diff --git a/.github/workflows/build_wheels.yml b/.github/workflows/build_wheels_linux.yml
similarity index 79%
rename from .github/workflows/build_wheels.yml
rename to .github/workflows/build_wheels_linux.yml
index 67f7ad8d..bbb7f7fe 100644
--- a/.github/workflows/build_wheels.yml
+++ b/.github/workflows/build_wheels_linux.yml
@@ -1,83 +1,17 @@
-name: Build PYPI wheels for opencv-python
+name: Build PYPI wheels for opencv-python on Linux x86_64
 
 on:
+  push:
+    branches:
+      - gs/fix-submodules-checkout
   pull_request:
     branches:
-      - master
+      - 3.4
   release:
     types: [published, edited]
 
 
 jobs:
-  build-windows-x86_64:
-    runs-on: ${{ matrix.os }}
-    defaults:
-      run:
-        shell: powershell
-
-    strategy:
-      fail-fast: false
-      matrix:
-        os: [windows-latest]
-        python-version: [3.6, 3.7, 3.8, 3.9]
-        platform: [x86, x64]
-        with_contrib: [0, 1]
-        without_gui: [0, 1]
-        build_sdist: [0]
-
-    env:
-      ACTIONS_ALLOW_UNSECURE_COMMANDS: true
-      SDIST: ${{ matrix.build_sdist || 0}}
-      ENABLE_HEADLESS: ${{ matrix.without_gui }}
-      ENABLE_CONTRIB: ${{ matrix.with_contrib }}
-
-    steps:
-    - name: Checkout
-      uses: actions/checkout@v2
-      with:
-        submodules: true
-        fetch-depth: 0
-
-    - name: Update submodules
-      run: |
-        git submodule update --remote
-
-    - name: Set up Python ${{ matrix.python-version }}
-      uses: actions/setup-python@v2
-      with:
-        python-version: ${{ matrix.python-version }}
-        architecture: ${{ matrix.platform }}
-
-    - name: Setup MSBuild.exe
-      uses: warrenbuckley/Setup-MSBuild@v1
-
-    - name: build script
-      run: |
-        python --version
-        python -m pip install --upgrade pip
-        python -m pip install --upgrade setuptools
-        set "CI_BUILD=1" && python -m pip wheel --wheel-dir=%cd%\wheelhouse . --verbose
-      shell: cmd
-
-    - name: before test
-      run: |
-        cd ${{ github.workspace }}/tests
-        &python -m pip install --user --no-warn-script-location (ls "../wheelhouse/opencv*.whl")
-        if ($LastExitCode -ne 0) {throw $LastExitCode}
-      shell: powershell
-
-    - name: run test
-      run: |
-        cd ${{ github.workspace }}/tests
-        python -m unittest test
-      shell: cmd
-
-    - name: saving artifacts
-      uses: actions/upload-artifact@v2
-      with:
-        name: wheels
-        path: wheelhouse/opencv*.whl
-
   build:
     runs-on: ${{ matrix.os }}
     defaults:
@@ -87,7 +21,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        os: [ubuntu-latest, macos-latest]
+        os: [ubuntu-latest]
         python-version: [3.6, 3.7, 3.8, 3.9]
         platform: [x64]
         with_contrib: [0, 1]
@@ -116,12 +50,15 @@ jobs:
     - name: Checkout
       uses: actions/checkout@v2
       with:
-        submodules: true
+        submodules: false
         fetch-depth: 0
 
+    - name: Update multibuild submodule
+      run: git submodule update --init --recursive multibuild
+
     - name: Update submodules
-      run: |
-        git submodule update --remote
+      if: github.event_name == 'pull_request'
+      run: git submodule update --remote
 
     - name: Set up Python ${{ matrix.python-version }}
       uses: actions/setup-python@v2
@@ -140,7 +77,7 @@ jobs:
         echo "BUILD_DEPENDS=$(echo $NP_BUILD_DEP)" >> $GITHUB_ENV;
         echo "TEST_DEPENDS=$(echo $NP_TEST_DEP)" >> $GITHUB_ENV;
 
