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whatsnew: Wave_write handles unseekable files. (#5202)

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Also clarify the documentation of this feature.
This commit is contained in:
R David Murray 2014-03-08 11:14:29 -05:00
parent 19f1df6414
commit 5d6240e871
2 changed files with 29 additions and 6 deletions
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31
Doc/library/wave.rst
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@ -150,14 +150,30 @@ them, and is otherwise implementation dependent.
Wave_write Objects
------------------
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
:meth:`~Wave_write.setnframes` or :meth:`~Wave_write.setparams` with the number
of frames that will be written before :meth:`~Wave_write.close` is called and
then using :meth:`~Wave_write.writeframesraw` to write the frame data, or by
calling :meth:`~Wave_write.writeframes` with all of the frame data to be
written. In the latter case :meth:`~Wave_write.writeframes` will calculate
the number of frames in the data and set *nframes* accordingly before writing
the frame data.
Wave_write objects, as returned by :func:`.open`, have the following methods:
.. versionchanged:: 3.4
Added support for unseekable files.
.. method:: Wave_write.close()
Make sure *nframes* is correct, and close the file if it was opened by
:mod:`wave`. This method is called upon object collection. Can raise an
exception if *nframes* is not correct and a file is not seekable.
:mod:`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.
.. method:: Wave_write.setnchannels(n)
@ -181,8 +197,9 @@ Wave_write objects, as returned by :func:`.open`, have the following methods:
.. method:: Wave_write.setnframes(n)
Set the number of frames to *n*. This will be changed later if more frames are
written.
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).
.. method:: Wave_write.setcomptype(type, name)
@ -214,8 +231,10 @@ Wave_write objects, as returned by :func:`.open`, have the following methods:
.. method:: Wave_write.writeframes(data)
Write audio frames and make sure *nframes* is correct. Can raise an
exception if a file is not seekable.
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*.
.. versionchanged:: 3.4
Any :term:`bytes-like object`\ s are now accepted.

4
Doc/whatsnew/3.4.rst
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@ -1439,6 +1439,10 @@ plain tuple. (Contributed by Claudiu Popa in :issue:`17487`.)
:meth:`wave.open` now supports the context manager protocol. (Contributed
by Claudiu Popa in :issue:`17616`.)
:mod:`wave` can now :ref:`write output to unssekable files
<wave-write-objects>`. (Contributed by David Jones, Guilherme Polo, and Serhiy
Storchaka in :issue:`5202`.)
weakref
-------