modules/wenet_extractor/dataset/kaldi_io.py

# This module is from [WeNet](https://github.com/wenet-e2e/wenet).

# ## Citations

# ```bibtex
# @inproceedings{yao2021wenet,
#   title={WeNet: Production oriented Streaming and Non-streaming End-to-End Speech Recognition Toolkit},
#   author={Yao, Zhuoyuan and Wu, Di and Wang, Xiong and Zhang, Binbin and Yu, Fan and Yang, Chao and Peng, Zhendong and Chen, Xiaoyu and Xie, Lei and Lei, Xin},
#   booktitle={Proc. Interspeech},
#   year={2021},
#   address={Brno, Czech Republic },
#   organization={IEEE}
# }

# @article{zhang2022wenet,
#   title={WeNet 2.0: More Productive End-to-End Speech Recognition Toolkit},
#   author={Zhang, Binbin and Wu, Di and Peng, Zhendong and Song, Xingchen and Yao, Zhuoyuan and Lv, Hang and Xie, Lei and Yang, Chao and Pan, Fuping and Niu, Jianwei},
#   journal={arXiv preprint arXiv:2203.15455},
#   year={2022}
# }
#

import numpy as np
import sys, os, re, gzip, struct

#################################################
# Adding kaldi tools to shell path,

# Select kaldi,
if not "KALDI_ROOT" in os.environ:
    # Default! To change run python with 'export KALDI_ROOT=/some_dir python'
    os.environ["KALDI_ROOT"] = "/mnt/matylda5/iveselyk/Tools/kaldi-trunk"

# Add kaldi tools to path,
os.environ["PATH"] = (
    os.popen(
        "echo $KALDI_ROOT/src/bin:$KALDI_ROOT/tools/openfst/bin:$KALDI_ROOT/src/fstbin/:$KALDI_ROOT/src/gmmbin/:$KALDI_ROOT/src/featbin/:$KALDI_ROOT/src/lm/:$KALDI_ROOT/src/sgmmbin/:$KALDI_ROOT/src/sgmm2bin/:$KALDI_ROOT/src/fgmmbin/:$KALDI_ROOT/src/latbin/:$KALDI_ROOT/src/nnetbin:$KALDI_ROOT/src/nnet2bin:$KALDI_ROOT/src/nnet3bin:$KALDI_ROOT/src/online2bin/:$KALDI_ROOT/src/ivectorbin/:$KALDI_ROOT/src/lmbin/"
    )
    .readline()
    .strip()
    + ":"
    + os.environ["PATH"]
)


#################################################
# Define all custom exceptions,
class UnsupportedDataType(Exception):
    pass


class UnknownVectorHeader(Exception):
    pass


class UnknownMatrixHeader(Exception):
    pass


class BadSampleSize(Exception):
    pass


class BadInputFormat(Exception):
    pass


class SubprocessFailed(Exception):
    pass


#################################################
# Data-type independent helper functions,


def open_or_fd(file, mode="rb"):
    """fd = open_or_fd(file)
    Open file, gzipped file, pipe, or forward the file-descriptor.
    Eventually seeks in the 'file' argument contains ':offset' suffix.
    """
    offset = None
    try:
        # strip 'ark:' prefix from r{x,w}filename (optional),
        if re.search("^(ark|scp)(,scp|,b|,t|,n?f|,n?p|,b?o|,n?s|,n?cs)*:", file):
            (prefix, file) = file.split(":", 1)
        # separate offset from filename (optional),
        if re.search(":[0-9]+$", file):
            (file, offset) = file.rsplit(":", 1)
        # input pipe?
        if file[-1] == "|":
            fd = popen(file[:-1], "rb")  # custom,
        # output pipe?
        elif file[0] == "|":
            fd = popen(file[1:], "wb")  # custom,
        # is it gzipped?
        elif file.split(".")[-1] == "gz":
            fd = gzip.open(file, mode)
        # a normal file...
        else:
            fd = open(file, mode)
    except TypeError:
        # 'file' is opened file descriptor,
        fd = file
    # Eventually seek to offset,
    if offset != None:
        fd.seek(int(offset))
    return fd


