Upgrade NDK to 28 to avoid memory pagination issues

[david-metrica]

From Nov 1, 2025, any new apps or updates targeting Android 15+ will be required to support 16 KB pages.

By May 1, 2026, updates to existing apps that don’t support this will be blocked from publishing on the Play Store.

Currently, crates like web-audio-api-rs (which depends on cpal) are still tied to older NDK versions that assume 4 KB page sizes.

Do we need to wait for dependent crates such as ndk-sys to be updated first, or can cpal migrate independently?

I opened another issue in the web-audio-api-rs repo mentioning this:
orottier/web-audio-api-rs#553

Proposed action:
Update cpal (and any related Android dependencies) to build against NDK r28 or higher, which ensures compatibility with 16 KB page sizes.

[roderickvd]

Not an Android developer myself, but as far as I understand this comment is right:

I might be wrong about this but I think api-level is unrelated to the NDK.
You can set any api level supported by the NDK.
NDK is probably pulling ndk-sys and this one is bound to a NDK version.

We need ndk-sys updated upstream.

[MarijnS95]

The ndk-sys crate is not responsible for this, see rust-mobile/ndk#506 (comment).

It depends on the tooling/NDK that was used to cross-compile your crate for Android and package it into an APK, like cargo-apk.

[roderickvd]

Thanks for the pointer. Happy to take any PRs to say what we need to do. If anything at all ‘cause are you saying it’s orthogonal to cpal too?

Like I said, I’m no Android developer myself so consider me totally unqualified here even with your suggestion.

[MarijnS95]

@roderickvd it depends on how users of cpal (and perhaps local samples) are targeting / building for Android. If folks are using cargo-apk they will need that PR (which I hope to release after implementing some good feedback when their build-tools is too old). If you can link me to something else (downstream crates, documentation) I can likely give you some pointers as well.

[MarijnS95]

I found at least an example: https://github.com/RustAudio/cpal/tree/master/examples/android
And built-in CI:

cpal/.github/workflows/cpal.yml

Lines 275 to 287 in c9d8e2e

	- name: Setup Android SDK
	uses: android-actions/setup-android@v3
	with:
	packages: platforms;android-30 build-tools;30.0.3
	- name: Install cargo-apk
	uses: taiki-e/install-action@v2
	with:
	tool: cargo-apk
	- name: Build APK
	working-directory: examples/android
	run: cargo apk build

Both use cargo-apk 🎉. If anyone wants to test it now, use:

cargo install --git https://github.com/rust-mobile/cargo-apk --branch lib-16kib

(This command becomes invalid as soon as rust-mobile/cargo-apk#76 is merged)

As mentioned above, the CI script will have to be updated to build-tools 35.0.0 (or cargo-apk needs to implement a fallback and big not 16KiB compatible warning).

[roderickvd]

Thanks a lot @MarijnS95. If I understand well, no changes needed in cpal for now but we need to await cargo-apk to be updated with this PR.

Closing for now, feel free to reopen if my understanding is incorrect.