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/* * Copyright (C) 2010 Preston Lacey http://javaflacencoder.sourceforge.net/ * All Rights Reserved.//from ww w .ja v a2s . c o m * * This library is free software; you can redistribute it and/or * modify it under the terms of the GNU Lesser General Public * License as published by the Free Software Foundation; either * version 2.1 of the License, or (at your option) any later version. * * This library is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * Lesser General Public License for more details. * * You should have received a copy of the GNU Lesser General Public * License along with this library; if not, write to the Free Software * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA */ package net.sourceforge.javaFlacEncoder; /** * This class is used to generate a Frame Header for a FLAC Frame. * * @author Preston Lacey */ public class FrameHeader { /** For Debugging: Higher level equals more debug statements */ public static int DEBUG_LEV = 0; private static final int definedBlockSizes[] = { -1, 192, 576, 1152, 2304, 4608, -1, -1, 256, 512, 1024, 2048, 4096, 8192, 16384, 32768 }; private static final int definedSampleRates[] = { 0, 88200, 176400, 192000, 8000, 16000, 22050, 24000, 32000, 44100, 48000, 96000, -1, -1, -1, -1 }; /** Maximum size a header can be according to FLAC specification. */ public static final int MAX_HEADER_SIZE = 128;//in bytes /** Synchronization code used at beginning of frame(low-order 14 bits * used) */ public static final short syncCode = 0x3FFE;//14 bits used static final byte reserved = 0;//1 bit used; 0 mandatory value byte blockingStrategy = 0;//1 bit used; 0=fixed-blocksize. 1=variable byte blockSize = 0xC;//4 bits used; see format docs byte sampleRate = 4;//0;//4 bits used; see format docs //byte channelAssignment = 0;//4 bits used; see format docs byte sampleSize = 4;//3 bits used; see format docs static final byte reserved2 = 0;//1 bit used; 0 mandatory value long frameNumber = 0;//8-56 bits used; UTF-8 coded sample number int blockSizeMod = 0;//if(blocksize bits == 011x) 8/16 bit (blocksize-1) int SampleRateMod = 0;//if(sample rate bits == 11xx) 8/16 bit sample rate byte crc8 = 0; CRC8 crcCalculator; /** * Constructor creates a new FrameHeader object which is ready to * generate headers. We can't use static functions to do this, since the * process uses a CRC8 object which must be instantiated. * */ public FrameHeader() { crcCalculator = new CRC8(); } /** * Create the header for a frame with the given parameters. Header data is * stored out to an EncodedElement, in the proper form for a FLAC stream. * * @param fixBlock True to use a fixed block size, false to use variable. At * this time, this *must* be set to True, as variable block size is * not yet implemented. * @param blockSize Block Size of this frame. * @param sampleRate Sample rate of this frame. * @param channelAssign Channel assignment used in this frame's encoding. * See EncodingConfiguration class documentation for * more information. * @param sampleSize Bits per sample. * @param frameNumber For fixed block-size encodings, this is the frame-number * starting at zero and incrementing by one. For variable * block encodings, this is the sample number of the * first sample in the frame. * @param channelCount Number of channels in the stream. * @return EncodedElement where the header is saved to. */ public EncodedElement createHeader(boolean fixBlock, int blockSize, int sampleRate, EncodingConfiguration.ChannelConfig channelAssign, int sampleSize, long frameNumber, int channelCount, EncodedElement result) { if(DEBUG_LEV > 0 ) System.err.println("FrameHeader::createHeader : Begin"); //EncodedElement result = new EncodedElement(); boolean useEndBlockSize = false; boolean useEndSampleRate = false; result.clear(MAX_HEADER_SIZE,0); int blockingStrat = (fixBlock)? 