python-pydub 0.20.0-1 / usr / lib / python2.7 / dist-packages / pydub / utils.py

from __future__ import division

from math import log, ceil, floor
import os
import re
from subprocess import Popen, PIPE
import sys
from tempfile import TemporaryFile
from warnings import warn

try:
    import audioop
except ImportError:
    import pyaudioop as audioop


if sys.version_info >= (3, 0):
    basestring = str



FRAME_WIDTHS = {
    8: 1,
    16: 2,
    32: 4,
}
ARRAY_TYPES = {
    8:  "b",
    16: "h",
    32: "i",
}
ARRAY_RANGES = {
    8: (-0x80, 0x7f),
    16: (-0x8000, 0x7fff),
    32: (-0x80000000, 0x7fffffff),
}


def get_frame_width(bit_depth):
    return FRAME_WIDTHS[bit_depth]


def get_array_type(bit_depth, signed=True):
    t = ARRAY_TYPES[bit_depth]
    if not signed:
        t = t.upper()
    return t


def get_min_max_value(bit_depth):
    return ARRAY_RANGES[bit_depth]


def _fd_or_path_or_tempfile(fd, mode='w+b', tempfile=True):
    if fd is None and tempfile:
        fd = TemporaryFile(mode=mode)

    if isinstance(fd, basestring):
        fd = open(fd, mode=mode)

    return fd


def db_to_float(db, using_amplitude=True):
    """
    Converts the input db to a float, which represents the equivalent
    ratio in power.
    """
    db = float(db)
    if using_amplitude:
        return 10 ** (db / 20)
    else: # using power
        return 10 ** (db / 10)


def ratio_to_db(ratio, val2=None, using_amplitude=True):
    """
    Converts the input float to db, which represents the equivalent
    to the ratio in power represented by the multiplier passed in.
    """
    ratio = float(ratio)

    # accept 2 values and use the ratio of val1 to val2
    if val2 is not None:
        ratio = ratio / val2
    
    # special case for multiply-by-zero (convert to silence)
    if ratio == 0:
        return -float('inf')

    if using_amplitude:
        return 20 * log(ratio, 10)
    else: # using power
        return 10 * log(ratio, 10)
    

def register_pydub_effect(fn, name=None):
    """
    decorator for adding pydub effects to the AudioSegment objects.

    example use:

        @register_pydub_effect
        def normalize(audio_segment):
            ...

    or you can specify a name:

        @register_pydub_effect("normalize")
        def normalize_audio_segment(audio_segment):
            ...

    """
    if isinstance(fn, basestring):
        name = fn
        return lambda fn: register_pydub_effect(fn, name)

    if name is None:
        name = fn.__name__

    from .audio_segment import AudioSegment
    setattr(AudioSegment, name, fn)
    return fn


def make_chunks(audio_segment, chunk_length):
    """
    Breaks an AudioSegment into chunks that are <chunk_length> milliseconds
    long.

    if chunk_length is 50 then you'll get a list of 50 millisecond long audio
    segments back (except the last one, which can be shorter)
    """
    number_of_chunks = ceil(len(audio_segment) / float(chunk_length))
    return [audio_segment[i * chunk_length:(i + 1) * chunk_length]
            for i in range(int(number_of_chunks))]


def which(program):
    """
    Mimics behavior of UNIX which command.
    """
    #Add .exe program extension for windows support
    if os.name == "nt" and not program.endswith(".exe"):
        program += ".exe"

    envdir_list = [os.curdir] + os.environ["PATH"].split(os.pathsep)

    for envdir in envdir_list:
        program_path = os.path.join(envdir, program)
        if os.path.isfile(program_path) and os.access(program_path, os.X_OK):
            return program_path


def get_encoder_name():
    """
    Return enconder default application for system, either avconv or ffmpeg
    """
    if which("avconv"):
        return "avconv"
    elif which("ffmpeg"):
        return "ffmpeg"
    else:
        # should raise exception
        warn("Couldn't find ffmpeg or avconv - defaulting to ffmpeg, but may not work", RuntimeWarning)
        return "ffmpeg"

def get_player_name():
    """
    Return enconder default application for system, either avconv or ffmpeg
    """
    if which("avplay"):
        return "avplay"
    elif which("ffplay"):
        return "ffplay"
    else:
        # should raise exception
        warn("Couldn't find ffplay or avplay - defaulting to ffplay, but may not work", RuntimeWarning)
        return "ffplay"


def get_prober_name():
    """
    Return probe application, either avconv or ffmpeg
    """
    if which("avprobe"):
        return "avprobe"
    elif which("ffprobe"):
        return "ffprobe"
    else:
        # should raise exception
        warn("Couldn't find ffprobe or avprobe - defaulting to ffprobe, but may not work", RuntimeWarning)
        return "ffprobe"


def mediainfo(filepath):
    """Return dictionary with media info(codec, duration, size, bitrate...) from filepath
    """

    from .audio_segment import AudioSegment

    prober = get_prober_name()
    command_args = [
        "-v", "quiet",
        "-show_format",
        "-show_streams",
        filepath
    ]

    command = [prober, '-of', 'old'] + command_args
    res = Popen(command, stdout=PIPE)
    output = res.communicate()[0].decode("utf-8")

    if res.returncode != 0:
        command = [prober] + command_args
        output = Popen(command, stdout=PIPE).communicate()[0].decode("utf-8")

    rgx = re.compile(r"(?:(?P<inner_dict>.*?):)?(?P<key>.*?)\=(?P<value>.*?)$")
    info = {}

    if sys.platform == 'win32':
        output = output.replace("\r", "")

    for line in output.split("\n"):
        # print(line)
        mobj = rgx.match(line)

        if mobj:
            # print(mobj.groups())
            inner_dict, key, value = mobj.groups()

            if inner_dict:
                try:
                    info[inner_dict]
                except KeyError:
                    info[inner_dict] = {}
                info[inner_dict][key] = value
            else:
                info[key] = value

    return info