Add metadata to mp4 files that usually would not need postprocessing

Extract MP4 metadata (udta) generation into separate helper class

Author: TobiGr

app/src/main/java/org/schabi/newpipe/download/DownloadDialog.java

@@ -1093,6 +1093,8 @@ private void continueSelectedDownload(@NonNull final StoredFileHelper storage) {
                     if (secondary.getSizeInBytes() > 0 && videoSize > 0) {
                         nearLength = secondary.getSizeInBytes() + videoSize;
                     }
+                } else if (selectedStream.getFormat() == MediaFormat.MPEG_4) {
+                    psName = Postprocessing.ALGORITHM_MP4_METADATA;
                 }
                 break;
             case R.id.subtitle_button:

app/src/main/java/org/schabi/newpipe/streams/Mp4FromDashWriter.java

@@ -11,23 +11,22 @@
 import org.schabi.newpipe.streams.Mp4DashReader.TrackKind;
 import org.schabi.newpipe.streams.Mp4DashReader.TrunEntry;
 import org.schabi.newpipe.streams.io.SharpStream;
-import org.schabi.newpipe.util.StreamInfoMetadataHelper;
 
-import java.io.ByteArrayOutputStream;
 import java.io.IOException;
 import java.nio.ByteBuffer;
-import java.nio.charset.StandardCharsets;
 import java.util.ArrayList;
 
+import us.shandian.giga.postprocessing.Mp4MetadataHelper;
+
 /**
  * MP4 muxer that builds a standard MP4 file from DASH fragmented MP4 sources.
  *
- * <p>
- * See <a href="https://atomicparsley.sourceforge.net/mpeg-4files.html">
- * https://atomicparsley.sourceforge.net/mpeg-4files.html</a> for information on
+ * @see <a href="https://atomicparsley.sourceforge.net/mpeg-4files.html">
+ * https://atomicparsley.sourceforge.net/mpeg-4files.html</a> for a quick summary on
  * the MP4 file format and its specification.
- * </p>
- *
+ * @see <a href="https://developer.apple.com/documentation/quicktime-file-format/">
+ *     Apple Quick Time Format Specification</a> which is the basis for MP4 file format
+ *     and contains detailed information about the structure of MP4 files.
  * @author kapodamy
  */
 public class Mp4FromDashWriter {
@@ -64,8 +63,8 @@ public class Mp4FromDashWriter {
 
     private final ArrayList<Integer> compatibleBrands = new ArrayList<>(5);
 
-    private final StreamInfo streamInfo;
-    private final Bitmap thumbnail;
+
+    private final Mp4MetadataHelper metadataHelper;
 
     public Mp4FromDashWriter(final StreamInfo streamInfo,
                              final Bitmap thumbnail,
@@ -76,8 +75,26 @@ public Mp4FromDashWriter(final StreamInfo streamInfo,
             }
         }
 
-        this.streamInfo = streamInfo;
-        this.thumbnail = thumbnail;
+        this.metadataHelper = new Mp4MetadataHelper(
+                this::auxOffset,
+                buffer -> {
+                    try {
+                        auxWrite(buffer);
+                    } catch (final IOException e) {
+                        throw new RuntimeException(e);
+                    }
+                },
+                offset -> {
+                    try {
+                        return lengthFor(offset);
+                    } catch (final IOException e) {
+                        throw new RuntimeException(e);
+                    }
+                },
+                streamInfo,
+                thumbnail
+        );
+
         sourceTracks = sources;
         readers = new Mp4DashReader[sourceTracks.length];
         readersChunks = new Mp4DashChunk[readers.length];
@@ -733,7 +750,7 @@ private int makeMoov(final int[] defaultMediaTime, final TablesInfo[] tablesInfo
 
         makeMvhd(longestTrack);
 
-        makeUdta();
+        metadataHelper.makeUdta();
 
         for (int i = 0; i < tracks.length; i++) {
             if (tracks[i].trak.tkhd.matrix.length != 36) {
@@ -929,191 +946,6 @@ private byte[] makeSgpd() {
     }
 
