TeamNewPipe/NewPipe · error · IOException

moof found without mdat

Error message

moof found without mdat

What it means

During nextChunk(), a second moof (Movie Fragment) box is encountered while a previous moof is still pending (moof != null). In a well-formed fragmented MP4 each moof is immediately followed by its mdat; a second moof before the first's mdat means the structure is out of order or corrupt. The IOException signals the parser cannot reconcile the overlapping fragment headers.

Source

Thrown at app/src/main/java/org/schabi/newpipe/streams/Mp4DashReader.java:194

    public Mp4DashChunk getNextChunk(final boolean infoOnly) throws IOException {
        final Mp4Track track = tracks[selectedTrack];

        while (stream.available()) {

            if (chunkZero) {
                ensure(box);
                if (!stream.available()) {
                    break;
                }
                box = readBox();
            } else {
                chunkZero = true;
            }

            switch (box.type) {
                case ATOM_MOOF:
                    if (moof != null) {
                        throw new IOException("moof found without mdat");
                    }

                    moof = parseMoof(box, track.trak.tkhd.trackId);

                    if (moof.traf != null) {

                        if (hasFlag(moof.traf.trun.bFlags, 0x0001)) {
                            moof.traf.trun.dataOffset -= box.size + 8;
                            if (moof.traf.trun.dataOffset < 0) {
                                throw new IOException("trun box has wrong data offset, "
                                        + "points outside of concurrent mdat box");
                            }
                        }

                        if (moof.traf.trun.chunkSize < 1) {
                            if (hasFlag(moof.traf.tfhd.bFlags, 0x10)) {
                                moof.traf.trun.chunkSize = moof.traf.tfhd.defaultSampleSize
                                        * moof.traf.trun.entryCount;

View on GitHub (pinned to 9e8be09156)

Solutions

1. Re-download the source file; box ordering corruption is almost always a damaged transfer.
2. Re-mux the content with a known-good tool (ffmpeg/MP4Box) to fix the box layout.
3. Validate the file with mp4info/MP4Box -info before feeding it to the reader.
4. Catch IOException around nextChunk() and skip to the next valid fragment boundary if lossy recovery is acceptable.

Example fix

// before
while ((chunk = reader.getNextChunk(false)) != null) { ... } // throws mid-iteration

// after — tolerate a single corrupt fragment and continue
try {
    while ((chunk = reader.getNextChunk(false)) != null) { ... }
} catch (IOException e) {
    Log.w(TAG, "fragment ordering broken, stopping at " + e.getMessage());
}

// No pre-check can predict interleaved box order without full parsing;
// instead, validate file integrity with MP4Box before demuxing.
// MP4Box -info file.mp4   (exit non-zero or reports errors ⇒ do not feed to reader)

// Not expressible as a type guard; this is runtime structural corruption.
// Use a boolean returned by a validation pass:
public static boolean boxOrderValid(Mp4DashReader r) { /* full scan */ return true; }

try {
    while ((chunk = reader.getNextChunk(false)) != null) { process(chunk); }
} catch (IOException e) {
    if (e.getMessage().contains("moof found without mdat")) {
        Log.w(TAG, "fragment ordering corrupt; stopping extraction here");
    } else throw e;
}

When it happens

Trigger: A fragmented MP4 where moof boxes appear consecutively without an intervening mdat; a corrupt/malformed segment; a file that was truncated or had boxes reordered by a faulty muxer.

Common situations: Corrupt download where mdat bytes were lost but moof headers survived; a buggy server-side fragmenter; manual concatenation of fragments that dropped mdat payloads.

Related errors

• mdat found without moof
• Not a MPEG-4 DASH container, major brand is not 'dash' or 'i
• The provided Mp4 doesn't have the 'moov' box
• trun box has wrong data offset, points outside of concurrent
• parser go beyond limits of the box. type=%s offset=%s size=%

AI-assisted analysis of TeamNewPipe/NewPipe@9e8be09156 (2026-08-14). Data as JSON: /api/errors/558f35439e179786. Report an issue: GitHub.