Android + Kivy: fails to run Camera demo, possibly library or permission problem?

Question

I'm looking for help getting theKivy Camera demo to work on Android. I believe there is some kind of library or permissions problem.

It builds and starts, but immediately after the Kivy loading splash screen it crashes with JVM exception occurred: Fail to connect to camera service . The identical file runs perfectly on Ubuntu.

It's not an obvious build or installation problem as I have had good success getting my own apps to run, with internet access, reading and writing files, but I can't get the camera to open on Android. On Ubuntu and MacOS the camera opens and works.

The Kivy demo file is just a minimal camera app which opens the camera, makes camera.play true on a button press. Full source below. This image is from it running on Ubuntu:

Could someone help advise what I need to do to get it to run in Android?

I don't believe it's a permissions issue , as I have buildozer.spec with android.permissions = INTERNET,CAMERA (full file below) and enabled those permissions in the App Info screen:

However, I am suspecting GStreamer , as the Kivy web site says

Note that not finding a camera, perhaps because gstreamer is not installed, will throw an exception during the kv language processing.

We see no message about Gstreamer in the Android logs, but we do on Ubuntu:

# UBUNTU LOG
[INFO   ] [CameraGi    ] Using Gstreamer 1.14.4.0
[INFO   ] [Camera      ] Provider: gi(['camera_picamera'] ignored)

# ANDROID LOG
[INFO   ] Camera: Provider: android
[WARNING] stderr:       4:    Camera:
[WARNING] stderr:       5:        id: camera
[WARNING] stderr: >>    6:        resolution: (640, 480)
[WARNING] stderr:       7:        play: False
[WARNING] stderr:       8:    ToggleButton:
[WARNING] stderr: ...
[WARNING] stderr: JavaException:
                  JVM exception occurred: Fail to connect to camera service

Do I need to install Gstreamer on the Android device? How do I do this? buildozer dependencies? Python import?

Thanks in advance for any help or suggestions.

Jonathan.

---

Details

• Build Environment is Ubuntu 18.04.1 LTS
• Target device Nokia 1 with Android 8.1.0 (new, unrooted)
• Also tested on Moto E 2nd Generation with Android 6.0 (old, unrooted)
• Debugging over USB
• Kivy 1.11.0 (1.11.1 on Ubuntu)
• Python 3.7.1 (3.6.7 on Ubuntu)

I compile with

buildozer -v android debug deploy run

Just to repeat: all my other apps compile and run in the same way, so it's at least not a basic installation problem.

Full log:

[INFO   ] Logger: Record log in /data/user/0/org.test.kivycamera/files/app/.kivy/logs/kivy_19-08-02_0.txt
[WARNING] [Config      ] Upgrading configuration in progress.
[WARNING] [Config      ] Older configuration version detected (0 instead of 21)
[INFO   ] Kivy: v1.11.0
[INFO   ] Kivy: Installed at "/data/user/0/org.test.kivycamera/files/app/_python_bundle/site-packages/kivy/__init__.pyc"
[INFO   ] Python: v3.7.1 (default, Aug  2 2019, 14:44:11) 
[Clang 6.0.2 (https://android.googlesource.com/toolchain/clang 183abd29fc496f55
[INFO   ] Python: Interpreter at "android_python"
[INFO   ] Logger: Purge log fired. Analysing...
[INFO   ] Logger: Purge finished!
[INFO   ] Factory: 184 symbols loaded
[INFO   ] Image: Providers: img_tex, img_dds, img_sdl2, img_gif (img_pil, img_ffpyplayer ignored)
[INFO   ] Window: Provider: sdl2
[INFO   ] GL: Using the "OpenGL ES 2" graphics system
[INFO   ] GL: Backend used <sdl2>
[INFO   ] GL: OpenGL version <b'OpenGL ES 3.1 v1.r18p0-00cet0.78299f586f7919862c85cb764ae43fad'>
[INFO   ] GL: OpenGL vendor <b'ARM'>
[INFO   ] GL: OpenGL renderer <b'Mali-T720'>
[INFO   ] GL: OpenGL parsed version: 3, 1
[INFO   ] GL: Texture max size <8192>
[INFO   ] GL: Texture max units <16>
[INFO   ] Window: auto add sdl2 input provider
[INFO   ] Window: virtual keyboard not allowed, single mode, not docked
[INFO   ] Camera: Provider: android
[INFO   ] Text: Provider: sdl2
[WARNING] stderr: Traceback (most recent call last):
[WARNING] stderr:   File "/home/projects/kivy/camera/.buildozer/android/platform/build/build/python-installs/kivycamera/kivy/lang/builder.py", line 700, in _apply_rule
[WARNING] stderr:   File "kivy/weakproxy.pyx", line 35, in kivy.weakproxy.WeakProxy.__setattr__
[WARNING] stderr:   File "kivy/properties.pyx", line 497, in kivy.properties.Property.__set__
[WARNING] stderr:   File "kivy/properties.pyx", line 839, in kivy.properties.ListProperty.set
[WARNING] stderr:   File "kivy/properties.pyx", line 544, in kivy.properties.Property.set
[WARNING] stderr:   File "kivy/properties.pyx", line 599, in kivy.properties.Property.dispatch
[WARNING] stderr:   File "kivy/_event.pyx", line 1214, in kivy._event.EventObservers.dispatch
[WARNING] stderr:   File "kivy/_event.pyx", line 1120, in kivy._event.EventObservers._dispatch
[WARNING] stderr:   File "/home/projects/kivy/camera/.buildozer/android/platform/build/build/python-installs/kivycamera/kivy/uix/camera.py", line 103, in _on_index
[WARNING] stderr:   File "/home/projects/kivy/camera/.buildozer/android/platform/build/build/python-installs/kivycamera/kivy/core/camera/camera_android.py", line 42, in __init__
[WARNING] stderr:   File "/home/projects/kivy/camera/.buildozer/android/platform/build/build/python-installs/kivycamera/kivy/core/camera/__init__.py", line 70, in __init__
[WARNING] stderr:   File "/home/projects/kivy/camera/.buildozer/android/platform/build/build/python-installs/kivycamera/kivy/core/camera/camera_android.py", line 49, in init_camera
[WARNING] stderr:   File "jnius/jnius_export_class.pxi", line 1044, in jnius.jnius.JavaMultipleMethod.__call__
[WARNING] stderr:   File "jnius/jnius_export_class.pxi", line 765, in jnius.jnius.JavaMethod.__call__
[WARNING] stderr:   File "jnius/jnius_export_class.pxi", line 931, in jnius.jnius.JavaMethod.call_staticmethod
[WARNING] stderr:   File "jnius/jnius_utils.pxi", line 91, in jnius.jnius.check_exception
[WARNING] stderr: jnius.jnius.JavaException: JVM exception occurred: Fail to connect to camera service
[WARNING] stderr: 
[WARNING] stderr: During handling of the above exception, another exception occurred:
[WARNING] stderr: 
[WARNING] stderr: Traceback (most recent call last):
[WARNING] stderr:   File "/home/projects/kivy/camera/.buildozer/android/app/main.py", line 59, in <module>
[WARNING] stderr:   File "/home/projects/kivy/camera/.buildozer/android/platform/build/build/python-installs/kivycamera/kivy/app.py", line 829, in run
[WARNING] stderr:   File "/home/projects/kivy/camera/.buildozer/android/app/main.py", line 56, in build
[WARNING] stderr:   File "/home/projects/kivy/camera/.buildozer/android/platform/build/build/python-installs/kivycamera/kivy/uix/boxlayout.py", line 145, in __init__
[WARNING] stderr:   File "/home/projects/kivy/camera/.buildozer/android/platform/build/build/python-installs/kivycamera/kivy/uix/layout.py", line 76, in __init__
[WARNING] stderr:   File "/home/projects/kivy/camera/.buildozer/android/platform/build/build/python-installs/kivycamera/kivy/uix/widget.py", line 361, in __init__
[WARNING] stderr:   File "/home/projects/kivy/camera/.buildozer/android/platform/build/build/python-installs/kivycamera/kivy/uix/widget.py", line 469, in apply_class_lang_rules
[WARNING] stderr:   File "/home/projects/kivy/camera/.buildozer/android/platform/build/build/python-installs/kivycamera/kivy/lang/builder.py", line 538, in apply
[WARNING] stderr:   File "/home/projects/kivy/camera/.buildozer/android/platform/build/build/python-installs/kivycamera/kivy/lang/builder.py", line 707, in _apply_rule
[WARNING] stderr: kivy.lang.builder.BuilderException: Parser: File "<inline>", line 6:
[WARNING] stderr: ...
[WARNING] stderr:       4:    Camera:
[WARNING] stderr:       5:        id: camera
[WARNING] stderr: >>    6:        resolution: (640, 480)
[WARNING] stderr:       7:        play: False
[WARNING] stderr:       8:    ToggleButton:
[WARNING] stderr: ...
[WARNING] stderr: JavaException: JVM exception occurred: Fail to connect to camera service
[WARNING] stderr:   File "/home/projects/kivy/camera/.buildozer/android/platform/build/build/python-installs/kivycamera/kivy/lang/builder.py", line 700, in _apply_rule
[WARNING] stderr:   File "kivy/weakproxy.pyx", line 35, in kivy.weakproxy.WeakProxy.__setattr__
[WARNING] stderr:   File "kivy/properties.pyx", line 497, in kivy.properties.Property.__set__
[WARNING] stderr:   File "kivy/properties.pyx", line 839, in kivy.properties.ListProperty.set
[WARNING] stderr:   File "kivy/properties.pyx", line 544, in kivy.properties.Property.set
[WARNING] stderr:   File "kivy/properties.pyx", line 599, in kivy.properties.Property.dispatch
[WARNING] stderr:   File "kivy/_event.pyx", line 1214, in kivy._event.EventObservers.dispatch
[WARNING] stderr:   File "kivy/_event.pyx", line 1120, in kivy._event.EventObservers._dispatch
[WARNING] stderr:   File "/home/projects/kivy/camera/.buildozer/android/platform/build/build/python-installs/kivycamera/kivy/uix/camera.py", line 103, in _on_index
[WARNING] stderr:   File "/home/projects/kivy/camera/.buildozer/android/platform/build/build/python-installs/kivycamera/kivy/core/camera/camera_android.py", line 42, in __init__
[WARNING] stderr:   File "/home/projects/kivy/camera/.buildozer/android/platform/build/build/python-installs/kivycamera/kivy/core/camera/__init__.py", line 70, in __init__
[WARNING] stderr:   File "/home/projects/kivy/camera/.buildozer/android/platform/build/build/python-installs/kivycamera/kivy/core/camera/camera_android.py", line 49, in init_camera
[WARNING] stderr:   File "jnius/jnius_export_class.pxi", line 1044, in jnius.jnius.JavaMultipleMethod.__call__
[WARNING] stderr:   File "jnius/jnius_export_class.pxi", line 765, in jnius.jnius.JavaMethod.__call__
[WARNING] stderr:   File "jnius/jnius_export_class.pxi", line 931, in jnius.jnius.JavaMethod.call_staticmethod
[WARNING] stderr:   File "jnius/jnius_utils.pxi", line 91, in jnius.jnius.check_exception
[WARNING] stderr: 