-    - name: before install
+    - name: build
       run: |
         set -e
         # Check out and prepare the source
@@ -157,8 +94,32 @@ jobs:
         echo $ENABLE_HEADLESS > headless.enabled
         set -x
         build_wheel $REPO_DIR $PLAT
+
+    - name: Checkout
+      uses: actions/checkout@v2
+      with:
+        submodules: true
+        fetch-depth: 0
+
+    - name: install and test
+      run: |
+        set -e
+        # Check out and prepare the source
+        # Multibuild doesn't have releases, so --depth would break eventually (see
+        # https://superuser.com/questions/1240216/server-does-not-allow-request-for-unadvertised)
+        git submodule update --init multibuild
+        source multibuild/common_utils.sh
+        # https://github.com/matthew-brett/multibuild/issues/116
+        if [[ "$TRAVIS_OS_NAME" == "osx" ]]; then export ARCH_FLAGS=" "; fi
+        source multibuild/travis_steps.sh
+        # This sets -x
+        # source travis_multibuild_customize.sh
+        echo $ENABLE_CONTRIB > contrib.enabled
+        echo $ENABLE_HEADLESS > headless.enabled
+        set -x
         install_run $PLAT
         set +x
+
     - name: saving artifacts
       uses: actions/upload-artifact@v2
       with:
@@ -205,10 +166,14 @@ jobs:
     - name: Checkout
       uses: actions/checkout@v2
       with:
-        submodules: true
+        submodules: false
         fetch-depth: 0
 
+    - name: Update multibuild submodule
+      run: git submodule update --init --recursive multibuild
+
     - name: Update submodules
+      if: github.event_name == 'pull_request'
       run: |
         git submodule update --remote
 
@@ -238,6 +203,7 @@ jobs:
         # Install and run tests
         set -x
         echo "skipping tests because of sdist"
+
     - name: saving artifacts
       uses: actions/upload-artifact@v2
       with:
@@ -246,7 +212,7 @@ jobs:
 
   test_release_opencv_python:
     if: github.event_name == 'release' && github.event.release.prerelease
-    needs: [build, build-windows-x86_64, build_sdist]
+    needs: [build, build_sdist]
     runs-on: ubuntu-latest
     environment: test-opencv-python-release
     defaults:
@@ -265,7 +231,7 @@ jobs:
 
