ref: f7eb13670a2aabafd990a84dd91f14cce156bc1a
dir: /libfaac/bitstream.c/
/*
* FAAC - Freeware Advanced Audio Coder
* Copyright (C) 2001 Menno Bakker
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
* $Id: bitstream.c,v 1.2 2001/01/23 13:46:18 menno Exp $
*/
#include <stdlib.h>
#include <memory.h>
#include "coder.h"
#include "channels.h"
#include "huffman.h"
#include "bitstream.h"
int WriteBitstream(faacEncHandle hEncoder,
CoderInfo *coderInfo,
ChannelInfo *channelInfo,
BitStream *bitStream,
int numChannel)
{
int channel;
int bits = 0;
int bitsLeftAfterFill, numFillBits;
CountBitstream(hEncoder, coderInfo, channelInfo, bitStream, numChannel);
bits += WriteADTSHeader(hEncoder, bitStream, 1);
for (channel = 0; channel < numChannel; channel++) {
if (channelInfo[channel].present) {
/* Write out a single_channel_element */
if (!channelInfo[channel].cpe) {
if (channelInfo[channel].lfe) {
/* Write out lfe */
bits += WriteLFE(&coderInfo[channel],
&channelInfo[channel],
bitStream,
1);
} else {
/* Write out sce */
bits += WriteSCE(&coderInfo[channel],
&channelInfo[channel],
bitStream,
1);
}
} else {
if (channelInfo[channel].ch_is_left) {
/* Write out cpe */
bits += WriteCPE(&coderInfo[channel],
&coderInfo[channelInfo[channel].paired_ch],
&channelInfo[channel],
bitStream,
1);
}
}
}
}
/* Compute how many fill bits are needed to avoid overflowing bit reservoir */
/* Save room for ID_END terminator */
if (bits < (8 - LEN_SE_ID) ) {
numFillBits = 8 - LEN_SE_ID - bits;
} else {
numFillBits = 0;
}
/* Write AAC fill_elements, smallest fill element is 7 bits. */
/* Function may leave up to 6 bits left after fill, so tell it to fill a few extra */
numFillBits += 6;
bitsLeftAfterFill = WriteAACFillBits(bitStream, numFillBits, 1);
bits += (numFillBits - bitsLeftAfterFill);
/* Write ID_END terminator */
bits += LEN_SE_ID;
PutBit(bitStream, ID_END, LEN_SE_ID);
/* Now byte align the bitstream */
bits += ByteAlign(bitStream, 1);
return bits;
}
static int CountBitstream(faacEncHandle hEncoder,
CoderInfo *coderInfo,
ChannelInfo *channelInfo,
BitStream *bitStream,
int numChannel)
{
int channel;
int bits = 0;
int bitsLeftAfterFill, numFillBits;
bits += WriteADTSHeader(hEncoder, bitStream, 0);
for (channel = 0; channel < numChannel; channel++) {
if (channelInfo[channel].present) {
/* Write out a single_channel_element */
if (!channelInfo[channel].cpe) {
if (channelInfo[channel].lfe) {
/* Write out lfe */
bits += WriteLFE(&coderInfo[channel],
&channelInfo[channel],
bitStream,
0);
} else {
/* Write out sce */
bits += WriteSCE(&coderInfo[channel],
&channelInfo[channel],
bitStream,
0);
}
} else {
if (channelInfo[channel].ch_is_left) {
/* Write out cpe */
bits += WriteCPE(&coderInfo[channel],
&coderInfo[channelInfo[channel].paired_ch],
&channelInfo[channel],
bitStream,
0);
}
}
}
}
/* Compute how many fill bits are needed to avoid overflowing bit reservoir */
/* Save room for ID_END terminator */
if (bits < (8 - LEN_SE_ID) ) {
numFillBits = 8 - LEN_SE_ID - bits;
} else {
numFillBits = 0;
}
/* Write AAC fill_elements, smallest fill element is 7 bits. */
/* Function may leave up to 6 bits left after fill, so tell it to fill a few extra */
numFillBits += 6;
bitsLeftAfterFill = WriteAACFillBits(bitStream, numFillBits, 0);
bits += (numFillBits - bitsLeftAfterFill);
/* Write ID_END terminator */
bits += LEN_SE_ID;
/* Now byte align the bitstream */
bits += ByteAlign(bitStream, 0);
