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`pygame.mixer`
  pygame module for loading and playing sounds

  This module contains classes for loading Sound objects and controlling playback. The mixer module is optional and depends on SDL_mixer. Your program should test that `pygame.mixer` pygame module for loading and playing sounds is available and initialized before using it.

  The mixer module has a limited number of channels for playback of sounds. Usually programs tell pygame to start playing audio and it selects an available channel automatically. The default is 8 simultaneous channels, but complex programs can get more precise control over the number of channels and their use.

  All sound playback is mixed in background threads. When you begin to play a Sound object, it will return immediately while the sound continues to play. A single Sound object can also be actively played back multiple times.

  The mixer also has a special streaming channel. This is for music playback and is accessed through the `pygame.mixer.music` pygame module for controlling streamed audio module. Consider using this module for playing long running music. Unlike mixer module, the music module streams the music from the files without loading music at once into memory.

  The mixer module must be initialized like other pygame modules, but it has some extra conditions. The `pygame.mixer.init()` function takes several optional arguments to control the playback rate and sample size. Pygame will default to reasonable values, but pygame cannot perform Sound resampling, so the mixer should be initialized to match the values of your audio resources.

  `NOTE`: For less laggy sound use a smaller buffer size. The default is set to reduce the chance of scratchy sounds on some computers. You can change the default buffer by calling `pygame.mixer.pre_init()`preset the mixer init arguments before `pygame.mixer.init()`initialize the mixer module or `pygame.init()`initialize all imported pygame modules is called. For example: `pygame.mixer.pre_init(44100,-16,2, 1024)`

  pygame.mixer.init()
    initialize the mixer module
    init(frequency=44100, size=-16, channels=2, buffer=512, devicename=None, allowedchanges=AUDIO_ALLOW_FREQUENCY_CHANGE | AUDIO_ALLOW_CHANNELS_CHANGE) -> None

    Initialize the mixer module for Sound loading and playback. The default arguments can be overridden to provide specific audio mixing. Keyword arguments are accepted. For backwards compatibility, argument values of 0 are replaced with the startup defaults, except for `allowedchanges`, where -1 is used. (startup defaults may be changed by a `pre_init()` call).

    The size argument represents how many bits are used for each audio sample. If the value is negative then signed sample values will be used. Positive values mean unsigned audio samples will be used. An invalid value raises an exception.

    The channels argument is used to specify whether to use mono or stereo. 1 for mono and 2 for stereo.

    The buffer argument controls the number of internal samples used in the sound mixer. The default value should work for most cases. It can be lowered to reduce latency, but sound dropout may occur. It can be raised to larger values to ensure playback never skips, but it will impose latency on sound playback. The buffer size must be a power of two (if not it is rounded up to the next nearest power of 2).

    Some platforms require the `pygame.mixer` pygame module for loading and playing sounds module to be initialized after the display modules have initialized. The top level `pygame.init()` takes care of this automatically, but cannot pass any arguments to the mixer init. To solve this, mixer has a function `pygame.mixer.pre_init()` to set the proper defaults before the toplevel init is used.

    When using allowedchanges=0 it will convert the samples at runtime to match what the hardware supports. For example a sound card may not support 16bit sound samples, so instead it will use 8bit samples internally. If AUDIO_ALLOW_FORMAT_CHANGE is supplied, then the requested format will change to the closest that SDL2 supports.

    Apart from 0, allowedchanged accepts the following constants ORed together:

    > - AUDIO_ALLOW_FREQUENCY_CHANGE

    > - AUDIO_ALLOW_FORMAT_CHANGE

    > - AUDIO_ALLOW_CHANNELS_CHANGE

    > - AUDIO_ALLOW_ANY_CHANGE

    It is safe to call this more than once, but after the mixer is initialized you cannot change the playback arguments without first calling `pygame.mixer.quit()`.

    Changed in pygame 1.8: The default `buffersize` changed from 1024 to 3072.

    Changed in pygame 1.9.1: The default `buffersize` changed from 3072 to 4096.

    Changed in pygame 2.0.0: The default `buffersize` changed from 4096 to 512.

    Changed in pygame 2.0.0: The default `frequency` changed from 22050 to 44100.

    Changed in pygame 2.0.0: `size` can be 32 (32-bit floats).

