Convert voice message to be able to play on Android 28 and below

vector/src/main/java/im/vector/app/features/home/room/detail/RoomDetailViewModel.kt

@@ -57,6 +57,7 @@ import im.vector.app.features.home.room.typing.TypingHelper
 import im.vector.app.features.powerlevel.PowerLevelsObservableFactory
 import im.vector.app.features.session.coroutineScope
 import im.vector.app.features.settings.VectorPreferences
+import im.vector.app.features.voice.VoicePlayerHelper
 import io.reactivex.Observable
 import io.reactivex.rxkotlin.subscribeBy
 import io.reactivex.schedulers.Schedulers
@@ -121,6 +122,7 @@ class RoomDetailViewModel @AssistedInject constructor(
         private val directRoomHelper: DirectRoomHelper,
         private val jitsiService: JitsiService,
         private val voiceMessageHelper: VoiceMessageHelper,
+        private val voicePlayerHelper: VoicePlayerHelper,
         timelineFactory: TimelineFactory
 ) : VectorViewModel<RoomDetailViewState, RoomDetailAction, RoomDetailViewEvents>(initialState),
         Timeline.Listener, ChatEffectManager.Delegate, CallProtocolsChecker.Listener {
@@ -647,8 +649,10 @@ class RoomDetailViewModel @AssistedInject constructor(
             try {
                 // Download can fail
                 val audioFile = session.fileService().downloadFile(action.messageAudioContent)
+                // Conversion can fail, fallback to the original file in this case and let the player fail for us
+                val convertedFile = voicePlayerHelper.convertFile(audioFile) ?: audioFile
                 // Play can fail
-                voiceMessageHelper.startOrPausePlayback(action.eventId, audioFile)
+                voiceMessageHelper.startOrPausePlayback(action.eventId, convertedFile)
             } catch (failure: Throwable) {
                 _viewEvents.post(RoomDetailViewEvents.Failure(failure))
             }

vector/src/main/java/im/vector/app/features/voice/VoicePlayerHelper.kt

@@ -0,0 +1,73 @@
+/*
+ * Copyright (c) 2021 New Vector Ltd
+ *
+ * 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.
+ */
+
+package im.vector.app.features.voice
+
+import android.content.Context
+import android.os.Build
+import com.arthenica.ffmpegkit.FFmpegKit
+import com.arthenica.ffmpegkit.ReturnCode
+import timber.log.Timber
+import java.io.File
+import javax.inject.Inject
+
+class VoicePlayerHelper @Inject constructor(
+        context: Context
+) {
+    private val outputDirectory = File(context.cacheDir, "voice_records")
+
+    init {
+        if (!outputDirectory.exists()) {
+            outputDirectory.mkdirs()
+        }
+    }
+
+    /**
+     * Ensure the file is encoded using aac audio codec
+     */
+    fun convertFile(file: File): File? {
+        return if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q) {
+            // Nothing to do
+            file
+        } else {
+            // Convert to mp4
+            val targetFile = File(outputDirectory, "Voice.mp4")
+            if (targetFile.exists()) {
+                targetFile.delete()
+            }
+            val start = System.currentTimeMillis()
+            val session = FFmpegKit.execute("-i \"${file.path}\" -c:a aac \"${targetFile.path}\"")
+            val duration = System.currentTimeMillis() - start
+            Timber.d("Convert to mp4 in $duration ms. Size in bytes from ${file.length()} to ${targetFile.length()}")
+            return when {
+                ReturnCode.isSuccess(session.returnCode) -> {
+                    // SUCCESS
+                    targetFile
+                }
+                ReturnCode.isCancel(session.returnCode)  -> {
+                    // CANCEL
+                    null
+                }
+                else                                     -> {
+                    // FAILURE
+                    Timber.e("Command failed with state ${session.state} and rc ${session.returnCode}.${session.failStackTrace}")
+                    // TODO throw?
+                    null
+                }
+            }
+        }
+    }
+}