aacdec.c

    return 0;
}

/**
 * Decode extension data (incomplete); reference: table 4.51.
 *
 * @param   cnt length of TYPE_FIL syntactic element in bytes
 *
 * @return Returns number of bytes consumed
 */
static int decode_extension_payload(AACContext *ac, GetBitContext *gb, int cnt,
                                    ChannelElement *che, enum RawDataBlockType elem_type)
{
    int crc_flag = 0;
    int res = cnt;
    switch (get_bits(gb, 4)) { // extension type
    case EXT_SBR_DATA_CRC:
        crc_flag++;
    case EXT_SBR_DATA:
        if (!che) {
            av_log(ac->avctx, AV_LOG_ERROR, "SBR was found before the first channel element.\n");
            return res;
        } else if (!ac->oc[1].m4ac.sbr) {
            av_log(ac->avctx, AV_LOG_ERROR, "SBR signaled to be not-present but was found in the bitstream.\n");
            skip_bits_long(gb, 8 * cnt - 4);
            return res;
        } else if (ac->oc[1].m4ac.sbr == -1 && ac->oc[1].status == OC_LOCKED) {
            av_log(ac->avctx, AV_LOG_ERROR, "Implicit SBR was found with a first occurrence after the first frame.\n");
            skip_bits_long(gb, 8 * cnt - 4);
            return res;
        } else if (ac->oc[1].m4ac.ps == -1 && ac->oc[1].status < OC_LOCKED && ac->avctx->channels == 1) {
            ac->oc[1].m4ac.sbr = 1;
            ac->oc[1].m4ac.ps = 1;
            output_configure(ac, ac->oc[1].layout_map, ac->oc[1].layout_map_tags,
                             ac->oc[1].status, 1);
        } else {
            ac->oc[1].m4ac.sbr = 1;
        }
        res = ff_decode_sbr_extension(ac, &che->sbr, gb, crc_flag, cnt, elem_type);
        break;
    case EXT_DYNAMIC_RANGE:
        res = decode_dynamic_range(&ac->che_drc, gb);
        break;
    case EXT_FILL:
        decode_fill(ac, gb, 8 * cnt - 4);
        break;
    case EXT_FILL_DATA:
    case EXT_DATA_ELEMENT:
    default:
        skip_bits_long(gb, 8 * cnt - 4);
        break;
    };
    return res;
}

/**
 * Decode Temporal Noise Shaping filter coefficients and apply all-pole filters; reference: 4.6.9.3.
 *
 * @param   decode  1 if tool is used normally, 0 if tool is used in LTP.
 * @param   coef    spectral coefficients
 */
static void apply_tns(float coef[1024], TemporalNoiseShaping *tns,
                      IndividualChannelStream *ics, int decode)
{
    const int mmm = FFMIN(ics->tns_max_bands, ics->max_sfb);
    int w, filt, m, i;
    int bottom, top, order, start, end, size, inc;
    float lpc[TNS_MAX_ORDER];
    float tmp[TNS_MAX_ORDER+1];

    for (w = 0; w < ics->num_windows; w++) {
        bottom = ics->num_swb;
        for (filt = 0; filt < tns->n_filt[w]; filt++) {
            top    = bottom;
            bottom = FFMAX(0, top - tns->length[w][filt]);
            order  = tns->order[w][filt];
            if (order == 0)
                continue;

            // tns_decode_coef
            compute_lpc_coefs(tns->coef[w][filt], order, lpc, 0, 0, 0);

            start = ics->swb_offset[FFMIN(bottom, mmm)];
            end   = ics->swb_offset[FFMIN(   top, mmm)];
            if ((size = end - start) <= 0)
                continue;
            if (tns->direction[w][filt]) {
                inc = -1;
                start = end - 1;
            } else {
                inc = 1;
            }
            start += w * 128;

            if (decode) {
                // ar filter
                for (m = 0; m < size; m++, start += inc)
                    for (i = 1; i <= FFMIN(m, order); i++)
                        coef[start] -= coef[start - i * inc] * lpc[i - 1];
            } else {
                // ma filter
                for (m = 0; m < size; m++, start += inc) {
                    tmp[0] = coef[start];
                    for (i = 1; i <= FFMIN(m, order); i++)
                        coef[start] += tmp[i] * lpc[i - 1];
                    for (i = order; i > 0; i--)
                        tmp[i] = tmp[i - 1];
                }
            }
        }
    }
}