    Changed in pygame 2.0.0: `channels` can also be 4 or 6.

    New in pygame 2.0.0: `allowedchanges`, `devicename` arguments added

  pygame.mixer.pre_init()
    preset the mixer init arguments
    pre_init(frequency=44100, size=-16, channels=2, buffer=512, devicename=None, allowedchanges=AUDIO_ALLOW_FREQUENCY_CHANGE | AUDIO_ALLOW_CHANNELS_CHANGE) -> None

    Call pre_init to change the defaults used when the real `pygame.mixer.init()` is called. Keyword arguments are accepted. The best way to set custom mixer playback values is to call `pygame.mixer.pre_init()` before calling the top level `pygame.init()`. For backwards compatibility, argument values of 0 are replaced with the startup defaults, except for `allowedchanges`, where -1 is used.

    Changed in pygame 1.8: The default `buffersize` changed from 1024 to 3072.

    Changed in pygame 1.9.1: The default `buffersize` changed from 3072 to 4096.

    Changed in pygame 2.0.0: The default `buffersize` changed from 4096 to 512.

    Changed in pygame 2.0.0: The default `frequency` changed from 22050 to 44100.

    New in pygame 2.0.0: `allowedchanges`, `devicename` arguments added

  pygame.mixer.quit()
    uninitialize the mixer
    quit() -> None

    This will uninitialize `pygame.mixer` pygame module for loading and playing sounds. All playback will stop and any loaded Sound objects may not be compatible with the mixer if it is reinitialized later.

  pygame.mixer.get_init()
    test if the mixer is initialized
    get_init() -> (frequency, format, channels)

    If the mixer is initialized, this returns the playback arguments it is using. If the mixer has not been initialized this returns `None`.

  pygame.mixer.stop()
    stop playback of all sound channels
    stop() -> None

    This will stop all playback of all active mixer channels.

  pygame.mixer.pause()
    temporarily stop playback of all sound channels
    pause() -> None

    This will temporarily stop all playback on the active mixer channels. The playback can later be resumed with `pygame.mixer.unpause()`

  pygame.mixer.unpause()
    resume paused playback of sound channels
    unpause() -> None

    This will resume all active sound channels after they have been paused.

  pygame.mixer.fadeout()
    fade out the volume on all sounds before stopping
    fadeout(time) -> None

    This will fade out the volume on all active channels over the time argument in milliseconds. After the sound is muted the playback will stop.

  pygame.mixer.set_num_channels()
    set the total number of playback channels
    set_num_channels(count) -> None

    Sets the number of available channels for the mixer. The default value is 8. The value can be increased or decreased. If the value is decreased, sounds playing on the truncated channels are stopped.

  pygame.mixer.get_num_channels()
    get the total number of playback channels
    get_num_channels() -> count

    Returns the number of currently active playback channels.

  pygame.mixer.set_reserved()
    reserve channels from being automatically used
    set_reserved(count) -> count

    The mixer can reserve any number of channels that will not be automatically selected for playback by Sounds. If sounds are currently playing on the reserved channels they will not be stopped.

    This allows the application to reserve a specific number of channels for important sounds that must not be dropped or have a guaranteed channel to play on.

    Will return number of channels actually reserved, this may be less than requested depending on the number of channels previously allocated.

  pygame.mixer.find_channel()
    find an unused channel
    find_channel(force=False) -> Channel

    This will find and return an inactive Channel object. If there are no inactive Channels this function will return `None`. If there are no inactive channels and the force argument is `True`, this will find the Channel with the longest running Sound and return it.

  pygame.mixer.get_busy()
    test if any sound is being mixed
    get_busy() -> bool

    Returns `True` if the mixer is busy mixing any channels. If the mixer is idle then this return `False`.

  pygame.mixer.get_sdl_mixer_version()
    get the mixer's SDL version
    get_sdl_mixer_version() -> (major, minor, patch)
    get_sdl_mixer_version(linked=True) -> (major, minor, patch)
    Parameters

      linked (bool) -- if `True` (default) the linked version number is returned, otherwise the compiled version number is returned

    Returns

      the mixer's SDL library version number (linked or compiled depending on the `linked` parameter) as a tuple of 3 integers `(major, minor, patch)`

    Return type

      tuple

    Note

    The linked and compile version numbers should be the same.

