Build IAMF libraries with gradle and ndk-build.

In order to support building with `gradle` a new `build.gradle` file was added together with `Android.mk`, `Application.mk`, and `libiamf.mk` necessary for local builds with NDK.

After this change, IAMF files may also be played in the ExoPlayer demo built locally (without blaze).

PiperOrigin-RevId: 664841684

core_settings.gradle

@@ -75,6 +75,8 @@ include modulePrefix + 'lib-decoder-ffmpeg'
 project(modulePrefix + 'lib-decoder-ffmpeg').projectDir = new File(rootDir, 'libraries/decoder_ffmpeg')
 include modulePrefix + 'lib-decoder-flac'
 project(modulePrefix + 'lib-decoder-flac').projectDir = new File(rootDir, 'libraries/decoder_flac')
+include modulePrefix + 'lib-decoder-iamf'
+project(modulePrefix + 'lib-decoder-iamf').projectDir = new File(rootDir, 'libraries/decoder_iamf')
 if (gradle.ext.has('androidxMediaEnableMidiModule') && gradle.ext.androidxMediaEnableMidiModule) {
     include modulePrefix + 'lib-decoder-midi'
     project(modulePrefix + 'lib-decoder-midi').projectDir = new File(rootDir, 'libraries/decoder_midi')

demos/main/build.gradle

@@ -87,6 +87,7 @@ dependencies {
     withDecoderExtensionsImplementation project(modulePrefix + 'lib-decoder-ffmpeg')
     withDecoderExtensionsImplementation project(modulePrefix + 'lib-decoder-flac')
     withDecoderExtensionsImplementation project(modulePrefix + 'lib-decoder-opus')
+    withDecoderExtensionsImplementation project(modulePrefix + 'lib-decoder-iamf')
     withDecoderExtensionsImplementation project(modulePrefix + 'lib-decoder-vp9')
     withDecoderExtensionsImplementation project(modulePrefix + 'lib-decoder-midi')
     withDecoderExtensionsImplementation project(modulePrefix + 'lib-datasource-rtmp')

