Improve frame rate calculation by using media duration from mdhd box

- Added logic to parse media duration from the `mdhd` box for accurate frame rate calculation.
- Fallbacks to track duration from `tkhd` when `mdhd` contains invalid or missing data.
- Avoids incorrect frame rate calculations in MP4 files with an edit list (`elst`) box.
- Adds frame rate calculations for partially fragmented MP4 files.
- Verified accuracy with tools like `mediainfo` and `ffprobe`.

Issue: #1531

**Note**: The slight difference in frame rate values in dump files that aren’t MP4s with an edit list or fragmented MP4s isn’t due to differences in `tkhd` and `mdhd` duration values (which should be identical for non-edited or non-fragmented files). Rather, it’s because they are calculated using different timescales. The `mvhd` box defines a global movie timescale, which is used for the track's `tkhd` duration. Meanwhile, each track’s `mdhd` box defines its own timescale specific to its content type, which we now use for more accurate frame rate calculation.

PiperOrigin-RevId: 676046744

Author: rohitjoins

RELEASENOTES.md

@@ -40,6 +40,9 @@
     *   Fix preroll sample handling for non-keyframe media start positions when
         processing edit lists in MP4 files
         ([#1659](https://github.com/google/ExoPlayer/issues/1659)).
+    *   Improved frame rate calculation by using media duration from the `mdhd`
+        box in `Mp4Extractor` and `FragmentedMp4Extractor`
+        ([#1531](https://github.com/androidx/media/issues/1531)).
 *   DataSource:
 *   Audio:
 *   Video:

libraries/exoplayer_smoothstreaming/src/main/java/androidx/media3/exoplayer/smoothstreaming/DefaultSsChunkSource.java

@@ -203,6 +203,7 @@ public DefaultSsChunkSource(
               streamElement.timescale,
               C.TIME_UNSET,
               manifest.durationUs,
+              /* mediaDurationUs= */ manifest.durationUs,
               format,
               Track.TRANSFORMATION_NONE,
               trackEncryptionBoxes,

libraries/extractor/src/main/java/androidx/media3/extractor/mp4/BoxParser.java

@@ -351,8 +351,7 @@ public static Track parseTrak(
             checkNotNull(mdia.getContainerBoxOfType(Mp4Box.TYPE_minf))
                 .getContainerBoxOfType(Mp4Box.TYPE_stbl));
 
-    Pair<Long, String> mdhdData =
-        parseMdhd(checkNotNull(mdia.getLeafBoxOfType(Mp4Box.TYPE_mdhd)).data);
+    MdhdData mdhdData = parseMdhd(checkNotNull(mdia.getLeafBoxOfType(Mp4Box.TYPE_mdhd)).data);
     LeafBox stsd = stbl.getLeafBoxOfType(Mp4Box.TYPE_stsd);
     if (stsd == null) {
       throw ParserException.createForMalformedContainer(
@@ -363,7 +362,7 @@ public static Track parseTrak(
             stsd.data,
             tkhdData.id,
             tkhdData.rotationDegrees,
-            mdhdData.second,
+            mdhdData.language,
             drmInitData,
             isQuickTime);
     @Nullable long[] editListDurations = null;
@@ -383,9 +382,10 @@ public static Track parseTrak(
         : new Track(
             tkhdData.id,
             trackType,
-            mdhdData.first,
+            mdhdData.timescale,
             movieTimescale,
             durationUs,
+            mdhdData.mediaDurationUs,
             stsdData.format,
             stsdData.requiredSampleTransformation,
             stsdData.trackEncryptionBoxes,
@@ -431,6 +431,12 @@ public static TrackSampleTable parseStbl(
           /* durationUs= */ 0);
     }
 
