bitstream.c

来自「faac-1.25.rar音频编解码器demo」· C语言 代码 · 共 1,492 行 · 第 1/4 页

        bits += ByteAlign(bitStream, writeFlag);
    */

#if 0 // Removed in corrigendum 14496-3:2002
    if (hEncoder->config.mpegVersion == 0)
        bits += 2; /* emphasis */
#endif

    return bits;
}

static int WriteCPE(CoderInfo *coderInfoL,
                    CoderInfo *coderInfoR,
                    ChannelInfo *channelInfo,
                    BitStream* bitStream,
                    int objectType,
                    int writeFlag)
{
    int bits = 0;

#ifndef DRM
    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;
#endif

    /* if common_window, write ics_info */
    if (channelInfo->common_window) {
        int numWindows, maxSfb;

        bits += WriteICSInfo(coderInfoL, bitStream, objectType, channelInfo->common_window, 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, objectType, writeFlag);
    bits += WriteICS(coderInfoR, bitStream, channelInfo->common_window, objectType, writeFlag);

    return bits;
}

static int WriteSCE(CoderInfo *coderInfo,
                    ChannelInfo *channelInfo,
                    BitStream *bitStream,
                    int objectType,
                    int writeFlag)
{
    int bits = 0;

#ifndef DRM
    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;
#endif

    /* Write an Individual Channel Stream element */
    bits += WriteICS(coderInfo, bitStream, 0, objectType, writeFlag);

    return bits;
}

static int WriteLFE(CoderInfo *coderInfo,
                    ChannelInfo *channelInfo,
                    BitStream *bitStream,
                    int objectType,
                    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, objectType, writeFlag);

    return bits;
}

static int WriteICSInfo(CoderInfo *coderInfo,
                        BitStream *bitStream,
                        int objectType,
                        int common_window,
                        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;
#ifdef DRM
    }
    if (writeFlag) {
        PutBit(bitStream,coderInfo->tnsInfo.tnsDataPresent,LEN_TNS_PRES);
    }
    bits += LEN_TNS_PRES;
#endif
        if (objectType == LTP)
        {
            bits++;
            if(writeFlag)
                PutBit(bitStream, coderInfo->ltpInfo.global_pred_flag, 1); /* Prediction Global used */

            bits += WriteLTPPredictorData(coderInfo, bitStream, writeFlag);
            if (common_window)
                bits += WriteLTPPredictorData(coderInfo, bitStream, writeFlag);
        } else {
            bits++;
            if (writeFlag)
                PutBit(bitStream, coderInfo->pred_global_flag, LEN_PRED_PRES);  /* predictor_data_present */

            bits += WritePredictorData(coderInfo, bitStream, writeFlag);
        }
#ifndef DRM
    }
#endif

    return bits;
}

static int WriteICS(CoderInfo *coderInfo,
                    BitStream *bitStream,
                    int commonWindow,
                    int objectType,
                    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;

#ifndef DRM
    /* Write the 8-bit global_gain */
    if (writeFlag)
        PutBit(bitStream, coderInfo->global_gain, LEN_GLOB_GAIN);
    bits += LEN_GLOB_GAIN;
#endif

    /* Write ics information */
    if (!commonWindow) {
        bits += WriteICSInfo(coderInfo, bitStream, objectType, commonWindow, writeFlag);
    }

#ifdef DRM
    /* Write the 8-bit global_gain */
    if (writeFlag)
        PutBit(bitStream, coderInfo->global_gain, LEN_GLOB_GAIN);
    bits += LEN_GLOB_GAIN;
#endif

    bits += SortBookNumbers(coderInfo, bitStream, writeFlag);
    bits += WriteScalefactors(coderInfo, bitStream, writeFlag);
#ifdef DRM
    if (writeFlag) {
        /* length_of_reordered_spectral_data */
        PutBit(bitStream, coderInfo->iLenReordSpData, LEN_HCR_REORDSD);