libraries/decoder_iamf/README.md

@@ -0,0 +1,120 @@
+# IAMF decoder module
+
+The IAMF module provides `LibiamfAudioRenderer`, which uses libiamf (the IAMF
+decoding library) to decode IAMF audio.
+
+## License note
+
+Please note that whilst the code in this repository is licensed under
+[Apache 2.0][], using this module also requires building and including one or
+more external libraries as described below. These are licensed separately.
+
+[Apache 2.0]: ../../LICENSE
+
+## Build instructions (Linux, macOS)
+
+To use the module you need to clone this GitHub project and depend on its
+modules locally. Instructions for doing this can be found in the
+[top level README][].
+
+In addition, it's necessary to build the module's native components as follows:
+
+* Set the following environment variables:
+
+```
+cd "<path to project checkout>"
+
+IAMF_MODULE_PATH="$(pwd)/libraries/decoder_iamf/src/main"
+```
+
+*   Download the [Android NDK][] and set its location in an environment
+    variable. This build configuration has been tested on NDK r27.
+
+```
+NDK_PATH="<path to Android NDK>"
+```
+
+*   Fetch libiamf:
+
+Clone the repository containing libiamf to a local folder of choice - preferably
+outside of the project checkout. Link it to the project's jni folder through
+symlink.
+
+```
+cd <preferred location for libiamf>
+
+
+git clone https://github.com/AOMediaCodec/libiamf.git libiamf && \
+cd libiamf && \
+LIBIAMF_PATH=$(pwd)
+```
+
+*   Symlink the folder containing libiamf to the project's JNI folder and run
+    the script to convert libiamf code to NDK compatible format:
+
+```
+cd "${IAMF_MODULE_PATH}"/jni && \
+ln -s $LIBIAMF_PATH libiamf && \
+cd libiamf/code &&\
+cmake . && \
+make
+```
+
+* Build the JNI native libraries from the command line:
+
+```
+cd "${IAMF_MODULE_PATH}"/jni && \
+${NDK_PATH}/ndk-build APP_ABI=all -j4
+```
+
+[top level README]: ../../README.md
+[Android NDK]: https://developer.android.com/tools/sdk/ndk/index.html
+
+## Build instructions (Windows)
+
+We do not provide support for building this module on Windows, however it should
+be possible to follow the Linux instructions in [Windows PowerShell][].
+
+[Windows PowerShell]: https://docs.microsoft.com/en-us/powershell/scripting/getting-started/getting-started-with-windows-powershell
+
+## Notes
+
+*   Every time there is a change to the libiamf checkout clean and re-build the
+    project.
+*   If you want to use your own version of libiamf, place it in
+    `${IAMF_MODULE_PATH}/jni/libiamf`.
+
+## Using the module with ExoPlayer
+
+Once you've followed the instructions above to check out, build and depend on
+the module, the next step is to tell ExoPlayer to use `LibiamfAudioRenderer`.
+How you do this depends on which player API you're using:
+
+*   If you're passing a `DefaultRenderersFactory` to `ExoPlayer.Builder`, you
+    can enable using the module by setting the `extensionRendererMode` parameter
+    of the `DefaultRenderersFactory` constructor to
+    `EXTENSION_RENDERER_MODE_ON`. This will use `LibiamfAudioRenderer` for
+    playback if `MediaCodecAudioRenderer` doesn't support the input format. Pass
+    `EXTENSION_RENDERER_MODE_PREFER` to give `LibiamfAudioRenderer` priority
+    over `MediaCodecAudioRenderer`.
+*   If you've subclassed `DefaultRenderersFactory`, add a `LibiamfAudioRenderer`
+    to the output list in `buildAudioRenderers`. ExoPlayer will use the first
+    `Renderer` in the list that supports the input media format.
+*   If you've implemented your own `RenderersFactory`, return a
+    `LibiamfAudioRenderer` instance from `createRenderers`. ExoPlayer will use
+    the first `Renderer` in the returned array that supports the input media
+    format.
+*   If you're using `ExoPlayer.Builder`, pass a `LibiamfAudioRenderer` in the
+    array of `Renderer`s. ExoPlayer will use the first `Renderer` in the list
+    that supports the input media format.
+
+Note: These instructions assume you're using `DefaultTrackSelector`. If you have
+a custom track selector the choice of `Renderer` is up to your implementation,
+so you need to make sure you are passing a `LibiamfAudioRenderer` to the
+player, then implement your own logic to use the renderer for a given track.
+
+## Links
+
+*   [Troubleshooting using decoding extensions][]
+
+[Troubleshooting using decoding extensions]: https://developer.android.com/media/media3/exoplayer/troubleshooting#how-can-i-get-a-decoding-library-to-load-and-be-used-for-playback

libraries/decoder_iamf/build.gradle

@@ -0,0 +1,39 @@
+// Copyright (C) 2024 The Android Open Source Project
+//
+// 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.
+apply from: "$gradle.ext.androidxMediaSettingsDir/common_library_config.gradle"
+
+android {
+    namespace 'androidx.media3.decoder.iamf'
+
+    sourceSets {
+        main {
+            jniLibs.srcDir 'src/main/libs'
+            jni.srcDirs = [] // Disable the automatic ndk-build call by Android Studio.
+        }
+        androidTest.assets.srcDir '../test_data/src/test/assets'
+    }
+}
+
+dependencies {
+    implementation project(modulePrefix + 'lib-decoder')
+    // TODO(b/203752526): Remove this dependency.
+    implementation project(modulePrefix + 'lib-exoplayer')
+    implementation 'androidx.annotation:annotation:' + androidxAnnotationVersion
+    compileOnly 'org.jetbrains.kotlin:kotlin-annotations-jvm:' + kotlinAnnotationsVersion
+    testImplementation project(modulePrefix + 'test-utils')
+    testImplementation 'org.robolectric:robolectric:' + robolectricVersion
+    androidTestImplementation project(modulePrefix + 'test-utils')
+    androidTestImplementation 'androidx.test:runner:' + androidxTestRunnerVersion
+    androidTestImplementation 'androidx.test.ext:junit:' + androidxTestJUnitVersion
+}

libraries/decoder_iamf/src/main/java/androidx/media3/decoder/iamf/IamfDecoder.java