   release_opencv_python:
     if: github.event_name == 'release' && !github.event.release.prerelease
-    needs: [build, build-windows-x86_64, build_sdist]
+    needs: [build, build_sdist]
     runs-on: ubuntu-latest
     environment: opencv-python-release
     defaults:
diff --git a/.github/workflows/build_wheels_linux_arm.yml b/.github/workflows/build_wheels_linux_arm.yml
new file mode 100644
index 00000000..01158eec
--- /dev/null
+++ b/.github/workflows/build_wheels_linux_arm.yml
@@ -0,0 +1,177 @@
+name: Build PYPI wheels for opencv-python on Linux ARM
+
+on:
+  push:
+    branches:
+      - asen/check_3.4_wo_submodules
+  pull_request:
+    branches:
+      - 3.4
+  release:
+    types: [published, edited]
+
+
+jobs:
+  build_arm:
+    runs-on: ${{ matrix.os }}
+    defaults:
+      run:
+        shell: bash
+
+    strategy:
+      fail-fast: false
+      matrix:
+        os: [ARM64]
+        python-version: [3.6, 3.7, 3.8, 3.9]
+        platform: [x64]
+        with_contrib: [0, 1]
+        without_gui: [0, 1]
+        build_sdist: [0]
+
+    env:
+      ACTIONS_ALLOW_UNSECURE_COMMANDS: true
+      REPO_DIR: .
+      BUILD_COMMIT: master
+      PROJECT_SPEC: opencv-python
+      MB_PYTHON_VERSION: ${{ matrix.python-version }}
+      TRAVIS_PYTHON_VERSION: ${{ matrix.python-version }}
+      PLAT: aarch64
+      MB_ML_VER: 2014
+      NP_TEST_DEP: numpy
+      TRAVIS_BUILD_DIR: ${{ github.workspace }}
+      CONFIG_PATH: travis_config.sh
+      DOCKER_IMAGE: quay.io/skvark/manylinux2014_${PLAT}
+      DOCKER_TEST_IMAGE: multibuild/xenial_arm64v8
+      USE_CCACHE: 0
+      UNICODE_WIDTH: 32
+      SDIST: ${{ matrix.build_sdist || 0}}
+      ENABLE_HEADLESS: ${{ matrix.without_gui }}
+      ENABLE_CONTRIB: ${{ matrix.with_contrib }}
+
+    steps:
+    - name: Cleanup
+      if: always()
+      uses: AutoModality/action-clean@v1
+
+    - name: Checkout
+      uses: actions/checkout@v2
+      with:
+        submodules: false
+        fetch-depth: 0
+
+    - name: Update multibuild submodule
+      run: git submodule update --init --recursive multibuild
+
+    - name: Update submodules
+      if: github.event_name == 'pull_request'
+      run: git submodule update --remote
+
+    - name: Setup Environment variables
+      run: |
+        if [ "ARM64" == "${{ matrix.os }}" ]; then echo "PLAT=aarch64" >> $GITHUB_ENV; fi
+        echo "BUILD_DEPENDS=$(echo $NP_BUILD_DEP)" >> $GITHUB_ENV;
+        echo "TEST_DEPENDS=$(echo $NP_TEST_DEP)" >> $GITHUB_ENV;
+
+    - name: before install
+      run: |
+        set -e
+        if [[ $SDIST == 0 ]]; then
+          # Check out and prepare the source
+          # Multibuild doesn't have releases, so --depth would break eventually (see
+          # https://superuser.com/questions/1240216/server-does-not-allow-request-for-unadvertised)
+          git submodule update --init multibuild
+          source multibuild/common_utils.sh
+          # https://github.com/matthew-brett/multibuild/issues/116
+          if [[ "$TRAVIS_OS_NAME" == "osx" ]]; then export ARCH_FLAGS=" "; fi
+          source multibuild/travis_steps.sh
+          # This sets -x
+          # source travis_multibuild_customize.sh
+          echo $ENABLE_CONTRIB > contrib.enabled
+          echo $ENABLE_HEADLESS > headless.enabled
+          echo "end"
+          # Not interested in travis internal scripts' output
+        fi
+        set +x
+        # Build and package
+        set -x
+        ls
+        if [[ $SDIST == 1 ]]; then
+          python -m pip install --upgrade pip
+          python -m pip install scikit-build
+          python setup.py sdist
+        else
+          build_wheel $REPO_DIR $PLAT
+        fi
+        set +x
+        # Install and run tests
+        set -x
+        if [[ $SDIST == 1 ]]; then
+          echo "skipping tests because of sdist"
+          rc=0
+        else
+          install_run $PLAT && rc=$? || rc=$?
+        fi
+        set +x
+        #otherwise, Travis logic terminates prematurely
+        #https://travis-ci.community/t/shell-session-update-command-not-found-in-build-log-causes-build-to-fail-if-trap-err-is-set/817
+        trap ERR
+        test "$rc" -eq 0
+
+    - name: saving artifacts
+      uses: actions/upload-artifact@v2
+      with:
+        name: wheels
+        path: wheelhouse/opencv*.whl
+
+  test_release_opencv_python:
+    if: github.event_name == 'release' && github.event.release.prerelease
+    needs: [build_arm]
+    runs-on: ubuntu-latest
+    environment: test-opencv-python-release
