident == ident),None)
else:
chunk_descriptor = next((chunk for chunk in self.main_list if chunk.ident == ident))
if chunk_descriptor:
return chunk_descriptor.read_data(from_stream)
else:
return None
def _describe_data(self,f):
data_chunk = next(c for c in self.main_list if c.ident == b'data')
return WavDataDescriptor(byte_count= data_chunk.length, frame_count= data_chunk.length / self.fmt.block_align)
def _get_format(self,chunks,f):
fmt_chunk = next(chunk for chunk in chunks if chunk.ident == b'fmt ')
fmt_data = fmt_chunk.read_data(f)
fmt_data = se._find_chunk_data(b'fmt ',f)
# The format chunk is
# audio_format U16
@@ -30,20 +63,28 @@ class WavInfoReader():
# byte_rate U32 == SampleRate * NumChannels * BitsPerSample/8
# block_align U16 == NumChannels * BitsPerSample/8
# bits_per_sampl U16
unpacked = struct.unpack("<HHIIHH", fmt_data)
return WavInfoFormat(audio_format = unpacked[0],
channel_count = unpacked[1],
sample_rate = unpacked[2],
byte_rate = unpacked[3],
block_align = unpacked[4],
bits_per_sample = unpacked[5]
)
packstring = "<HHIIHH",
rest_starts = struct.calcsize(packstring)
unpacked = struct.unpack(packstring, fmt_data[:rest_starts])
#0x0001 WAVE_FORMAT_PCM PCM
#0x0003 WAVE_FORMAT_IEEE_FLOAT IEEE float
#0x0006 WAVE_FORMAT_ALAW 8-bit ITU-T G.711 A-law
#0x0007 WAVE_FORMAT_MULAW 8-bit ITU-T G.711 µ-law
#0xFFFE WAVE_FORMAT_EXTENSIBLE Determined by SubFormat
if unpacked[0] == 0x0001:
return WavInfoFormat(audio_format = unpacked[0],
channel_count = unpacked[1],
sample_rate = unpacked[2],
byte_rate = unpacked[3],
block_align = unpacked[4],
bits_per_sample = unpacked[5]
)
def _get_bext(self,chunks,f):
bext_chunk = next((chunk for chunk in chunks if chunk.ident == b'bext'),None)
bext_data = bext_chunk.read_data(from_stream=f)
bext_data = self._find_chunk_data(b'bext',f,default_none=True
# description[256]
# originator[32]
@@ -63,13 +104,14 @@ class WavInfoReader():
# maxshorttermloudness S16 (LUFS*100)
# reserved[180]
# codinghistory []
print(len(bext_data))
if bext_data == None:
return None
packstring = "<256s"+ "32s" + "32s" + "10s" + "8s" + "QH" + "64s" + "hhhhh" + "180s"
rest_starts = struct.calcsize(packstring)
unpacked = struct.unpack(packstring, bext_data[:rest_starts])
return WavBextFormat(description=unpacked[0].decode('ascii').rstrip(' \t\r\n\0'),
originator = unpacked[1].decode('ascii').rstrip(' \t\r\n\0'),
originator_ref = unpacked[2].decode('ascii').rstrip(' \t\r\n\0'),
@@ -88,10 +130,11 @@ class WavInfoReader():
def _get_ixml(self,chunks,f):
ixml_chunk = next((chunk for chunk in chunks if chunk.ident == b'iXML'),None)
ixml_data = ixml_chunk.read_data(from_stream=f)
ixml_string = ixml_data.decode('utf-8')
ixml_data = self._find_chunk_data(b'iXML',f,default_none=True)
if ixml_data == None:
return None
ixml_string = ixml_data.decode('utf-8')
return WavIXMLFormat(ixml_string)