@@ -15,9 +15,10 @@
  */
 package androidx.media3.decoder.iamf;
 
-import static android.support.annotation.VisibleForTesting.PACKAGE_PRIVATE;
+import static androidx.annotation.VisibleForTesting.PACKAGE_PRIVATE;
 
 import android.media.AudioFormat;
+import androidx.annotation.Nullable;
 import androidx.annotation.VisibleForTesting;
 import androidx.media3.common.C;
 import androidx.media3.common.util.Util;
@@ -26,7 +27,6 @@
 import androidx.media3.decoder.SimpleDecoderOutputBuffer;
 import java.nio.ByteBuffer;
 import java.util.List;
-import javax.annotation.Nullable;
 
 /** IAMF decoder. */
 @VisibleForTesting(otherwise = PACKAGE_PRIVATE)

libraries/decoder_iamf/src/main/jni/Android.mk

@@ -0,0 +1,32 @@
+#
+# Copyright (C) 2024 The Android Open Source Project
+#
+# 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.
+#
+WORKING_DIR := $(call my-dir)
+include $(CLEAR_VARS)
+
+# build libiamf.a
+LOCAL_PATH := $(WORKING_DIR)
+include libiamf.mk
+
+# build libiamfJNI.so
+include $(CLEAR_VARS)
+LOCAL_PATH := $(WORKING_DIR)
+LOCAL_MODULE := libiamfJNI
+LOCAL_ARM_MODE := arm
+LOCAL_CPP_EXTENSION := .cc
+LOCAL_SRC_FILES := iamf_jni.cc
+LOCAL_LDLIBS := -llog -lz -lm
+LOCAL_STATIC_LIBRARIES := libiamf
+include $(BUILD_SHARED_LIBRARY)

libraries/decoder_iamf/src/main/jni/Application.mk

@@ -0,0 +1,18 @@
+#
+# Copyright (C) 2024 The Android Open Source Project
+#
+# 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.
+#
+
+APP_ABI := all
+APP_PLATFORM := android-21

libraries/decoder_iamf/src/main/jni/libiamf.mk

@@ -0,0 +1,35 @@
+#
+# Copyright (C) 2024 The Android Open Source Project
+#
+# 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.
+#
+
+LOCAL_PATH := $(WORKING_DIR)/libiamf
+
+include $(CLEAR_VARS)
+
+LOCAL_MODULE := libiamf
+LOCAL_ARM_MODE := arm
+LOCAL_C_INCLUDES := $(LOCAL_PATH)/code/include \
+                    $(LOCAL_PATH)/code/src/iamf_dec \
+                    $(LOCAL_PATH)/code/src/common \
+                    $(LOCAL_PATH)/code/dep_codecs/include \
+                    $(LOCAL_PATH)/code/dep_external/include
+LOCAL_SRC_FILES := $(shell find $(LOCAL_PATH)/code/src -name "*.c")
+LOCAL_EXPORT_C_INCLUDES := $(LOCAL_PATH)/code/include \
+                    $(LOCAL_PATH)/code/src/iamf_dec \
+                    $(LOCAL_PATH)/code/src/common \
+                    $(LOCAL_PATH)/code/dep_codecs/include \
+                    $(LOCAL_PATH)/code/dep_external/include
+
+include $(BUILD_STATIC_LIBRARY)