"wave" --- Read and write WAV files
***********************************

**Código-fonte:** Lib/wave.py

======================================================================

The "wave" module provides a convenient interface to the Waveform
Audio "WAVE" (or "WAV") file format. Only files using
"WAVE_FORMAT_PCM" are supported. Note that this does not include files
using "WAVE_FORMAT_EXTENSIBLE" even if the subformat is PCM.

The "wave" module defines the following function and exception:

wave.open(file, mode=None)

   If *file* is a string, open the file by that name, otherwise treat
   it as a file-like object.  *mode* can be:

   "'rb'"
      Modo somente para leitura.

   "'wb'"
      Modo somente para escrita.

   Note that it does not allow read/write WAV files.

   A *mode* of "'rb'" returns a "Wave_read" object, while a *mode* of
   "'wb'" returns a "Wave_write" object.  If *mode* is omitted and a
   file-like object is passed as *file*, "file.mode" is used as the
   default value for *mode*.

   If you pass in a file-like object, the wave object will not close
   it when its "close()" method is called; it is the caller's
   responsibility to close the file object.

   The "open()" function may be used in a "with" statement.  When the
   "with" block completes, the "Wave_read.close()" or
   "Wave_write.close()" method is called.

   Alterado na versão 3.4: Added support for unseekable files.

exception wave.Error

   An error raised when something is impossible because it violates
   the WAV specification or hits an implementation deficiency.


Objetos Wave_read
=================

class wave.Wave_read

   Read a WAV file.

   Wave_read objects, as returned by "open()", have the following
   methods:

   close()

      Close the stream if it was opened by "wave", and make the
      instance unusable.  This is called automatically on object
      collection.

   getnchannels()

      Returns number of audio channels ("1" for mono, "2" for stereo).

   getsampwidth()

      Retorna a largura da amostra em bytes.

   getframerate()

      Retorna a frequência de amostragem.

   getnframes()

      Retorna o número de quadros de áudio.

   getcomptype()

      Returns compression type ("'NONE'" is the only supported type).

   getcompname()

      Human-readable version of "getcomptype()". Usually "'not
      compressed'" parallels "'NONE'".

   getparams()

      Returns a "namedtuple()" "(nchannels, sampwidth, framerate,
      nframes, comptype, compname)", equivalent to output of the
      "get*()" methods.

   readframes(n)

      Reads and returns at most *n* frames of audio, as a "bytes"
      object.

   rewind()

      Volta o ponteiro do arquivo para o início do fluxo de áudio.

   The following two methods are defined for compatibility with the
   "aifc" module, and don't do anything interesting.

   getmarkers()

      Retorna "None".

   getmark(id)

      Levanta um erro.

   Os dois métodos a seguir definem um termo "posição" que é
   compatível entre eles e é dependente da implementação.

   setpos(pos)

      Set the file pointer to the specified position.

   tell()

      Return current file pointer position.


Objetos Wave_write
==================

class wave.Wave_write

   Write a WAV file.

   Wave_write objects, as returned by "open()".

   For seekable output streams, the "wave" header will automatically
   be updated to reflect the number of frames actually written.  For
   unseekable streams, the *nframes* value must be accurate when the
   first frame data is written.  An accurate *nframes* value can be
   achieved either by calling "setnframes()" or "setparams()" with the
   number of frames that will be written before "close()" is called
   and then using "writeframesraw()" to write the frame data, or by
   calling "writeframes()" with all of the frame data to be written.
   In the latter case "writeframes()" will calculate the number of
   frames in the data and set *nframes* accordingly before writing the
   frame data.

   Alterado na versão 3.4: Added support for unseekable files.

   Wave_write objects have the following methods:

   close()

      Make sure *nframes* is correct, and close the file if it was
      opened by "wave".  This method is called upon object collection.
      It will raise an exception if the output stream is not seekable
      and *nframes* does not match the number of frames actually
      written.

   setnchannels(n)

      Define o número de canais.

   setsampwidth(n)

      Set the sample width to *n* bytes.

   setframerate(n)

      Set the frame rate to *n*.

      Alterado na versão 3.2: A non-integral input to this method is
      rounded to the nearest integer.

   setnframes(n)

      Set the number of frames to *n*.  This will be changed later if
      the number of frames actually written is different (this update
      attempt will raise an error if the output stream is not
      seekable).

   setcomptype(type, name)

      Set the compression type and description. At the moment, only
      compression type "NONE" is supported, meaning no compression.

   setparams(tuple)

      The *tuple* should be "(nchannels, sampwidth, framerate,
      nframes, comptype, compname)", with values valid for the
      "set*()" methods.  Sets all parameters.

   tell()

      Return current position in the file, with the same disclaimer
      for the "Wave_read.tell()" and "Wave_read.setpos()" methods.

   writeframesraw(data)

      Escreve quadros de áudio, sem corrigir *nframes*.

      Alterado na versão 3.4: Todo *objeto bytes ou similar* agora é
      aceito.

   writeframes(data)

      Write audio frames and make sure *nframes* is correct.  It will
      raise an error if the output stream is not seekable and the
      total number of frames that have been written after *data* has
      been written does not match the previously set value for
      *nframes*.

      Alterado na versão 3.4: Todo *objeto bytes ou similar* agora é
      aceito.

      Note that it is invalid to set any parameters after calling
      "writeframes()" or "writeframesraw()", and any attempt to do so
      will raise "wave.Error".
