playback: use custom exoplayer

Use a custom ExoPlayer fork with the FLAC extension enabled. This
greatly improves the listening experience, as it enables metadata
support on OGG files and FLAC files to be played below API 27.

README.md

@@ -61,6 +61,14 @@ I primarily built Auxio for myself, but you can use it too, I guess.
 - Storage (`READ_EXTERNAL_STORAGE`): to read and play your media files
 - Services (`FOREGROUND_SERVICE`, `WAKE_LOCK`): to keep the music playing even if the app itself is in background
 
+## Building
+
+Auxio relies on a local version of ExoPlayer that enables some extra features. So, the build process is as follows:
+
+1. Change into the project directory
+2. Run `python3 prebuild.py`, which installs ExoPlayer and it's extensions.
+3. Build the project normally in Android Studio.
+
 ## Contributing
 
 Auxio accepts most contributions as long as they follow the [Contribution Guidelines](/.github/CONTRIBUTING.md).

app/build.gradle

@@ -95,7 +95,8 @@ dependencies {
     // --- THIRD PARTY ---
 
     // ExoPlayer
-    implementation "com.google.android.exoplayer:exoplayer-core:2.16.1"
+    implementation project(':exoplayer-library-core')
+    implementation project(':exoplayer-extension-flac')
 
     // Image loading
     implementation 'io.coil-kt:coil:2.0.0-alpha06'

app/src/main/java/org/oxycblt/auxio/coil/AuxioFetcher.kt

@@ -18,8 +18,8 @@ import coil.size.pxOrElse
 import com.google.android.exoplayer2.MediaItem
 import com.google.android.exoplayer2.MediaMetadata
 import com.google.android.exoplayer2.MetadataRetriever
-import com.google.android.exoplayer2.metadata.flac.PictureFrame
 import com.google.android.exoplayer2.metadata.id3.ApicFrame
+import com.google.android.exoplayer2.metadata.xiph.PictureFrame
 import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.withContext
 import okio.buffer

app/src/main/java/org/oxycblt/auxio/playback/system/AudioReactor.kt

@@ -25,8 +25,8 @@ import androidx.media.AudioAttributesCompat
 import androidx.media.AudioFocusRequestCompat
 import androidx.media.AudioManagerCompat
 import com.google.android.exoplayer2.metadata.Metadata
-import com.google.android.exoplayer2.metadata.flac.VorbisComment
 import com.google.android.exoplayer2.metadata.id3.TextInformationFrame
+import com.google.android.exoplayer2.metadata.xiph.VorbisComment
 import org.oxycblt.auxio.playback.state.PlaybackStateManager
 import org.oxycblt.auxio.settings.SettingsManager
 import org.oxycblt.auxio.util.getSystemServiceSafe

app/src/main/java/org/oxycblt/auxio/playback/system/PlaybackService.kt

@@ -39,6 +39,7 @@ import com.google.android.exoplayer2.RenderersFactory
 import com.google.android.exoplayer2.TracksInfo
 import com.google.android.exoplayer2.audio.AudioAttributes
 import com.google.android.exoplayer2.audio.MediaCodecAudioRenderer
+import com.google.android.exoplayer2.ext.flac.LibflacAudioRenderer
 import com.google.android.exoplayer2.extractor.DefaultExtractorsFactory
 import com.google.android.exoplayer2.mediacodec.MediaCodecSelector
 import com.google.android.exoplayer2.source.DefaultMediaSourceFactory
@@ -46,9 +47,8 @@ import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.Job
 import kotlinx.coroutines.delay
-import kotlinx.coroutines.flow.flow
-import kotlinx.coroutines.flow.collect
 import kotlinx.coroutines.flow.conflate
+import kotlinx.coroutines.flow.flow
 import kotlinx.coroutines.flow.takeWhile
 import kotlinx.coroutines.launch
 import org.oxycblt.auxio.BuildConfig
@@ -371,7 +371,8 @@ class PlaybackService : Service(), Player.Listener, PlaybackStateManager.Callbac
         // battery/apk size/cache size
         val audioRenderer = RenderersFactory { handler, _, audioListener, _, _ ->
             arrayOf(
-                MediaCodecAudioRenderer(this, MediaCodecSelector.DEFAULT, handler, audioListener)
+                MediaCodecAudioRenderer(this, MediaCodecSelector.DEFAULT, handler, audioListener),
+                LibflacAudioRenderer(handler, audioListener)
             )
         }
 

info/FAQ.md

@@ -27,8 +27,8 @@ ability to be extended to music sources outside of local files. You can read mor
 #### What formats does Auxio support?
 