+    if (track.type == C.TRACK_TYPE_VIDEO && track.mediaDurationUs > 0) {
+      float frameRate = sampleCount / (track.mediaDurationUs / 1000000f);
+      Format format = track.format.buildUpon().setFrameRate(frameRate).build();
+      track = track.copyWithFormat(format);
+    }
+
     // Entries are byte offsets of chunks.
     boolean chunkOffsetsAreLongs = false;
     @Nullable LeafBox chunkOffsetsAtom = stblBox.getLeafBoxOfType(Mp4Box.TYPE_stco);
@@ -927,23 +933,30 @@ private static int parseHdlr(ParsableByteArray hdlr) {
    * Parses an mdhd atom (defined in ISO/IEC 14496-12).
    *
    * @param mdhd The mdhd atom to decode.
-   * @return A pair consisting of the media timescale defined as the number of time units that pass
-   *     in one second, and the language code.
+   * @return An {@link MdhdData} object containing the parsed data.
    */
-  private static Pair<Long, String> parseMdhd(ParsableByteArray mdhd) {
+  private static MdhdData parseMdhd(ParsableByteArray mdhd) {
     mdhd.setPosition(Mp4Box.HEADER_SIZE);
     int fullAtom = mdhd.readInt();
     int version = parseFullBoxVersion(fullAtom);
     mdhd.skipBytes(version == 0 ? 8 : 16);
     long timescale = mdhd.readUnsignedInt();
-    mdhd.skipBytes(version == 0 ? 4 : 8);
+    long mediaDuration = version == 0 ? mdhd.readUnsignedInt() : mdhd.readUnsignedLongToLong();
+    long mediaDurationUs;
+    if (mediaDuration == 0) {
+      // 0 duration normally indicates that the file is fully fragmented (i.e. all of the media
+      // samples are in fragments). Treat as unknown.
+      mediaDurationUs = C.TIME_UNSET;
+    } else {
+      mediaDurationUs = Util.scaleLargeTimestamp(mediaDuration, C.MICROS_PER_SECOND, timescale);
+    }
     int languageCode = mdhd.readUnsignedShort();
     String language =
         ""
             + (char) (((languageCode >> 10) & 0x1F) + 0x60)
             + (char) (((languageCode >> 5) & 0x1F) + 0x60)
             + (char) ((languageCode & 0x1F) + 0x60);
-    return Pair.create(timescale, language);
+    return new MdhdData(timescale, mediaDurationUs, language);
   }
 
   /**
@@ -2408,6 +2421,19 @@ public EyesData(StriData striData) {
     }
   }
 
+  /** Data parsed from mdhd box. */
+  private static final class MdhdData {
+    private final long timescale;
+    private final long mediaDurationUs;
+    private final String language;
+
+    public MdhdData(long timescale, long mediaDurationUs, String language) {
+      this.timescale = timescale;
+      this.mediaDurationUs = mediaDurationUs;
+      this.language = language;
+    }
+  }
+
   /** Data parsed from vexu box. */
   /* package */ static final class VexuData {
     @Nullable private final EyesData eyesData;

libraries/extractor/src/main/java/androidx/media3/extractor/mp4/Mp4Extractor.java

@@ -738,7 +738,9 @@ private void processMoovAtom(ContainerBox moov) throws ParserException {
           roleFlags |=
               firstVideoTrackIndex == C.INDEX_UNSET ? C.ROLE_FLAG_MAIN : C.ROLE_FLAG_ALTERNATE;
         }
-        if (trackDurationUs > 0 && trackSampleTable.sampleCount > 0) {
+        if (track.format.frameRate == Format.NO_VALUE
+            && trackDurationUs > 0
+            && trackSampleTable.sampleCount > 0) {
           float frameRate = trackSampleTable.sampleCount / (trackDurationUs / 1000000f);
           formatBuilder.setFrameRate(frameRate);
         }

libraries/extractor/src/main/java/androidx/media3/extractor/mp4/Track.java

@@ -64,6 +64,9 @@ public final class Track {
   /** The duration of the track in microseconds, or {@link C#TIME_UNSET} if unknown. */
   public final long durationUs;
 