hEncoder->usedBytes = bit2byte(bits);
return bits;
}
static int WriteADTSHeader(faacEncHandle hEncoder,
BitStream *bitStream,
int writeFlag)
{
if (writeFlag) {
/* Fixed ADTS header */
PutBit(bitStream, 0xFFFF, 12); // 12 bit Syncword
PutBit(bitStream, 1, 1); // ID
PutBit(bitStream, 0, 2); // layer
PutBit(bitStream, 1, 1); // protection absent
PutBit(bitStream, hEncoder->aacProfile, 2); // profile
PutBit(bitStream, hEncoder->sampleRateIdx, 4); // sampling rate
PutBit(bitStream, 0, 1); // private bit
PutBit(bitStream, 1, 3); // ch. config (must be > 0)
PutBit(bitStream, 0, 1); // original/copy
PutBit(bitStream, 0, 1); // home
PutBit(bitStream, 0, 2); // emphasis
/* Variable ADTS header */
PutBit(bitStream, 0, 1); // copyr. id. bit
PutBit(bitStream, 0, 1); // copyr. id. start
PutBit(bitStream, hEncoder->usedBytes, 13);
PutBit(bitStream, 0x7FF, 11); // buffer fullness (0x7FF for VBR)
PutBit(bitStream, 0, 2); // raw data blocks (0+1=1)
}
return 58;
}
static int WriteCPE(CoderInfo *coderInfoL,
CoderInfo *coderInfoR,
ChannelInfo *channelInfo,
BitStream* bitStream,
int writeFlag)
{
int bits = 0;
if (writeFlag) {
/* write ID_CPE, single_element_channel() identifier */
PutBit(bitStream, ID_CPE, LEN_SE_ID);
/* write the element_identifier_tag */
PutBit(bitStream, channelInfo->tag, LEN_TAG);
/* common_window? */
PutBit(bitStream, channelInfo->common_window, LEN_COM_WIN);
}
bits += LEN_SE_ID;
bits += LEN_TAG;
bits += LEN_COM_WIN;
/* if common_window, write ics_info */
if (channelInfo->common_window) {
int numWindows, maxSfb;
bits += WriteICSInfo(coderInfoL, bitStream, writeFlag);
numWindows = coderInfoL->num_window_groups;
maxSfb = coderInfoL->max_sfb;
if (writeFlag) {
PutBit(bitStream, channelInfo->msInfo.is_present, LEN_MASK_PRES);
if (channelInfo->msInfo.is_present == 1) {
int g;
int b;
for (g=0;g<numWindows;g++) {
for (b=0;b<maxSfb;b++) {
PutBit(bitStream, channelInfo->msInfo.ms_used[g*maxSfb+b], LEN_MASK);
}
}
}
}
bits += LEN_MASK_PRES;
if (channelInfo->msInfo.is_present == 1)
bits += (numWindows*maxSfb*LEN_MASK);
}
/* Write individual_channel_stream elements */
bits += WriteICS(coderInfoL, bitStream, channelInfo->common_window, writeFlag);
bits += WriteICS(coderInfoR, bitStream, channelInfo->common_window, writeFlag);
return bits;
}
static int WriteSCE(CoderInfo *coderInfo,
ChannelInfo *channelInfo,
BitStream *bitStream,
int writeFlag)
{
int bits = 0;
if (writeFlag) {
/* write Single Element Channel (SCE) identifier */
PutBit(bitStream, ID_SCE, LEN_SE_ID);
/* write the element identifier tag */
PutBit(bitStream, channelInfo->tag, LEN_TAG);
}
bits += LEN_SE_ID;
bits += LEN_TAG;
/* Write an Individual Channel Stream element */
bits += WriteICS(coderInfo, bitStream, 0, writeFlag);
return bits;
}
static int WriteLFE(CoderInfo *coderInfo,
ChannelInfo *channelInfo,
BitStream *bitStream,
int writeFlag)
{
int bits = 0;
if (writeFlag) {
/* write ID_LFE, lfe_element_channel() identifier */
PutBit(bitStream, ID_LFE, LEN_SE_ID);
/* write the element_identifier_tag */
PutBit(bitStream, channelInfo->tag, LEN_TAG);
}
bits += LEN_SE_ID;
bits += LEN_TAG;
/* Write an individual_channel_stream element */
bits += WriteICS(coderInfo, bitStream, 0, writeFlag);
return bits;
}
static int WriteICSInfo(CoderInfo *coderInfo,
BitStream *bitStream,
int writeFlag)
{
int grouping_bits;
int bits = 0;
if (writeFlag) {
/* write out ics_info() information */