0:1; byte[] encodedFrameNumber = UTF8Modified.convertToExtendedUTF8(frameNumber); //set block size bits byte encodedBlockSize = encodeBlockSize(blockSize); if(encodedBlockSize == 0x6 || encodedBlockSize == 0x7) useEndBlockSize = true; //set sample rate bits byte encodedSampleRate = encodeSampleRate(sampleRate); if(encodedSampleRate >= 12 && encodedSampleRate <= 14) useEndSampleRate = true; //set channelAssignment bits int channelAssignment = 0; if(channelAssign == EncodingConfiguration.ChannelConfig.INDEPENDENT) channelAssignment = channelCount-1; else if(channelAssign == EncodingConfiguration.ChannelConfig.LEFT_SIDE) channelAssignment = 8; else if(channelAssign == EncodingConfiguration.ChannelConfig.RIGHT_SIDE) channelAssignment = 9; else if(channelAssign == EncodingConfiguration.ChannelConfig.MID_SIDE) channelAssignment = 10; //set sample size bits byte encodedSampleSize = 0; switch(sampleSize) { case 8: encodedSampleSize = 0x1; break; case 12: encodedSampleSize = 0x2; break; case 16: encodedSampleSize = 0x4; break; case 20: encodedSampleSize = 0x5; break; case 24: encodedSampleSize = 0x6; break; default: encodedSampleSize = 0x0; } result.addInt(syncCode,14); result.addInt(reserved, 1); result.addInt(blockingStrat, 1); result.addInt(encodedBlockSize, 4); result.addInt(encodedSampleRate, 4); result.addInt(channelAssignment, 4); result.addInt(encodedSampleSize, 3); result.addInt(reserved2, 1); for(int i = 0; i < encodedFrameNumber.length; i++) { result.addInt(encodedFrameNumber[i], 8); } //write blockSize if needed(two formats possible) if(useEndBlockSize) { if(encodedBlockSize == 0x6) { result.addInt(blockSize-1, 8); } else { result.addInt(blockSize-1, 16); } } //write sampleRate if needed(three formats possible) if(useEndSampleRate) { switch(encodedSampleRate) { case 0xC: result.addInt(sampleRate/1000, 8); break; case 0xD: result.addInt(sampleRate, 16); break; case 0xE: result.addInt(sampleRate/10, 16); break; } } if(DEBUG_LEV > 20 ) System.err.println("FrameHeader::createHeader : pre-CRC"); crcCalculator.reset(); crcCalculator.updateCRC8(result.getData(), 0, result.getTotalBits()/8); crc8 = crcCalculator.checksum(); if(DEBUG_LEV > 20 ) System.err.println("FrameHeader::createHeader : post-CRC"); result.addInt(crc8, 8); if(DEBUG_LEV > 0 ) System.err.println("FrameHeader::createHeader : End"); return result; } /** * Given a block size, select the proper bit settings to use according to * the FLAC stream. * @param blockSize * @return */ private static byte encodeBlockSize(int blockSize) { if(DEBUG_LEV > 0 ) System.err.println("FrameHeader::encodeBlockSize : Begin"); byte value = 0; int i; for(i = 0; i < definedBlockSizes.length; i++) { if(blockSize == definedBlockSizes[i]) { value = (byte)i; break; } } if(i >= definedBlockSizes.length) { if(blockSize <= 255) value = 0x6; else value = 0x7; } if(DEBUG_LEV > 0 ) System.err.println("FrameHeader::encodeBlockSize : End"); return value; } private static byte encodeSampleRate(int sampleRate) { if(DEBUG_LEV > 0 ) System.err.println("FrameHeader::encodeSampleRate : Begin"); byte value = 0; int i; for(i = 0; i < definedSampleRates.length; i++) { if(sampleRate == definedSampleRates[i]) { value = (byte)i; break; } } if(i >= definedSampleRates.length) { if(sampleRate % 1000 == 0 && sampleRate < 256000) value = 0xC; else if(sampleRate < 65536) value = 0xD; else if(sampleRate % 10 == 0 && sampleRate <= 655350) value = 0xE; else value = 0x0; } if(DEBUG_LEV > 0 ) System.err.println("FrameHeader::encodeSampleRate : End"); return value; } }