+  /** The duration of the media in microseconds, or {@link C#TIME_UNSET} if unknown. */
+  public final long mediaDurationUs;
+
   /** The format. */
   public final Format format;
 
@@ -93,6 +96,7 @@ public Track(
       long timescale,
       long movieTimescale,
       long durationUs,
+      long mediaDurationUs,
       Format format,
       @Transformation int sampleTransformation,
       @Nullable TrackEncryptionBox[] sampleDescriptionEncryptionBoxes,
@@ -104,6 +108,7 @@ public Track(
     this.timescale = timescale;
     this.movieTimescale = movieTimescale;
     this.durationUs = durationUs;
+    this.mediaDurationUs = mediaDurationUs;
     this.format = format;
     this.sampleTransformation = sampleTransformation;
     this.sampleDescriptionEncryptionBoxes = sampleDescriptionEncryptionBoxes;
@@ -133,6 +138,7 @@ public Track copyWithFormat(Format format) {
         timescale,
         movieTimescale,
         durationUs,
+        mediaDurationUs,
         format,
         sampleTransformation,
         sampleDescriptionEncryptionBoxes,
@@ -148,6 +154,7 @@ public Track copyWithoutEditLists() {
         timescale,
         movieTimescale,
         durationUs,
+        mediaDurationUs,
         format,
         sampleTransformation,
         sampleDescriptionEncryptionBoxes,

libraries/extractor/src/test/java/androidx/media3/extractor/mp4/FragmentedMp4ExtractorNoSniffingTest.java

@@ -45,6 +45,7 @@ public class FragmentedMp4ExtractorNoSniffingTest {
           /* timescale= */ 30_000,
           /* movieTimescale= */ 1000,
           /* durationUs= */ C.TIME_UNSET,
+          /* mediaDurationUs= */ C.TIME_UNSET,
           new Format.Builder().setSampleMimeType(MimeTypes.VIDEO_H264).build(),
           /* sampleTransformation= */ Track.TRANSFORMATION_NONE,
           /* sampleDescriptionEncryptionBoxes= */ null,

libraries/test_data/src/test/assets/extractordumps/mp4/sample_android_slow_motion.mp4.0.dump

@@ -17,7 +17,7 @@ track 0:
     maxNumReorderSamples = 0
     width = 1280
     height = 720
-    frameRate = 13.31
+    frameRate = 13.32
     colorInfo:
       colorSpace = 2
       colorRange = 1

libraries/test_data/src/test/assets/extractordumps/mp4/sample_android_slow_motion.mp4.1.dump

@@ -17,7 +17,7 @@ track 0:
     maxNumReorderSamples = 0
     width = 1280
     height = 720
-    frameRate = 13.31
+    frameRate = 13.32
     colorInfo:
       colorSpace = 2
       colorRange = 1

libraries/test_data/src/test/assets/extractordumps/mp4/sample_android_slow_motion.mp4.2.dump

@@ -17,7 +17,7 @@ track 0:
     maxNumReorderSamples = 0
     width = 1280
     height = 720
-    frameRate = 13.31
+    frameRate = 13.32
     colorInfo:
       colorSpace = 2
       colorRange = 1

libraries/test_data/src/test/assets/extractordumps/mp4/sample_android_slow_motion.mp4.3.dump

@@ -17,7 +17,7 @@ track 0:
     maxNumReorderSamples = 0
     width = 1280
     height = 720
-    frameRate = 13.31
+    frameRate = 13.32
     colorInfo:
       colorSpace = 2
       colorRange = 1

libraries/test_data/src/test/assets/extractordumps/mp4/sample_android_slow_motion.mp4.reading_within_gop_sample_dependencies.0.dump

@@ -17,7 +17,7 @@ track 0:
     maxNumReorderSamples = 0
     width = 1280
     height = 720
-    frameRate = 13.31
+    frameRate = 13.32
     colorInfo:
       colorSpace = 2
       colorRange = 1

libraries/test_data/src/test/assets/extractordumps/mp4/sample_android_slow_motion.mp4.reading_within_gop_sample_dependencies.1.dump