 
-    /**
-     * Create the 'udta' box with metadata fields.
-     * {@code udta} is a user data box that can contain various types of metadata,
-     * including title, artist, date, and cover art.
-     * @see <a href="https://developer.apple.com/documentation/quicktime-file-format/
-     * user_data_atoms">Apple Quick Time Format Specification for user data atoms</a>
-     * @see <a href="https://wiki.multimedia.cx/index.php?title=FFmpeg_Metadata
-     * #QuickTime/MOV/MP4/M4A/et_al.">Multimedia Wiki FFmpeg Metadata</a>
-     * @see <a href="https://atomicparsley.sourceforge.net/mpeg-4files.html">atomicparsley docs</a>
-     * for a short and understandable reference about metadata keys and values
-     * @throws IOException
-     */
-    private void makeUdta() throws IOException {
-        if (streamInfo == null) {
-            return;
-        }
-
-        // udta
-        final int startUdta = auxOffset();
-        auxWrite(ByteBuffer.allocate(8).putInt(0).putInt(0x75647461).array()); // "udta"
-
-        // meta (full box: type + version/flags)
-        final int startMeta = auxOffset();
-        auxWrite(ByteBuffer.allocate(8).putInt(0).putInt(0x6D657461).array()); // "meta"
-        auxWrite(ByteBuffer.allocate(4).putInt(0).array()); // version & flags = 0
-
-        // hdlr inside meta
-        auxWrite(makeMetaHdlr());
-
-        // ilst container
-        final int startIlst = auxOffset();
-        auxWrite(ByteBuffer.allocate(8).putInt(0).putInt(0x696C7374).array()); // "ilst"
-
-        // write metadata items
-
-        final var metaHelper = new StreamInfoMetadataHelper(streamInfo);
-        final String title = metaHelper.getTitle();
-        final String artist = metaHelper.getArtist();
-        final String date = metaHelper.getReleaseDate().getLocalDateTime()
-                .toLocalDate().toString();
-        final String recordLabel = metaHelper.getRecordLabel();
-        final String copyright = metaHelper.getCopyright();
-
-        if (title != null && !title.isEmpty()) {
-            writeMetaItem("©nam", title);
-        }
-        if (artist != null && !artist.isEmpty()) {
-            writeMetaItem("©ART", artist);
-        }
-        if (date != null && !date.isEmpty()) {
-            // this means 'year' in mp4 metadata, who the hell thought that?
-            writeMetaItem("©day", date);
-        }
-        if (recordLabel != null && !recordLabel.isEmpty()) {
-            writeMetaItem("©lab", recordLabel);
-        }
-        if (copyright != null && !copyright.isEmpty()) {
-            writeMetaItem("©cpy", copyright);
-        }
-
-        if (thumbnail != null) {
-            final ByteArrayOutputStream baos = new ByteArrayOutputStream();
-            thumbnail.compress(Bitmap.CompressFormat.PNG, 100, baos);
-            final byte[] imgBytes = baos.toByteArray();
-            baos.close();
-            // 0x0000000E = PNG type indicator for 'data' box (0x0D = JPEG)
-            writeMetaCover(imgBytes, 0x0000000E);
-
-        }
-
-        // fix lengths
-        lengthFor(startIlst);
-        lengthFor(startMeta);
-        lengthFor(startUdta);
-
-    }
-
-    /**
-     * Helper to write a metadata item inside the 'ilst' box.
-     *
-     * <pre>
-     *     [size][key] [data_box]
-     *     data_box = [size]["data"][type(4bytes)=1][locale(4bytes)=0][payload]
-     * </pre>
-     *
-     * @param keyStr 4-char metadata key
-     * @param value the metadata value
-     * @throws IOException
-     */
-    //