/**
 *  Apply windowing and MDCT to obtain the spectral
 *  coefficient from the predicted sample by LTP.
 */
static void windowing_and_mdct_ltp(AACContext *ac, float *out,
                                   float *in, IndividualChannelStream *ics)
{
    const float *lwindow      = ics->use_kb_window[0] ? ff_aac_kbd_long_1024 : ff_sine_1024;
    const float *swindow      = ics->use_kb_window[0] ? ff_aac_kbd_short_128 : ff_sine_128;
    const float *lwindow_prev = ics->use_kb_window[1] ? ff_aac_kbd_long_1024 : ff_sine_1024;
    const float *swindow_prev = ics->use_kb_window[1] ? ff_aac_kbd_short_128 : ff_sine_128;

    if (ics->window_sequence[0] != LONG_STOP_SEQUENCE) {
        ac->fdsp.vector_fmul(in, in, lwindow_prev, 1024);
    } else {
        memset(in, 0, 448 * sizeof(float));
        ac->fdsp.vector_fmul(in + 448, in + 448, swindow_prev, 128);
    }
    if (ics->window_sequence[0] != LONG_START_SEQUENCE) {
        ac->dsp.vector_fmul_reverse(in + 1024, in + 1024, lwindow, 1024);
    } else {
        ac->dsp.vector_fmul_reverse(in + 1024 + 448, in + 1024 + 448, swindow, 128);
        memset(in + 1024 + 576, 0, 448 * sizeof(float));
    }
    ac->mdct_ltp.mdct_calc(&ac->mdct_ltp, out, in);
}

/**
 * Apply the long term prediction
 */
static void apply_ltp(AACContext *ac, SingleChannelElement *sce)
{
    const LongTermPrediction *ltp = &sce->ics.ltp;
    const uint16_t *offsets = sce->ics.swb_offset;
    int i, sfb;

    if (sce->ics.window_sequence[0] != EIGHT_SHORT_SEQUENCE) {
        float *predTime = sce->ret;
        float *predFreq = ac->buf_mdct;
        int16_t num_samples = 2048;

        if (ltp->lag < 1024)
            num_samples = ltp->lag + 1024;
        for (i = 0; i < num_samples; i++)
            predTime[i] = sce->ltp_state[i + 2048 - ltp->lag] * ltp->coef;
        memset(&predTime[i], 0, (2048 - i) * sizeof(float));

        windowing_and_mdct_ltp(ac, predFreq, predTime, &sce->ics);

        if (sce->tns.present)
            apply_tns(predFreq, &sce->tns, &sce->ics, 0);

        for (sfb = 0; sfb < FFMIN(sce->ics.max_sfb, MAX_LTP_LONG_SFB); sfb++)
            if (ltp->used[sfb])
                for (i = offsets[sfb]; i < offsets[sfb + 1]; i++)
                    sce->coeffs[i] += predFreq[i];
    }
}

/**
 * Update the LTP buffer for next frame
 */
static void update_ltp(AACContext *ac, SingleChannelElement *sce)
{
    IndividualChannelStream *ics = &sce->ics;
    float *saved     = sce->saved;
    float *saved_ltp = sce->coeffs;
    const float *lwindow = ics->use_kb_window[0] ? ff_aac_kbd_long_1024 : ff_sine_1024;
    const float *swindow = ics->use_kb_window[0] ? ff_aac_kbd_short_128 : ff_sine_128;
    int i;

    if (ics->window_sequence[0] == EIGHT_SHORT_SEQUENCE) {
        memcpy(saved_ltp,       saved, 512 * sizeof(float));
        memset(saved_ltp + 576, 0,     448 * sizeof(float));
        ac->dsp.vector_fmul_reverse(saved_ltp + 448, ac->buf_mdct + 960,     &swindow[64],      64);
        for (i = 0; i < 64; i++)
            saved_ltp[i + 512] = ac->buf_mdct[1023 - i] * swindow[63 - i];
    } else if (ics->window_sequence[0] == LONG_START_SEQUENCE) {
        memcpy(saved_ltp,       ac->buf_mdct + 512, 448 * sizeof(float));
        memset(saved_ltp + 576, 0,                  448 * sizeof(float));
        ac->dsp.vector_fmul_reverse(saved_ltp + 448, ac->buf_mdct + 960,     &swindow[64],      64);
        for (i = 0; i < 64; i++)
            saved_ltp[i + 512] = ac->buf_mdct[1023 - i] * swindow[63 - i];
    } else { // LONG_STOP or ONLY_LONG
        ac->dsp.vector_fmul_reverse(saved_ltp,       ac->buf_mdct + 512,     &lwindow[512],     512);
        for (i = 0; i < 512; i++)
            saved_ltp[i + 512] = ac->buf_mdct[1023 - i] * lwindow[511 - i];
    }

    memcpy(sce->ltp_state,      sce->ltp_state+1024, 1024 * sizeof(*sce->ltp_state));
    memcpy(sce->ltp_state+1024, sce->ret,            1024 * sizeof(*sce->ltp_state));
    memcpy(sce->ltp_state+2048, saved_ltp,           1024 * sizeof(*sce->ltp_state));
}

/**
 * Conduct IMDCT and windowing.
 */
static void imdct_and_windowing(AACContext *ac, SingleChannelElement *sce)
{
    IndividualChannelStream *ics = &sce->ics;
    float *in    = sce->coeffs;
    float *out   = sce->ret;
    float *saved = sce->saved;
    const float *swindow      = ics->use_kb_window[0] ? ff_aac_kbd_short_128 : ff_sine_128;
    const float *lwindow_prev = ics->use_kb_window[1] ? ff_aac_kbd_long_1024 : ff_sine_1024;
    const float *swindow_prev = ics->use_kb_window[1] ? ff_aac_kbd_short_128 : ff_sine_128;
    float *buf  = ac->buf_mdct;
    float *temp = ac->temp;
    int i;

