static int aac_encode_frame(AVCodecContext *avctx,

                            uint8_t *frame, int buf_size, void *data)

{

    AACEncContext *s = avctx->priv_data;

    int16_t *samples = s->samples, *samples2, *la;

    ChannelElement *cpe;

    int i, j, chans, tag, start_ch;

    const uint8_t *chan_map = aac_chan_configs[avctx->channels-1];

    int chan_el_counter[4];

    FFPsyWindowInfo windows[avctx->channels];



    if (s->last_frame)

        return 0;

    if (data) {

        if (!s->psypp) {

            memcpy(s->samples + 1024 * avctx->channels, data,

                   1024 * avctx->channels * sizeof(s->samples[0]));

        } else {

            start_ch = 0;

            samples2 = s->samples + 1024 * avctx->channels;

            for (i = 0; i < chan_map[0]; i++) {

                tag = chan_map[i+1];

                chans = tag == TYPE_CPE ? 2 : 1;

                ff_psy_preprocess(s->psypp, (uint16_t*)data + start_ch,

                                  samples2 + start_ch, start_ch, chans);

                start_ch += chans;

            }

        }

    }

    if (!avctx->frame_number) {

        memcpy(s->samples, s->samples + 1024 * avctx->channels,

               1024 * avctx->channels * sizeof(s->samples[0]));

        return 0;

    }



    start_ch = 0;

    for (i = 0; i < chan_map[0]; i++) {

        FFPsyWindowInfo* wi = windows + start_ch;

        tag      = chan_map[i+1];

        chans    = tag == TYPE_CPE ? 2 : 1;

        cpe      = &s->cpe[i];

        samples2 = samples + start_ch;

        la       = samples2 + 1024 * avctx->channels + start_ch;

        if (!data)

            la = NULL;

        for (j = 0; j < chans; j++) {

            IndividualChannelStream *ics = &cpe->ch[j].ics;

            int k;

            wi[j] = ff_psy_suggest_window(&s->psy, samples2, la, start_ch + j, ics->window_sequence[0]);

            ics->window_sequence[1] = ics->window_sequence[0];

            ics->window_sequence[0] = wi[j].window_type[0];

            ics->use_kb_window[1]   = ics->use_kb_window[0];

            ics->use_kb_window[0]   = wi[j].window_shape;

            ics->num_windows        = wi[j].num_windows;

            ics->swb_sizes          = s->psy.bands    [ics->num_windows == 8];

            ics->num_swb            = s->psy.num_bands[ics->num_windows == 8];

            for (k = 0; k < ics->num_windows; k++)

                ics->group_len[k] = wi[j].grouping[k];



            s->cur_channel = start_ch + j;

            apply_window_and_mdct(avctx, s, &cpe->ch[j], samples2, j);

        }

        start_ch += chans;

    }

    init_put_bits(&s->pb, frame, buf_size*8);

    if ((avctx->frame_number & 0xFF)==1 && !(avctx->flags & CODEC_FLAG_BITEXACT))

        put_bitstream_info(avctx, s, LIBAVCODEC_IDENT);

    start_ch = 0;

    memset(chan_el_counter, 0, sizeof(chan_el_counter));

    for (i = 0; i < chan_map[0]; i++) {

        FFPsyWindowInfo* wi = windows + start_ch;

        tag      = chan_map[i+1];

        chans    = tag == TYPE_CPE ? 2 : 1;

        cpe      = &s->cpe[i];

        for (j = 0; j < chans; j++) {

            s->coder->search_for_quantizers(avctx, s, &cpe->ch[j], s->lambda);

        }

        cpe->common_window = 0;

        if (chans > 1

            && wi[0].window_type[0] == wi[1].window_type[0]

            && wi[0].window_shape   == wi[1].window_shape) {



            cpe->common_window = 1;

            for (j = 0; j < wi[0].num_windows; j++) {

                if (wi[0].grouping[j] != wi[1].grouping[j]) {

                    cpe->common_window = 0;

                    break;

                }

            }

        }

        if (cpe->common_window && s->coder->search_for_ms)

            s->coder->search_for_ms(s, cpe, s->lambda);

        adjust_frame_information(s, cpe, chans);

        put_bits(&s->pb, 3, tag);

        put_bits(&s->pb, 4, chan_el_counter[tag]++);

        if (chans == 2) {

            put_bits(&s->pb, 1, cpe->common_window);

            if (cpe->common_window) {

                put_ics_info(s, &cpe->ch[0].ics);

                encode_ms_info(&s->pb, cpe);

            }

        }

        for (j = 0; j < chans; j++) {

            s->cur_channel = start_ch + j;

            ff_psy_set_band_info(&s->psy, s->cur_channel, cpe->ch[j].coeffs, &wi[j]);

            encode_individual_channel(avctx, s, &cpe->ch[j], cpe->common_window);

        }

        start_ch += chans;

    }



    put_bits(&s->pb, 3, TYPE_END);

    flush_put_bits(&s->pb);

    avctx->frame_bits = put_bits_count(&s->pb);



    // rate control stuff

    if (!(avctx->flags & CODEC_FLAG_QSCALE)) {

        float ratio = avctx->bit_rate * 1024.0f / avctx->sample_rate / avctx->frame_bits;

        s->lambda *= ratio;

        s->lambda = fminf(s->lambda, 65536.f);

    }



    if (avctx->frame_bits > 6144*avctx->channels)

        av_log(avctx, AV_LOG_ERROR, "input buffer violation %d > %d.\n",

               avctx->frame_bits, 6144*avctx->channels);



    if (!data)

        s->last_frame = 1;

    memcpy(s->samples, s->samples + 1024 * avctx->channels,

           1024 * avctx->channels * sizeof(s->samples[0]));

    return put_bits_count(&s->pb)>>3;

}
