{"record":{"id":"ac0786819db5c57e","repo":"TeamNewPipe/NewPipe","slug":"unexpected-simpleblock-element-size-missing-s-by","errorCode":null,"errorMessage":"Unexpected SimpleBlock element size, missing %s bytes","messagePattern":"Unexpected SimpleBlock element size, missing (.+?) bytes","errorType":"exception","errorClass":"IOException","httpStatus":null,"severity":"error","filePath":"app/src/main/java/org/schabi/newpipe/streams/WebMReader.java","lineNumber":380,"sourceCode":"                    entry.kind = TrackKind.Other;\n                    break;\n            }\n        }\n\n        return entries;\n    }\n\n    private SimpleBlock readSimpleBlock(final Element ref) throws IOException {\n        final SimpleBlock obj = new SimpleBlock(ref);\n        obj.trackNumber = readEncodedNumber();\n        obj.relativeTimeCode = stream.readShort();\n        obj.flags = (byte) stream.read();\n        obj.dataSize = (int) ((ref.offset + ref.size) - stream.position());\n        obj.createdFromBlock = ref.type == ID_BLOCK;\n\n        // NOTE: lacing is not implemented, and will be mixed with the stream data\n        if (obj.dataSize < 0) {\n            throw new IOException(String.format(\n                    \"Unexpected SimpleBlock element size, missing %s bytes\", -obj.dataSize));\n        }\n        return obj;\n    }\n\n    private Cluster readCluster(final Element ref) throws IOException {\n        final Cluster obj = new Cluster(ref);\n\n        final Element elem = untilElement(ref, ID_TIMECODE);\n        if (elem == null) {\n            throw new NoSuchElementException(\"Cluster at \" + ref.offset\n                    + \" without Timecode element\");\n        }\n        obj.timecode = readNumber(elem);\n\n        return obj;\n    }\n","sourceCodeStart":362,"sourceCodeEnd":398,"githubUrl":"https://github.com/TeamNewPipe/NewPipe/blob/9e8be091560a69f35d44bd252eb00bc7911c977b/app/src/main/java/org/schabi/newpipe/streams/WebMReader.java#L362-L398","documentation":"Thrown while reading a SimpleBlock inside a WebM Cluster. After consuming the block header (variable-length track number = readEncodedNumber(), a 2-byte relativeTimeCode via readShort(), and a 1-byte flags field), the reader computes dataSize as (ref.offset + ref.size) - stream.position(). If that value is negative it means the three header fields consumed more bytes than the SimpleBlock element actually contains — the element's declared size is inconsistent with the stream contents. This is a structural integrity check: a block must have room for at least its header plus payload.","triggerScenarios":"readSimpleBlock() is called on an Element whose contentSize/size is smaller than the sum of the encoded track number length + 2 (short) + 1 (byte). Occurs when the EBML element size field is wrong, the stream is truncated mid-block, or the reader is misaligned due to a preceding parse error.","commonSituations":"Truncated download (file cut off inside a Block); byte-level corruption of the WebM container changing an element size field; seek/demux logic that advanced the stream pointer to the wrong offset; a malformed server response or proxy that altered byte ranges.","solutions":["Verify the file is not truncated: compare its length against the expected Content-Length or the WebM Segment size element.","Re-download the media: a negative dataSize almost always means the file bytes are damaged or incomplete.","Catch IOException at the demux call site and treat the file as corrupt rather than retrying in-place.","If this occurs during live streaming, check that the byte-range request that fetched this Cluster returned the correct, complete range."],"exampleFix":null,"handlingStrategy":"validation","validationCode":"// Before reading SimpleBlocks, sanity-check the element content size\n// is at least large enough for the header (trackNum + 2 + 1 = 4 bytes min):\nlong minHeader = 4; // conservative lower bound for encoded track number + short + byte\nif (ref.contentSize < minHeader) {\n    throw new IOException(\"SimpleBlock element too small at offset \" + ref.offset);\n}","typeGuard":null,"tryCatchPattern":"try {\n    SimpleBlock block = readSimpleBlock(elem);\n} catch (IOException e) {\n    if (e.getMessage() != null && e.getMessage().startsWith(\"Unexpected SimpleBlock element size\")) {\n        // stream is corrupt or truncated — abort demux of this cluster\n        Log.w(TAG, \"Corrupt SimpleBlock, skipping cluster\", e);\n    } else throw e;\n}","preventionTips":["Verify file size matches expected length before demuxing.","Handle IOException from the demuxer as a non-retryable corrupt-file condition unless you re-download."],"tags":["webm","simpleblock","media-demuxer","corrupt-file","io"],"backgroundTag":null,"analyzedSha":"9e8be091560a69f35d44bd252eb00bc7911c977b","analyzedAt":"2026-08-14T00:11:33.519Z","schemaVersion":2},"datasetVersion":"2026-08-14T00:17:13.853Z"}