    // imdct
    if (ics->window_sequence[0] == EIGHT_SHORT_SEQUENCE) {
        for (i = 0; i < 1024; i += 128)
            ac->mdct_small.imdct_half(&ac->mdct_small, buf + i, in + i);
    } else
        ac->mdct.imdct_half(&ac->mdct, buf, in);

    /* window overlapping
     * NOTE: To simplify the overlapping code, all 'meaningless' short to long
     * and long to short transitions are considered to be short to short
     * transitions. This leaves just two cases (long to long and short to short)
     * with a little special sauce for EIGHT_SHORT_SEQUENCE.
     */
    if ((ics->window_sequence[1] == ONLY_LONG_SEQUENCE || ics->window_sequence[1] == LONG_STOP_SEQUENCE) &&
            (ics->window_sequence[0] == ONLY_LONG_SEQUENCE || ics->window_sequence[0] == LONG_START_SEQUENCE)) {
        ac->dsp.vector_fmul_window(    out,               saved,            buf,         lwindow_prev, 512);
    } else {
        memcpy(                        out,               saved,            448 * sizeof(float));

        if (ics->window_sequence[0] == EIGHT_SHORT_SEQUENCE) {
            ac->dsp.vector_fmul_window(out + 448 + 0*128, saved + 448,      buf + 0*128, swindow_prev, 64);
            ac->dsp.vector_fmul_window(out + 448 + 1*128, buf + 0*128 + 64, buf + 1*128, swindow,      64);
            ac->dsp.vector_fmul_window(out + 448 + 2*128, buf + 1*128 + 64, buf + 2*128, swindow,      64);
            ac->dsp.vector_fmul_window(out + 448 + 3*128, buf + 2*128 + 64, buf + 3*128, swindow,      64);
            ac->dsp.vector_fmul_window(temp,              buf + 3*128 + 64, buf + 4*128, swindow,      64);
            memcpy(                    out + 448 + 4*128, temp, 64 * sizeof(float));
        } else {
            ac->dsp.vector_fmul_window(out + 448,         saved + 448,      buf,         swindow_prev, 64);
            memcpy(                    out + 576,         buf + 64,         448 * sizeof(float));
        }
    }

    // buffer update
    if (ics->window_sequence[0] == EIGHT_SHORT_SEQUENCE) {
        memcpy(                    saved,       temp + 64,         64 * sizeof(float));
        ac->dsp.vector_fmul_window(saved + 64,  buf + 4*128 + 64, buf + 5*128, swindow, 64);
        ac->dsp.vector_fmul_window(saved + 192, buf + 5*128 + 64, buf + 6*128, swindow, 64);
        ac->dsp.vector_fmul_window(saved + 320, buf + 6*128 + 64, buf + 7*128, swindow, 64);
        memcpy(                    saved + 448, buf + 7*128 + 64,  64 * sizeof(float));
    } else if (ics->window_sequence[0] == LONG_START_SEQUENCE) {
        memcpy(                    saved,       buf + 512,        448 * sizeof(float));
        memcpy(                    saved + 448, buf + 7*128 + 64,  64 * sizeof(float));
    } else { // LONG_STOP or ONLY_LONG
        memcpy(                    saved,       buf + 512,        512 * sizeof(float));
    }
}

/**
 * Apply dependent channel coupling (applied before IMDCT).
 *
 * @param   index   index into coupling gain array
 */
static void apply_dependent_coupling(AACContext *ac,
                                     SingleChannelElement *target,
                                     ChannelElement *cce, int index)
{
    IndividualChannelStream *ics = &cce->ch[0].ics;
    const uint16_t *offsets = ics->swb_offset;
    float *dest = target->coeffs;
    const float *src = cce->ch[0].coeffs;
    int g, i, group, k, idx = 0;
    if (ac->oc[1].m4ac.object_type == AOT_AAC_LTP) {
        av_log(ac->avctx, AV_LOG_ERROR,
               "Dependent coupling is not supported together with LTP\n");
        return;
    }
    for (g = 0; g < ics->num_window_groups; g++) {
        for (i = 0; i < ics->max_sfb; i++, idx++) {
            if (cce->ch[0].band_type[idx] != ZERO_BT) {
                const float gain = cce->coup.gain[index][idx];
                for (group = 0; group < ics->group_len[g]; group++) {
                    for (k = offsets[i]; k < offsets[i + 1]; k++) {
                        // XXX dsputil-ize
                        dest[group * 128 + k] += gain * src[group * 128 + k];
                    }
                }
            }
        }
        dest += ics->group_len[g] * 128;
        src  += ics->group_len[g] * 128;
    }
}

