syntax.c

the mpeg2/4 aac decoder

void raw_data_block(NeAACDecHandle hDecoder, NeAACDecFrameInfo *hInfo,
                    bitfile *ld, program_config *pce, drc_info *drc)
{
    uint8_t id_syn_ele;

    hDecoder->fr_channels = 0;
    hDecoder->fr_ch_ele = 0;
    hDecoder->first_syn_ele = 25;
    hDecoder->has_lfe = 0;

#ifdef ERROR_RESILIENCE
    if (hDecoder->object_type < ER_OBJECT_START)
    {
#endif
        /* Table 4.4.3: raw_data_block() */
        while ((id_syn_ele = (uint8_t)faad_getbits(ld, LEN_SE_ID
            DEBUGVAR(1,4,"NeAACDecDecode(): id_syn_ele"))) != ID_END)
        {
            switch (id_syn_ele) {
            case ID_SCE:
                if (hDecoder->first_syn_ele == 25) hDecoder->first_syn_ele = id_syn_ele;
                decode_sce_lfe(hDecoder, hInfo, ld, id_syn_ele);
                if (hInfo->error > 0)
                    return;
                break;
            case ID_CPE:
                if (hDecoder->first_syn_ele == 25) hDecoder->first_syn_ele = id_syn_ele;
                decode_cpe(hDecoder, hInfo, ld, id_syn_ele);
                if (hInfo->error > 0)
                    return;
                break;
            case ID_LFE:
                hDecoder->has_lfe++;
                decode_sce_lfe(hDecoder, hInfo, ld, id_syn_ele);
                if (hInfo->error > 0)
                    return;
                break;
            case ID_CCE: /* not implemented yet, but skip the bits */
#ifdef COUPLING_DEC
                hInfo->error = coupling_channel_element(hDecoder, ld);
#else
                hInfo->error = 6;
#endif
                if (hInfo->error > 0)
                    return;
                break;
            case ID_DSE:
                data_stream_element(hDecoder, ld);
                break;
            case ID_PCE:
                /* 14496-4: 5.6.4.1.2.1.3: */
                /* program_configuration_element()'s in access units shall be ignored */
                program_config_element(pce, ld);
                //if ((hInfo->error = program_config_element(pce, ld)) > 0)
                //    return;
                //hDecoder->pce_set = 1;
                break;
            case ID_FIL:
                /* one sbr_info describes a channel_element not a channel! */
                /* if we encounter SBR data here: error */
                /* SBR data will be read directly in the SCE/LFE/CPE element */
                if ((hInfo->error = fill_element(hDecoder, ld, drc
#ifdef SBR_DEC
                    , INVALID_SBR_ELEMENT
#endif
                    )) > 0)
                    return;
                break;
            }
        }
#ifdef ERROR_RESILIENCE
    } else {
        /* Table 262: er_raw_data_block() */
        switch (hDecoder->channelConfiguration)
        {
        case 1:
            decode_sce_lfe(hDecoder, hInfo, ld, ID_SCE);
            if (hInfo->error > 0)
                return;
            break;
        case 2:
            decode_cpe(hDecoder, hInfo, ld, ID_CPE);
            if (hInfo->error > 0)
                return;
            break;
        case 3:
            decode_sce_lfe(hDecoder, hInfo, ld, ID_SCE);
            decode_cpe(hDecoder, hInfo, ld, ID_CPE);
            if (hInfo->error > 0)
                return;
            break;
        case 4:
            decode_sce_lfe(hDecoder, hInfo, ld, ID_SCE);
            decode_cpe(hDecoder, hInfo, ld, ID_CPE);
            decode_sce_lfe(hDecoder, hInfo, ld, ID_SCE);
            if (hInfo->error > 0)
                return;
            break;
        case 5:
            decode_sce_lfe(hDecoder, hInfo, ld, ID_SCE);
            decode_cpe(hDecoder, hInfo, ld, ID_CPE);
            decode_cpe(hDecoder, hInfo, ld, ID_CPE);
            if (hInfo->error > 0)
                return;
            break;
        case 6:
            decode_sce_lfe(hDecoder, hInfo, ld, ID_SCE);
            decode_cpe(hDecoder, hInfo, ld, ID_CPE);
            decode_cpe(hDecoder, hInfo, ld, ID_CPE);
            decode_sce_lfe(hDecoder, hInfo, ld, ID_LFE);
            if (hInfo->error > 0)
                return;
            break;
        case 7: /* 8 channels */
            decode_sce_lfe(hDecoder, hInfo, ld, ID_SCE);
            decode_cpe(hDecoder, hInfo, ld, ID_CPE);
            decode_cpe(hDecoder, hInfo, ld, ID_CPE);
            decode_cpe(hDecoder, hInfo, ld, ID_CPE);
            decode_sce_lfe(hDecoder, hInfo, ld, ID_LFE);
            if (hInfo->error > 0)
                return;
            break;
        default:
            hInfo->error = 7;
            return;
        }
#if 0
        cnt = bits_to_decode() / 8;
        while (cnt >= 1)
        {
            cnt -= extension_payload(cnt);
        }
#endif
    }
#endif

