Build libcamera against Android SDK

[kbingham]

References to get started:

https://proandroiddev.com/how-to-setup-android-sdk-without-android-studio-6d60d0f2812a?gi=6f859505330e

https://github.com/ppetraki/meson-android-helloworld

[rsglobal]

You probably meant NDK: https://developer.android.com/ndk/downloads

As far as I know SDK is for Android apps.

[rsglobal]

Here's the starting point:

1. Download ndk into /opt/ndk directory
2. Clone libcamera
3. Download build.sh and meson_cross_compile.txt into libcamera directory
4. Run ./build.sh
5. $ cd ./build
6. $ ninja

meson_cross_compile.txt
build.zip

[kbingham]

Thanks!, that looks like clear for me to integrate.

[rsglobal]

There're some system dependencies to be installed before building (especially when cross-compiling for ARM). It would be nice to come-up with a dockerfile which will include all required dependencies.

[kbingham]

Is https://github.com/CactiChameleon9/Libcamera-RPiOS-Build-Enviroment useful to you ?

[rsglobal]

I don't have any issues building for Android. But my solution is not upstreamable.
I would like to see initial official Android support to reduce my local delta and then see what can I upstream.

[kbingham]

Which part of your solution is not upstreamable? Nicholas Roth from the other issue is working on the mailing list to determine adding (I expect /your/ makefile wrapper).

The work can only get upstream if someone works on it.

[rsglobal]

Which part of your solution is not upstreamable?

Here's my WIP branch. It's very dirty right now, but it can partially answer the question.
https://github.com/GloDroid/glodroid_forks/commits/libcamera-next

The work can only get upstream if someone works on it.

That won't be me, sorry. I'm already supporting a lot of FOSS repos. And only benefit I have from my FOSS activity is a feeling that world is becoming better. Nobody want to pay for that.

[rsglobal]

@kbingham ,

Can you help me please to understand this line?

adb shell LIBCAMERA_LOG_LEVELS=*:DEBUG lc-compliance
[17:41:46.203161361] [5713]  WARN IPAManager ipa_manager.cpp:114 Public key not valid

Why public key may be invalid?

Here's my generated key:
ipa_pub_key.cpp

UPDATE: libcrypto dep was missing, now it works, signature check is working.

[kbingham]

I've tried following these steps to build with android ndk:

I've created a meson cross file as mesoncross/android-ndk-r25b

[binaries]
ar = '/opt/ndk/android-ndk-r25b/toolchains/llvm/prebuilt/linux-x86_64/bin/llvm-ar'
c = '/opt/ndk/android-ndk-r25b/toolchains/llvm/prebuilt/linux-x86_64/bin/x86_64-linux-android33-clang'
cpp = '/opt/ndk/android-ndk-r25b/toolchains/llvm/prebuilt/linux-x86_64/bin/x86_64-linux-android33-clang++'
c_ld = 'lld'
cpp_ld = 'lld'
pkgconfig = '/usr/bin/pkg-config'
strip = '/opt/ndk/android-ndk-r25b/toolchains/llvm/prebuilt/linux-x86_64/bin/llvm-strip'

[host_machine]
system = 'linux'
cpu_family = 'x86_64'
cpu = ''
endian = 'little'

and configured with:

meson build/android-ndk-25b/ \
	--cross mesoncross/android-ndk-r25b \
	-Dsysconfdir=/vendor/etc \
	-Dandroid=enabled

...

libcamera 0.0.1

  Versions
    Sources                  : 0.0.1+70-0eb4ccd3

  Paths
    LIBCAMERA_DATA_DIR       : "/usr/local/share/libcamera"
    LIBCAMERA_SYSCONF_DIR    : "/vendor/etc/libcamera"
    IPA_PROXY_DIR            : "/usr/local/libexec/libcamera"
    IPA_CONFIG_DIR           : "/vendor/etc/libcamera/ipa:/usr/local/share/libcamera/ipa"
    IPA_MODULE_DIR           : "/usr/local/lib/libcamera"

