172 lines
5.4 KiB
TeX
172 lines
5.4 KiB
TeX
% Documentations stolen and LaTeX'ed from comments in file.
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\section{\module{wave} ---
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Read and write WAV files}
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\declaremodule{standard}{wave}
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\sectionauthor{Moshe Zadka}{moshez@zadka.site.co.il}
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\modulesynopsis{Provide an interface to the WAV sound format.}
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The \module{wave} module provides a convenient interface to the WAV sound
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format. It does not support compression/decompression, but it does support
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mono/stereo.
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The \module{wave} module defines the following function and exception:
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\begin{funcdesc}{open}{file\optional{, mode}}
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If \var{file} is a string, open the file by that name, other treat it
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as a seekable file-like object. \var{mode} can be any of
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\begin{description}
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\item[\code{'r'}, \code{'rb'}] Read only mode.
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\item[\code{'w'}, \code{'wb'}] Write only mode.
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\end{description}
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Note that it does not allow read/write WAV files.
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A \var{mode} of \code{'r'} or \code{'rb'} returns a \class{Wave_read}
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object, while a \var{mode} of \code{'w'} or \code{'wb'} returns
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a \class{Wave_write} object. If \var{mode} is omitted and a file-like
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object is passed as \var{file}, \code{\var{file}.mode} is used as the
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default value for \var{mode} (the \character{b} flag is still added if
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necessary).
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\end{funcdesc}
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\begin{funcdesc}{openfp}{file, mode}
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A synonym for \function{open()}, maintained for backwards compatibility.
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\end{funcdesc}
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\begin{excdesc}{Error}
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An error raised when something is impossible because it violates the
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WAV specification or hits an implementation deficiency.
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\end{excdesc}
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\subsection{Wave_read Objects \label{Wave-read-objects}}
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Wave_read objects, as returned by \function{open()}, have the
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following methods:
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\begin{methoddesc}[Wave_read]{close}{}
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Close the stream, and make the instance unusable. This is
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called automatically on object collection.
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\end{methoddesc}
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\begin{methoddesc}[Wave_read]{getnchannels}{}
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Returns number of audio channels (\code{1} for mono, \code{2} for
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stereo).
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\end{methoddesc}
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\begin{methoddesc}[Wave_read]{getsampwidth}{}
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Returns sample width in bytes.
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\end{methoddesc}
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\begin{methoddesc}[Wave_read]{getframerate}{}
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Returns sampling frequency.
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\end{methoddesc}
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\begin{methoddesc}[Wave_read]{getnframes}{}
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Returns number of audio frames.
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\end{methoddesc}
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\begin{methoddesc}[Wave_read]{getcomptype}{}
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Returns compression type (\code{'NONE'} is the only supported type).
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\end{methoddesc}
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\begin{methoddesc}[Wave_read]{getcompname}{}
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Human-readable version of \method{getcomptype()}.
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Usually \code{'not compressed'} parallels \code{'NONE'}.
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\end{methoddesc}
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\begin{methoddesc}[Wave_read]{getparams}{}
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Returns a tuple
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\code{(\var{nchannels}, \var{sampwidth}, \var{framerate},
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\var{nframes}, \var{comptype}, \var{compname})}, equivalent to output
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of the \method{get*()} methods.
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\end{methoddesc}
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\begin{methoddesc}[Wave_read]{readframes}{n}
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Reads and returns at most \var{n} frames of audio, as a string of bytes.
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\end{methoddesc}
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\begin{methoddesc}[Wave_read]{rewind}{}
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Rewind the file pointer to the beginning of the audio stream.
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\end{methoddesc}
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The following two methods are defined for compatibility with the
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\refmodule{aifc} module, and don't do anything interesting.
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\begin{methoddesc}[Wave_read]{getmarkers}{}
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Returns \code{None}.
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\end{methoddesc}
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\begin{methoddesc}[Wave_read]{getmark}{id}
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Raise an error.
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\end{methoddesc}
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The following two methods define a term ``position'' which is compatible
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between them, and is otherwise implementation dependent.
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\begin{methoddesc}[Wave_read]{setpos}{pos}
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Set the file pointer to the specified position.
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\end{methoddesc}
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\begin{methoddesc}[Wave_read]{tell}{}
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Return current file pointer position.
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\end{methoddesc}
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\subsection{Wave_write Objects \label{Wave-write-objects}}
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Wave_write objects, as returned by \function{open()}, have the
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following methods:
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\begin{methoddesc}[Wave_write]{close}{}
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Make sure \var{nframes} is correct, and close the file.
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This method is called upon deletion.
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\end{methoddesc}
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\begin{methoddesc}[Wave_write]{setnchannels}{n}
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Set the number of channels.
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\end{methoddesc}
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\begin{methoddesc}[Wave_write]{setsampwidth}{n}
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Set the sample width to \var{n} bytes.
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\end{methoddesc}
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\begin{methoddesc}[Wave_write]{setframerate}{n}
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Set the frame rate to \var{n}.
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\end{methoddesc}
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\begin{methoddesc}[Wave_write]{setnframes}{n}
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Set the number of frames to \var{n}. This will be changed later if
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more frames are written.
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\end{methoddesc}
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\begin{methoddesc}[Wave_write]{setcomptype}{type, name}
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Set the compression type and description.
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At the moment, only compression type \samp{NONE} is supported,
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meaning no compression.
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\end{methoddesc}
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\begin{methoddesc}[Wave_write]{setparams}{tuple}
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The \var{tuple} should be \code{(\var{nchannels}, \var{sampwidth},
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\var{framerate}, \var{nframes}, \var{comptype}, \var{compname})}, with
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values valid for the \method{set*()} methods. Sets all parameters.
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\end{methoddesc}
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\begin{methoddesc}[Wave_write]{tell}{}
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Return current position in the file, with the same disclaimer for
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the \method{Wave_read.tell()} and \method{Wave_read.setpos()}
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methods.
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\end{methoddesc}
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\begin{methoddesc}[Wave_write]{writeframesraw}{data}
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Write audio frames, without correcting \var{nframes}.
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\end{methoddesc}
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\begin{methoddesc}[Wave_write]{writeframes}{data}
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Write audio frames and make sure \var{nframes} is correct.
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\end{methoddesc}
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Note that it is invalid to set any parameters after calling
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\method{writeframes()} or \method{writeframesraw()}, and any attempt
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to do so will raise \exception{wave.Error}.
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