@@ -17,7 +17,7 @@ track 0:
     maxNumReorderSamples = 0
     width = 1280
     height = 720
-    frameRate = 13.31
+    frameRate = 13.32
     colorInfo:
       colorSpace = 2
       colorRange = 1

libraries/test_data/src/test/assets/extractordumps/mp4/sample_android_slow_motion.mp4.reading_within_gop_sample_dependencies.2.dump

@@ -17,7 +17,7 @@ track 0:
     maxNumReorderSamples = 0
     width = 1280
     height = 720
-    frameRate = 13.31
+    frameRate = 13.32
     colorInfo:
       colorSpace = 2
       colorRange = 1

libraries/test_data/src/test/assets/extractordumps/mp4/sample_android_slow_motion.mp4.reading_within_gop_sample_dependencies.3.dump

@@ -17,7 +17,7 @@ track 0:
     maxNumReorderSamples = 0
     width = 1280
     height = 720
-    frameRate = 13.31
+    frameRate = 13.32
     colorInfo:
       colorSpace = 2
       colorRange = 1

libraries/test_data/src/test/assets/extractordumps/mp4/sample_android_slow_motion.mp4.reading_within_gop_sample_dependencies.unknown_length.dump

@@ -17,7 +17,7 @@ track 0:
     maxNumReorderSamples = 0
     width = 1280
     height = 720
-    frameRate = 13.31
+    frameRate = 13.32
     colorInfo:
       colorSpace = 2
       colorRange = 1

libraries/test_data/src/test/assets/extractordumps/mp4/sample_android_slow_motion.mp4.unknown_length.dump

@@ -17,7 +17,7 @@ track 0:
     maxNumReorderSamples = 0
     width = 1280
     height = 720
-    frameRate = 13.31
+    frameRate = 13.32
     colorInfo:
       colorSpace = 2
       colorRange = 1

libraries/test_data/src/test/assets/extractordumps/mp4/sample_edit_list.mp4.0.dump

@@ -17,7 +17,7 @@ track 0:
     maxNumReorderSamples = 2
     width = 1920
     height = 1080
-    frameRate = 32.57
+    frameRate = 28.03
     rotationDegrees = 90
     colorInfo:
       colorSpace = 6

libraries/test_data/src/test/assets/extractordumps/mp4/sample_edit_list.mp4.1.dump

@@ -17,7 +17,7 @@ track 0:
     maxNumReorderSamples = 2
     width = 1920
     height = 1080
-    frameRate = 32.57
+    frameRate = 28.03
     rotationDegrees = 90
     colorInfo:
       colorSpace = 6

libraries/test_data/src/test/assets/extractordumps/mp4/sample_edit_list.mp4.2.dump

@@ -17,7 +17,7 @@ track 0:
     maxNumReorderSamples = 2
     width = 1920
     height = 1080
-    frameRate = 32.57
+    frameRate = 28.03
     rotationDegrees = 90
     colorInfo:
       colorSpace = 6

libraries/test_data/src/test/assets/extractordumps/mp4/sample_edit_list.mp4.3.dump

@@ -17,7 +17,7 @@ track 0:
     maxNumReorderSamples = 2
     width = 1920
     height = 1080
-    frameRate = 32.57
+    frameRate = 28.03
     rotationDegrees = 90
     colorInfo:
       colorSpace = 6

libraries/test_data/src/test/assets/extractordumps/mp4/sample_edit_list.mp4.reading_within_gop_sample_dependencies.0.dump

@@ -17,7 +17,7 @@ track 0:
     maxNumReorderSamples = 2
     width = 1920
     height = 1080
-    frameRate = 32.57
+    frameRate = 28.03
     rotationDegrees = 90
     colorInfo:
       colorSpace = 6

libraries/test_data/src/test/assets/extractordumps/mp4/sample_edit_list.mp4.reading_within_gop_sample_dependencies.1.dump