# based on '/usr/local/lib/python3.4/os.py'
def popen(cmd, mode="rb"):
    if not isinstance(cmd, str):
        raise TypeError("invalid cmd type (%s, expected string)" % type(cmd))

    import subprocess, io, threading

    # cleanup function for subprocesses,
    def cleanup(proc, cmd):
        ret = proc.wait()
        if ret > 0:
            raise SubprocessFailed("cmd %s returned %d !" % (cmd, ret))
        return

    # text-mode,
    if mode == "r":
        proc = subprocess.Popen(cmd, shell=True, stdout=subprocess.PIPE)
        threading.Thread(target=cleanup, args=(proc, cmd)).start()  # clean-up thread,
        return io.TextIOWrapper(proc.stdout)
    elif mode == "w":
        proc = subprocess.Popen(cmd, shell=True, stdin=subprocess.PIPE)
        threading.Thread(target=cleanup, args=(proc, cmd)).start()  # clean-up thread,
        return io.TextIOWrapper(proc.stdin)
    # binary,
    elif mode == "rb":
        proc = subprocess.Popen(cmd, shell=True, stdout=subprocess.PIPE)
        threading.Thread(target=cleanup, args=(proc, cmd)).start()  # clean-up thread,
        return proc.stdout
    elif mode == "wb":
        proc = subprocess.Popen(cmd, shell=True, stdin=subprocess.PIPE)
        threading.Thread(target=cleanup, args=(proc, cmd)).start()  # clean-up thread,
        return proc.stdin
    # sanity,
    else:
        raise ValueError("invalid mode %s" % mode)


def read_key(fd):
    """[key] = read_key(fd)
    Read the utterance-key from the opened ark/stream descriptor 'fd'.
    """
    key = ""
    while 1:
        char = fd.read(1).decode("latin1")
        if char == "":
            break
        if char == " ":
            break
        key += char
    key = key.strip()
    if key == "":
        return None  # end of file,
    assert re.match("^\S+$", key) != None  # check format (no whitespace!)
    return key


#################################################
# Integer vectors (alignments, ...),


def read_ali_ark(file_or_fd):
    """Alias to 'read_vec_int_ark()'"""
    return read_vec_int_ark(file_or_fd)


def read_vec_int_ark(file_or_fd):
    """generator(key,vec) = read_vec_int_ark(file_or_fd)
    Create generator of (key,vector<int>) tuples, which reads from the ark file/stream.
    file_or_fd : ark, gzipped ark, pipe or opened file descriptor.

    Read ark to a 'dictionary':
    d = { u:d for u,d in kaldi_io.read_vec_int_ark(file) }
    """
    fd = open_or_fd(file_or_fd)
    try:
        key = read_key(fd)
        while key:
            ali = read_vec_int(fd)
            yield key, ali
            key = read_key(fd)
    finally:
        if fd is not file_or_fd:
            fd.close()


def read_vec_int_scp(file_or_fd):
    """generator(key,vec) = read_vec_int_scp(file_or_fd)
    Returns generator of (key,vector<int>) tuples, read according to kaldi scp.
    file_or_fd : scp, gzipped scp, pipe or opened file descriptor.

    Iterate the scp:
    for key,vec in kaldi_io.read_vec_int_scp(file):
      ...

    Read scp to a 'dictionary':
    d = { key:vec for key,mat in kaldi_io.read_vec_int_scp(file) }
    """
    fd = open_or_fd(file_or_fd)
    try:
        for line in fd:
            (key, rxfile) = line.decode().split(" ")
            vec = read_vec_int(rxfile)
            yield key, vec
    finally:
        if fd is not file_or_fd:
            fd.close()


def read_vec_int(file_or_fd):
    """[int-vec] = read_vec_int(file_or_fd)
    Read kaldi integer vector, ascii or binary input,
    """
    fd = open_or_fd(file_or_fd)
    binary = fd.read(2).decode()
    if binary == "\0B":  # binary flag
        assert fd.read(1).decode() == "\4"
        # int-size
        vec_size = np.frombuffer(fd.read(4), dtype="int32", count=1)[0]  # vector dim
        # Elements from int32 vector are sored in tuples: (sizeof(int32), value),
        vec = np.frombuffer(
            fd.read(vec_size * 5),
            dtype=[("size", "int8"), ("value", "int32")],
            count=vec_size,
        )
        assert vec[0]["size"] == 4  # int32 size,
        ans = vec[:]["value"]  # values are in 2nd column,
    else:  # ascii,
        arr = (binary + fd.readline().decode()).strip().split()
        try:
            arr.remove("[")
            arr.remove("]")  # optionally
        except ValueError:
            pass
        ans = np.array(arr, dtype=int)
    if fd is not file_or_fd:
        fd.close()  # cleanup
    return ans