/**
 * Apply independent channel coupling (applied after IMDCT).
 *
 * @param   index   index into coupling gain array
 */
static void apply_independent_coupling(AACContext *ac,
                                       SingleChannelElement *target,
                                       ChannelElement *cce, int index)
{
    int i;
    const float gain = cce->coup.gain[index][0];
    const float *src = cce->ch[0].ret;
    float *dest = target->ret;
    const int len = 1024 << (ac->oc[1].m4ac.sbr == 1);

    for (i = 0; i < len; i++)
        dest[i] += gain * src[i];
}

/**
 * channel coupling transformation interface
 *
 * @param   apply_coupling_method   pointer to (in)dependent coupling function
 */
static void apply_channel_coupling(AACContext *ac, ChannelElement *cc,
                                   enum RawDataBlockType type, int elem_id,
                                   enum CouplingPoint coupling_point,
                                   void (*apply_coupling_method)(AACContext *ac, SingleChannelElement *target, ChannelElement *cce, int index))
{
    int i, c;

    for (i = 0; i < MAX_ELEM_ID; i++) {
        ChannelElement *cce = ac->che[TYPE_CCE][i];
        int index = 0;

        if (cce && cce->coup.coupling_point == coupling_point) {
            ChannelCoupling *coup = &cce->coup;

            for (c = 0; c <= coup->num_coupled; c++) {
                if (coup->type[c] == type && coup->id_select[c] == elem_id) {
                    if (coup->ch_select[c] != 1) {
                        apply_coupling_method(ac, &cc->ch[0], cce, index);
                        if (coup->ch_select[c] != 0)
                            index++;
                    }
                    if (coup->ch_select[c] != 2)
                        apply_coupling_method(ac, &cc->ch[1], cce, index++);
                } else
                    index += 1 + (coup->ch_select[c] == 3);
            }
        }
    }
}

/**
 * Convert spectral data to float samples, applying all supported tools as appropriate.
 */
static void spectral_to_sample(AACContext *ac)
{
    int i, type;
    for (type = 3; type >= 0; type--) {
        for (i = 0; i < MAX_ELEM_ID; i++) {
            ChannelElement *che = ac->che[type][i];
            if (che) {
                if (type <= TYPE_CPE)
                    apply_channel_coupling(ac, che, type, i, BEFORE_TNS, apply_dependent_coupling);
                if (ac->oc[1].m4ac.object_type == AOT_AAC_LTP) {
                    if (che->ch[0].ics.predictor_present) {
                        if (che->ch[0].ics.ltp.present)
                            apply_ltp(ac, &che->ch[0]);
                        if (che->ch[1].ics.ltp.present && type == TYPE_CPE)
                            apply_ltp(ac, &che->ch[1]);
                    }
                }
                if (che->ch[0].tns.present)
                    apply_tns(che->ch[0].coeffs, &che->ch[0].tns, &che->ch[0].ics, 1);
                if (che->ch[1].tns.present)
                    apply_tns(che->ch[1].coeffs, &che->ch[1].tns, &che->ch[1].ics, 1);
                if (type <= TYPE_CPE)
                    apply_channel_coupling(ac, che, type, i, BETWEEN_TNS_AND_IMDCT, apply_dependent_coupling);
                if (type != TYPE_CCE || che->coup.coupling_point == AFTER_IMDCT) {
                    imdct_and_windowing(ac, &che->ch[0]);
                    if (ac->oc[1].m4ac.object_type == AOT_AAC_LTP)
                        update_ltp(ac, &che->ch[0]);
                    if (type == TYPE_CPE) {
                        imdct_and_windowing(ac, &che->ch[1]);
                        if (ac->oc[1].m4ac.object_type == AOT_AAC_LTP)
                            update_ltp(ac, &che->ch[1]);
                    }
                    if (ac->oc[1].m4ac.sbr > 0) {
                        ff_sbr_apply(ac, &che->sbr, type, che->ch[0].ret, che->ch[1].ret);
                    }
                }
                if (type <= TYPE_CCE)
                    apply_channel_coupling(ac, che, type, i, AFTER_IMDCT, apply_independent_coupling);
            }
        }
    }
}

static int parse_adts_frame_header(AACContext *ac, GetBitContext *gb)
{
    int size;
    AACADTSHeaderInfo hdr_info;
    uint8_t layout_map[MAX_ELEM_ID*4][3];
    int layout_map_tags;