    /* new in corrigendum 14496-3:2002 */
#ifdef DRM
    if (hDecoder->object_type != DRM_ER_LC)
#endif
    {
        faad_byte_align(ld);
    }

    return;
}

/* Table 4.4.4 and */
/* Table 4.4.9 */
static uint8_t single_lfe_channel_element(NeAACDecHandle hDecoder, bitfile *ld,
                                          uint8_t channel, uint8_t *tag)
{
    uint8_t retval = 0;
    element sce = {0};
    ic_stream *ics = &(sce.ics1);
    ALIGN int16_t spec_data[1024] = {0};

    sce.element_instance_tag = (uint8_t)faad_getbits(ld, LEN_TAG
        DEBUGVAR(1,38,"single_lfe_channel_element(): element_instance_tag"));

    *tag = sce.element_instance_tag;
    sce.channel = channel;
    sce.paired_channel = -1;

    retval = individual_channel_stream(hDecoder, &sce, ld, ics, 0, spec_data);
    if (retval > 0)
        return retval;

#ifdef SBR_DEC
    /* check if next bitstream element is a fill element */
    /* if so, read it now so SBR decoding can be done in case of a file with SBR */
    if (faad_showbits(ld, LEN_SE_ID) == ID_FIL)
    {
        faad_flushbits(ld, LEN_SE_ID);

        /* one sbr_info describes a channel_element not a channel! */
        if ((retval = fill_element(hDecoder, ld, hDecoder->drc, hDecoder->fr_ch_ele)) > 0)
        {
            return retval;
        }
    }
#endif

    /* noiseless coding is done, spectral reconstruction is done now */
    retval = reconstruct_single_channel(hDecoder, ics, &sce, spec_data);
    if (retval > 0)
        return retval;

    return 0;
}

/* Table 4.4.5 */
static uint8_t channel_pair_element(NeAACDecHandle hDecoder, bitfile *ld,
                                    uint8_t channels, uint8_t *tag)
{
    ALIGN int16_t spec_data1[1024] = {0};
    ALIGN int16_t spec_data2[1024] = {0};
    element cpe = {0};
    ic_stream *ics1 = &(cpe.ics1);
    ic_stream *ics2 = &(cpe.ics2);
    uint8_t result;

    cpe.channel        = channels;
    cpe.paired_channel = channels+1;

    cpe.element_instance_tag = (uint8_t)faad_getbits(ld, LEN_TAG
        DEBUGVAR(1,39,"channel_pair_element(): element_instance_tag"));
    *tag = cpe.element_instance_tag;

    if ((cpe.common_window = faad_get1bit(ld
        DEBUGVAR(1,40,"channel_pair_element(): common_window"))) & 1)
    {
        /* both channels have common ics information */
        if ((result = ics_info(hDecoder, ics1, ld, cpe.common_window)) > 0)
            return result;

        ics1->ms_mask_present = (uint8_t)faad_getbits(ld, 2
            DEBUGVAR(1,41,"channel_pair_element(): ms_mask_present"));
        if (ics1->ms_mask_present == 1)
        {
            uint8_t g, sfb;
            for (g = 0; g < ics1->num_window_groups; g++)
            {
                for (sfb = 0; sfb < ics1->max_sfb; sfb++)
                {
                    ics1->ms_used[g][sfb] = faad_get1bit(ld
                        DEBUGVAR(1,42,"channel_pair_element(): faad_get1bit"));
                }
            }
        }

#ifdef ERROR_RESILIENCE
        if ((hDecoder->object_type >= ER_OBJECT_START) && (ics1->predictor_data_present))
        {
            if ((
#ifdef LTP_DEC
                ics1->ltp.data_present =
#endif
                faad_get1bit(ld DEBUGVAR(1,50,"channel_pair_element(): ltp.data_present"))) & 1)
            {
#ifdef LTP_DEC
                if ((result = ltp_data(hDecoder, ics1, &(ics1->ltp), ld)) > 0)
                {
                    return result;
                }
#else
                return 26;
#endif
            }
        }
#endif

        memcpy(ics2, ics1, sizeof(ic_stream));
    } else {
        ics1->ms_mask_present = 0;
    }

    if ((result = individual_channel_stream(hDecoder, &cpe, ld, ics1,
        0, spec_data1)) > 0)
    {
        return result;
    }

#ifdef ERROR_RESILIENCE
    if (cpe.common_window && (hDecoder->object_type >= ER_OBJECT_START) &&
        (ics1->predictor_data_present))
    {
        if ((
#ifdef LTP_DEC
            ics1->ltp2.data_present =
#endif
            faad_get1bit(ld DEBUGVAR(1,50,"channel_pair_element(): ltp.data_present"))) & 1)
        {
#ifdef LTP_DEC
            if ((result = ltp_data(hDecoder, ics1, &(ics1->ltp2), ld)) > 0)
            {
                return result;
            }
#else
            return 26;
#endif
        }
    }
#endif

    if ((result = individual_channel_stream(hDecoder, &cpe, ld, ics2,
        0, spec_data2)) > 0)
    {
        return result;
    }

