mediapipe/docs/getting_started/building_examples.md

layout	title	parent	nav_order
default	Building MediaPipe Examples	Getting Started	2

Building MediaPipe Examples

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Android

Prerequisite

• Java Runtime.
• Android SDK release 28.0.3 and above.
• Android NDK r18b and above.

MediaPipe recommends setting up Android SDK and NDK via Android Studio (and see below for Android Studio setup). However, if you prefer using MediaPipe without Android Studio, please run setup_android_sdk_and_ndk.sh to download and setup Android SDK and NDK before building any Android example apps.

If Android SDK and NDK are already installed (e.g., by Android Studio), set $ANDROID_HOME and $ANDROID_NDK_HOME to point to the installed SDK and NDK.

export ANDROID_HOME=<path to the Android SDK>
export ANDROID_NDK_HOME=<path to the Android NDK>

In order to use MediaPipe on earlier Android versions, MediaPipe needs to switch to a lower Android API level. You can achieve this by specifying api_level = $YOUR_INTENDED_API_LEVEL in android_ndk_repository() and/or android_sdk_repository() in the WORKSPACE file.

Please verify all the necessary packages are installed.

• Android SDK Platform API Level 28 or 29
• Android SDK Build-Tools 28 or 29
• Android SDK Platform-Tools 28 or 29
• Android SDK Tools 26.1.1
• Android NDK 17c or above

Option 1: Build with Bazel in Command Line

Tip: You can run this script to build (and install) all MediaPipe Android example apps.

1. To build an Android example app, build against the corresponding android_binary build target. For instance, for MediaPipe Hands the target is handtrackinggpu in the BUILD file:

   Note: To reduce the binary size, consider appending --linkopt="-s" to the command below to strip symbols.

   bazel build -c opt --config=android_arm64 mediapipe/examples/android/src/java/com/google/mediapipe/apps/handtrackinggpu:handtrackinggpu
   

2. Install it on a device with:

   adb install bazel-bin/mediapipe/examples/android/src/java/com/google/mediapipe/apps/handtrackinggpu/handtrackinggpu.apk
   

Option 2: Build with Bazel in Android Studio

The MediaPipe project can be imported into Android Studio using the Bazel plugins. This allows the MediaPipe examples to be built and modified in Android Studio.

To incorporate MediaPipe into an existing Android Studio project, see these instructions that use Android Archive (AAR) and Gradle.

The steps below use Android Studio 3.5 to build and install a MediaPipe example app:

1. Install and launch Android Studio 3.5.

2. Select Configure -> SDK Manager -> SDK Platforms.

   • Verify that Android SDK Platform API Level 28 or 29 is installed.
   • Take note of the Android SDK Location, e.g., /usr/local/home/Android/Sdk.

3. Select Configure -> SDK Manager -> SDK Tools.

   • Verify that Android SDK Build-Tools 28 or 29 is installed.
   • Verify that Android SDK Platform-Tools 28 or 29 is installed.
   • Verify that Android SDK Tools 26.1.1 is installed.
   • Verify that Android NDK 17c or above is installed.
   • Take note of the Android NDK Location, e.g., /usr/local/home/Android/Sdk/ndk-bundle or /usr/local/home/Android/Sdk/ndk/20.0.5594570.

4. Set environment variables $ANDROID_HOME and $ANDROID_NDK_HOME to point to the installed SDK and NDK.

   export ANDROID_HOME=/usr/local/home/Android/Sdk
   
   # If the NDK libraries are installed by a previous version of Android Studio, do
   export ANDROID_NDK_HOME=/usr/local/home/Android/Sdk/ndk-bundle
   # If the NDK libraries are installed by Android Studio 3.5, do
   export ANDROID_NDK_HOME=/usr/local/home/Android/Sdk/ndk/<version number>
   

5. Select Configure -> Plugins to install Bazel.

6. On Linux, select File -> Settings -> Bazel settings. On macos, select Android Studio -> Preferences -> Bazel settings. Then, modify Bazel binary location to be the same as the output of $ which bazel.

