PR has been updated for version 6.8.1 by the workflow Bump dependencies (create-prs).

I'd assume that this breaks on every Qt6 build.

OK, this could have an impact on our plans for Jamulus 4 but it shouldn't hold up 3.12.0, I agree.

The linked issue from Qt has had an update. It's now in progress

PR has been updated for version 6.8.3 by the workflow Bump dependencies (create-prs).

PR has been updated for version 6.9.0 by the workflow Bump dependencies (create-prs).

OK, so now that's even noisier about FFMpeg dependencies not met. Have they made it clearer how to remove the dependency?

I believe that the next version should have a fix.

PR has been updated for version 6.9.1 by the workflow Bump dependencies (create-prs).

Still failing -- are we turning on stuff that's not needed for audio?

Undefined symbols for architecture arm64:
  "_av_buffer_create", referenced from:
      QFFmpeg::VideoEncoder::processOne() in libQt6FFmpegMediaPluginImpl.a[arm64][47](qffmpegvideoencoder.cpp.o)
      -[QAVFSampleBufferDelegate captureOutput:didOutputSampleBuffer:fromConnection:] in libQt6FFmpegMediaPluginImpl.a[arm64][53](qavfsamplebufferdelegate.mm.o)

Maybe that's needed. I thought they fixed it on the Qt side...

https://bugreports.qt.io/browse/QTBUG-129651 (?)

Ah: https://codereview.qt-project.org/c/qt/qtmultimedia/+/630015

We might need to add add_ios_ffmpeg_libraries to the CONFIG variable

OK, having read up a bit I'm convinced we stick with the Qt-preferred approach and use FFmpeg...

Even if we did

export QT_MEDIA_BACKEND=darwin

that wouldn't remove the dependency, just tell the runtime to ignore FFmpeg and use darwin directly.

So yeah, https://doc.qt.io/qt-6/qtmultimedia-apple.html:

CONFIG += add_ios_ffmpeg_libraries

looks like it should do the trick -- although it sounds like that's also a deployment time issue:

FFmpeg binaries from the online installer must be embedded into the application's bundle.

I'm not sure how much it'll help at build time.

CoPilot took some convincing that it was wrong about this as usual (now out of date documentation being more prevalently referenced in once-correct answers).

It's suggested we'd need to amend autobuild.yml (and ios.sh potentially) to build/cache the ffmpeg libraries for the link stage to work.

I also asked if there were any existing actions - but none for iOS, according to CoPilot. It's top answer was:

iOS-Specific FFmpeg Build Scripts
There are community-maintained shell scripts and projects for building FFmpeg for iOS (arm64), such as:
- kewlbear/FFmpeg-iOS-build-script
- tanersener/ffmpeg-kit
These are not GitHub Actions per se, but can easily be wrapped in your own workflow step or custom action.

- name: Build FFmpeg for iOS
  run: |
    git clone https://github.com/kewlbear/FFmpeg-iOS-build-script.git
    cd FFmpeg-iOS-build-script
    ./build-ffmpeg.sh

https://github.com/copilot/share/42365326-43c0-8404-9102-2648a4486807

Now, given that the first of those is FFmpeg 4 and the current version is 7 and the second of those has been archived... I'm thinking we might want to brew from https://github.com/FFmpeg/FFmpeg -- but it'd need someone to knock up the build, possible from cobbling it up from the above.

(It does seem to be becoming increasingly difficult to support Qt6 as time progresses...)

https://doc.qt.io/qt-6/qtmultimedia-building-ffmpeg-ios.html -- there's actually an official page on how hard it is...