+    defaults:
+      run:
+        shell: bash
+    steps:
+      - uses: actions/download-artifact@v2
+        with:
+          name: wheels
+          path: wheelhouse/
+
+      - name: Upload all wheels
+        run: |
+          python -m pip install twine
+          python -m twine upload --repository testpypi -u ${{ secrets.PYPI_USERNAME }} -p ${{ secrets.PYPI_PASSWORD }} --skip-existing wheelhouse/opencv_*
+
+  release_opencv_python:
+    if: github.event_name == 'release' && !github.event.release.prerelease
+    needs: [build_arm]
+    runs-on: ubuntu-latest
+    environment: opencv-python-release
+    defaults:
+      run:
+        shell: bash
+    steps:
+      - uses: actions/download-artifact@v2
+        with:
+          name: wheels
+          path: wheelhouse/
+
+      - name: Upload wheels for opencv_python
+        run: |
+          python -m pip install twine
+          python -m twine upload -u ${{ secrets.OPENCV_PYTHON_USERNAME }} -p ${{ secrets.OPENCV_PYTHON_PASSWORD }} --skip-existing wheelhouse/opencv_python-*
+
+      - name: Upload wheels for opencv_contrib_python
+        run: |
+          python -m pip install twine
+          python -m twine upload -u ${{ secrets.OPENCV_CONTRIB_PYTHON_USERNAME }} -p ${{ secrets.OPENCV_CONTRIB_PYTHON_PASSWORD }} --skip-existing wheelhouse/opencv_contrib_python-*
+
+      - name: Upload wheels for opencv_python_headless
+        run: |
+          python -m pip install twine
+          python -m twine upload -u ${{ secrets.OPENCV_PYTHON_HEADLESS_USERNAME }} -p ${{ secrets.OPENCV_PYTHON_HEADLESS_PASSWORD }} --skip-existing wheelhouse/opencv_python_headless-*
+
+      - name: Upload wheels for opencv_contrib_python_headless
+        run: |
+          python -m pip install twine
+          python -m twine upload -u ${{ secrets.OPENCV_CONTRIB_PYTHON_HEADLESS_USERNAME }} -p ${{ secrets.OPENCV_CONTRIB_PYTHON_HEADLESS_PASSWORD }} --skip-existing wheelhouse/opencv_contrib_python_headless-*
diff --git a/.github/workflows/build_wheels_macos.yml b/.github/workflows/build_wheels_macos.yml
new file mode 100644
index 00000000..9af6d384
--- /dev/null
+++ b/.github/workflows/build_wheels_macos.yml
@@ -0,0 +1,157 @@
+name: Build PYPI wheels for opencv-python on Macos
+
+on:
+  push:
+    branches:
+      - asen/check_3.4_wo_submodules
+  pull_request:
+    branches:
+      - 3.4
+  release:
+    types: [published, edited]
+
+
+jobs:
+  build:
+    runs-on: ${{ matrix.os }}
+    defaults:
+      run:
+        shell: bash
+
+    strategy:
+      fail-fast: false
+      matrix:
+        os: [macos-latest]
+        python-version: [3.6, 3.7, 3.8, 3.9]
+        platform: [x64]
+        with_contrib: [0, 1]
+        without_gui: [0, 1]
+        build_sdist: [0]
+
+    env:
+      ACTIONS_ALLOW_UNSECURE_COMMANDS: true
+      REPO_DIR: .
+      BUILD_COMMIT: master
+      PROJECT_SPEC: opencv-python
+      MB_PYTHON_VERSION: ${{ matrix.python-version }}
+      TRAVIS_PYTHON_VERSION: ${{ matrix.python-version }}
+      MB_ML_VER: 2014
+      NP_TEST_DEP: numpy
+      TRAVIS_BUILD_DIR: ${{ github.workspace }}
+      CONFIG_PATH: travis_config.sh
+      DOCKER_IMAGE: quay.io/skvark/manylinux2014_${PLAT}
+      USE_CCACHE: 1
+      UNICODE_WIDTH: 32
+      SDIST: ${{ matrix.build_sdist || 0}}
+      ENABLE_HEADLESS: ${{ matrix.without_gui }}
+      ENABLE_CONTRIB: ${{ matrix.with_contrib }}
+
+    steps:
+    - name: Checkout
+      uses: actions/checkout@v2
+      with:
+        submodules: false
+        fetch-depth: 0
+
+    - name: Update multibuild submodule
+      run: git submodule update --init --recursive multibuild
+
+    - name: Update submodules
+      if: github.event_name == 'pull_request'
+      run: git submodule update --remote
+
+    - name: Set up Python ${{ matrix.python-version }}
+      uses: actions/setup-python@v2
+      if: ${{ 'macos-latest' == matrix.os }}
+      with:
+        python-version: ${{ matrix.python-version }}
+        architecture: ${{ matrix.platform }}
+
+    - name: Setup Environment variables
+      run: |
+        if [ "macos-latest" == "${{ matrix.os }}" ]; then echo "TRAVIS_OS_NAME=osx" >> $GITHUB_ENV; else echo "TRAVIS_OS_NAME=${{ matrix.os }}" >> $GITHUB_ENV; fi
+        if [ "schedule" == "${{ github.event_name }}" ]; then echo "TRAVIS_EVENT_TYPE=cron" >> $GITHUB_ENV; else echo "TRAVIS_EVENT_TYPE=${{ github.event_name }}" >> $GITHUB_ENV; fi
+        if [ "schedule" == "${{ github.event_name }}" ]; then echo "BUILD_COMMIT=master" >> $GITHUB_ENV; else echo "BUILD_COMMIT=$BUILD_COMMIT" >> $GITHUB_ENV; fi
