GH-60729: Add IEEE format wave audio support by mbeijen · Pull Request #145384 · python/cpython

mbeijen · 2026-03-01T08:57:47Z

This is an updated version of #102574, the original PR where @lkoenig added support for IEEE Wave Audio.

As requested by @encukou

I've

Renamed the new 'getencoding/setencoding' to 'getformat/setformat' - format is the term used in the specifications
Added format to getparams
Added FACT chunk to written non-PCM wave files, which is required by the spec (and is what Audacity does)
Added documentation!

Closes: #102574

Issue: wave file module does not support 32bit float format #60729

📚 Documentation preview 📚: https://cpython-previews--145384.org.readthedocs.build/

This adds support for floating point wav files and fix python#60729.

'format' is the term used in the wave audio specification

Per the RIFF/WAVE Rev. 3 documentation, non-PCM formats require a fact chunk, while PCM does not. This is also what libsdnfile/audacity do Reference: https://mmsp.ece.mcgill.ca/Documents/AudioFormats/WAVE/WAVE.html (see the 'fact Chunk' section and linked Rev. 3 RIFF docs).

These methods are public but were previously not documented. This caused the unit tests to fail when I mentioned changes to getparams() in the whats new ;-)

Misc/NEWS.d/next/Library/2023-03-10-13-10-06.gh-issue-60729.KCCHTe.rst

…CHTe.rst Co-authored-by: AN Long <aisk@users.noreply.github.com>

lkoenig

Thanks for pushing that forward.

encukou

Thank you for the PR!
I didn't finish reviewing today; sending the comments I have.

Doc/library/wave.rst

encukou · 2026-03-02T16:34:14Z

Doc/library/wave.rst

+      This is one of ``WAVE_FORMAT_PCM``, ``WAVE_FORMAT_IEEE_FLOAT``, or
+      ``WAVE_FORMAT_EXTENSIBLE``.


Could you document these using .. data::, and link to them using :data:?

encukou · 2026-03-02T16:47:20Z

Doc/library/wave.rst

+      framerate, nframes, comptype, compname, format)``, equivalent to output
+      of the ``get*()`` methods.


This is a backwards-incompatible change: before someone could write:

nc, sw, fr, nf, ct, cn = wav.getparams()

This could be solved by adding format as a named-only attribute (which, unfortunately, isn't easy with namedtuple), or maybe an argument to getparams.
You might want to leave getparams alone for now & tackle this in a focused follow-up PR.

Sure, I reverted those changes now

Doc/library/wave.rst

encukou · 2026-03-02T16:59:32Z

Lib/test/test_wave.py

 class MiscTestCase(unittest.TestCase):
    def test__all__(self):
-        not_exported = {'WAVE_FORMAT_PCM', 'WAVE_FORMAT_EXTENSIBLE', 'KSDATAFORMAT_SUBTYPE_PCM'}
+        not_exported = {'WAVE_FORMAT_PCM', 'WAVE_FORMAT_IEEE_FLOAT', 'WAVE_FORMAT_EXTENSIBLE', 'KSDATAFORMAT_SUBTYPE_PCM'}


Please export the WAVE_FORMAT_ ones (add to __all__) instead, and remove them here.
No point in hiding them; they're needed for documented functionality.

(I'd keep KSDATAFORMAT_SUBTYPE_PCM hidden until it's documented; that seems out of scope for this PR.)

Sure, they're exported now

encukou · 2026-03-02T17:17:01Z

Lib/wave.py

+            try:
+                self._fact_sample_count_pos = self._file.tell()
+            except (AttributeError, OSError):
+                self._fact_sample_count_pos = None


Hmm, what's the story about supporting files without tell?

I’m not trying to extend unseekable support in this PR. I’m keeping the existing behavior: if output is seekable, header fields (including fact) are patched as needed; for unseekable outputs, writing works when header values are already final, and mismatches can still fail as before.

Co-authored-by: Petr Viktorin <encukou@gmail.com>

…ieee-wave-audio-support # Conflicts: # Doc/library/wave.rst

vstinner · 2026-03-04T23:11:03Z

Doc/library/wave.rst

+
+.. data:: WAVE_FORMAT_IEEE_FLOAT
+
+   Format code for IEEE floating-point audio.