# Writing,
def write_vec_int(file_or_fd, v, key=""):
    """write_vec_int(f, v, key='')
    Write a binary kaldi integer vector to filename or stream.
    Arguments:
    file_or_fd : filename or opened file descriptor for writing,
    v : the vector to be stored,
    key (optional) : used for writing ark-file, the utterance-id gets written before the vector.

    Example of writing single vector:
    kaldi_io.write_vec_int(filename, vec)

    Example of writing arkfile:
    with open(ark_file,'w') as f:
      for key,vec in dict.iteritems():
        kaldi_io.write_vec_flt(f, vec, key=key)
    """
    fd = open_or_fd(file_or_fd, mode="wb")
    if sys.version_info[0] == 3:
        assert fd.mode == "wb"
    try:
        if key != "":
            fd.write(
                (key + " ").encode("latin1")
            )  # ark-files have keys (utterance-id),
        fd.write("\0B".encode())  # we write binary!
        # dim,
        fd.write("\4".encode())  # int32 type,
        fd.write(struct.pack(np.dtype("int32").char, v.shape[0]))
        # data,
        for i in range(len(v)):
            fd.write("\4".encode())  # int32 type,
            fd.write(struct.pack(np.dtype("int32").char, v[i]))  # binary,
    finally:
        if fd is not file_or_fd:
            fd.close()


#################################################
# Float vectors (confidences, ivectors, ...),


# Reading,
def read_vec_flt_scp(file_or_fd):
    """generator(key,mat) = read_vec_flt_scp(file_or_fd)
    Returns generator of (key,vector) tuples, read according to kaldi scp.
    file_or_fd : scp, gzipped scp, pipe or opened file descriptor.

    Iterate the scp:
    for key,vec in kaldi_io.read_vec_flt_scp(file):
      ...

    Read scp to a 'dictionary':
    d = { key:mat for key,mat in kaldi_io.read_mat_scp(file) }
    """
    fd = open_or_fd(file_or_fd)
    try:
        for line in fd:
            (key, rxfile) = line.decode().split(" ")
            vec = read_vec_flt(rxfile)
            yield key, vec
    finally:
        if fd is not file_or_fd:
            fd.close()


def read_vec_flt_ark(file_or_fd):
    """generator(key,vec) = read_vec_flt_ark(file_or_fd)
    Create generator of (key,vector<float>) tuples, reading from an ark file/stream.
    file_or_fd : ark, gzipped ark, pipe or opened file descriptor.

    Read ark to a 'dictionary':
    d = { u:d for u,d in kaldi_io.read_vec_flt_ark(file) }
    """
    fd = open_or_fd(file_or_fd)
    try:
        key = read_key(fd)
        while key:
            ali = read_vec_flt(fd)
            yield key, ali
            key = read_key(fd)
    finally:
        if fd is not file_or_fd:
            fd.close()


def read_vec_flt(file_or_fd):
    """[flt-vec] = read_vec_flt(file_or_fd)
    Read kaldi float vector, ascii or binary input,
    """
    fd = open_or_fd(file_or_fd)
    binary = fd.read(2).decode()
    if binary == "\0B":  # binary flag
        # Data type,
        header = fd.read(3).decode()
        if header == "FV ":
            sample_size = 4  # floats
        elif header == "DV ":
            sample_size = 8  # doubles
        else:
            raise UnknownVectorHeader("The header contained '%s'" % header)
        assert sample_size > 0
        # Dimension,
        assert fd.read(1).decode() == "\4"
        # int-size
        vec_size = np.frombuffer(fd.read(4), dtype="int32", count=1)[0]  # vector dim
        # Read whole vector,
        buf = fd.read(vec_size * sample_size)
        if sample_size == 4:
            ans = np.frombuffer(buf, dtype="float32")
        elif sample_size == 8:
            ans = np.frombuffer(buf, dtype="float64")
        else:
            raise BadSampleSize
        return ans
    else:  # ascii,
        arr = (binary + fd.readline().decode()).strip().split()
        try:
            arr.remove("[")
            arr.remove("]")  # optionally
        except ValueError:
            pass
        ans = np.array(arr, dtype=float)
    if fd is not file_or_fd:
        fd.close()  # cleanup
    return ans