+        if [ "x64" == "${{ matrix.platform }}" ]; then echo "PLAT=x86_64" >> $GITHUB_ENV; fi
+        if [ "x86" == "${{ matrix.platform }}" ]; then echo "PLAT=i686" >> $GITHUB_ENV; fi
+        echo "BUILD_DEPENDS=$(echo $NP_BUILD_DEP)" >> $GITHUB_ENV;
+        echo "TEST_DEPENDS=$(echo $NP_TEST_DEP)" >> $GITHUB_ENV;
+
+    - name: before install
+      run: |
+        set -e
+        # Check out and prepare the source
+        # Multibuild doesn't have releases, so --depth would break eventually (see
+        # https://superuser.com/questions/1240216/server-does-not-allow-request-for-unadvertised)
+        git submodule update --init multibuild
+        source multibuild/common_utils.sh
+        # https://github.com/matthew-brett/multibuild/issues/116
+        if [[ "$TRAVIS_OS_NAME" == "osx" ]]; then export ARCH_FLAGS=" "; fi
+        source multibuild/travis_steps.sh
+        # This sets -x
+        # source travis_multibuild_customize.sh
+        echo $ENABLE_CONTRIB > contrib.enabled
+        echo $ENABLE_HEADLESS > headless.enabled
+        set -x
+        build_wheel $REPO_DIR $PLAT
+        install_run $PLAT
+        set +x
+
+    - name: saving artifacts
+      uses: actions/upload-artifact@v2
+      with:
+        name: wheels
+        path: wheelhouse/opencv*.whl
+
+  test_release_opencv_python:
+    if: github.event_name == 'release' && github.event.release.prerelease
+    needs: [build]
+    runs-on: ubuntu-latest
+    environment: test-opencv-python-release
+    defaults:
+      run:
+        shell: bash
+    steps:
+      - uses: actions/download-artifact@v2
+        with:
+          name: wheels
+          path: wheelhouse/
+
+      - name: Upload all wheels
+        run: |
+          python -m pip install twine
+          python -m twine upload --repository testpypi -u ${{ secrets.PYPI_USERNAME }} -p ${{ secrets.PYPI_PASSWORD }} --skip-existing wheelhouse/opencv_*
+
+  release_opencv_python:
+    if: github.event_name == 'release' && !github.event.release.prerelease
+    needs: [build]
+    runs-on: ubuntu-latest
+    environment: opencv-python-release
+    defaults:
+      run:
+        shell: bash
+    steps:
+      - uses: actions/download-artifact@v2
+        with:
+          name: wheels
+          path: wheelhouse/
+
+      - name: Upload wheels for opencv_python
+        run: |
+          python -m pip install twine
+          python -m twine upload -u ${{ secrets.OPENCV_PYTHON_USERNAME }} -p ${{ secrets.OPENCV_PYTHON_PASSWORD }} --skip-existing wheelhouse/opencv_python-*
+
+      - name: Upload wheels for opencv_contrib_python
+        run: |
+          python -m pip install twine
+          python -m twine upload -u ${{ secrets.OPENCV_CONTRIB_PYTHON_USERNAME }} -p ${{ secrets.OPENCV_CONTRIB_PYTHON_PASSWORD }} --skip-existing wheelhouse/opencv_contrib_python-*
+
+      - name: Upload wheels for opencv_python_headless
+        run: |
+          python -m pip install twine
+          python -m twine upload -u ${{ secrets.OPENCV_PYTHON_HEADLESS_USERNAME }} -p ${{ secrets.OPENCV_PYTHON_HEADLESS_PASSWORD }} --skip-existing wheelhouse/opencv_python_headless-*
+
+      - name: Upload wheels for opencv_contrib_python_headless
+        run: |
+          python -m pip install twine
+          python -m twine upload -u ${{ secrets.OPENCV_CONTRIB_PYTHON_HEADLESS_USERNAME }} -p ${{ secrets.OPENCV_CONTRIB_PYTHON_HEADLESS_PASSWORD }} --skip-existing wheelhouse/opencv_contrib_python_headless-*
diff --git a/.github/workflows/build_wheels_windows.yml b/.github/workflows/build_wheels_windows.yml
new file mode 100644
index 00000000..64f02cca
--- /dev/null
+++ b/.github/workflows/build_wheels_windows.yml
@@ -0,0 +1,138 @@
+name: Build PYPI wheels for opencv-python on Windows
+
+on:
+  push:
+    branches:
+      - asen/check_3.4_wo_submodules
+  pull_request:
+    branches:
+      - 3.4
+  release:
+    types: [published, edited]
+
+
+jobs:
+  build-windows-x86_64:
+    runs-on: ${{ matrix.os }}
+    defaults:
+      run:
+        shell: powershell
+
+    strategy:
+      fail-fast: false
+      matrix:
+        os: [windows-latest]
+        python-version: [3.6, 3.7, 3.8, 3.9]
+        platform: [x86, x64]
+        with_contrib: [0, 1]
+        without_gui: [0, 1]
+        build_sdist: [0]
+
+    env:
+      ACTIONS_ALLOW_UNSECURE_COMMANDS: true
+      SDIST: ${{ matrix.build_sdist || 0}}
+      ENABLE_HEADLESS: ${{ matrix.without_gui }}
+      ENABLE_CONTRIB: ${{ matrix.with_contrib }}
+
+    steps:
