BW64 I/O¶

To read or write a BW64 file, the primary interface is the openBw64Adm() and openBw64() functions.

To read samples and ADM metadata (as an ADM object) from a file, use something like:

from ear.fileio import openBw64Adm

with openBw64Adm("path/to/file.wav") as f:
    adm = f.adm # get the ADM metadata

    for sample_block in f.iter_sample_blocks(1024):
        # do something with sample_block, which will be a numpy float array
        # of (nsamples, nchannels)
        print(sample_block.shape)

For lower level access without parsing ADM data:

from ear.fileio import openBw64

with openBw64("path/to/file.wav") as f:
    print(f.axml) # get the raw AXML data
    print(f.chna) # get the CHNA data

    while True:
        sample_block = f.read(1024)
        if not len(sample_block):
            break
        print(sample_block.shape)

To write a file, you have to construct the format chunk manually:

from ear.fileio.bw64.chunks import FormatInfoChunk, ChnaChunk, AudioID
import numpy as np

# dummy ADM data
axml = b'some AXML data here'
chna = ChnaChunk([
    AudioID(1, 'ATU_00000001', 'AT_00010001_01', 'AP_00010003'),
])

formatInfo = FormatInfoChunk(formatTag=1,
                             channelCount=1,
                             sampleRate=48000,
                             bitsPerSample=24)

with openBw64("path/to/file.wav", "w", formatInfo=formatInfo) as f:
    # optionally write axml and chna data
    f.axml = axml
    f.chna = chna

    # write some sample blocks
    for i in range(10):
        f.write(np.zeros((1024, 1)))

To write some generated adm data, use something like this to generate the CHNA and AXML chunk data:

from ear.fileio.adm.chna import populate_chna_chunk
from ear.fileio.adm.generate_ids import generate_ids
from ear.fileio.adm.xml import adm_to_xml
import lxml.etree

adm = ...

generate_ids(adm)

chna = ChnaChunk()
populate_chna_chunk(chna, adm)

xml = adm_to_xml(adm)
axml = lxml.etree.tostring(xml, pretty_print=True)

Chunk Classes¶

These classes represent chunks (or parts of chunks) in a BW64 file:

class ear.fileio.bw64.chunks.ChnaChunk(audioIDs=NOTHING)¶

Class representation of the ChannelAllocationChunk

audioIDs¶

CHNA entries

Type: list of AudioID

asByteArray()¶: Get the binary representation of this chunk data.

class ear.fileio.bw64.chunks.AudioID(trackIndex, audioTrackUID, audioTrackFormatIDRef, audioPackFormatIDRef)¶

Class representation of a chna audioIDs list entry.

trackIndex¶

1-based index of the track in the sample data

Type: int

audioTrackUID¶

audioTrackUID of the track

Type: str

audioTrackFormatIDRef¶

audioTrackFormatID of the track

Type: str

audioPackFormatIDRef¶

optional audioPackFormatID of the track

Type: str or None

class ear.fileio.bw64.chunks.FormatInfoChunk(formatTag=1, channelCount=1, sampleRate=48000, bytesPerSecond=None, blockAlignment=None, bitsPerSample=16, cbSize=None, extraData=None)¶

Class representation of the FormatChunk

This class can be either used to create a new format chunk or simplify reading and validation of a format chunk. Once created the object cannot be changed. You can only read the saved data. The order of the constructor arguments might seem a bit strange at first sight. The order corresponds to the order within a BW64 file. This makes it easier to create an object from the data read from a file. Cumbersome values like bytesPerSecond or blockAlignment can be omitted (thus set to None). But: if they are set, they have to be correct. Otherwise a ValueError is raised.

To simplify the writing of files the FormatChunk (like every Chunk class in this module) has a asByteArray method. This method returns the correct byte array representation of the FormatChunk, which can be directly written to a file.

asByteArray()¶

property bitsPerSample¶

property blockAlignment¶

property bytesPerSecond¶

property cbSize¶

property channelCount¶

property extraData¶

property formatTag¶

property sampleRate¶