# Writing,
def write_vec_flt(file_or_fd, v, key=""):
    """write_vec_flt(f, v, key='')
    Write a binary kaldi vector to filename or stream. Supports 32bit and 64bit floats.
    Arguments:
    file_or_fd : filename or opened file descriptor for writing,
    v : the vector to be stored,
    key (optional) : used for writing ark-file, the utterance-id gets written before the vector.

    Example of writing single vector:
    kaldi_io.write_vec_flt(filename, vec)

    Example of writing arkfile:
    with open(ark_file,'w') as f:
      for key,vec in dict.iteritems():
        kaldi_io.write_vec_flt(f, vec, key=key)
    """
    fd = open_or_fd(file_or_fd, mode="wb")
    if sys.version_info[0] == 3:
        assert fd.mode == "wb"
    try:
        if key != "":
            fd.write(
                (key + " ").encode("latin1")
            )  # ark-files have keys (utterance-id),
        fd.write("\0B".encode())  # we write binary!
        # Data-type,
        if v.dtype == "float32":
            fd.write("FV ".encode())
        elif v.dtype == "float64":
            fd.write("DV ".encode())
        else:
            raise UnsupportedDataType(
                "'%s', please use 'float32' or 'float64'" % v.dtype
            )
        # Dim,
        fd.write("\04".encode())
        fd.write(struct.pack(np.dtype("uint32").char, v.shape[0]))  # dim
        # Data,
        fd.write(v.tobytes())
    finally:
        if fd is not file_or_fd:
            fd.close()


#################################################
# Float matrices (features, transformations, ...),


# Reading,
def read_mat_scp(file_or_fd):
    """generator(key,mat) = read_mat_scp(file_or_fd)
    Returns generator of (key,matrix) tuples, read according to kaldi scp.
    file_or_fd : scp, gzipped scp, pipe or opened file descriptor.

    Iterate the scp:
    for key,mat in kaldi_io.read_mat_scp(file):
      ...

    Read scp to a 'dictionary':
    d = { key:mat for key,mat in kaldi_io.read_mat_scp(file) }
    """
    fd = open_or_fd(file_or_fd)
    try:
        for line in fd:
            (key, rxfile) = line.decode().split(" ")
            mat = read_mat(rxfile)
            yield key, mat
    finally:
        if fd is not file_or_fd:
            fd.close()


def read_mat_ark(file_or_fd):
    """generator(key,mat) = read_mat_ark(file_or_fd)
    Returns generator of (key,matrix) tuples, read from ark file/stream.
    file_or_fd : scp, gzipped scp, pipe or opened file descriptor.

    Iterate the ark:
    for key,mat in kaldi_io.read_mat_ark(file):
      ...

    Read ark to a 'dictionary':
    d = { key:mat for key,mat in kaldi_io.read_mat_ark(file) }
    """
    fd = open_or_fd(file_or_fd)
    try:
        key = read_key(fd)
        while key:
            mat = read_mat(fd)
            yield key, mat
            key = read_key(fd)
    finally:
        if fd is not file_or_fd:
            fd.close()


def read_mat(file_or_fd):
    """[mat] = read_mat(file_or_fd)
    Reads single kaldi matrix, supports ascii and binary.
    file_or_fd : file, gzipped file, pipe or opened file descriptor.
    """
    fd = open_or_fd(file_or_fd)
    try:
        binary = fd.read(2).decode()
        if binary == "\0B":
            mat = _read_mat_binary(fd)
        else:
            assert binary == " ["
            mat = _read_mat_ascii(fd)
    finally:
        if fd is not file_or_fd:
            fd.close()
    return mat