+    - name: Checkout
+      uses: actions/checkout@v2
+      with:
+        submodules: false
+        fetch-depth: 0
+
+    - name: Update multibuild submodule
+      run: git submodule update --init --recursive multibuild
+
+    - name: Update submodules
+      if: github.event_name == 'pull_request'
+      run: git submodule update --remote
+
+    - name: Set up Python ${{ matrix.python-version }}
+      uses: actions/setup-python@v2
+      with:
+        python-version: ${{ matrix.python-version }}
+        architecture: ${{ matrix.platform }}
+
+    - name: Setup MSBuild.exe
+      uses: warrenbuckley/Setup-MSBuild@v1
+
+    - name: build script
+      run: |
+        python --version
+        python -m pip install --upgrade pip
+        python -m pip install --upgrade setuptools
+        set "CI_BUILD=1" && python -m pip wheel --wheel-dir=%cd%\wheelhouse . --verbose
+      shell: cmd
+
+    - name: before test
+      run: |
+        cd ${{ github.workspace }}/tests
+        &python -m pip install --user --no-warn-script-location (ls "../wheelhouse/opencv*.whl")
+        if ($LastExitCode -ne 0) {throw $LastExitCode}
+      shell: powershell
+
+    - name: run test
+      run: |
+        cd ${{ github.workspace }}/tests
+        python -m unittest test
+      shell: cmd
+
+    - name: saving artifacts
+      uses: actions/upload-artifact@v2
+      with:
+        name: wheels
+        path: wheelhouse/opencv*.whl
+
+  test_release_opencv_python:
+    if: github.event_name == 'release' && github.event.release.prerelease
+    needs: [build-windows-x86_64]
+    runs-on: ubuntu-latest
+    environment: test-opencv-python-release
+    defaults:
+      run:
+        shell: bash
+    steps:
+      - uses: actions/download-artifact@v2
+        with:
+          name: wheels
+          path: wheelhouse/
+
+      - name: Upload all wheels
+        run: |
+          python -m pip install twine
+          python -m twine upload --repository testpypi -u ${{ secrets.PYPI_USERNAME }} -p ${{ secrets.PYPI_PASSWORD }} --skip-existing wheelhouse/opencv_*
+
+  release_opencv_python:
+    if: github.event_name == 'release' && !github.event.release.prerelease
+    needs: [build-windows-x86_64]
+    runs-on: ubuntu-latest
+    environment: opencv-python-release
+    defaults:
+      run:
+        shell: bash
+    steps:
+      - uses: actions/download-artifact@v2
+        with:
+          name: wheels
+          path: wheelhouse/
+
+      - name: Upload wheels for opencv_python
+        run: |
+          python -m pip install twine
+          python -m twine upload -u ${{ secrets.OPENCV_PYTHON_USERNAME }} -p ${{ secrets.OPENCV_PYTHON_PASSWORD }} --skip-existing wheelhouse/opencv_python-*
+
+      - name: Upload wheels for opencv_contrib_python
+        run: |
+          python -m pip install twine
+          python -m twine upload -u ${{ secrets.OPENCV_CONTRIB_PYTHON_USERNAME }} -p ${{ secrets.OPENCV_CONTRIB_PYTHON_PASSWORD }} --skip-existing wheelhouse/opencv_contrib_python-*
+
+      - name: Upload wheels for opencv_python_headless
+        run: |
+          python -m pip install twine
+          python -m twine upload -u ${{ secrets.OPENCV_PYTHON_HEADLESS_USERNAME }} -p ${{ secrets.OPENCV_PYTHON_HEADLESS_PASSWORD }} --skip-existing wheelhouse/opencv_python_headless-*
+
+      - name: Upload wheels for opencv_contrib_python_headless
+        run: |
+          python -m pip install twine
+          python -m twine upload -u ${{ secrets.OPENCV_CONTRIB_PYTHON_HEADLESS_USERNAME }} -p ${{ secrets.OPENCV_CONTRIB_PYTHON_HEADLESS_PASSWORD }} --skip-existing wheelhouse/opencv_contrib_python_headless-*
diff --git a/.gitmodules b/.gitmodules
index f2e0d283..8ebdff3d 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -1,9 +1,15 @@
 [submodule "opencv"]
 	path = opencv
 	url = https://github.com/opencv/opencv.git
+        branch = 3.4
 [submodule "opencv_contrib"]
 	path = opencv_contrib
 	url = https://github.com/opencv/opencv_contrib.git
+        branch = 3.4
 [submodule "multibuild"]
 	path = multibuild
 	url = https://github.com/matthew-brett/multibuild.git
+[submodule "opencv_extra"]
+	path = opencv_extra
+	url = https://github.com/opencv/opencv_extra.git
+        branch = 3.4
diff --git a/LICENSE-3RD-PARTY.txt b/LICENSE-3RD-PARTY.txt
index 20f4fb37..87c0514e 100644
--- a/LICENSE-3RD-PARTY.txt
+++ b/LICENSE-3RD-PARTY.txt
@@ -1,208 +1,48 @@
 OpenCV library is redistributed within opencv-python package.
 This license applies to OpenCV binary in the directory cv2/.
 