    size = avpriv_aac_parse_header(gb, &hdr_info);
    if (size > 0) {
        if (!ac->warned_num_aac_frames && hdr_info.num_aac_frames != 1) {
            // This is 2 for "VLB " audio in NSV files.
            // See samples/nsv/vlb_audio.
            av_log_missing_feature(ac->avctx, "More than one AAC RDB per ADTS frame", 0);
            ac->warned_num_aac_frames = 1;
        }
        push_output_configuration(ac);
        if (hdr_info.chan_config) {
            ac->oc[1].m4ac.chan_config = hdr_info.chan_config;
            if (set_default_channel_config(ac->avctx, layout_map,
                    &layout_map_tags, hdr_info.chan_config))
                return -7;
            if (output_configure(ac, layout_map, layout_map_tags,
                                 FFMAX(ac->oc[1].status, OC_TRIAL_FRAME), 0))
                return -7;
        } else {
            ac->oc[1].m4ac.chan_config = 0;
            /**
             * dual mono frames in Japanese DTV can have chan_config 0
             * WITHOUT specifying PCE.
             *  thus, set dual mono as default.
             */
            if (ac->dmono_mode && ac->oc[0].status == OC_NONE) {
                layout_map_tags = 2;
                layout_map[0][0] = layout_map[1][0] = TYPE_SCE;
                layout_map[0][2] = layout_map[1][2] = AAC_CHANNEL_FRONT;
                layout_map[0][1] = 0;
                layout_map[1][1] = 1;
                if (output_configure(ac, layout_map, layout_map_tags,
                                     OC_TRIAL_FRAME, 0))
                    return -7;
            }
        }
        ac->oc[1].m4ac.sample_rate     = hdr_info.sample_rate;
        ac->oc[1].m4ac.sampling_index  = hdr_info.sampling_index;
        ac->oc[1].m4ac.object_type     = hdr_info.object_type;
        if (ac->oc[0].status != OC_LOCKED ||
            ac->oc[0].m4ac.chan_config != hdr_info.chan_config ||
            ac->oc[0].m4ac.sample_rate != hdr_info.sample_rate) {
            ac->oc[1].m4ac.sbr = -1;
            ac->oc[1].m4ac.ps  = -1;
        }
        if (!hdr_info.crc_absent)
            skip_bits(gb, 16);
    }
    return size;
}

static int aac_decode_frame_int(AVCodecContext *avctx, void *data,
                                int *got_frame_ptr, GetBitContext *gb, AVPacket *avpkt)
{
    AACContext *ac = avctx->priv_data;
    ChannelElement *che = NULL, *che_prev = NULL;
    enum RawDataBlockType elem_type, elem_type_prev = TYPE_END;
    int err, elem_id;
    int samples = 0, multiplier, audio_found = 0, pce_found = 0;
    int is_dmono, sce_count = 0;

    if (show_bits(gb, 12) == 0xfff) {
        if (parse_adts_frame_header(ac, gb) < 0) {
            av_log(avctx, AV_LOG_ERROR, "Error decoding AAC frame header.\n");
            err = -1;
            goto fail;
        }
        if (ac->oc[1].m4ac.sampling_index > 12) {
            av_log(ac->avctx, AV_LOG_ERROR, "invalid sampling rate index %d\n", ac->oc[1].m4ac.sampling_index);
            err = -1;
            goto fail;
        }
    }

    if (frame_configure_elements(avctx) < 0) {
        err = -1;
        goto fail;
    }

    ac->tags_mapped = 0;
    // parse
    while ((elem_type = get_bits(gb, 3)) != TYPE_END) {
        elem_id = get_bits(gb, 4);

        if (elem_type < TYPE_DSE) {
            if (!(che=get_che(ac, elem_type, elem_id))) {
                av_log(ac->avctx, AV_LOG_ERROR, "channel element %d.%d is not allocated\n",
                       elem_type, elem_id);
                err = -1;
                goto fail;
            }
            samples = 1024;
        }

        switch (elem_type) {

        case TYPE_SCE:
            err = decode_ics(ac, &che->ch[0], gb, 0, 0);
            audio_found = 1;
            sce_count++;
            break;

        case TYPE_CPE:
            err = decode_cpe(ac, gb, che);
            audio_found = 1;
            break;

        case TYPE_CCE:
            err = decode_cce(ac, gb, che);
            break;

        case TYPE_LFE:
            err = decode_ics(ac, &che->ch[0], gb, 0, 0);
            audio_found = 1;
            break;

        case TYPE_DSE:
            err = skip_data_stream_element(ac, gb);
            break;

        case TYPE_PCE: {
            uint8_t layout_map[MAX_ELEM_ID*4][3];
            int tags;
            push_output_configuration(ac);
            tags = decode_pce(avctx, &ac->oc[1].m4ac, layout_map, gb);
            if (tags < 0) {
                err = tags;
                break;
            }
            if (pce_found) {
                av_log(avctx, AV_LOG_ERROR,
                       "Not evaluating a further program_config_element as this construct is dubious at best.\n");
                pop_output_configuration(ac);
            } else {
                err = output_configure(ac, layout_map, tags, OC_TRIAL_PCE, 1);
                if (!err)
                    ac->oc[1].m4ac.chan_config = 0;
                pce_found = 1;
            }
            break;
        }

        case TYPE_FIL:
            if (elem_id == 15)
                elem_id += get_bits(gb, 8) - 1;
            if (get_bits_left(gb) < 8 * elem_id) {
                    av_log(avctx, AV_LOG_ERROR, "TYPE_FIL: "overread_err);
                    err = -1;
                    goto fail;
            }
            while (elem_id > 0)
                elem_id -= decode_extension_payload(ac, gb, elem_id, che_prev, elem_type_prev);
            err = 0; /* FIXME */
            break;

        default:
            err = -1; /* should not happen, but keeps compiler happy */
            break;
        }

        che_prev       = che;
        elem_type_prev = elem_type;

        if (err)
            goto fail;

