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/*

 * H261 encoder

 * Copyright (c) 2002-2004 Michael Niedermayer 

 * Copyright (c) 2004 Maarten Daniels

 *

 * This file is part of FFmpeg.

 *

 * FFmpeg is free software; you can redistribute it and/or

 * modify it under the terms of the GNU Lesser General Public

 * License as published by the Free Software Foundation; either

 * version 2.1 of the License, or (at your option) any later version.

 *

 * FFmpeg 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

 * Lesser General Public License for more details.

 *

 * You should have received a copy of the GNU Lesser General Public

 * License along with FFmpeg; if not, write to the Free Software

 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

 */

/**

 * @file

 * H.261 encoder.

 */

#include "libavutil/attributes.h"

#include "libavutil/avassert.h"

#include "avcodec.h"

#include "mpegvideo.h"

#include "h263.h"

#include "h261.h"

int ff_h261_get_picture_format(int width, int height)

{

    // QCIF

    if (width == 176 && height == 144)

        return 0;

    // CIF

    else if (width == 352 && height == 288)

        return 1;

    // ERROR

    else

        return -1;

}

void ff_h261_encode_picture_header(MpegEncContext *s, int picture_number)

{

    H261Context *h = (H261Context *)s;

    int format, temp_ref;

    avpriv_align_put_bits(&s->pb);

    /* Update the pointer to last GOB */

    s->ptr_lastgob = put_bits_ptr(&s->pb);

    put_bits(&s->pb, 20, 0x10); /* PSC */

    temp_ref = s->picture_number * (int64_t)30000 * s->avctx->time_base.num /

               (1001 * (int64_t)s->avctx->time_base.den);   // FIXME maybe this should use a timestamp

    put_sbits(&s->pb, 5, temp_ref); /* TemporalReference */

    put_bits(&s->pb, 1, 0); /* split screen off */

    put_bits(&s->pb, 1, 0); /* camera  off */

    put_bits(&s->pb, 1, 0); /* freeze picture release off */

    format = ff_h261_get_picture_format(s->width, s->height);

    put_bits(&s->pb, 1, format); /* 0 == QCIF, 1 == CIF */

    put_bits(&s->pb, 1, 0); /* still image mode */

    put_bits(&s->pb, 1, 0); /* reserved */

    put_bits(&s->pb, 1, 0); /* no PEI */

    if (format == 0)

        h->gob_number = -1;

    else

        h->gob_number = 0;

    h->current_mba = 0;

}

/**

 * Encode a group of blocks header.

 */

static void h261_encode_gob_header(MpegEncContext *s, int mb_line)

{

    H261Context *h = (H261Context *)s;

    if (ff_h261_get_picture_format(s->width, s->height) == 0) {

        h->gob_number += 2; // QCIF

    } else {

        h->gob_number++;    // CIF

    }

    put_bits(&s->pb, 16, 1);            /* GBSC */

    put_bits(&s->pb, 4, h->gob_number); /* GN */

    put_bits(&s->pb, 5, s->qscale);     /* GQUANT */

    put_bits(&s->pb, 1, 0);             /* no GEI */

    h->current_mba  = 0;

    h->previous_mba = 0;

    h->current_mv_x = 0;

    h->current_mv_y = 0;

}

void ff_h261_reorder_mb_index(MpegEncContext *s)

{

    int index = s->mb_x + s->mb_y * s->mb_width;

    if (index % 33 == 0)

        h261_encode_gob_header(s, 0);

    /* for CIF the GOB's are fragmented in the middle of a scanline

     * that's why we need to adjust the x and y index of the macroblocks */

    if (ff_h261_get_picture_format(s->width, s->height) == 1) { // CIF

        s->mb_x  = index % 11;

        index   /= 11;

        s->mb_y  = index % 3;

        index   /= 3;

        s->mb_x += 11 * (index % 2);

        index   /= 2;

        s->mb_y += 3 * index;

        ff_init_block_index(s);

        ff_update_block_index(s);