 As per the [Supported ExoPlayer Formats](https://exoplayer.dev/supported-formats.html), Auxio supports
-MP4, MP3, MKA, OGG, WAV, MPEG, ACC on all versions of Android. However, FLAC files can only be played
-on Android 8.1 and above. Below that, Auxio must be patched with the [FLAC Extension](https://github.com/google/ExoPlayer/tree/release-v2/extensions/flac).
+MP4, MP3, MKA, OGG, WAV, MPEG, AAC on all versions of Android. Auxio also supports FLAC on all versions
+of Android through the use of the ExoPlayer FLAC extension.
 
 #### Why are accents lighter/less saturated in dark mode?
 

prebuild.py

@@ -0,0 +1,85 @@
+#!/usr/bin/env python3
+# This script automatically installs exoplayer with the necessary components.
+# This is written in version-agnostic python3, because I'd rather
+# not have to deal with the insanity of bash.
+import os
+import platform
+import sys
+import subprocess
+import re
+
+FLAC_VERSION = "1.3.2"
+
+FATAL="\033[1;31m"
+WARN="\033[1;91m"
+INFO="\033[1;94m"
+OK="\033[1;92m"
+NC="\033[0m"
+
+system = platform.system()
+
+# We do some shell scripting later on, so we can't support windows.
+if system not in ["Linux", "Darwin"]:
+	print("fatal: unsupported platform " + system)
+	sys.exit(1)
+
+def sh(cmd):
+	code = subprocess.call(["sh", "-c", "set -e; " + cmd])
+
+	if code != 0:
+		print(FATAL + "fatal:" + NC + " command failed with exit code " + str(code))
+		sys.exit(1)
+		
+exoplayer_path = os.path.join(os.path.abspath(os.curdir), "deps", "exoplayer")
+
+if os.path.exists(exoplayer_path):
+	reinstall = input(INFO + "info:" + NC + " ExoPlayer is already installed. Would you like to reinstall it? [y/n] ")
+
+	if not re.match("[yY][eE][sS]|[yY]", reinstall):
+		sys.exit(0)
+
+ndk_path = os.getenv("NDK_PATH")
+
+if ndk_path is None or not os.path.isfile(os.path.join(ndk_path, "ndk_build")):
+	# We don't have a proper path. Do some digging on the Android SDK directory
+	# to see if we can find it.
+	if system == "Linux":
+		ndk_root = os.path.join(os.getenv("HOME"), "Android", "Sdk", "ndk")
+	elif system == "Darwin":
+		ndk_root = os.path.join(os.getenv("HOME"), "Library", "Android", "sdk", "ndk")
+
+	candidates = []
+
+	for entry in os.scandir(ndk_root):
+		if entry.is_dir():
+			candidates.append(entry.path)
+
+	if len(candidates) > 0:
+		print(WARN + "warn:" + NC + " NDK_PATH was not set or invalid. Multiple candidates were found however:")
+
+		for i, candidate in enumerate(candidates):
+			print("[" + str(i) + "] " + candidate)
+
+		try:
+			ndk_path = candidates[int(input("Enter the NDK to use [Default 0]: "))]
+		except:
+			ndk_path = candidates[0]
+	else:
+		print(FATAL + "fatal:" + NC + " NDK_PATH is either invalid, or the Android NDK was not installed at a recognized location.")
+		system.exit(1)
+
+# Now try to install ExoPlayer.
+sh("rm -rf deps")
+
+print(INFO + "info:" + NC + " Cloning ExoPlayer...")
+sh("git clone https://github.com/oxygencobalt/ExoPlayer.git " + exoplayer_path)
+os.chdir(exoplayer_path)
+sh("git checkout release-v2")
+
+flac_ext_jni_path = os.path.join("extensions", "flac", "src", "main", "jni")
+print(INFO + "info:" + NC + " Installing FLAC extension...")
+os.chdir(flac_ext_jni_path)
+sh('curl "https://ftp.osuosl.org/pub/xiph/releases/flac/flac-' + FLAC_VERSION + '.tar.xz" | tar xJ && mv "flac-' + FLAC_VERSION + '" flac')
+sh(ndk_path + "/ndk-build APP_ABI=all -j4")
+
+print(OK + "Prebuild successful." + NC)

settings.gradle

@@ -1,2 +1,4 @@
 include ':app'
 rootProject.name = "Auxio"
+gradle.ext.exoplayerModulePrefix = 'exoplayer-'
+apply from: file("deps/exoplayer/core_settings.gradle")