#ifdef SBR_DEC
    /* check if next bitstream element is a fill element */
    /* if so, read it now so SBR decoding can be done in case of a file with SBR */
    if (faad_showbits(ld, LEN_SE_ID) == ID_FIL)
    {
        faad_flushbits(ld, LEN_SE_ID);

        /* one sbr_info describes a channel_element not a channel! */
        if ((result = fill_element(hDecoder, ld, hDecoder->drc, hDecoder->fr_ch_ele)) > 0)
        {
            return result;
        }
    }
#endif

    /* noiseless coding is done, spectral reconstruction is done now */
    if ((result = reconstruct_channel_pair(hDecoder, ics1, ics2, &cpe,
        spec_data1, spec_data2)) > 0)
    {
        return result;
    }

    return 0;
}

/* Table 4.4.6 */
static uint8_t ics_info(NeAACDecHandle hDecoder, ic_stream *ics, bitfile *ld,
                        uint8_t common_window)
{
    uint8_t retval = 0;

    /* ics->ics_reserved_bit = */ faad_get1bit(ld
        DEBUGVAR(1,43,"ics_info(): ics_reserved_bit"));
    ics->window_sequence = (uint8_t)faad_getbits(ld, 2
        DEBUGVAR(1,44,"ics_info(): window_sequence"));
    ics->window_shape = faad_get1bit(ld
        DEBUGVAR(1,45,"ics_info(): window_shape"));

    if (ics->window_sequence == EIGHT_SHORT_SEQUENCE)
    {
        ics->max_sfb = (uint8_t)faad_getbits(ld, 4
            DEBUGVAR(1,46,"ics_info(): max_sfb (short)"));
        ics->scale_factor_grouping = (uint8_t)faad_getbits(ld, 7
            DEBUGVAR(1,47,"ics_info(): scale_factor_grouping"));
    } else {
        ics->max_sfb = (uint8_t)faad_getbits(ld, 6
            DEBUGVAR(1,48,"ics_info(): max_sfb (long)"));
    }

    /* get the grouping information */
    if ((retval = window_grouping_info(hDecoder, ics)) > 0)
        return retval;

    /* should be an error */
    /* check the range of max_sfb */
    if (ics->max_sfb > ics->num_swb)
        return 16;

    if (ics->window_sequence != EIGHT_SHORT_SEQUENCE)
    {
        if ((ics->predictor_data_present = faad_get1bit(ld
            DEBUGVAR(1,49,"ics_info(): predictor_data_present"))) & 1)
        {
            if (hDecoder->object_type == MAIN) /* MPEG2 style AAC predictor */
            {
                uint8_t sfb;

                uint8_t limit = min(ics->max_sfb, max_pred_sfb(hDecoder->sf_index));
#ifdef MAIN_DEC
                ics->pred.limit = limit;
#endif

                if ((
#ifdef MAIN_DEC
                    ics->pred.predictor_reset =
#endif
                    faad_get1bit(ld DEBUGVAR(1,53,"ics_info(): pred.predictor_reset"))) & 1)
                {
#ifdef MAIN_DEC
                    ics->pred.predictor_reset_group_number =
#endif
                        (uint8_t)faad_getbits(ld, 5 DEBUGVAR(1,54,"ics_info(): pred.predictor_reset_group_number"));
                }

                for (sfb = 0; sfb < limit; sfb++)
                {
#ifdef MAIN_DEC
                    ics->pred.prediction_used[sfb] =
#endif
                        faad_get1bit(ld DEBUGVAR(1,55,"ics_info(): pred.prediction_used"));
                }
            }
#ifdef LTP_DEC
            else { /* Long Term Prediction */
                if (hDecoder->object_type < ER_OBJECT_START)
                {
                    if ((ics->ltp.data_present = faad_get1bit(ld
                        DEBUGVAR(1,50,"ics_info(): ltp.data_present"))) & 1)
                    {
                        if ((retval = ltp_data(hDecoder, ics, &(ics->ltp), ld)) > 0)
                        {
                            return retval;
                        }
                    }
                    if (common_window)
                    {
                        if ((ics->ltp2.data_present = faad_get1bit(ld
                            DEBUGVAR(1,51,"ics_info(): ltp2.data_present"))) & 1)
                        {
                            if ((retval = ltp_data(hDecoder, ics, &(ics->ltp2), ld)) > 0)
                            {
                                return retval;
                            }
                        }
                    }
                }
#ifdef ERROR_RESILIENCE
                if (!common_window && (hDecoder->object_type >= ER_OBJECT_START))
                {
                    if ((ics->ltp.data_present = faad_get1bit(ld