Source main.py

It's just a single file, fromhttps://kivy.org/doc/stable/examples/gen__camera__main__py.html

With comments stripped for SE brevity:

from kivy.app import App
from kivy.lang import Builder
from kivy.uix.boxlayout import BoxLayout
import time
Builder.load_string('''
<CameraClick>:
    orientation: 'vertical'
    Camera:
        id: camera
        resolution: (640, 480)
        play: False
    ToggleButton:
        text: 'Play'
        on_press: camera.play = not camera.play
        size_hint_y: None
        height: '48dp'
    Button:
        text: 'Capture'
        size_hint_y: None
        height: '48dp'
        on_press: root.capture()
''')

class CameraClick(BoxLayout):
    def capture(self):
        camera = self.ids['camera']
        timestr = time.strftime("%Y%m%d_%H%M%S")
        camera.export_to_png("IMG_{}.png".format(timestr))
        print("Captured")

class TestCamera(App):
    def build(self):
        return CameraClick()

TestCamera().run()

Buildozer spec

$ diff buildozer.spec.INIT buildozer.spec
4c4
< title = My Application
---
> title = Kivy Camera Demo
7c7
< package.name = myapp
---
> package.name = kivycamera
88c88
< #android.permissions = INTERNET
---
> android.permissions = INTERNET,CAMERA

In full, it's:

[app]

# (str) Title of your application
title = Kivy Camera Demo

# (str) Package name
package.name = kivycamera

# (str) Package domain (needed for android/ios packaging)
package.domain = org.test

# (str) Source code where the main.py live
source.dir = .

# (list) Source files to include (let empty to include all the files)
source.include_exts = py,png,jpg,kv,atlas

# (list) List of inclusions using pattern matching
#source.include_patterns = assets/*,images/*.png

# (list) Source files to exclude (let empty to not exclude anything)
#source.exclude_exts = spec

# (list) List of directory to exclude (let empty to not exclude anything)
#source.exclude_dirs = tests, bin

# (list) List of exclusions using pattern matching
#source.exclude_patterns = license,images/*/*.jpg

# (str) Application versioning (method 1)
version = 0.1

# (str) Application versioning (method 2)
# version.regex = __version__ = ['"](.*)['"]
# version.filename = %(source.dir)s/main.py

