refactor: Improve BatchesFolder concatenation behavior

app/src/main/java/app/myzel394/alibi/helpers/AudioBatchesFolder.kt

@@ -3,6 +3,7 @@ package app.myzel394.alibi.helpers
 import android.content.Context
 import android.net.Uri
 import androidx.documentfile.provider.DocumentFile
+import app.myzel394.alibi.helpers.MediaConverter.Companion.concatenateAudioFiles
 import com.arthenica.ffmpegkit.FFmpegKitConfig
 import java.time.LocalDateTime
 
@@ -17,6 +18,9 @@ class AudioBatchesFolder(
     customFolder,
     subfolderName,
 ) {
+    override val concatenateFunction = ::concatenateAudioFiles
+    override val ffmpegParameters = FFMPEG_PARAMETERS
+
     override fun getOutputFileForFFmpeg(
         date: LocalDateTime,
         extension: String,
@@ -33,28 +37,6 @@ class AudioBatchesFolder(
         }
     }
 
-    override suspend fun concatenate(
-        recordingStart: LocalDateTime,
-        extension: String,
-        disableCache: Boolean,
-    ): String {
-        val outputFile = getOutputFileForFFmpeg(
-            date = recordingStart,
-            extension = extension,
-        )
-
-        if (disableCache || checkIfOutputAlreadyExists(recordingStart, extension)) {
-            val filePaths = getBatchesForFFmpeg()
-
-            MediaConverter.concatenateAudioFiles(
-                inputFiles = filePaths,
-                outputFile = outputFile,
-            ).await()
-        }
-
-        return outputFile
-    }
-
     companion object {
         fun viaInternalFolder(context: Context) = AudioBatchesFolder(context, BatchType.INTERNAL)
 
@@ -65,5 +47,18 @@ class AudioBatchesFolder(
             "_'internal" -> viaInternalFolder(context)
             else -> viaCustomFolder(context, DocumentFile.fromTreeUri(context, Uri.parse(folder))!!)
         }
+
+        // Parameters to be passed in descending order
+        // Those parameters first try to concatenate without re-encoding
+        // if that fails, it'll try several fallback methods
+        // this is audio only
+        val FFMPEG_PARAMETERS = arrayOf(
+            " -c copy",
+            " -acodec copy",
+            " -c:a aac",
+            " -c:a libmp3lame",
+            " -c:a libopus",
+            " -c:a libvorbis",
+        )
     }
 }

app/src/main/java/app/myzel394/alibi/helpers/BatchesFolder.kt

@@ -2,14 +2,14 @@ package app.myzel394.alibi.helpers
 
 import android.content.Context
 import androidx.documentfile.provider.DocumentFile
-import app.myzel394.alibi.ui.RECORDER_SUBFOLDER_NAME
 import java.io.File
 import java.time.LocalDateTime
 import java.time.format.DateTimeFormatter
 import com.arthenica.ffmpegkit.FFmpegKitConfig
-import android.net.Uri
 import android.os.ParcelFileDescriptor
+import kotlinx.coroutines.CompletableDeferred
 import java.io.FileDescriptor
+import kotlin.reflect.KFunction3
 
 abstract class BatchesFolder(
     open val context: Context,
@@ -19,6 +19,9 @@ abstract class BatchesFolder(
 ) {
     private var customFileFileDescriptor: ParcelFileDescriptor? = null
 
+    abstract val concatenateFunction: KFunction3<Iterable<String>, String, String, CompletableDeferred<Unit>>
+    abstract val ffmpegParameters: Array<String>
+
     fun initFolders() {
         when (type) {
             BatchType.INTERNAL -> getInternalFolder().mkdirs()
@@ -111,11 +114,37 @@ abstract class BatchesFolder(
         extension: String,
     ): String
 
-    abstract suspend fun concatenate(
+    open suspend fun concatenate(
         recordingStart: LocalDateTime,
         extension: String,
         disableCache: Boolean = false,
-    ): String
+        onNextParameterTry: (String) -> Unit = {},
+    ): String {
+        val outputFile = getOutputFileForFFmpeg(
+            date = recordingStart,
+            extension = extension,
+        )
+
+        if (disableCache || !checkIfOutputAlreadyExists(recordingStart, extension)) {
+            val filePaths = getBatchesForFFmpeg()
+
+            for (parameter in ffmpegParameters) {
+                onNextParameterTry(parameter)
+
+                try {
+                    concatenateFunction(
+                        filePaths,
+                        outputFile,
+                        parameter,
+                    )
+                } catch (e: MediaConverter.FFmpegException) {
+                    continue
+                }
+            }
+        }
+
+        return outputFile
+    }
 
     fun exportFolderForSettings(): String {
         return when (type) {

app/src/main/java/app/myzel394/alibi/helpers/MediaConverter.kt

@@ -22,7 +22,6 @@ class MediaConverter {
                 "-protocol_whitelist saf,concat,content,file,subfile" +
                         " -i 'concat:$filePathsConcatenated'" +
                         " -y" +
-                        " -acodec copy" +
                         extraCommand +
                         " $outputFile"
 