+By downloading, copying, installing or using the software you agree to this license.
+If you do not agree to this license, do not download, install,
+copy or use the software.
 
-                                 Apache License
-                           Version 2.0, January 2004
-                        http://www.apache.org/licenses/
-
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-
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-      appropriateness of using or redistributing the Work and assume any
-      risks associated with Your exercise of permissions under this License.
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-   8. Limitation of Liability. In no event and under no legal theory,
-      whether in tort (including negligence), contract, or otherwise,
-      unless required by applicable law (such as deliberate and grossly
-      negligent acts) or agreed to in writing, shall any Contributor be
-      liable to You for damages, including any direct, indirect, special,
-      incidental, or consequential damages of any character arising as a
-      result of this License or out of the use or inability to use the
-      Work (including but not limited to damages for loss of goodwill,
-      work stoppage, computer failure or malfunction, or any and all
-      other commercial damages or losses), even if such Contributor
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-      the Work or Derivative Works thereof, You may choose to offer,
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-      of any other Contributor, and only if You agree to indemnify,
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-   Copyright [yyyy] [name of copyright owner]
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-   Licensed under the Apache License, Version 2.0 (the "License");
-   you may not use this file except in compliance with the License.
-   You may obtain a copy of the License at
-
-       http://www.apache.org/licenses/LICENSE-2.0
-
-   Unless required by applicable law or agreed to in writing, software
-   distributed under the License is distributed on an "AS IS" BASIS,
-   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-   See the License for the specific language governing permissions and
-   limitations under the License.
+
+                          License Agreement
+               For Open Source Computer Vision Library
+                       (3-clause BSD License)
+
+Copyright (C) 2000-2021, Intel Corporation, all rights reserved.
+Copyright (C) 2009-2011, Willow Garage Inc., all rights reserved.
+Copyright (C) 2009-2016, NVIDIA Corporation, all rights reserved.
+Copyright (C) 2010-2013, Advanced Micro Devices, Inc., all rights reserved.
+Copyright (C) 2015-2021, OpenCV Foundation, all rights reserved.
+Copyright (C) 2015-2016, Itseez Inc., all rights reserved.
+Copyright (C) 2019-2021, Xperience AI, all rights reserved.
+Third party copyrights are property of their respective owners.
+
+Redistribution and use in source and binary forms, with or without modification,
+are permitted provided that the following conditions are met:
+
+  * Redistributions of source code must retain the above copyright notice,
+    this list of conditions and the following disclaimer.
+
+  * Redistributions in binary form must reproduce the above copyright notice,
+    this list of conditions and the following disclaimer in the documentation
+    and/or other materials provided with the distribution.
+
+  * Neither the names of the copyright holders nor the names of the contributors
+    may be used to endorse or promote products derived from this software
+    without specific prior written permission.
+
+This software is provided by the copyright holders and contributors "as is" and
+any express or implied warranties, including, but not limited to, the implied
+warranties of merchantability and fitness for a particular purpose are disclaimed.
+In no event shall copyright holders or contributors be liable for any direct,
+indirect, incidental, special, exemplary, or consequential damages
+(including, but not limited to, procurement of substitute goods or services;
+loss of use, data, or profits; or business interruption) however caused
+and on any theory of liability, whether in contract, strict liability,
+or tort (including negligence or otherwise) arising in any way out of
+the use of this software, even if advised of the possibility of such damage.
 