        if (get_bits_left(gb) < 3) {
            av_log(avctx, AV_LOG_ERROR, overread_err);
            err = -1;
            goto fail;
        }
    }

    spectral_to_sample(ac);

    multiplier = (ac->oc[1].m4ac.sbr == 1) ? ac->oc[1].m4ac.ext_sample_rate > ac->oc[1].m4ac.sample_rate : 0;
    samples <<= multiplier;
    /* for dual-mono audio (SCE + SCE) */
    is_dmono = ac->dmono_mode && sce_count == 2 &&
               ac->oc[1].channel_layout == (AV_CH_FRONT_LEFT | AV_CH_FRONT_RIGHT);

    if (samples) {
        ac->frame.nb_samples = samples;
        *(AVFrame *)data = ac->frame;
    }
    *got_frame_ptr = !!samples;

    if (is_dmono) {
        if (ac->dmono_mode == 1)
            ((AVFrame *)data)->data[1] =((AVFrame *)data)->data[0];
        else if (ac->dmono_mode == 2)
            ((AVFrame *)data)->data[0] =((AVFrame *)data)->data[1];
    }

    if (ac->oc[1].status && audio_found) {
        avctx->sample_rate = ac->oc[1].m4ac.sample_rate << multiplier;
        avctx->frame_size = samples;
        ac->oc[1].status = OC_LOCKED;
    }

    if (multiplier) {
        int side_size;
        uint32_t *side = av_packet_get_side_data(avpkt, AV_PKT_DATA_SKIP_SAMPLES, &side_size);
        if (side && side_size>=4)
            AV_WL32(side, 2*AV_RL32(side));
    }
    return 0;
fail:
    pop_output_configuration(ac);
    return err;
}

static int aac_decode_frame(AVCodecContext *avctx, void *data,
                            int *got_frame_ptr, AVPacket *avpkt)
{
    AACContext *ac = avctx->priv_data;
    const uint8_t *buf = avpkt->data;
    int buf_size = avpkt->size;
    GetBitContext gb;
    int buf_consumed;
    int buf_offset;
    int err;
    int new_extradata_size;
    const uint8_t *new_extradata = av_packet_get_side_data(avpkt,
                                       AV_PKT_DATA_NEW_EXTRADATA,
                                       &new_extradata_size);
    int jp_dualmono_size;
    const uint8_t *jp_dualmono   = av_packet_get_side_data(avpkt,
                                       AV_PKT_DATA_JP_DUALMONO,
                                       &jp_dualmono_size);

    if (new_extradata && 0) {
        av_free(avctx->extradata);
        avctx->extradata = av_mallocz(new_extradata_size +
                                      FF_INPUT_BUFFER_PADDING_SIZE);
        if (!avctx->extradata)
            return AVERROR(ENOMEM);
        avctx->extradata_size = new_extradata_size;
        memcpy(avctx->extradata, new_extradata, new_extradata_size);
        push_output_configuration(ac);
        if (decode_audio_specific_config(ac, ac->avctx, &ac->oc[1].m4ac,
                                         avctx->extradata,
                                         avctx->extradata_size*8, 1) < 0) {
            pop_output_configuration(ac);
            return AVERROR_INVALIDDATA;
        }
    }

    ac->dmono_mode = 0;
    if (jp_dualmono && jp_dualmono_size > 0)
        ac->dmono_mode =  1 + *jp_dualmono;

    init_get_bits(&gb, buf, buf_size * 8);

    if ((err = aac_decode_frame_int(avctx, data, got_frame_ptr, &gb, avpkt)) < 0)
        return err;

    buf_consumed = (get_bits_count(&gb) + 7) >> 3;
    for (buf_offset = buf_consumed; buf_offset < buf_size; buf_offset++)
        if (buf[buf_offset])
            break;

    return buf_size > buf_offset ? buf_consumed : buf_size;
}

static av_cold int aac_decode_close(AVCodecContext *avctx)
{
    AACContext *ac = avctx->priv_data;
    int i, type;

    for (i = 0; i < MAX_ELEM_ID; i++) {
        for (type = 0; type < 4; type++) {
            if (ac->che[type][i])
                ff_aac_sbr_ctx_close(&ac->che[type][i]->sbr);
            av_freep(&ac->che[type][i]);
        }
    }

    ff_mdct_end(&ac->mdct);
    ff_mdct_end(&ac->mdct_small);
    ff_mdct_end(&ac->mdct_ltp);
    return 0;
}


#define LOAS_SYNC_WORD   0x2b7       ///< 11 bits LOAS sync word

struct LATMContext {
    AACContext      aac_ctx;             ///< containing AACContext
    int             initialized;         ///< initialized after a valid extradata was seen