# (list) Application requirements
# comma separated e.g. requirements = sqlite3,kivy
requirements = python3,kivy

# (str) Custom source folders for requirements
# Sets custom source for any requirements with recipes
# requirements.source.kivy = ../../kivy

# (list) Garden requirements
#garden_requirements =

# (str) Presplash of the application
#presplash.filename = %(source.dir)s/data/presplash.png

# (str) Icon of the application
#icon.filename = %(source.dir)s/data/icon.png

# (str) Supported orientation (one of landscape, sensorLandscape, portrait or all)
orientation = portrait

# (list) List of service to declare
#services = NAME:ENTRYPOINT_TO_PY,NAME2:ENTRYPOINT2_TO_PY

#
# OSX Specific
#

#
# author = © Copyright Info

# change the major version of python used by the app
osx.python_version = 3

# Kivy version to use
osx.kivy_version = 1.9.1

#
# Android specific
#

# (bool) Indicate if the application should be fullscreen or not
fullscreen = 0

# (string) Presplash background color (for new android toolchain)
# Supported formats are: #RRGGBB #AARRGGBB or one of the following names:
# red, blue, green, black, white, gray, cyan, magenta, yellow, lightgray,
# darkgray, grey, lightgrey, darkgrey, aqua, fuchsia, lime, maroon, navy,
# olive, purple, silver, teal.
#android.presplash_color = #FFFFFF

# (list) Permissions
android.permissions = INTERNET,CAMERA

# (int) Target Android API, should be as high as possible.
#android.api = 27

# (int) Minimum API your APK will support.
#android.minapi = 21

# (int) Android SDK version to use
#android.sdk = 20

# (str) Android NDK version to use
#android.ndk = 17c

# (int) Android NDK API to use. This is the minimum API your app will support, it should usually match android.minapi.
#android.ndk_api = 21

# (bool) Use --private data storage (True) or --dir public storage (False)
#android.private_storage = True

# (str) Android NDK directory (if empty, it will be automatically downloaded.)
#android.ndk_path =

# (str) Android SDK directory (if empty, it will be automatically downloaded.)
#android.sdk_path =

# (str) ANT directory (if empty, it will be automatically downloaded.)
#android.ant_path =

# (bool) If True, then skip trying to update the Android sdk
# This can be useful to avoid excess Internet downloads or save time
# when an update is due and you just want to test/build your package
# android.skip_update = False

# (bool) If True, then automatically accept SDK license
# agreements. This is intended for automation only. If set to False,
# the default, you will be shown the license when first running
# buildozer.
# android.accept_sdk_license = False

# (str) Android entry point, default is ok for Kivy-based app
#android.entrypoint = org.renpy.android.PythonActivity

# (list) Pattern to whitelist for the whole project
#android.whitelist =

# (str) Path to a custom whitelist file
#android.whitelist_src =

# (str) Path to a custom blacklist file
#android.blacklist_src =

# (list) List of Java .jar files to add to the libs so that pyjnius can access
# their classes. Don't add jars that you do not need, since extra jars can slow
# down the build process. Allows wildcards matching, for example:
# OUYA-ODK/libs/*.jar
#android.add_jars = foo.jar,bar.jar,path/to/more/*.jar

# (list) List of Java files to add to the android project (can be java or a
# directory containing the files)
#android.add_src =

# (list) Android AAR archives to add (currently works only with sdl2_gradle
# bootstrap)
#android.add_aars =

# (list) Gradle dependencies to add (currently works only with sdl2_gradle
# bootstrap)
#android.gradle_dependencies =

# (list) Java classes to add as activities to the manifest.
#android.add_activites = com.example.ExampleActivity

# (str) python-for-android branch to use, defaults to master
#p4a.branch = master

# (str) OUYA Console category. Should be one of GAME or APP
# If you leave this blank, OUYA support will not be enabled
#android.ouya.category = GAME

# (str) Filename of OUYA Console icon. It must be a 732x412 png image.
#android.ouya.icon.filename = %(source.dir)s/data/ouya_icon.png

# (str) XML file to include as an intent filters in <activity> tag
#android.manifest.intent_filters =

# (str) launchMode to set for the main activity
#android.manifest.launch_mode = standard

# (list) Android additional libraries to copy into libs/armeabi
#android.add_libs_armeabi = libs/android/*.so
#android.add_libs_armeabi_v7a = libs/android-v7/*.so
#android.add_libs_x86 = libs/android-x86/*.so
#android.add_libs_mips = libs/android-mips/*.so

