Source:
<code>protected void parsePayload(ParsableByteArray data, long timeUs) throws ParserException { int packetType = data.readUnsignedByte(); int compositionTimeMs = data.readUnsignedInt24(); timeUs += compositionTimeMs * 1000L; if (packetType == AVC_PACKET_TYPE_SEQUENCE_HEADER && !hasOutputFormat) { ParsableByteArray videoSequence = new ParsableByteArray(new byte[data.bytesLeft()]); data.readBytes(videoSequence.data, 0, data.bytesLeft()); AvcConfig avcConfig = AvcConfig.parse(videoSequence); nalUnitLengthFieldLength = avcConfig.nalUnitLengthFieldLength; Format format = Format.createVideoSampleFormat(null, MimeTypes.VIDEO_H264, null, Format.NO_VALUE, Format.NO_VALUE, avcConfig.width, avcConfig.height, Format.NO_VALUE, avcConfig.initializationData, Format.NO_VALUE, avcConfig.pixelWidthAspectRatio, null); output.format(format); hasOutputFormat = true; } else if (packetType == AVC_PACKET_TYPE_AVC_NALU && hasOutputFormat) { byte[] nalLengthData = nalLength.data; nalLengthData[0] = 0; nalLengthData[1] = 0; nalLengthData[2] = 0; <START> if(nalUnitLengthFieldLength == 0) nalUnitLengthFieldLength = 4; <END> int nalUnitLengthFieldLengthDiff = 4 - nalUnitLengthFieldLength; int bytesWritten = 0; int bytesToWrite; while (data.bytesLeft() > 0) { data.readBytes(nalLength.data, nalUnitLengthFieldLengthDiff, nalUnitLengthFieldLength); nalLength.setPosition(0); bytesToWrite = nalLength.readUnsignedIntToInt(); nalStartCode.setPosition(0); output.sampleData(nalStartCode, 4); bytesWritten += 4; output.sampleData(data, bytesToWrite); bytesWritten += bytesToWrite; } output.sampleMetadata(timeUs, frameType == VIDEO_FRAME_KEYFRAME ? C.BUFFER_FLAG_KEY_FRAME : 0, bytesWritten, 0, null); } }</code><technical_language>I understand this is for. L96, nalUnitLengthFieldLength 0 here</technical_language>

Target:
protected void parsePayload(ParsableByteArray data, long timeUs) throws ParserException { int packetType = data.readUnsignedByte(); int compositionTimeMs = data.readUnsignedInt24(); timeUs += compositionTimeMs * 1000L; if (packetType == AVC_PACKET_TYPE_SEQUENCE_HEADER && !hasOutputFormat) { ParsableByteArray videoSequence = new ParsableByteArray(new byte[data.bytesLeft()]); data.readBytes(videoSequence.data, 0, data.bytesLeft()); AvcConfig avcConfig = AvcConfig.parse(videoSequence); nalUnitLengthFieldLength = avcConfig.nalUnitLengthFieldLength; Format format = Format.createVideoSampleFormat(null, MimeTypes.VIDEO_H264, null, Format.NO_VALUE, Format.NO_VALUE, avcConfig.width, avcConfig.height, Format.NO_VALUE, avcConfig.initializationData, Format.NO_VALUE, avcConfig.pixelWidthAspectRatio, null); output.format(format); hasOutputFormat = true; } else if (packetType == AVC_PACKET_TYPE_AVC_NALU && hasOutputFormat) { byte[] nalLengthData = nalLength.data; nalLengthData[0] = 0; nalLengthData[1] = 0; nalLengthData[2] = 0; int nalUnitLengthFieldLengthDiff = 4 - nalUnitLengthFieldLength; int bytesWritten = 0; int bytesToWrite; while (data.bytesLeft() > 0) { data.readBytes(nalLength.data, nalUnitLengthFieldLengthDiff, nalUnitLengthFieldLength); nalLength.setPosition(0); bytesToWrite = nalLength.readUnsignedIntToInt(); nalStartCode.setPosition(0); output.sampleData(nalStartCode, 4); bytesWritten += 4; output.sampleData(data, bytesToWrite); bytesWritten += bytesToWrite; } output.sampleMetadata(timeUs, frameType == VIDEO_FRAME_KEYFRAME ? C.BUFFER_FLAG_KEY_FRAME : 0, bytesWritten, 0, null); } }