    // parser data
    int             audio_mux_version_A; ///< LATM syntax version
    int             frame_length_type;   ///< 0/1 variable/fixed frame length
    int             frame_length;        ///< frame length for fixed frame length
};

static inline uint32_t latm_get_value(GetBitContext *b)
{
    int length = get_bits(b, 2);

    return get_bits_long(b, (length+1)*8);
}

static int latm_decode_audio_specific_config(struct LATMContext *latmctx,
                                             GetBitContext *gb, int asclen)
{
    AACContext *ac        = &latmctx->aac_ctx;
    AVCodecContext *avctx = ac->avctx;
    MPEG4AudioConfig m4ac = { 0 };
    int config_start_bit  = get_bits_count(gb);
    int sync_extension    = 0;
    int bits_consumed, esize;

    if (asclen) {
        sync_extension = 1;
        asclen         = FFMIN(asclen, get_bits_left(gb));
    } else
        asclen         = get_bits_left(gb);

    if (config_start_bit % 8) {
        av_log_missing_feature(latmctx->aac_ctx.avctx,
                               "Non-byte-aligned audio-specific config", 1);
        return AVERROR_PATCHWELCOME;
    }
    if (asclen <= 0)
        return AVERROR_INVALIDDATA;
    bits_consumed = decode_audio_specific_config(NULL, avctx, &m4ac,
                                         gb->buffer + (config_start_bit / 8),
                                         asclen, sync_extension);

    if (bits_consumed < 0)
        return AVERROR_INVALIDDATA;

    if (!latmctx->initialized ||
        ac->oc[1].m4ac.sample_rate != m4ac.sample_rate ||
        ac->oc[1].m4ac.chan_config != m4ac.chan_config) {

        if(latmctx->initialized) {
            av_log(avctx, AV_LOG_INFO, "audio config changed\n");
        } else {
            av_log(avctx, AV_LOG_INFO, "initializing latmctx\n");
        }
        latmctx->initialized = 0;

        esize = (bits_consumed+7) / 8;

        if (avctx->extradata_size < esize) {
            av_free(avctx->extradata);
            avctx->extradata = av_malloc(esize + FF_INPUT_BUFFER_PADDING_SIZE);
            if (!avctx->extradata)
                return AVERROR(ENOMEM);
        }

        avctx->extradata_size = esize;
        memcpy(avctx->extradata, gb->buffer + (config_start_bit/8), esize);
        memset(avctx->extradata+esize, 0, FF_INPUT_BUFFER_PADDING_SIZE);
    }
    skip_bits_long(gb, bits_consumed);

    return bits_consumed;
}

static int read_stream_mux_config(struct LATMContext *latmctx,
                                  GetBitContext *gb)
{
    int ret, audio_mux_version = get_bits(gb, 1);

    latmctx->audio_mux_version_A = 0;
    if (audio_mux_version)
        latmctx->audio_mux_version_A = get_bits(gb, 1);

    if (!latmctx->audio_mux_version_A) {

        if (audio_mux_version)
            latm_get_value(gb);                 // taraFullness

        skip_bits(gb, 1);                       // allStreamSameTimeFraming
        skip_bits(gb, 6);                       // numSubFrames
        // numPrograms
        if (get_bits(gb, 4)) {                  // numPrograms
            av_log_missing_feature(latmctx->aac_ctx.avctx,
                                   "Multiple programs", 1);
            return AVERROR_PATCHWELCOME;
        }

        // for each program (which there is only one in DVB)

        // for each layer (which there is only one in DVB)
        if (get_bits(gb, 3)) {                   // numLayer
            av_log_missing_feature(latmctx->aac_ctx.avctx,
                                   "Multiple layers", 1);
            return AVERROR_PATCHWELCOME;
        }

        // for all but first stream: use_same_config = get_bits(gb, 1);
        if (!audio_mux_version) {
            if ((ret = latm_decode_audio_specific_config(latmctx, gb, 0)) < 0)
                return ret;
        } else {
            int ascLen = latm_get_value(gb);
            if ((ret = latm_decode_audio_specific_config(latmctx, gb, ascLen)) < 0)
                return ret;
            ascLen -= ret;
            skip_bits_long(gb, ascLen);
        }

        latmctx->frame_length_type = get_bits(gb, 3);
        switch (latmctx->frame_length_type) {
        case 0:
            skip_bits(gb, 8);       // latmBufferFullness
            break;
        case 1:
            latmctx->frame_length = get_bits(gb, 9);
            break;
        case 3:
        case 4:
        case 5:
            skip_bits(gb, 6);       // CELP frame length table index
            break;
        case 6:
        case 7:
            skip_bits(gb, 1);       // HVXC frame length table index
            break;
        }

        if (get_bits(gb, 1)) {                  // other data
            if (audio_mux_version) {
                latm_get_value(gb);             // other_data_bits
            } else {
                int esc;
                do {
                    esc = get_bits(gb, 1);
                    skip_bits(gb, 8);
                } while (esc);
            }
        }

        if (get_bits(gb, 1))                     // crc present
            skip_bits(gb, 8);                    // config_crc
    }

    return 0;
}

static int read_payload_length_info(struct LATMContext *ctx, GetBitContext *gb)
{
    uint8_t tmp;

    if (ctx->frame_length_type == 0) {
        int mux_slot_length = 0;
        do {
            tmp = get_bits(gb, 8);
            mux_slot_length += tmp;
        } while (tmp == 255);
        return mux_slot_length;
    } else if (ctx->frame_length_type == 1) {
        return ctx->frame_length;
    } else if (ctx->frame_length_type == 3 ||
               ctx->frame_length_type == 5 ||
               ctx->frame_length_type == 7) {
        skip_bits(gb, 2);          // mux_slot_length_coded
    }
    return 0;
}