@@ -68,16 +67,17 @@ class MediaConverter {
 
             val command =
                 " -f concat" +
-                        " -y" +
                         " -safe 0" +
                         " -i ${listFile.absolutePath}" +
-                        " -c copy" +
                         extraCommand +
+                        " -y" +
                         " $outputFile"
 
             FFmpegKit.executeAsync(
                 command
             ) { session ->
+                listFile.delete()
+
                 if (!ReturnCode.isSuccess(session!!.returnCode)) {
                     Log.d(
                         "Video Concatenation",
@@ -89,7 +89,7 @@ class MediaConverter {
                         )
                     )
 
-                    completer.completeExceptionally(Exception("Failed to concatenate videos"))
+                    completer.completeExceptionally(FFmpegException("Failed to concatenate videos"))
                 } else {
                     completer.complete(Unit)
                 }
@@ -98,4 +98,6 @@ class MediaConverter {
             return completer
         }
     }
+
+    class FFmpegException(message: String) : Exception(message)
 }

app/src/main/java/app/myzel394/alibi/helpers/VideoBatchesFolder.kt

@@ -3,7 +3,9 @@ package app.myzel394.alibi.helpers
 import android.content.Context
 import android.net.Uri
 import androidx.documentfile.provider.DocumentFile
+import app.myzel394.alibi.helpers.MediaConverter.Companion.concatenateVideoFiles
 import com.arthenica.ffmpegkit.FFmpegKitConfig
+import com.arthenica.ffmpegkit.ReturnCode
 import java.time.LocalDateTime
 
 class VideoBatchesFolder(
@@ -17,6 +19,9 @@ class VideoBatchesFolder(
     customFolder,
     subfolderName,
 ) {
+    override val concatenateFunction = ::concatenateVideoFiles
+    override val ffmpegParameters = FFMPEG_PARAMETERS
+
     override fun getOutputFileForFFmpeg(date: LocalDateTime, extension: String): String {
         return when (type) {
             BatchType.INTERNAL -> asInternalGetOutputFile(date, extension).absolutePath
@@ -30,28 +35,6 @@ class VideoBatchesFolder(
         }
     }
 
-    override suspend fun concatenate(
-        recordingStart: LocalDateTime,
-        extension: String,
-        disableCache: Boolean
-    ): String {
-        val outputFile = getOutputFileForFFmpeg(
-            date = recordingStart,
-            extension = extension,
-        )
-
-        if (disableCache || !checkIfOutputAlreadyExists(recordingStart, extension)) {
-            val filePaths = getBatchesForFFmpeg()
-
-            MediaConverter.concatenateVideoFiles(
-                inputFiles = filePaths,
-                outputFile = outputFile,
-            ).await()
-        }
-
-        return outputFile
-    }
-
     companion object {
         fun viaInternalFolder(context: Context) = VideoBatchesFolder(context, BatchType.INTERNAL)
 
@@ -65,5 +48,31 @@ class VideoBatchesFolder(
                 DocumentFile.fromTreeUri(context, Uri.parse(folder))!!
             )
         }
+
+        // Parameters to be passed in descending order
+        // Those parameters first try to concatenate without re-encoding
+        // if that fails, it'll try several fallback methods
+        val FFMPEG_PARAMETERS = arrayOf(
+            " -c copy",
+            " -c:v copy",
+            " -c:v copy -c:a aac",
+            " -c:v copy -c:a libmp3lame",
+            " -c:v copy -c:a libopus",
+            " -c:v copy -c:a libvorbis",
+            " -c:a copy",
+            // There's nothing else we can do to avoid re-encoding,
+            // so we'll just have to re-encode the whole thing
+            " -c:v libx264 -c:a copy",
+            " -c:v libx264 -c:a aac",
+            " -c:v libx265 -c:a aac",
+            " -c:v libx264 -c:a libmp3lame",
+            " -c:v libx264 -c:a libopus",
+            " -c:v libx264 -c:a libvorbis",
+            " -c:v libx265 -c:a copy",
+            " -c:v libx265 -c:a aac",
+            " -c:v libx265 -c:a libmp3lame",
+            " -c:v libx265 -c:a libopus",
+            " -c:v libx265 -c:a libvorbis",
+        )
     }
 }