PutBit(bitStream, 0, LEN_ICS_RESERV); /* reserved Bit*/
/* Write out window sequence */
PutBit(bitStream, coderInfo->block_type, LEN_WIN_SEQ); /* block type */
/* Write out window shape */
PutBit(bitStream, coderInfo->window_shape, LEN_WIN_SH); /* window shape */
}
bits += LEN_ICS_RESERV;
bits += LEN_WIN_SEQ;
bits += LEN_WIN_SH;
/* For short windows, write out max_sfb and scale_factor_grouping */
if (coderInfo->block_type == ONLY_SHORT_WINDOW){
if (writeFlag) {
PutBit(bitStream, coderInfo->max_sfb, LEN_MAX_SFBS);
grouping_bits = FindGroupingBits(coderInfo);
PutBit(bitStream, grouping_bits, MAX_SHORT_WINDOWS - 1); /* the grouping bits */
}
bits += LEN_MAX_SFBS;
bits += MAX_SHORT_WINDOWS - 1;
} else { /* Otherwise, write out max_sfb and predictor data */
if (writeFlag) {
PutBit(bitStream, coderInfo->max_sfb, LEN_MAX_SFBL);
}
bits += LEN_MAX_SFBL;
bits += WriteLTPPredictorData(coderInfo, bitStream, writeFlag);
/* bits += WritePredictorData(coderInfo, bitStream, writeFlag); */
}
return bits;
}
static int WriteICS(CoderInfo *coderInfo,
BitStream *bitStream,
int commonWindow,
int writeFlag)
{
/* this function writes out an individual_channel_stream to the bitstream and */
/* returns the number of bits written to the bitstream */
int bits = 0;
/* Write the 8-bit global_gain */
if (writeFlag)
PutBit(bitStream, coderInfo->global_gain, LEN_GLOB_GAIN);
bits += LEN_GLOB_GAIN;
/* Write ics information */
if (!commonWindow) {
bits += WriteICSInfo(coderInfo, bitStream, writeFlag);
}
bits += SortBookNumbers(coderInfo, bitStream, writeFlag);
bits += WriteScalefactors(coderInfo, bitStream, writeFlag);
bits += WritePulseData(coderInfo, bitStream, writeFlag);
bits += WriteTNSData(coderInfo, bitStream, writeFlag);
bits += WriteGainControlData(coderInfo, bitStream, writeFlag);
bits += WriteSpectralData(coderInfo, bitStream, writeFlag);
/* Return number of bits */
return bits;
}
static int WriteLTPPredictorData(CoderInfo *coderInfo,
BitStream *bitStream,
int writeFlag)
{
int bits = 0;
if(writeFlag)
PutBit (bitStream, 0, 1); /* LTP not used */
bits += 1;
return bits;
}
static int WritePulseData(CoderInfo *coderInfo,
BitStream *bitStream,
int writeFlag)
{
int bits = 0;
if (writeFlag) {
PutBit(bitStream, 0, LEN_PULSE_PRES); /* no pulse_data_present */
}
bits += LEN_PULSE_PRES;
return bits;
}
static int WriteTNSData(CoderInfo *coderInfo,
BitStream *bitStream,
int writeFlag)
{
int bits = 0;
if (writeFlag) {
PutBit(bitStream, 0, LEN_TNS_PRES);
}
bits += LEN_TNS_PRES;
return bits;
}
static int WriteGainControlData(CoderInfo *coderInfo,
BitStream *bitStream,
int writeFlag)
{
int bits = 0;
if (writeFlag) {
PutBit(bitStream, 0, LEN_GAIN_PRES);
}
bits += LEN_GAIN_PRES;
return bits;
}
static int WriteSpectralData(CoderInfo *coderInfo,
BitStream *bitStream,
int writeFlag)
{
int i, bits = 0;
/* set up local pointers to data and len */
/* data array contains data to be written */
/* len array contains lengths of data words */
int* data = coderInfo->data;
int* len = coderInfo->len;
if (writeFlag) {
for(i = 0; i < coderInfo->spectral_count; i++) {
if (len[i] > 0) { /* only send out non-zero codebook data */
PutBit(bitStream, data[i], len[i]); /* write data */
bits += len[i];
}
}
} else {
for(i = 0; i < coderInfo->spectral_count; i++) {
bits += len[i];
}
}
return bits;
}
static int WriteAACFillBits(BitStream* bitStream,
int numBits,
int writeFlag)
{
int numberOfBitsLeft = numBits;