static int read_audio_mux_element(struct LATMContext *latmctx,
                                  GetBitContext *gb)
{
    int err;
    uint8_t use_same_mux = get_bits(gb, 1);
    if (!use_same_mux) {
        if ((err = read_stream_mux_config(latmctx, gb)) < 0)
            return err;
    } else if (!latmctx->aac_ctx.avctx->extradata) {
        av_log(latmctx->aac_ctx.avctx, AV_LOG_DEBUG,
               "no decoder config found\n");
        return AVERROR(EAGAIN);
    }
    if (latmctx->audio_mux_version_A == 0) {
        int mux_slot_length_bytes = read_payload_length_info(latmctx, gb);
        if (mux_slot_length_bytes * 8 > get_bits_left(gb)) {
            av_log(latmctx->aac_ctx.avctx, AV_LOG_ERROR, "incomplete frame\n");
            return AVERROR_INVALIDDATA;
        } else if (mux_slot_length_bytes * 8 + 256 < get_bits_left(gb)) {
            av_log(latmctx->aac_ctx.avctx, AV_LOG_ERROR,
                   "frame length mismatch %d << %d\n",
                   mux_slot_length_bytes * 8, get_bits_left(gb));
            return AVERROR_INVALIDDATA;
        }
    }
    return 0;
}


static int latm_decode_frame(AVCodecContext *avctx, void *out,
                             int *got_frame_ptr, AVPacket *avpkt)
{
    struct LATMContext *latmctx = avctx->priv_data;
    int                 muxlength, err;
    GetBitContext       gb;

    init_get_bits(&gb, avpkt->data, avpkt->size * 8);

    // check for LOAS sync word
    if (get_bits(&gb, 11) != LOAS_SYNC_WORD)
        return AVERROR_INVALIDDATA;

    muxlength = get_bits(&gb, 13) + 3;
    // not enough data, the parser should have sorted this out
    if (muxlength > avpkt->size)
        return AVERROR_INVALIDDATA;

    if ((err = read_audio_mux_element(latmctx, &gb)) < 0)
        return err;

    if (!latmctx->initialized) {
        if (!avctx->extradata) {
            *got_frame_ptr = 0;
            return avpkt->size;
        } else {
            push_output_configuration(&latmctx->aac_ctx);
            if ((err = decode_audio_specific_config(
                    &latmctx->aac_ctx, avctx, &latmctx->aac_ctx.oc[1].m4ac,
                    avctx->extradata, avctx->extradata_size*8, 1)) < 0) {
                pop_output_configuration(&latmctx->aac_ctx);
                return err;
            }
            latmctx->initialized = 1;
        }
    }

    if (show_bits(&gb, 12) == 0xfff) {
        av_log(latmctx->aac_ctx.avctx, AV_LOG_ERROR,
               "ADTS header detected, probably as result of configuration "
               "misparsing\n");
        return AVERROR_INVALIDDATA;
    }

    if ((err = aac_decode_frame_int(avctx, out, got_frame_ptr, &gb, avpkt)) < 0)
        return err;

    return muxlength;
}

static av_cold int latm_decode_init(AVCodecContext *avctx)
{
    struct LATMContext *latmctx = avctx->priv_data;
    int ret = aac_decode_init(avctx);

    if (avctx->extradata_size > 0)
        latmctx->initialized = !ret;

    return ret;
}


AVCodec ff_aac_decoder = {
    .name            = "aac",
    .type            = AVMEDIA_TYPE_AUDIO,
    .id              = AV_CODEC_ID_AAC,
    .priv_data_size  = sizeof(AACContext),
    .init            = aac_decode_init,
    .close           = aac_decode_close,
    .decode          = aac_decode_frame,
    .long_name       = NULL_IF_CONFIG_SMALL("AAC (Advanced Audio Coding)"),
    .sample_fmts     = (const enum AVSampleFormat[]) {
        AV_SAMPLE_FMT_FLTP, AV_SAMPLE_FMT_NONE
    },
    .capabilities    = CODEC_CAP_CHANNEL_CONF | CODEC_CAP_DR1,
    .channel_layouts = aac_channel_layout,
    .flush = flush,
};

/*
    Note: This decoder filter is intended to decode LATM streams transferred
    in MPEG transport streams which only contain one program.
    To do a more complex LATM demuxing a separate LATM demuxer should be used.
*/
AVCodec ff_aac_latm_decoder = {
    .name            = "aac_latm",
    .type            = AVMEDIA_TYPE_AUDIO,
    .id              = AV_CODEC_ID_AAC_LATM,
    .priv_data_size  = sizeof(struct LATMContext),
    .init            = latm_decode_init,
    .close           = aac_decode_close,
    .decode          = latm_decode_frame,
    .long_name       = NULL_IF_CONFIG_SMALL("AAC LATM (Advanced Audio Coding LATM syntax)"),