# (bool) Indicate whether the screen should stay on
# Don't forget to add the WAKE_LOCK permission if you set this to True
#android.wakelock = False

# (list) Android application meta-data to set (key=value format)
#android.meta_data =

# (list) Android library project to add (will be added in the
# project.properties automatically.)
#android.library_references =

# (list) Android shared libraries which will be added to AndroidManifest.xml using <uses-library> tag
#android.uses_library =

# (str) Android logcat filters to use
#android.logcat_filters = *:S python:D

# (bool) Copy library instead of making a libpymodules.so
#android.copy_libs = 1

# (str) The Android arch to build for, choices: armeabi-v7a, arm64-v8a, x86, x86_64
android.arch = armeabi-v7a

#
# Python for android (p4a) specific
#

# (str) python-for-android git clone directory (if empty, it will be automatically cloned from github)
#p4a.source_dir =

# (str) The directory in which python-for-android should look for your own build recipes (if any)
#p4a.local_recipes =

# (str) Filename to the hook for p4a
#p4a.hook =

# (str) Bootstrap to use for android builds
# p4a.bootstrap = sdl2

# (int) port number to specify an explicit --port= p4a argument (eg for bootstrap flask)
#p4a.port =


#
# iOS specific
#

# (str) Path to a custom kivy-ios folder
#ios.kivy_ios_dir = ../kivy-ios
# Alternately, specify the URL and branch of a git checkout:
ios.kivy_ios_url = https://github.com/kivy/kivy-ios
ios.kivy_ios_branch = master

# Another platform dependency: ios-deploy
# Uncomment to use a custom checkout
#ios.ios_deploy_dir = ../ios_deploy
# Or specify URL and branch
ios.ios_deploy_url = https://github.com/phonegap/ios-deploy
ios.ios_deploy_branch = 1.7.0

# (str) Name of the certificate to use for signing the debug version
# Get a list of available identities: buildozer ios list_identities
#ios.codesign.debug = "iPhone Developer: <lastname> <firstname> (<hexstring>)"

# (str) Name of the certificate to use for signing the release version
#ios.codesign.release = %(ios.codesign.debug)s


[buildozer]

# (int) Log level (0 = error only, 1 = info, 2 = debug (with command output))
log_level = 2

# (int) Display warning if buildozer is run as root (0 = False, 1 = True)
warn_on_root = 1

# (str) Path to build artifact storage, absolute or relative to spec file
# build_dir = ./.buildozer

# (str) Path to build output (i.e. .apk, .ipa) storage
# bin_dir = ./bin

#    -----------------------------------------------------------------------------
#    List as sections
#
#    You can define all the "list" as [section:key].
#    Each line will be considered as a option to the list.
#    Let's take [app] / source.exclude_patterns.
#    Instead of doing:
#
#[app]
#source.exclude_patterns = license,data/audio/*.wav,data/images/original/*
#
#    This can be translated into:
#
#[app:source.exclude_patterns]
#license
#data/audio/*.wav
#data/images/original/*
#


#    -----------------------------------------------------------------------------
#    Profiles
#
#    You can extend section / key with a profile
#    For example, you want to deploy a demo version of your application without
#    HD content. You could first change the title to add "(demo)" in the name
#    and extend the excluded directories to remove the HD content.
#
#[app@demo]
#title = My Application (demo)
#
#[app:source.exclude_patterns@demo]
#images/hd/*
#
#    Then, invoke the command line with the "demo" profile:
#
#buildozer --profile demo android debug

Installation notes

How kivy/buildozer etc installed on Ubuntu:

pip3 install --upgrade buildozer
sudo apt update
# from https://buildozer.readthedocs.io/en/latest/installation.html#targeting-ios
sudo apt install -y git zip unzip openjdk-8-jdk python3-pip autoconf libtool pkg-config zlib1g-dev libncurses5-dev libncursesw5-dev libtinfo5
pip3 install --user --upgrade cython virtualenv
echo 'export PATH=$PATH:~/.local/bin/' >> ~/.bashrc
# log out, back in, check cython in path
which cython # says /home/username/.local/bin/cython

cython --version # says Cython version 0.29.12

Answer 1

You need to put this code into build method:

request_permissions([
    Permission.CAMERA,
    Permission.WRITE_EXTERNAL_STORAGE,
    Permission.READ_EXTERNAL_STORAGE
])

And, of course, imports in the beginning of the file:

from android.permissions import request_permissions, Permission

See the related Issue in kivy repository: https://github.com/kivy/kivy/issues/6995