-    private void writeMetaItem(final String keyStr, final String value) throws IOException {
-        final byte[] valBytes = value.getBytes(StandardCharsets.UTF_8);
-        final byte[] keyBytes = keyStr.getBytes(StandardCharsets.ISO_8859_1);
-
-        final int dataBoxSize = 16 + valBytes.length; // 4(size)+4("data")+4(type/locale)+payload
-        final int itemBoxSize = 8 + dataBoxSize; // 4(size)+4(key)+dataBox
-
-        final ByteBuffer buf = ByteBuffer.allocate(itemBoxSize);
-        buf.putInt(itemBoxSize);
-        // key (4 bytes)
-        if (keyBytes.length == 4) {
-            buf.put(keyBytes);
-        } else {
-            // fallback: pad or truncate
-            final byte[] kb = new byte[4];
-            System.arraycopy(keyBytes, 0, kb, 0, Math.min(keyBytes.length, 4));
-            buf.put(kb);
-        }
-
-        // data box
-        buf.putInt(dataBoxSize);
-        buf.putInt(0x64617461); // "data"
-        buf.putInt(0x00000001); // well-known type indicator (UTF-8)
-        buf.putInt(0x00000000); // locale
-        buf.put(valBytes);
-
-        auxWrite(buf.array());
-    }
-
-    /**
-     * Create a minimal hdlr box for the meta container.
-     * The boxsize is fixed (33 bytes) as no name is provided.
-     * @return byte array with the hdlr box
-     */
-    private byte[] makeMetaHdlr() {
-        final ByteBuffer buf = ByteBuffer.allocate(33);
-        buf.putInt(33);
-        buf.putInt(0x68646C72); // "hdlr"
-        buf.putInt(0x00000000); // pre-defined
-        buf.putInt(0x6D646972); // "mdir" handler_type (metadata directory)
-        buf.putInt(0x00000000); // subtype / reserved
-        buf.put(new byte[12]);  // reserved
-        buf.put((byte) 0x00);   // name (empty, null-terminated)
-        return buf.array();
-    }
-
-    /**
-     * Helper to add cover image inside the 'udta' box.
-     * <p>
-     * This method writes the 'covr' metadata item which contains the cover image.
-     * The cover image is displayed as thumbnail in many media players and file managers.
-     * </p>
-     * <pre>
-     *     [size][key] [data_box]
-     *     data_box = [size]["data"][type(4bytes)][locale(4bytes)=0][payload]
-     * </pre>
-     *
-     * @param imageData image byte data
-     * @param dataType  type indicator: 0x0000000E = PNG, 0x0000000D = JPEG
-     * @throws IOException
-     */
-    private void writeMetaCover(final byte[] imageData, final int dataType) throws IOException {
-        if (imageData == null || imageData.length == 0) {
-            return;
-        }
-
-        final byte[] keyBytes = "covr".getBytes(StandardCharsets.ISO_8859_1);
-
-        // data box: 4(size) + 4("data") + 4(type) + 4(locale) + payload
-        final int dataBoxSize = 16 + imageData.length;
-        final int itemBoxSize = 8 + dataBoxSize;
-
-        final ByteBuffer buf = ByteBuffer.allocate(itemBoxSize);
-        buf.putInt(itemBoxSize);
-
-        // key (4 chars)
-        if (keyBytes.length == 4) {
-            buf.put(keyBytes);
-        } else {
-            final byte[] kb = new byte[4];
-            System.arraycopy(keyBytes, 0, kb, 0, Math.min(keyBytes.length, 4));
-            buf.put(kb);
-        }
-
-        // data box
-        buf.putInt(dataBoxSize);
-        buf.putInt(0x64617461); // "data"
-        buf.putInt(dataType);   // type indicator: 0x0000000E = PNG, 0x0000000D = JPEG
-        buf.putInt(0x00000000); // locale
-        buf.put(imageData);
-
-        auxWrite(buf.array());
-    }
-
-
     static class TablesInfo {
         int stts;
         int stsc;