        /* length_of_longest_codeword */
        PutBit(bitStream, coderInfo->iLenLongestCW, LEN_HCR_LONGCW);
    }
    bits += LEN_HCR_REORDSD + LEN_HCR_LONGCW;
#else
    bits += WritePulseData(coderInfo, bitStream, writeFlag);
#endif
    bits += WriteTNSData(coderInfo, bitStream, writeFlag);
#ifndef DRM
    bits += WriteGainControlData(coderInfo, bitStream, writeFlag);
#endif

#ifdef DRM
    /* DRM CRC calculation */
    if (writeFlag)
        calc_CRC(bitStream, bits);

    bits += WriteReorderedSpectralData(coderInfo, bitStream, writeFlag);
#else
    bits += WriteSpectralData(coderInfo, bitStream, writeFlag);
#endif

    /* Return number of bits */
    return bits;
}

static int WriteLTPPredictorData(CoderInfo *coderInfo, BitStream *bitStream, int writeFlag)
{
    int i, last_band;
    int bits;
    LtpInfo *ltpInfo = &coderInfo->ltpInfo;

    bits = 0;

    if (ltpInfo->global_pred_flag)
    {

        if(writeFlag)
            PutBit(bitStream, 1, 1); /* LTP used */
        bits++;

        switch(coderInfo->block_type)
        {
        case ONLY_LONG_WINDOW:
        case LONG_SHORT_WINDOW:
        case SHORT_LONG_WINDOW:
            bits += LEN_LTP_LAG;
            bits += LEN_LTP_COEF;
            if(writeFlag)
            {
                PutBit(bitStream, ltpInfo->delay[0], LEN_LTP_LAG);
                PutBit(bitStream, ltpInfo->weight_idx,  LEN_LTP_COEF);
            }

            last_band = ((coderInfo->nr_of_sfb < MAX_LT_PRED_LONG_SFB) ?
                coderInfo->nr_of_sfb : MAX_LT_PRED_LONG_SFB);
//            last_band = coderInfo->nr_of_sfb;

            bits += last_band;
            if(writeFlag)
                for (i = 0; i < last_band; i++)
                    PutBit(bitStream, ltpInfo->sfb_prediction_used[i], LEN_LTP_LONG_USED);
            break;

        default:
            break;
        }
    }

    return (bits);
}

static int WritePredictorData(CoderInfo *coderInfo,
                              BitStream *bitStream,
                              int writeFlag)
{
    int bits = 0;

    /* Write global predictor data present */
    short predictorDataPresent = coderInfo->pred_global_flag;
    int numBands = min(coderInfo->max_pred_sfb, coderInfo->nr_of_sfb);

    if (writeFlag) {
        if (predictorDataPresent) {
            int b;
            if (coderInfo->reset_group_number == -1) {
                PutBit(bitStream, 0, LEN_PRED_RST); /* No prediction reset */
            } else {
                PutBit(bitStream, 1, LEN_PRED_RST);
                PutBit(bitStream, (unsigned long)coderInfo->reset_group_number,
                    LEN_PRED_RSTGRP);
            }

            for (b=0;b<numBands;b++) {
                PutBit(bitStream, coderInfo->pred_sfb_flag[b], LEN_PRED_ENAB);
            }
        }
    }
    bits += (predictorDataPresent) ?
        (LEN_PRED_RST +
        ((coderInfo->reset_group_number)!=-1)*LEN_PRED_RSTGRP +
        numBands*LEN_PRED_ENAB) : 0;

    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;
    int numWindows;
    int len_tns_nfilt;
    int len_tns_length;
    int len_tns_order;
    int filtNumber;
    int resInBits;
    int bitsToTransmit;
    unsigned long unsignedIndex;
    int w;

    TnsInfo* tnsInfoPtr = &coderInfo->tnsInfo;

#ifndef DRM
    if (writeFlag) {
        PutBit(bitStream,tnsInfoPtr->tnsDataPresent,LEN_TNS_PRES);
    }
    bits += LEN_TNS_PRES;
#endif

    /* If TNS is not present, bail */
    if (!tnsInfoPtr->tnsDataPresent) {
        return bits;