@@ -17,7 +17,7 @@ track 0:
     maxNumReorderSamples = 2
     width = 1920
     height = 1080
-    frameRate = 32.57
+    frameRate = 28.03
     rotationDegrees = 90
     colorInfo:
       colorSpace = 6

libraries/test_data/src/test/assets/extractordumps/mp4/sample_edit_list.mp4.reading_within_gop_sample_dependencies.2.dump

@@ -17,7 +17,7 @@ track 0:
     maxNumReorderSamples = 2
     width = 1920
     height = 1080
-    frameRate = 32.57
+    frameRate = 28.03
     rotationDegrees = 90
     colorInfo:
       colorSpace = 6

libraries/test_data/src/test/assets/extractordumps/mp4/sample_edit_list.mp4.reading_within_gop_sample_dependencies.3.dump

@@ -17,7 +17,7 @@ track 0:
     maxNumReorderSamples = 2
     width = 1920
     height = 1080
-    frameRate = 32.57
+    frameRate = 28.03
     rotationDegrees = 90
     colorInfo:
       colorSpace = 6

libraries/test_data/src/test/assets/extractordumps/mp4/sample_edit_list.mp4.reading_within_gop_sample_dependencies.unknown_length.dump

@@ -17,7 +17,7 @@ track 0:
     maxNumReorderSamples = 2
     width = 1920
     height = 1080
-    frameRate = 32.57
+    frameRate = 28.03
     rotationDegrees = 90
     colorInfo:
       colorSpace = 6

libraries/test_data/src/test/assets/extractordumps/mp4/sample_edit_list.mp4.unknown_length.dump

@@ -17,7 +17,7 @@ track 0:
     maxNumReorderSamples = 2
     width = 1920
     height = 1080
-    frameRate = 32.57
+    frameRate = 28.03
     rotationDegrees = 90
     colorInfo:
       colorSpace = 6

libraries/test_data/src/test/assets/extractordumps/mp4/sample_partially_fragmented.mp4.0.dump

@@ -13,6 +13,7 @@ track 0:
     maxNumReorderSamples = 2
     width = 1080
     height = 720
+    frameRate = 29.97
     colorInfo:
       lumaBitdepth = 8
       chromaBitdepth = 8

libraries/test_data/src/test/assets/extractordumps/mp4/sample_partially_fragmented.mp4.reading_within_gop_sample_dependencies.0.dump

@@ -13,6 +13,7 @@ track 0:
     maxNumReorderSamples = 2
     width = 1080
     height = 720
+    frameRate = 29.97
     colorInfo:
       lumaBitdepth = 8
       chromaBitdepth = 8

libraries/test_data/src/test/assets/extractordumps/mp4/sample_partially_fragmented.mp4.reading_within_gop_sample_dependencies.unknown_length.dump

@@ -13,6 +13,7 @@ track 0:
     maxNumReorderSamples = 2
     width = 1080
     height = 720
+    frameRate = 29.97
     colorInfo:
       lumaBitdepth = 8
       chromaBitdepth = 8

libraries/test_data/src/test/assets/extractordumps/mp4/sample_partially_fragmented.mp4.unknown_length.dump

@@ -13,6 +13,7 @@ track 0:
     maxNumReorderSamples = 2
     width = 1080
     height = 720
+    frameRate = 29.97
     colorInfo:
       lumaBitdepth = 8
       chromaBitdepth = 8

libraries/test_data/src/test/assets/extractordumps/mp4/sample_with_color_info.mp4.0.dump

@@ -17,7 +17,7 @@ track 0:
     maxNumReorderSamples = 2
     width = 1920
     height = 1080
-    frameRate = 30.17
+    frameRate = 30.00
     rotationDegrees = 90
     colorInfo:
       colorSpace = 6