  Configuration
    Enabled pipelines        : ipu3
                               raspberrypi
                               rkisp1
                               simple
                               uvcvideo
                               vimc
    Enabled IPA modules      : ipu3
                               raspberrypi
                               rkisp1
                               vimc
    Tracing support          : YES
    Android support          : YES
    GStreamer support        : YES
    Python bindings          : NO
    V4L2 emulation support   : NO
    cam application          : YES
    qcam application         : YES
    lc-compliance application: YES
    Unit tests               : NO

  Subprojects
    libyuv                   : YES

  User defined options
    Cross files              : mesoncross/android-ndk-r25b
    sysconfdir               : /vendor/etc
    android                  : enabled

But I get a lot of host header pollution:

In file included from /opt/ndk/android-ndk-r25b/toolchains/llvm/prebuilt/linux-x86_64/bin/../sysroot/usr/include/features.h:36:
/usr/include/x86_64-linux-gnu/sys/cdefs.h:64:6: error: function-like macro '__GNUC_PREREQ' is not defined
# if __GNUC_PREREQ (4, 6) && !defined _LIBC
     ^

Do you get this? or have you already resolved such issues ?

[kbingham]

pkgconfig = '/usr/bin/pkg-config'

Seems 'suspicious' to me...

[rsglobal]

Try pkgconfig = ['env', 'PKG_CONFIG_LIBDIR='path_to_NDK_pkgs_dir', '/usr/bin/pkg-config']

[rsglobal]

I haven't tried to build libcamera using NDK yet. I think it would require some minimal sysroot preparation with packages and C headers from AOSP.

[kbingham]

Oh - I thought #54 (comment) was something you had done.
I don't seem to have much in the way of a sysroot for the NDK indeed, so not much for the pkg-config to point to ..

[kbingham]

/opt/ndk/android-ndk-r25b/toolchains/llvm/prebuilt/linux-x86_64/sysroot seems to be a reasonable sysroot starting point though...

[rsglobal]

May be useful:

That's how env. variables can be overridden for service to enable logcat debug:

+++ /vendor/etc/init/[email protected]_64.rc
service vendor.camera-provider-2-5 /vendor/bin/hw/[email protected]_64
    interface [email protected]::ICameraProvider legacy/0
    interface [email protected]::ICameraProvider legacy/0
    class hal
    user cameraserver
    group audio camera input drmrpc
    ioprio rt 4
    capabilities SYS_NICE
    task_profiles CameraServiceCapacity MaxPerformance
+    setenv LIBCAMERA_LOG_LEVELS *:DEBUG
+    setenv LIBCAMERA_LOG_FILE syslog

[rsglobal]

Oh - I thought #54 (comment) was something you had done.

Not yet, but have the plans to do it in a future.

EDIT:

But I tested this manual before posting: #54 (comment)
IIRC I got successful build.

[kbingham]

Ok, good to know you were able to build ... I got further with setting the sysroot - but still get linker errors:

ld.lld: error: unable to find library -ldw
ld.lld: error: unable to find library -lelf

So I'll have to do some more digging next time I get chance.

[rsglobal]

It should not be able to find, therefore require libdw:
Meson config should print this:

Run-time dependency libdw found: NO (tried pkgconfig and cmake)

[kbingham]

So preventing finding the host libraries requires setting (correctly, without typos!) the pkg_config_libdir property in the mesoncross file.

But now I'm hit by not having libexif available in the NDK sysroot, which is required for the android layer. Next steps, identify how to provide libexif to the NDK sysroot.

[rsglobal]

Sharing my thoughts:

1. Create synthetic libexif.pc file
2. Add headers from https://android.googlesource.com/platform/external/libexif/+/refs/heads/master/libexif/ to sysroot/usr/include/libexif directory
3. Pull libexif.so from /vendor/lib{64}/ of Android you're building for (you may try pulling it from the waydroid in case you have it installed)