A few useful additions to wavfile.py (24 bit read/write support, cue markers support, loop makers support, etc.)

[josephernest]

I've modified the file https://github.com/scipy/scipy/blob/master/scipy/io/wavfile.py over the past years to add 24-bit WAV files read/write support, cue markers support, loop makers support, etc.

Here is the result.

If you're interested, feel free to reuse this / commit (I won't have time to do a pull request soon).

Note: In WAV audio files, 24-bit is probably the most used bitrate for instrument sample sets, music production, sound engineering; much more than 16-bit (CD) or 32-bit (used in music software as internal processing bitrate).

[rgommers]

Thanks @josephernest. 24-bit support would indeed be nice. cross-linking the issue about that: gh-1930.

[josephernest]

Thanks @rgommers
I use my code (especially 24-bit part) in many of my projects, and I confirm that it works and has been widely tested.

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More informations:

Normally wavfile.py works like this:

(sr, samples) = read('hello.wav')

To keep backwards compatibility, I added parameters (default False) that state if we want extra metadatas while reading (br: bitrate, cue: list of markers, f0: frequency of the root note in Hz stored in some wav files (often the case in instrument sample sets), etc.):

(sr, samples, br, cue, f0, cuechunkstr, smplchunkstr, cuelabels) = read('hello.wav', \
   readmarkers=True, readpitch=True, cuechunk=True, smplchunk=True, cuelabels=True)

Drawbacks of my code:

• not documented

• to go fast, I removed RIFX support (I have never seen a single RIFX big-endian WAV audio file in 10+ years of audio production / audio programming), you probably wouldn't like this

So in short, I'm open to do a pull request, but I'd need help :)

[perimosocordiae]

@josephernest I got this started in gh-6852. Could you contribute a small test file that exercises the additional functionality?

[josephernest]

Here is a 24-bit 44.1 khz stereo WAV file named test24bit.wav. It has:

• a marker at 0'04", another marker at 0'08"
• an infinite loop from 0'12" to 0'16"
• a pitch metadata of A5 (Sony SoundForge notation) that is the standard A4, i.e. 440 Hz

With my API proposal here,

read('test24bit.wav', metadata=True)

should return:

(44100, 
 array([[  ...  ]]), 
 {'loops': [[..., ...]], 
  'markers': [..., ....], 
  'markerlabels': ['...', '...'], 
  'pitch': 440.0, 
  'bitrate': 24})

[perimosocordiae]

Thanks, no git shenanigans required! The test file you provided is pretty large (5.1MB vs a couple KB for most of the existing test fixtures). Is it possible to make a similar one with a tiny amount of data to keep filesize low?

[josephernest]

Here is a small test file. I won't go below 250 milliseconds, because testing if a loop works wouldn't make sense with a 10 ms sound file.
Markers at 0.100 sec and 0.200 sec. Loop between 0.050 and 0.150 sec. A4 440 hz pitch metadata.

[perimosocordiae]

Great, I've added this to the PR as a new test fixture. Thanks!

[josephernest]

Thanks!

[X-Raym]

The write function for loops was broken, and few other things with markers,

I made an updated version here https://github.com/X-Raym/wavfile.py

It also fix various issues, like the loss of metadata (unsupported chinks are now supported), have LIST - INFO etc...

[ilayn]

@X-Raym Would you care to open a Pull Request for a more general audience? Then interested people can review and leave comments. Also your code can be tested against the existing codebase for regressions.