audiocore: Factor from audioio

[jepler]

When nrf pwm audio is introduced, it will be called audiopwmio. To enable code sharing with the existing (dac-based) audioio, factor the sample and mixer types to audiocore.

INCOMPATIBLE CHANGE: Now, Mixer, RawSample and WaveFile must be imported from audiocore, not audioio.

Testing performed: On a metro m4 express, I imported both modules and (without a speaker attached) played a RawSample out the A0 pin

[tannewt]

Thanks for doing this! I removed unneeded headers from shared-bindings/audioio/init.c and looks good otherwise! We'll need to fix example code when we release a 5.0 beta. We should also get the mixer changes in since we're changing things.

[jerryneedell]

FYI -- this is a breaking change for the CircuitPlayground Express express library since it uses audioio to call RawSample and WaveFIle.

[jepler]

fwiw, I think that it would be possible to keep the classes in audioio either for a limited time (like, would appear in both places in 5.x, and be only in audiocore in 6.x) or even forever. The "price" would be just a few dozen bytes in the dictionary of audioio. I'd be happy to double check this and submit a pull request if that's what @tannewt would like.

Meanwhile, I would also be happy to help out with some import logic in cpx to adapt to either circuitpython version, if that would be helpful. Let me know if that would be useful to you, @jerryneedell

[jerryneedell]

@jepler its not a problem for me -- I have already implemented the changes I need for the test I was doing. I just wanted to make sure it was a known issues since it is likely to cause some problems for users.

[tannewt]

@jepler My preference is to just move it. If you leave it in the old place there is no reason to update code. That being said, could someone post a sample import that is backwards compatible for folks? Thanks!

[jepler]

Untested, but I believe you would want to write, for any or all items that you wanted from audiocore,

try:
    from audiocore import RawSample
except:
    from audioio import RawSample

At this point, RawSample will be available as an unqualified name. You could also write (untested)

try:
    import audiocore
except:
    import audioio as audiocore

At this point audiocore.RawSample will be available as a qualified name.

When I'm at home, I have a CPX I can flash with 4.0.2 and current and verify that these both work in both cases.

Should this be written up somewhere in the docs? or in a guide?

[tannewt]

I think this PR is fine and maybe release notes too. I'd tweak the except line to be except ImportError: to ensure it's only due to the module missing.

[jepler]

@tannewt you mentioned getting "the mixer" fixes -- if there's an issue or pull, can you link it?

I verified both workarounds,

try:
    import audiocore
except ImportError:
    import audioio as audiocore

and

try:
    from audiocore import RawSample
except ImportError:
    from audioio import RawSample

with a circutplayground express using 4.0.2 and tip-of-master.

[tannewt]

@jepler This is the PR I'm thinking of: #1365