 ------------------------------------------------------------------------------
 libvpx is redistributed within all opencv-python Linux packages.
diff --git a/README.md b/README.md
index 232aa318..3b181532 100644
--- a/README.md
+++ b/README.md
@@ -171,13 +171,13 @@ On slow systems such as Raspberry Pi the full build may take several hours. On a
 
 Opencv-python package (scripts in this repository) is available under MIT license.
 
-OpenCV itself is available under [Apache 2](https://github.com/opencv/opencv/blob/master/LICENSE) license.
+OpenCV itself is available under [3-clause BSD License](https://github.com/opencv/opencv/blob/master/LICENSE).
 
 Third party package licenses are at [LICENSE-3RD-PARTY.txt](https://github.com/skvark/opencv-python/blob/master/LICENSE-3RD-PARTY.txt).
 
 All wheels ship with [FFmpeg](http://ffmpeg.org) licensed under the [LGPLv2.1](http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html).
 
-Non-headless Linux and MacOS wheels ship with [Qt 5](http://doc.qt.io/qt-5/lgpl.html) licensed under the [LGPLv3](http://www.gnu.org/licenses/lgpl-3.0.html).
+Non-headless Linux wheels ship with [Qt 5](http://doc.qt.io/qt-5/lgpl.html) licensed under the [LGPLv3](http://www.gnu.org/licenses/lgpl-3.0.html).
 
 The packages include also other binaries. Full list of licenses can be found from [LICENSE-3RD-PARTY.txt](https://github.com/skvark/opencv-python/blob/master/LICENSE-3RD-PARTY.txt).
 
diff --git a/opencv b/opencv
index 69357b1e..d0e3e638 160000
--- a/opencv
+++ b/opencv
@@ -1 +1 @@
-Subproject commit 69357b1e88680658a07cffde7678a4d697469f03
+Subproject commit d0e3e638c35d875c86fac3410d93f02f885e27ba
diff --git a/opencv_contrib b/opencv_contrib
index f5d7f671..4de4edeb 160000
--- a/opencv_contrib
+++ b/opencv_contrib
@@ -1 +1 @@
-Subproject commit f5d7f6712d4ff229ba4f45cf79dfd11c557d56fd
+Subproject commit 4de4edeba691d8ed0420f3581fb80133589f4cdf
diff --git a/opencv_extra b/opencv_extra
new file mode 160000
index 00000000..b6430dee
--- /dev/null
+++ b/opencv_extra
@@ -0,0 +1 @@
+Subproject commit b6430deee16b91dce946a6e66feb8dc110c39834
diff --git a/setup.py b/setup.py
index a3265206..a40488b1 100644
--- a/setup.py
+++ b/setup.py
@@ -97,7 +97,7 @@ def main():
     # Path regexes with forward slashes relative to CMake install dir.
     rearrange_cmake_output_data = {
         "cv2": (
-            [r"bin/opencv_videoio_ffmpeg\d{3}%s\.dll" % ("_64" if x64 else "")]
+            [r"bin/opencv_ffmpeg\d{3,4}%s\.dll" % ("_64" if x64 else "")]
             if os.name == "nt"
             else []
         )
@@ -110,7 +110,7 @@ def main():
             % {"ext": re.escape(sysconfig.get_config_var("EXT_SUFFIX"))}
         ],
         "cv2.data": [  # OPENCV_OTHER_INSTALL_PATH
-            ("etc" if os.name == "nt" else "share/opencv4") + r"/haarcascades/.*\.xml"
+            ("etc" if os.name == "nt" else "share/OpenCV") + r"/haarcascades/.*\.xml"
         ],
     }
 
diff --git a/travis_config.sh b/travis_config.sh
index aac66317..b1a991a4 100644
--- a/travis_config.sh
+++ b/travis_config.sh
@@ -146,24 +146,31 @@ function run_tests {
     echo "Run tests..."
     echo $PWD
 
+    PYTHON=python$PYTHON_VERSION
+
     if [ -n "$IS_OSX" ]; then
       echo "Running for OS X"
-      cd ../tests/
+      cd ../opencv/
+      export OPENCV_TEST_DATA_PATH=../opencv_extra/testdata
     else
       echo "Running for linux"
-      cd /io/tests/
+
+      if [ $PYTHON == "python3.6" ]; then
+        $PYTHON -m pip install -U numpy==1.19.4
+      fi
+      cd /io/opencv
+      export OPENCV_TEST_DATA_PATH=/io/opencv_extra/testdata
     fi
 
     test_wheels
 }
 
 function test_wheels {
-    PYTHON=python$PYTHON_VERSION
 
     echo "Starting tests..."
 
     #Test package
-    $PYTHON -m unittest test
+    $PYTHON modules/python/test/test.py -v --repo .
 }
 
 export PS4='+(${BASH_SOURCE}:${LINENO}): ${FUNCNAME[0]:+${FUNCNAME[0]}(): }'