def _read_mat_binary(fd):
    # Data type
    header = fd.read(3).decode()
    # 'CM', 'CM2', 'CM3' are possible values,
    if header.startswith("CM"):
        return _read_compressed_mat(fd, header)
    elif header == "FM ":
        sample_size = 4  # floats
    elif header == "DM ":
        sample_size = 8  # doubles
    else:
        raise UnknownMatrixHeader("The header contained '%s'" % header)
    assert sample_size > 0
    # Dimensions
    s1, rows, s2, cols = np.frombuffer(
        fd.read(10), dtype="int8,int32,int8,int32", count=1
    )[0]
    # Read whole matrix
    buf = fd.read(rows * cols * sample_size)
    if sample_size == 4:
        vec = np.frombuffer(buf, dtype="float32")
    elif sample_size == 8:
        vec = np.frombuffer(buf, dtype="float64")
    else:
        raise BadSampleSize
    mat = np.reshape(vec, (rows, cols))
    return mat


def _read_mat_ascii(fd):
    rows = []
    while 1:
        line = fd.readline().decode()
        if len(line) == 0:
            raise BadInputFormat  # eof, should not happen!
        if len(line.strip()) == 0:
            continue  # skip empty line
        arr = line.strip().split()
        if arr[-1] != "]":
            rows.append(np.array(arr, dtype="float32"))  # not last line
        else:
            rows.append(np.array(arr[:-1], dtype="float32"))  # last line
            mat = np.vstack(rows)
            return mat


def _read_compressed_mat(fd, format):
    """Read a compressed matrix,
    see: https://github.com/kaldi-asr/kaldi/blob/master/src/matrix/compressed-matrix.h
    methods: CompressedMatrix::Read(...), CompressedMatrix::CopyToMat(...),
    """
    assert format == "CM "  # The formats CM2, CM3 are not supported...

    # Format of header 'struct',
    global_header = np.dtype(
        [
            ("minvalue", "float32"),
            ("range", "float32"),
            ("num_rows", "int32"),
            ("num_cols", "int32"),
        ]
    )  # member '.format' is not written,
    per_col_header = np.dtype(
        [
            ("percentile_0", "uint16"),
            ("percentile_25", "uint16"),
            ("percentile_75", "uint16"),
            ("percentile_100", "uint16"),
        ]
    )

    # Mapping for percentiles in col-headers,
    def uint16_to_float(value, min, range):
        return np.float32(min + range * 1.52590218966964e-05 * value)

    # Mapping for matrix elements,
    def uint8_to_float_v2(vec, p0, p25, p75, p100):
        # Split the vector by masks,
        mask_0_64 = vec <= 64
        mask_193_255 = vec > 192
        mask_65_192 = ~(mask_0_64 | mask_193_255)
        # Sanity check (useful but slow...),
        # assert(len(vec) == np.sum(np.hstack([mask_0_64,mask_65_192,mask_193_255])))
        # assert(len(vec) == np.sum(np.any([mask_0_64,mask_65_192,mask_193_255], axis=0)))
        # Build the float vector,
        ans = np.empty(len(vec), dtype="float32")
        ans[mask_0_64] = p0 + (p25 - p0) / 64.0 * vec[mask_0_64]
        ans[mask_65_192] = p25 + (p75 - p25) / 128.0 * (vec[mask_65_192] - 64)
        ans[mask_193_255] = p75 + (p100 - p75) / 63.0 * (vec[mask_193_255] - 192)
        return ans

    # Read global header,
    globmin, globrange, rows, cols = np.frombuffer(
        fd.read(16), dtype=global_header, count=1
    )[0]

    # The data is structed as [Colheader, ... , Colheader, Data, Data , .... ]
    #                         {           cols           }{     size         }
    col_headers = np.frombuffer(fd.read(cols * 8), dtype=per_col_header, count=cols)
    data = np.reshape(
        np.frombuffer(fd.read(cols * rows), dtype="uint8", count=cols * rows),
        newshape=(cols, rows),
    )  # stored as col-major,

    mat = np.empty((cols, rows), dtype="float32")
    for i, col_header in enumerate(col_headers):
        col_header_flt = [
            uint16_to_float(percentile, globmin, globrange) for percentile in col_header
        ]
        mat[i] = uint8_to_float_v2(data[i], *col_header_flt)

    return mat.T  # transpose! col-major -> row-major,


def write_ark_scp(key, mat, ark_fout, scp_out):
    mat_offset = write_mat(ark_fout, mat, key)
    scp_line = "{}\t{}:{}".format(key, ark_fout.name, mat_offset)
    scp_out.write(scp_line)
    scp_out.write("\n")