7. Select Import Bazel Project.

   • Select Workspace: /path/to/mediapipe and select Next.
   • Select Generate from BUILD file: /path/to/mediapipe/BUILD and select Next.
   • Modify Project View to be the following and select Finish.

   directories:
     # read project settings, e.g., .bazelrc
     .
     -mediapipe/objc
     -mediapipe/examples/ios
   
   targets:
     //mediapipe/examples/android/...:all
     //mediapipe/java/...:all
   
   android_sdk_platform: android-29
   
   sync_flags:
     --host_crosstool_top=@bazel_tools//tools/cpp:toolchain
   

8. Select Bazel -> Sync -> Sync project with Build files.

   Note: Even after doing step 4, if you still see the error: "no such package '@androidsdk//': Either the path attribute of android_sdk_repository or the ANDROID_HOME environment variable must be set.", please modify the WORKSPACE file to point to your SDK and NDK library locations, as below:

   android_sdk_repository(
       name = "androidsdk",
       path = "/path/to/android/sdk"
   )
   
   android_ndk_repository(
       name = "androidndk",
       path = "/path/to/android/ndk"
   )
   

9. Connect an Android device to the workstation.

10. Select Run... -> Edit Configurations....

    • Select Templates -> Bazel Command.
    • Enter Target Expression: //mediapipe/examples/android/src/java/com/google/mediapipe/apps/handtrackinggpu:handtrackinggpu
    • Enter Bazel command: mobile-install.
    • Enter Bazel flags: -c opt --config=android_arm64.
    • Press the [+] button to add the new configuration.
    • Select Run to run the example app on the connected Android device.

iOS

Prerequisite

1. Install Xcode, then install the Command Line Tools using:

   xcode-select --install
   

2. Install Bazel.

   We recommend using Homebrew to get the latest version.

3. Set Python 3.7 as the default Python version and install the Python "six" library. This is needed for TensorFlow.

   pip3 install --user six
   

4. Clone the MediaPipe repository.

   git clone https://github.com/google/mediapipe.git
   

Set up a bundle ID prefix

All iOS apps must have a bundle ID, and you must have a provisioning profile that lets you install an app with that ID onto your phone. To avoid clashes between different MediaPipe users, you need to configure a unique prefix for the bundle IDs of our iOS demo apps.

If you have a custom provisioning profile, see Custom provisioning below.

Otherwise, run this command to generate a unique prefix:

python3 mediapipe/examples/ios/link_local_profiles.py

Create an Xcode project

This allows you to edit and debug one of the example apps in Xcode. It also allows you to make use of automatic provisioning (see later section).

1. We will use a tool called Tulsi for generating Xcode projects from Bazel build configurations.

   # cd out of the mediapipe directory, then:
   git clone https://github.com/bazelbuild/tulsi.git
   cd tulsi
   # remove Xcode version from Tulsi's .bazelrc (see http://github.com/bazelbuild/tulsi#building-and-installing):
   sed -i .orig '/xcode_version/d' .bazelrc
   # build and run Tulsi:
   sh build_and_run.sh
   

   This will install Tulsi.app inside the Applications directory in your home directory.

2. Open mediapipe/Mediapipe.tulsiproj using the Tulsi app.

   Tip: If Tulsi displays an error saying "Bazel could not be found", press the "Bazel..." button in the Packages tab and select the bazel executable in your homebrew /bin/ directory.

3. Select the MediaPipe config in the Configs tab, then press the Generate button below. You will be asked for a location to save the Xcode project. Once the project is generated, it will be opened in Xcode.

   If you get an error about bundle IDs, see the previous section.

Set up provisioning

To install applications on an iOS device, you need a provisioning profile. There are two options:

1. Automatic provisioning. This allows you to build and install an app to your personal device. The provisining profile is managed by Xcode, and has to be updated often (it is valid for about a week).

2. Custom provisioning. This uses a provisioning profile associated with an Apple developer account. These profiles have a longer validity period and can target multiple devices, but you need a paid developer account with Apple to obtain one.

Automatic provisioning

1. Create an Xcode project for MediaPipe, as discussed earlier.

2. In the project navigator in the left sidebar, select the "Mediapipe" project.

3. Select one of the application targets, e.g. HandTrackingGpuApp.

4. Select the "Signing & Capabilities" tab.

5. Check "Automatically manage signing", and confirm the dialog box.

6. Select "Your Name (Personal Team)" in the Team pop-up menu.

7. This set-up needs to be done once for each application you want to install. Repeat steps 3-6 as needed.

This generates provisioning profiles for each app you have selected. Now we need to tell Bazel to use them. We have provided a script to make this easier.

