DrKLO/Telegram · error · FlacDecoderException

Initialization data must be of length 1

Error message

Initialization data must be of length 1

What it means

FlacDecoder's constructor throws FlacDecoderException('Initialization data must be of length 1') unless the initializationData list contains exactly one entry — that entry being the FLAC file/stream header used to bootstrap the native decoder. Any other length means the decoder cannot locate the stream header.

Source

Thrown at TMessagesProj/src/main/java/com/google/android/exoplayer2/ext/flac/FlacDecoder.java:60

   * Creates a Flac decoder.
   *
   * @param numInputBuffers The number of input buffers.
   * @param numOutputBuffers The number of output buffers.
   * @param maxInputBufferSize The maximum required input buffer size if known, or {@link
   *     Format#NO_VALUE} otherwise.
   * @param initializationData Codec-specific initialization data. It should contain only one entry
   *     which is the flac file header.
   * @throws FlacDecoderException Thrown if an exception occurs when initializing the decoder.
   */
  public FlacDecoder(
      int numInputBuffers,
      int numOutputBuffers,
      int maxInputBufferSize,
      List<byte[]> initializationData)
      throws FlacDecoderException {
    super(new DecoderInputBuffer[numInputBuffers], new SimpleDecoderOutputBuffer[numOutputBuffers]);
    if (initializationData.size() != 1) {
      throw new FlacDecoderException("Initialization data must be of length 1");
    }
    decoderJni = new FlacDecoderJni();
    decoderJni.setData(ByteBuffer.wrap(initializationData.get(0)));
    try {
      streamMetadata = decoderJni.decodeStreamMetadata();
    } catch (ParserException e) {
      throw new FlacDecoderException("Failed to decode StreamInfo", e);
    } catch (IOException e) {
      // Never happens.
      throw new IllegalStateException(e);
    }

    int initialInputBufferSize =
        maxInputBufferSize != Format.NO_VALUE ? maxInputBufferSize : streamMetadata.maxFrameSize;
    setInitialInputBufferSize(initialInputBufferSize);
  }

  @Override

View on GitHub (pinned to 45ab8f4308)

Solutions

1. Ensure the FLAC extractor supplies exactly one initialization entry containing the full FLAC stream header.
2. Validate initializationData.size()==1 before instantiating FlacDecoder.
3. Use the platform FLAC decoder or re-extract the stream if the header cannot be supplied as a single entry.

Example fix

// before
new FlacDecoder(nIn, nOut, maxIn, /* size 0 or 2 */ init);

// after
checkArgument(init.size() == 1, "FLAC init must be a single header entry");
new FlacDecoder(nIn, nOut, maxIn, init);

// enforce the single-entry invariant before constructing
checkArgument(initializationData.size() == 1,
    "FLAC init must contain exactly one header entry");
new FlacDecoder(nIn, nOut, maxIn, initializationData);

try { new FlacDecoder(nIn, nOut, maxIn, init); }
catch (FlacDecoderException e) { /* fall back to platform FLAC decoder */ }

When it happens

Trigger: Constructing FlacDecoder with an initializationData list whose size() != 1 (zero entries, or more than one entry, e.g. because multiple headers were collected).

Common situations: A FLAC extractor or source providing zero or multiple initialization entries; a malformed FLAC stream whose header was split or absent; feeding non-FLAC initialization data.

Related errors

• Failed to decode StreamInfo
• Failed to load decoder native libraries.
• Failed to initialize decoder
• Cannot decode FLAC frame
• Cannot read frame at position {lastDecodePosition}

AI-assisted analysis of DrKLO/Telegram@45ab8f4308 (2026-08-14). Data as JSON: /api/errors/8b1a0dd396c0206f. Report an issue: GitHub.