/* Need at least (LEN_SE_ID + LEN_F_CNT) bits for a fill_element */
int minNumberOfBits = LEN_SE_ID + LEN_F_CNT;
while (numberOfBitsLeft >= minNumberOfBits)
{
int numberOfBytes;
int maxCount;
if (writeFlag) {
PutBit(bitStream, ID_FIL, LEN_SE_ID); /* Write fill_element ID */
}
numberOfBitsLeft -= minNumberOfBits; /* Subtract for ID,count */
numberOfBytes = (int)(numberOfBitsLeft/LEN_BYTE);
maxCount = (1<<LEN_F_CNT) - 1; /* Max count without escaping */
/* if we have less than maxCount bytes, write them now */
if (numberOfBytes < maxCount) {
int i;
if (writeFlag) {
PutBit(bitStream, numberOfBytes, LEN_F_CNT);
for (i = 0; i < numberOfBytes; i++) {
PutBit(bitStream, 0, LEN_BYTE);
}
}
/* otherwise, we need to write an escape count */
}
else {
int maxEscapeCount, maxNumberOfBytes, escCount;
int i;
if (writeFlag) {
PutBit(bitStream, maxCount, LEN_F_CNT);
}
maxEscapeCount = (1<<LEN_BYTE) - 1; /* Max escape count */
maxNumberOfBytes = maxCount + maxEscapeCount;
numberOfBytes = (numberOfBytes > maxNumberOfBytes ) ? (maxNumberOfBytes) : (numberOfBytes);
escCount = numberOfBytes - maxCount;
if (writeFlag) {
PutBit(bitStream, escCount, LEN_BYTE);
for (i = 0; i < numberOfBytes-1; i++) {
PutBit(bitStream, 0, LEN_BYTE);
}
}
}
numberOfBitsLeft -= LEN_BYTE*numberOfBytes;
}
return numberOfBitsLeft;
}
static int FindGroupingBits(CoderInfo *coderInfo)
{
/* This function inputs the grouping information and outputs the seven bit
'grouping_bits' field that the AAC decoder expects. */
int grouping_bits = 0;
int tmp[8];
int i, j;
int index = 0;
for(i = 0; i < coderInfo->num_window_groups; i++){
for (j = 0; j < coderInfo->window_group_length[i]; j++){
tmp[index++] = i;
}
}
for(i = 1; i < 8; i++){
grouping_bits = grouping_bits << 1;
if(tmp[i] == tmp[i-1]) {
grouping_bits++;
}
}
return grouping_bits;
}
/* size in bytes! */
BitStream *OpenBitStream(int size, unsigned char *buffer)
{
BitStream *bitStream;
bitStream = malloc(sizeof(BitStream));
bitStream->size = size;
bitStream->numBit = 0;
bitStream->currentBit = 0;
bitStream->data = buffer;
memset(bitStream->data, 0, size);
return bitStream;
}
int CloseBitStream(BitStream *bitStream)
{
int bytes = bit2byte(bitStream->numBit);
free(bitStream);
return bytes;
}
static long BufferNumBit(BitStream *bitStream)
{
return bitStream->numBit;
}
static int WriteByte(BitStream *bitStream,
unsigned long data,
int numBit)
{
long numUsed,idx;
idx = (bitStream->currentBit / BYTE_NUMBIT) % bitStream->size;
numUsed = bitStream->currentBit % BYTE_NUMBIT;
if (numUsed == 0)
bitStream->data[idx] = 0;
bitStream->data[idx] |= (data & ((1<<numBit)-1)) <<
(BYTE_NUMBIT-numUsed-numBit);
bitStream->currentBit += numBit;
bitStream->numBit = bitStream->currentBit;
return 0;
}
int PutBit(BitStream *bitStream,
unsigned long data,
int numBit)
{
int num,maxNum,curNum;
unsigned long bits;
if (numBit == 0)
return 0;
/* write bits in packets according to buffer byte boundaries */
num = 0;
maxNum = BYTE_NUMBIT - bitStream->currentBit % BYTE_NUMBIT;
while (num < numBit) {
curNum = min(numBit-num,maxNum);
bits = data>>(numBit-num-curNum);
if (WriteByte(bitStream, bits, curNum)) {
return 1;
}
num += curNum;
maxNum = BYTE_NUMBIT;
}
return 0;
}
static int ByteAlign(BitStream *bitStream, int writeFlag)
{
int len, i,j;
len = BufferNumBit(bitStream);
j = (8 - (len%8))%8;
if ((len % 8) == 0) j = 0;
if (writeFlag) {
for( i=0; i<j; i++ ) {
PutBit(bitStream, 0, 1);
}
}
return j;
}