1. In the terminal, to the mediapipe directory where you cloned the repository.

2. Run this command:

   python3 mediapipe/examples/ios/link_local_profiles.py
   

This will find and link the provisioning profile for all applications for which you have enabled automatic provisioning in Xcode.

Note: once a profile expires, Xcode will generate a new one; you must then run this script again to link the updated profiles.

Custom provisioning

1. Obtain a provisioning profile from Apple.

Tip: You can use this command to see the provisioning profiles you have previously downloaded using Xcode: open ~/Library/MobileDevice/"Provisioning Profiles". If there are none, generate and download a profile on Apple's developer site.

1. Symlink or copy your provisioning profile to mediapipe/mediapipe/provisioning_profile.mobileprovision.

   cd mediapipe
   ln -s ~/Downloads/MyProvisioningProfile.mobileprovision mediapipe/provisioning_profile.mobileprovision
   

Note: if you had previously set up automatic provisioning, you should remove the provisioning_profile.mobileprovision symlink in each example's directory, since it will take precedence over the common one. You can also overwrite it with you own profile if you need a different profile for different apps.

1. Open mediapipe/examples/ios/bundle_id.bzl, and change the BUNDLE_ID_PREFIX to a prefix associated with your provisioning profile.

Build and run an app using Xcode

1. Create the Xcode project, and make sure you have set up either automatic or custom provisioning.

2. You can now select any of the MediaPipe demos in the target menu, and build and run them as normal.

Note: When you ask Xcode to run an app, by default it will use the Debug configuration. Some of our demos are computationally heavy; you may want to use the Release configuration for better performance.

Tip: To switch build configuration in Xcode, click on the target menu, choose "Edit Scheme...", select the Run action, and switch the Build Configuration from Debug to Release. Note that this is set independently for each target.

Tip: On the device, in Settings > General > Device Management, make sure the developer (yourself) is trusted.

Build an app using the command line

1. Make sure you have set up either automatic or custom provisioning.

2. Using MediaPipe Hands for example, run:

   bazel build -c opt --config=ios_arm64 mediapipe/examples/ios/handtrackinggpu:HandTrackingGpuApp
   

   You may see a permission request from codesign in order to sign the app.

   Tip: If you are using custom provisioning, you can run this script to build all MediaPipe iOS example apps.

3. In Xcode, open the Devices and Simulators window (command-shift-2).

4. Make sure your device is connected. You will see a list of installed apps. Press the "+" button under the list, and select the .ipa file built by Bazel.

5. You can now run the app on your device.

Tip: On the device, in Settings > General > Device Management, make sure the developer (yourself) is trusted.

Desktop

Option 1: Running on CPU

1. To build, for example, MediaPipe Hands, run:

   bazel build -c opt --define MEDIAPIPE_DISABLE_GPU=1 mediapipe/examples/desktop/hand_tracking:hand_tracking_cpu
   

2. To run the application:

   GLOG_logtostderr=1 bazel-bin/mediapipe/examples/desktop/hand_tracking/hand_tracking_cpu \
     --calculator_graph_config_file=mediapipe/graphs/hand_tracking/hand_tracking_desktop_live.pbtxt
   

   This will open up your webcam as long as it is connected and on. Any errors is likely due to your webcam being not accessible.

Option 2: Running on GPU

Note: This currently works only on Linux, and please first follow OpenGL ES Setup on Linux Desktop.

1. To build, for example, MediaPipe Hands, run:

   bazel build -c opt --copt -DMESA_EGL_NO_X11_HEADERS --copt -DEGL_NO_X11 \
     mediapipe/examples/desktop/hand_tracking:hand_tracking_gpu
   

2. To run the application:

   GLOG_logtostderr=1 bazel-bin/mediapipe/examples/desktop/hand_tracking/hand_tracking_gpu \
     --calculator_graph_config_file=mediapipe/graphs/hand_tracking/hand_tracking_mobile.pbtxt
   

   This will open up your webcam as long as it is connected and on. Any errors is likely due to your webcam being not accessible, or GPU drivers not setup properly.