What is the size of a sample? 32-bit? Or does it accept different sizes?

for IEEE Float it can only be 32-bit or 64-bit. I've amended the documentation and added raising errors in case of setting sampwidth to different values for IEEE or setting format to IEEE if sampwidth is incorrect values

This is also similar to what libsndfile does

encukou

Looks good to me, thank you!
Will merge tomorrow if there are no objections.

mbeijen · 2026-03-13T08:11:32Z

awesome and thanks in advance! While you're at it I'd like to ask you to also consider these (smaller) PRs I made for wave.py that did not get much attention yet:

There's also this but it might warrant some rework after this IEEE PR is merged, I might want to make a new one for that

encukou · 2026-03-13T13:11:29Z

I put them on my list :)

lkoenig and others added 5 commits March 1, 2026 09:54

Add support for floating point wave files.

9263225

This adds support for floating point wav files and fix python#60729.

wave: rename encoding API to format

e025d53

'format' is the term used in the wave audio specification

wave: add format to getparams

0ad941f

wave: add documentation on IEEE support, format API

7a1fce1

mbeijen requested a review from AA-Turner as a code owner March 1, 2026 08:57

bedevere-app bot added the awaiting review label Mar 1, 2026

bedevere-app bot mentioned this pull request Mar 1, 2026

wave file module does not support 32bit float format #60729

Open

mbeijen mentioned this pull request Mar 1, 2026

gh-60729: Add support for floating point wave files. #102574

Closed

wave: add documentation for undocumented methods

9bae85b

These methods are public but were previously not documented. This caused the unit tests to fail when I mentioned changes to getparams() in the whats new ;-)

aisk reviewed Mar 1, 2026

View reviewed changes

Misc/NEWS.d/next/Library/2023-03-10-13-10-06.gh-issue-60729.KCCHTe.rst Outdated Show resolved Hide resolved

Update Misc/NEWS.d/next/Library/2023-03-10-13-10-06.gh-issue-60729.KC…

1db52c0

…CHTe.rst Co-authored-by: AN Long <aisk@users.noreply.github.com>

mbeijen requested a review from aisk March 1, 2026 15:49

lkoenig reviewed Mar 2, 2026

View reviewed changes

encukou reviewed Mar 2, 2026

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versionchanged

f87efee

Co-authored-by: Petr Viktorin <encukou@gmail.com>

mbeijen mentioned this pull request Mar 3, 2026

GH-145450: Document missing wave.Wave_write getter methods #145451

Merged

mbeijen added 4 commits March 3, 2026 20:38

Merge remote-tracking branch 'upstream/main' into pythonGH-60729-add-…

cd49a3b

…ieee-wave-audio-support # Conflicts: # Doc/library/wave.rst

wave: restore getparams() backward compatibility

2cdf66d

wave: export WAVE_FORMAT constants

de0c82e

wave docs: add format constants as data

689ae2d

mbeijen requested a review from encukou March 3, 2026 20:06

vstinner reviewed Mar 4, 2026

View reviewed changes

wave: sampwidth for IEEE Float must be 4 or 8

6d62e66

This is also similar to what libsndfile does

mbeijen force-pushed the GH-60729-add-ieee-wave-audio-support branch from eeee8cd to 6d62e66 Compare March 7, 2026 17:04

mbeijen requested a review from vstinner March 7, 2026 19:00

encukou approved these changes Mar 12, 2026

View reviewed changes

bedevere-app bot added awaiting merge and removed awaiting review labels Mar 12, 2026

encukou merged commit 61f2a1a into python:main Mar 13, 2026
51 checks passed

bedevere-app bot removed the awaiting merge label Mar 13, 2026

		This is one of ``WAVE_FORMAT_PCM``, ``WAVE_FORMAT_IEEE_FLOAT``, or
		``WAVE_FORMAT_EXTENSIBLE``.

		framerate, nframes, comptype, compname, format)``, equivalent to output
		of the ``get*()`` methods.


		.. data:: WAVE_FORMAT_IEEE_FLOAT

		Format code for IEEE floating-point audio.

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mbeijen commented Mar 13, 2026

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mbeijen commented Mar 1, 2026 •

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