# Writing,
def write_mat(file_or_fd, m, key=""):
    """write_mat(f, m, key='')
    Write a binary kaldi matrix to filename or stream. Supports 32bit and 64bit floats.
    Arguments:
     file_or_fd : filename of opened file descriptor for writing,
     m : the matrix to be stored,
     key (optional) : used for writing ark-file, the utterance-id gets written before the matrix.

     Example of writing single matrix:
     kaldi_io.write_mat(filename, mat)

     Example of writing arkfile:
     with open(ark_file,'w') as f:
       for key,mat in dict.iteritems():
         kaldi_io.write_mat(f, mat, key=key)
    """
    mat_offset = 0
    fd = open_or_fd(file_or_fd, mode="wb")
    if sys.version_info[0] == 3:
        assert fd.mode == "wb"
    try:
        if key != "":
            fd.write(
                (key + " ").encode("latin1")
            )  # ark-files have keys (utterance-id),
        mat_offset = fd.tell()
        fd.write("\0B".encode())  # we write binary!
        # Data-type,
        if m.dtype == "float32":
            fd.write("FM ".encode())
        elif m.dtype == "float64":
            fd.write("DM ".encode())
        else:
            raise UnsupportedDataType(
                "'%s', please use 'float32' or 'float64'" % m.dtype
            )
        # Dims,
        fd.write("\04".encode())
        fd.write(struct.pack(np.dtype("uint32").char, m.shape[0]))  # rows
        fd.write("\04".encode())
        fd.write(struct.pack(np.dtype("uint32").char, m.shape[1]))  # cols
        # Data,
        fd.write(m.tobytes())
    finally:
        if fd is not file_or_fd:
            fd.close()
    return mat_offset


#################################################
# 'Posterior' kaldi type (posteriors, confusion network, nnet1 training targets, ...)
# Corresponds to: vector<vector<tuple<int,float> > >
# - outer vector: time axis
# - inner vector: records at the time
# - tuple: int = index, float = value
#


def read_cnet_ark(file_or_fd):
    """Alias of function 'read_post_ark()', 'cnet' = confusion network"""
    return read_post_ark(file_or_fd)


def read_post_ark(file_or_fd):
    """generator(key,vec<vec<int,float>>) = read_post_ark(file)
    Returns generator of (key,posterior) tuples, read from ark file.
    file_or_fd : ark, gzipped ark, pipe or opened file descriptor.

    Iterate the ark:
    for key,post in kaldi_io.read_post_ark(file):
      ...

    Read ark to a 'dictionary':
    d = { key:post for key,post in kaldi_io.read_post_ark(file) }
    """
    fd = open_or_fd(file_or_fd)
    try:
        key = read_key(fd)
        while key:
            post = read_post(fd)
            yield key, post
            key = read_key(fd)
    finally:
        if fd is not file_or_fd:
            fd.close()


def read_post(file_or_fd):
    """[post] = read_post(file_or_fd)
    Reads single kaldi 'Posterior' in binary format.

    The 'Posterior' is C++ type 'vector<vector<tuple<int,float> > >',
    the outer-vector is usually time axis, inner-vector are the records
    at given time,  and the tuple is composed of an 'index' (integer)
    and a 'float-value'. The 'float-value' can represent a probability
    or any other numeric value.

