Fix crash when remuxing Opus downloads with missing metadata

app/src/main/java/org/schabi/newpipe/streams/OggFromWebMWriter.java

@@ -7,6 +7,7 @@
 
 import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
+import androidx.annotation.VisibleForTesting;
 
 import org.schabi.newpipe.extractor.stream.StreamInfo;
 import org.schabi.newpipe.streams.WebMReader.Cluster;
@@ -194,7 +195,7 @@
         }
 
         /* step 3: create packet with metadata */
-        final byte[] buffer = makeMetadata();
+        final byte[] buffer = makeMetadata(webmTrack.codecId, streamInfo);
         if (buffer != null) {
             addPacketSegment(buffer.length);
             makePacketheader(0x00, header, buffer);
@@ -283,22 +284,27 @@
     }
 
     @Nullable
-    private byte[] makeMetadata() {
+    @VisibleForTesting
+    static byte[] makeMetadata(@Nullable final String codecId,
+                               @Nullable final StreamInfo streamInfo) {
         if (DEBUG) {
-            Log.d("OggFromWebMWriter", "Downloading media with codec ID " + webmTrack.codecId);
+            Log.d("OggFromWebMWriter", "Downloading media with codec ID " + codecId);
         }
 
-        if ("A_OPUS".equals(webmTrack.codecId)) {
+        if ("A_OPUS".equals(codecId)) {
             final var metadata = new ArrayList<Pair<String, String>>();
             if (streamInfo != null) {
                 metadata.add(Pair.create("COMMENT", streamInfo.getUrl()));
                 metadata.add(Pair.create("GENRE", streamInfo.getCategory()));
                 metadata.add(Pair.create("ARTIST", streamInfo.getUploaderName()));
                 metadata.add(Pair.create("TITLE", streamInfo.getName()));
-                metadata.add(Pair.create("DATE", streamInfo
-                        .getUploadDate()
-                        .getLocalDateTime()
-                        .format(DateTimeFormatter.ISO_DATE)));
+                // the upload date is optional and null when the service does not provide it
+                if (streamInfo.getUploadDate() != null) {
+                    metadata.add(Pair.create("DATE", streamInfo
+                            .getUploadDate()
+                            .getLocalDateTime()
+                            .format(DateTimeFormatter.ISO_DATE)));
+                }
             }
 
             if (DEBUG) {
@@ -309,7 +315,7 @@
             }
 
             return makeOpusTagsHeader(metadata);
-        } else if ("A_VORBIS".equals(webmTrack.codecId)) {
+        } else if ("A_VORBIS".equals(codecId)) {
             return new byte[]{
                     0x03, // ¿¿¿???
                     0x76, 0x6f, 0x72, 0x62, 0x69, 0x73, // "vorbis" binary string
@@ -354,7 +360,7 @@
     private static byte[] makeOpusTagsHeader(final List<Pair<String, String>> keyValueLines) {
         final var tags = keyValueLines
                 .stream()
-                .filter(p -> !p.second.isBlank())
+                .filter(p -> p.second != null && !p.second.isBlank())
                 .map(OggFromWebMWriter::makeOpusMetadataTag)
                 .collect(Collectors.toUnmodifiableList());
 

app/src/test/java/org/schabi/newpipe/streams/OggFromWebMWriterTest.kt

@@ -0,0 +1,101 @@
+/*
+ * SPDX-FileCopyrightText: 2026 NewPipe contributors <https://newpipe.net>
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+package org.schabi.newpipe.streams
+
+import android.util.Log
+import android.util.Pair
+import java.nio.ByteBuffer
+import java.nio.ByteOrder
+import java.time.OffsetDateTime
+import java.time.ZoneOffset
+import org.junit.After
+import org.junit.Assert.assertEquals
+import org.junit.Assert.assertFalse
+import org.junit.Assert.assertTrue
+import org.junit.Before
+import org.junit.Test
+import org.mockito.ArgumentMatchers.any
+import org.mockito.MockedStatic
+import org.mockito.Mockito.mock
+import org.mockito.Mockito.mockStatic
+import org.mockito.Mockito.`when`
+import org.schabi.newpipe.extractor.localization.DateWrapper
+import org.schabi.newpipe.extractor.stream.StreamInfo
+
+/**
+ * Tests the Opus metadata header built by [OggFromWebMWriter].
+ *
+ * [Pair] and [Log] are only stubs in local unit tests and are mocked statically.
+ */
+class OggFromWebMWriterTest {
+    private lateinit var logMock: MockedStatic<Log>
+    private lateinit var pairMock: MockedStatic<Pair<*, *>>
+
+    @Before
+    fun setUp() {
+        logMock = mockStatic(Log::class.java)
+        pairMock = mockStatic(Pair::class.java)
+        pairMock.`when`<Pair<Any?, Any?>> { Pair.create<Any?, Any?>(any(), any()) }
+            .thenAnswer { pair(it.getArgument(0), it.getArgument(1)) }
+    }
+
+    @After
+    fun tearDown() {
+        pairMock.close()
+        logMock.close()
+    }
+
+    @Test
+    fun opusMetadataWithoutUploadDate() {
+        val info = mock(StreamInfo::class.java)
+        `when`(info.url).thenReturn("https://example.com/watch?v=1")
+        `when`(info.category).thenReturn("Music")
+        `when`(info.uploaderName).thenReturn("Uploader")
+        `when`(info.name).thenReturn("Title")
+        `when`(info.uploadDate).thenReturn(null)
+
+        val header = OggFromWebMWriter.makeMetadata("A_OPUS", info)!!
+
+        val text = String(header, Charsets.UTF_8)
+        assertTrue(text.startsWith("OpusTags"))
+        assertEquals(4, tagCount(header))
+        assertTrue(text.contains("COMMENT=https://example.com/watch?v=1"))
+        assertTrue(text.contains("TITLE=Title"))
+        assertFalse(text.contains("DATE="))
+    }
+
+    @Test
+    fun opusMetadataSkipsNullTextFields() {
+        val info = mock(StreamInfo::class.java)
+        `when`(info.url).thenReturn("https://example.com/watch?v=1")
+        `when`(info.category).thenReturn(null)
+        `when`(info.uploaderName).thenReturn(null)
+        `when`(info.name).thenReturn("Title")
+        `when`(info.uploadDate).thenReturn(
+            DateWrapper(OffsetDateTime.of(2026, 10, 1, 12, 0, 0, 0, ZoneOffset.UTC))
+        )
+
+        val header = OggFromWebMWriter.makeMetadata("A_OPUS", info)!!
+
+        val text = String(header, Charsets.UTF_8)
+        assertEquals(3, tagCount(header))
+        assertTrue(text.contains("DATE=2026-10-01"))
+        assertFalse(text.contains("GENRE="))
+        assertFalse(text.contains("ARTIST="))
+    }
+
+    // number of comments, stored after "OpusTags" and the empty vendor string
+    private fun tagCount(header: ByteArray): Int = ByteBuffer.wrap(header, 12, 4).order(ByteOrder.LITTLE_ENDIAN).int
+
+    // the stub constructor of Pair throws, so its final fields are set directly
+    private fun pair(first: Any?, second: Any?): Pair<Any?, Any?> {
+        @Suppress("UNCHECKED_CAST")
+        val pair = mock(Pair::class.java) as Pair<Any?, Any?>
+        Pair::class.java.getField("first").apply { isAccessible = true }.set(pair, first)
+        Pair::class.java.getField("second").apply { isAccessible = true }.set(pair, second)
+        return pair
+    }
+}