    New in pygame 2.0.0.

  pygame.mixer.Sound
    Create a new Sound object from a file or buffer object
    Sound(filename) -> Sound
    Sound(file=filename) -> Sound
    Sound(file=pathlib_path) -> Sound
    Sound(buffer) -> Sound
    Sound(buffer=buffer) -> Sound
    Sound(object) -> Sound
    Sound(file=object) -> Sound
    Sound(array=object) -> Sound

    Load a new sound buffer from a filename, a python file object or a readable buffer object. Limited resampling will be performed to help the sample match the initialize arguments for the mixer. A Unicode string can only be a file pathname. A bytes object can be either a pathname or a buffer object. Use the 'file' or 'buffer' keywords to avoid ambiguity; otherwise Sound may guess wrong. If the array keyword is used, the object is expected to export a new buffer interface (The object is checked for a buffer interface first.)

    The Sound object represents actual sound sample data. Methods that change the state of the Sound object will the all instances of the Sound playback. A Sound object also exports a new buffer interface.

    The Sound can be loaded from an `OGG` audio file or from an uncompressed `WAV`.

    Note: The buffer will be copied internally, no data will be shared between it and the Sound object.

    For now buffer and array support is consistent with `sndarray.make_sound` for Numeric arrays, in that sample sign and byte order are ignored. This will change, either by correctly handling sign and byte order, or by raising an exception when different. Also, source samples are truncated to fit the audio sample size. This will not change.

    New in pygame 1.8: `pygame.mixer.Sound(buffer)`

    New in pygame 1.9.2: `pygame.mixer.Sound` Create a new Sound object from a file or buffer object keyword arguments and array interface support

    New in pygame 2.0.1: pathlib.Path support on Python 3.

    play()
      begin sound playback
      play(loops=0, maxtime=0, fade_ms=0) -> Channel

      Begin playback of the Sound (i.e., on the computer's speakers) on an available Channel. This will forcibly select a Channel, so playback may cut off a currently playing sound if necessary.

      The loops argument controls how many times the sample will be repeated after being played the first time. A value of 5 means that the sound will be played once, then repeated five times, and so is played a total of six times. The default value (zero) means the Sound is not repeated, and so is only played once. If loops is set to -1 the Sound will loop indefinitely (though you can still call `stop()` to stop it).

      The maxtime argument can be used to stop playback after a given number of milliseconds.

      The fade_ms argument will make the sound start playing at 0 volume and fade up to full volume over the time given. The sample may end before the fade-in is complete.

      This returns the Channel object for the channel that was selected.

    stop()
      stop sound playback
      stop() -> None

      This will stop the playback of this Sound on any active Channels.

    fadeout()
      stop sound playback after fading out
      fadeout(time) -> None

      This will stop playback of the sound after fading it out over the time argument in milliseconds. The Sound will fade and stop on all actively playing channels.

    set_volume()
      set the playback volume for this Sound
      set_volume(value) -> None

      This will set the playback volume (loudness) for this Sound. This will immediately affect the Sound if it is playing. It will also affect any future playback of this Sound.

      Parameters

        value (float) --

        volume in the range of 0.0 to 1.0 (inclusive)

        If value < 0.0, the volume will not be changed
        If value > 1.0, the volume will be set to 1.0
    get_volume()
      get the playback volume
      get_volume() -> value

      Return a value from 0.0 to 1.0 representing the volume for this Sound.

    get_num_channels()
      count how many times this Sound is playing
      get_num_channels() -> count

      Return the number of active channels this sound is playing on.

    get_length()
      get the length of the Sound
      get_length() -> seconds

      Return the length of this Sound in seconds.

    get_raw()
      return a bytestring copy of the Sound samples.
      get_raw() -> bytes

      Return a copy of the Sound object buffer as a bytes.

      New in pygame 1.9.2.

  pygame.mixer.Channel
    Create a Channel object for controlling playback
    Channel(id) -> Channel

    Return a Channel object for one of the current channels. The id must be a value from 0 to the value of `pygame.mixer.get_num_channels()`.

    The Channel object can be used to get fine control over the playback of Sounds. A channel can only playback a single Sound at time. Using channels is entirely optional since pygame can manage them by default.

    play()
      play a Sound on a specific Channel
      play(Sound, loops=0, maxtime=0, fade_ms=0) -> None

      This will begin playback of a Sound on a specific Channel. If the Channel is currently playing any other Sound it will be stopped.