    Returns vector of vectors of tuples.
    """
    fd = open_or_fd(file_or_fd)
    ans = []
    binary = fd.read(2).decode()
    assert binary == "\0B"
    # binary flag
    assert fd.read(1).decode() == "\4"
    # int-size
    outer_vec_size = np.frombuffer(fd.read(4), dtype="int32", count=1)[
        0
    ]  # number of frames (or bins)

    # Loop over 'outer-vector',
    for i in range(outer_vec_size):
        assert fd.read(1).decode() == "\4"
        # int-size
        inner_vec_size = np.frombuffer(fd.read(4), dtype="int32", count=1)[
            0
        ]  # number of records for frame (or bin)
        data = np.frombuffer(
            fd.read(inner_vec_size * 10),
            dtype=[
                ("size_idx", "int8"),
                ("idx", "int32"),
                ("size_post", "int8"),
                ("post", "float32"),
            ],
            count=inner_vec_size,
        )
        assert data[0]["size_idx"] == 4
        assert data[0]["size_post"] == 4
        ans.append(data[["idx", "post"]].tolist())

    if fd is not file_or_fd:
        fd.close()
    return ans


#################################################
# Kaldi Confusion Network bin begin/end times,
# (kaldi stores CNs time info separately from the Posterior).
#


def read_cntime_ark(file_or_fd):
    """generator(key,vec<tuple<float,float>>) = read_cntime_ark(file_or_fd)
    Returns generator of (key,cntime) tuples, read from ark file.
    file_or_fd : file, gzipped file, pipe or opened file descriptor.

    Iterate the ark:
    for key,time in kaldi_io.read_cntime_ark(file):
      ...

    Read ark to a 'dictionary':
    d = { key:time for key,time in kaldi_io.read_post_ark(file) }
    """
    fd = open_or_fd(file_or_fd)
    try:
        key = read_key(fd)
        while key:
            cntime = read_cntime(fd)
            yield key, cntime
            key = read_key(fd)
    finally:
        if fd is not file_or_fd:
            fd.close()


def read_cntime(file_or_fd):
    """[cntime] = read_cntime(file_or_fd)
    Reads single kaldi 'Confusion Network time info', in binary format:
    C++ type: vector<tuple<float,float> >.
    (begin/end times of bins at the confusion network).

    Binary layout is '<num-bins> <beg1> <end1> <beg2> <end2> ...'

    file_or_fd : file, gzipped file, pipe or opened file descriptor.

    Returns vector of tuples.
    """
    fd = open_or_fd(file_or_fd)
    binary = fd.read(2).decode()
    assert binary == "\0B"
    # assuming it's binary

    assert fd.read(1).decode() == "\4"
    # int-size
    vec_size = np.frombuffer(fd.read(4), dtype="int32", count=1)[
        0
    ]  # number of frames (or bins)

    data = np.frombuffer(
        fd.read(vec_size * 10),
        dtype=[
            ("size_beg", "int8"),
            ("t_beg", "float32"),
            ("size_end", "int8"),
            ("t_end", "float32"),
        ],
        count=vec_size,
    )
    assert data[0]["size_beg"] == 4
    assert data[0]["size_end"] == 4
    ans = data[["t_beg", "t_end"]].tolist()  # Return vector of tuples (t_beg,t_end),

    if fd is not file_or_fd:
        fd.close()
    return ans


#################################################
# Segments related,
#


# Segments as 'Bool vectors' can be handy,
# - for 'superposing' the segmentations,
# - for frame-selection in Speaker-ID experiments,
def read_segments_as_bool_vec(segments_file):
    """[ bool_vec ] = read_segments_as_bool_vec(segments_file)
    using kaldi 'segments' file for 1 wav, format : '<utt> <rec> <t-beg> <t-end>'
    - t-beg, t-end is in seconds,
    - assumed 100 frames/second,
    """
    segs = np.loadtxt(segments_file, dtype="object,object,f,f", ndmin=1)
    # Sanity checks,
    assert len(segs) > 0  # empty segmentation is an error,
    assert (
        len(np.unique([rec[1] for rec in segs])) == 1
    )  # segments with only 1 wav-file,
    # Convert time to frame-indexes,
    start = np.rint([100 * rec[2] for rec in segs]).astype(int)
    end = np.rint([100 * rec[3] for rec in segs]).astype(int)
    # Taken from 'read_lab_to_bool_vec', htk.py,
    frms = np.repeat(
        np.r_[np.tile([False, True], len(end)), False],
        np.r_[np.c_[start - np.r_[0, end[:-1]], end - start].flat, 0],
    )
    assert np.sum(end - start) == np.sum(frms)
    return frms