chore(sabr): add infrastructure for chunked streaming

Adds the required classes that are needed to create and handle chunked sample
streams.

Author: FineFindus

app/src/main/java/com/github/libretube/player/DefaultSABRChunkSource.kt

@@ -0,0 +1,72 @@
+package com.github.libretube.player
+
+import androidx.annotation.OptIn
+import androidx.media3.common.util.UnstableApi
+import androidx.media3.exoplayer.LoadingInfo
+import androidx.media3.exoplayer.SeekParameters
+import androidx.media3.exoplayer.source.chunk.Chunk
+import androidx.media3.exoplayer.source.chunk.ChunkHolder
+import androidx.media3.exoplayer.source.chunk.MediaChunk
+import androidx.media3.exoplayer.trackselection.ExoTrackSelection
+import androidx.media3.exoplayer.upstream.LoadErrorHandlingPolicy
+import androidx.media3.extractor.mp4.FragmentedMp4Extractor
+import com.github.libretube.player.manifest.SABRManifest
+
+@OptIn(UnstableApi::class)
+class DefaultSABRChunkSource : SABRChunkSource {
+    override fun updateManifest(newManifest: SABRManifest?) {}
+
+    override fun updateTrackSelection(trackSelection: ExoTrackSelection?) {
+        TODO("Not yet implemented")
+    }
+
+    override fun getAdjustedSeekPositionUs(
+        positionUs: Long,
+        seekParameters: SeekParameters
+    ): Long {
+        TODO("Not yet implemented")
+    }
+
+    override fun maybeThrowError() {}
+
+    override fun getPreferredQueueSize(
+        playbackPositionUs: Long,
+        queue: List<out MediaChunk>
+    ): Int {
+        TODO("Not yet implemented")
+    }
+
+    override fun shouldCancelLoad(
+        playbackPositionUs: Long,
+        loadingChunk: Chunk,
+        queue: List<out MediaChunk>
+    ): Boolean {
+        TODO("Not yet implemented")
+    }
+
+    override fun getNextChunk(
+        loadingInfo: LoadingInfo,
+        loadPositionUs: Long,
+        queue: List<out MediaChunk>,
+        out: ChunkHolder
+    ) {
+        TODO("Not yet implemented")
+    }
+
+    override fun onChunkLoadCompleted(chunk: Chunk) {
+        TODO("Not yet implemented")
+    }
+
+    override fun onChunkLoadError(
+        chunk: Chunk,
+        cancelable: Boolean,
+        loadErrorInfo: LoadErrorHandlingPolicy.LoadErrorInfo,
+        loadErrorHandlingPolicy: LoadErrorHandlingPolicy
+    ): Boolean {
+        TODO("Not yet implemented")
+    }
+
+    override fun release() {
+        TODO("Not yet implemented")
+    }
+}

app/src/main/java/com/github/libretube/player/SABRChunkSource.kt

@@ -0,0 +1,50 @@
+package com.github.libretube.player
+
+import androidx.media3.common.Format
+import androidx.media3.common.util.UnstableApi
+import androidx.media3.datasource.TransferListener
+import androidx.media3.exoplayer.source.chunk.ChunkSource
+import androidx.media3.exoplayer.trackselection.ExoTrackSelection
+import androidx.media3.exoplayer.upstream.CmcdConfiguration
+import androidx.media3.exoplayer.upstream.LoaderErrorThrower
+import androidx.media3.extractor.text.SubtitleParser
+import com.github.libretube.player.manifest.SABRManifest
+
+/** A [ChunkSource] for SABR streams.  */
+@UnstableApi
+interface SABRChunkSource : ChunkSource {
+    interface Factory {
+        /**
+         * Creates a new [SABRChunkSource].
+         *
+         * @param manifestLoaderErrorThrower Throws errors affecting loading of manifests.
+         * @param manifest The initial manifest.
+         * @param streamElementIndex The index of the corresponding stream element in the manifest.
+         * @param trackSelection The track selection.
+         * @param transferListener The transfer listener which should be informed of any data transfers.
+         * May be null if no listener is available.
+         * @param cmcdConfiguration The [CmcdConfiguration] for this chunk source.
+         * @return The created [SABRChunkSource].
+         */
+        fun createChunkSource(
+            manifestLoaderErrorThrower: LoaderErrorThrower?,
+            manifest: SABRManifest?,
+            streamElementIndex: Int,
+            trackSelection: ExoTrackSelection?,
+        ): SABRChunkSource?
+    }
+
+    /**
+     * Updates the manifest.
+     *
+     * @param newManifest The new manifest.
+     */
+    fun updateManifest(newManifest: SABRManifest?)
+
+    /**
+     * Updates the track selection.
+     *
+     * @param trackSelection The new track selection instance. Must be equivalent to the previous one.
+     */
+    fun updateTrackSelection(trackSelection: ExoTrackSelection?)
+}

app/src/main/java/com/github/libretube/player/manifest/SABRManifest.kt

@@ -0,0 +1,23 @@
+package com.github.libretube.player.manifest
+
+import androidx.media3.common.C
+import androidx.media3.common.StreamKey
+import androidx.media3.common.util.UnstableApi
+import androidx.media3.exoplayer.offline.FilterableManifest
+
+/**
+ * Represents a SABR streaming manifest.
+ */
+@UnstableApi
+class SABRManifest private constructor(
+    /**
+     * The overall presentation duration of the media in microseconds, or [C.TIME_UNSET] if the
+     * duration is unknown.
+     */
+    val durationUs: Long,
+) : FilterableManifest<SABRManifest?> {
+
+    override fun copy(streamKeys: List<StreamKey>): SABRManifest {
+        TODO("Not yet implemented")
+    }
+}