      The loops argument has the same meaning as in `Sound.play()`: it is the number of times to repeat the sound after the first time. If it is 3, the sound will be played 4 times (the first time, then three more). If loops is -1 then the playback will repeat indefinitely.

      As in `Sound.play()`, the maxtime argument can be used to stop playback of the Sound after a given number of milliseconds.

      As in `Sound.play()`, the fade_ms argument can be used fade in the sound.

    stop()
      stop playback on a Channel
      stop() -> None

      Stop sound playback on a channel. After playback is stopped the channel becomes available for new Sounds to play on it.

    pause()
      temporarily stop playback of a channel
      pause() -> None

      Temporarily stop the playback of sound on a channel. It can be resumed at a later time with `Channel.unpause()`

    unpause()
      resume pause playback of a channel
      unpause() -> None

      Resume the playback on a paused channel.

    fadeout()
      stop playback after fading channel out
      fadeout(time) -> None

      Stop playback of a channel after fading out the sound over the given time argument in milliseconds.

    set_volume()
      set the volume of a playing channel
      set_volume(value) -> None
      set_volume(left, right) -> None

      Set the volume (loudness) of a playing sound. When a channel starts to play its volume value is reset. This only affects the current sound. The value argument is between 0.0 and 1.0.

      If one argument is passed, it will be the volume of both speakers. If two arguments are passed and the mixer is in stereo mode, the first argument will be the volume of the left speaker and the second will be the volume of the right speaker. (If the second argument is `None`, the first argument will be the volume of both speakers.)

      If the channel is playing a Sound on which `set_volume()` has also been called, both calls are taken into account. For example:

          sound = pygame.mixer.Sound("s.wav")
          channel = s.play()      # Sound plays at full volume by default
          sound.set_volume(0.9)   # Now plays at 90% of full volume.
          sound.set_volume(0.6)   # Now plays at 60% (previous value replaced).
          channel.set_volume(0.5) # Now plays at 30% (0.6 * 0.5).

    get_volume()
      get the volume of the playing channel
      get_volume() -> value

      Return the volume of the channel for the current playing sound. This does not take into account stereo separation used by `Channel.set_volume()`. The Sound object also has its own volume which is mixed with the channel.

    get_busy()
      check if the channel is active
      get_busy() -> bool

      Returns `True` if the channel is actively mixing sound. If the channel is idle this returns `False`.

    get_sound()
      get the currently playing Sound
      get_sound() -> Sound

      Return the actual Sound object currently playing on this channel. If the channel is idle `None` is returned.

    queue()
      queue a Sound object to follow the current
      queue(Sound) -> None

      When a Sound is queued on a Channel, it will begin playing immediately after the current Sound is finished. Each channel can only have a single Sound queued at a time. The queued Sound will only play if the current playback finished automatically. It is cleared on any other call to `Channel.stop()` or `Channel.play()`.

      If there is no sound actively playing on the Channel then the Sound will begin playing immediately.

    get_queue()
      return any Sound that is queued
      get_queue() -> Sound

      If a Sound is already queued on this channel it will be returned. Once the queued sound begins playback it will no longer be on the queue.

    set_endevent()
      have the channel send an event when playback stops
      set_endevent() -> None
      set_endevent(type) -> None

      When an endevent is set for a channel, it will send an event to the pygame queue every time a sound finishes playing on that channel (not just the first time). Use `pygame.event.get()` to retrieve the endevent once it's sent.

      Note that if you called `Sound.play(n)` or `Channel.play(sound,n)`, the end event is sent only once: after the sound has been played "n+1" times (see the documentation of Sound.play).

      If `Channel.stop()` or `Channel.play()` is called while the sound was still playing, the event will be posted immediately.

      The type argument will be the event id sent to the queue. This can be any valid event type, but a good choice would be a value between `pygame.locals.USEREVENT` and `pygame.locals.NUMEVENTS`. If no type argument is given then the Channel will stop sending endevents.

    get_endevent()
      get the event a channel sends when playback stops
      get_endevent() -> type

      Returns the event type to be sent every time the Channel finishes playback of a Sound. If there is no endevent the function returns `pygame.NOEVENT`.

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