    }

}

static void h261_encode_motion(H261Context *h, int val)

{

    MpegEncContext *const s = &h->s;

    int sign, code;

    if (val == 0) {

        code = 0;

        put_bits(&s->pb, ff_h261_mv_tab[code][1], ff_h261_mv_tab[code][0]);

    } else {

        if (val > 15)

            val -= 32;

        if (val < -16)

            val += 32;

        sign = val < 0;

        code = sign ? -val : val;

        put_bits(&s->pb, ff_h261_mv_tab[code][1], ff_h261_mv_tab[code][0]);

        put_bits(&s->pb, 1, sign);

    }

}

static inline int get_cbp(MpegEncContext *s, int16_t block[6][64])

{

    int i, cbp;

    cbp = 0;

    for (i = 0; i < 6; i++)

        if (s->block_last_index[i] >= 0)

            cbp |= 1 << (5 - i);

    return cbp;

}

/**

 * Encode an 8x8 block.

 * @param block the 8x8 block

 * @param n block index (0-3 are luma, 4-5 are chroma)

 */

static void h261_encode_block(H261Context *h, int16_t *block, int n)

{

    MpegEncContext *const s = &h->s;

    int level, run, i, j, last_index, last_non_zero, sign, slevel, code;

    RLTable *rl;

    rl = &ff_h261_rl_tcoeff;

    if (s->mb_intra) {

        /* DC coef */

        level = block[0];

        /* 255 cannot be represented, so we clamp */

        if (level > 254) {

            level    = 254;

            block[0] = 254;

        }

        /* 0 cannot be represented also */

        else if (level < 1) {

            level    = 1;

            block[0] = 1;

        }

        if (level == 128)

            put_bits(&s->pb, 8, 0xff);

        else

            put_bits(&s->pb, 8, level);

        i = 1;

    } else if ((block[0] == 1 || block[0] == -1) &&

               (s->block_last_index[n] > -1)) {

        // special case

        put_bits(&s->pb, 2, block[0] > 0 ? 2 : 3);

        i = 1;

    } else {

        i = 0;

    }

    /* AC coefs */

    last_index    = s->block_last_index[n];

    last_non_zero = i - 1;

    for (; i <= last_index; i++) {

        j     = s->intra_scantable.permutated[i];

        level = block[j];

        if (level) {

            run    = i - last_non_zero - 1;

            sign   = 0;

            slevel = level;

            if (level < 0) {

                sign  = 1;

                level = -level;

            }

            code = get_rl_index(rl, 0 /*no last in H.261, EOB is used*/,

                                run, level);

            if (run == 0 && level < 16)

                code += 1;

            put_bits(&s->pb, rl->table_vlc[code][1], rl->table_vlc[code][0]);

            if (code == rl->n) {

                put_bits(&s->pb, 6, run);

                av_assert1(slevel != 0);

                av_assert1(level <= 127);

                put_sbits(&s->pb, 8, slevel);

            } else {

                put_bits(&s->pb, 1, sign);

            }

            last_non_zero = i;

        }

    }

    if (last_index > -1)

        put_bits(&s->pb, rl->table_vlc[0][1], rl->table_vlc[0][0]); // EOB

}

void ff_h261_encode_mb(MpegEncContext *s, int16_t block[6][64],

                       int motion_x, int motion_y)

{

    H261Context *h = (H261Context *)s;

    int mvd, mv_diff_x, mv_diff_y, i, cbp;

    cbp = 63; // avoid warning

    mvd = 0;

    h->current_mba++;

    h->mtype = 0;

    if (!s->mb_intra) {

        /* compute cbp */

        cbp = get_cbp(s, block);

        /* mvd indicates if this block is motion compensated */

        mvd = motion_x | motion_y;

        if ((cbp | mvd | s->dquant) == 0) {

            /* skip macroblock */

            s->skip_count++;

            h->current_mv_x = 0;

            h->current_mv_y = 0;

            return;

        }

    }

    /* MB is not skipped, encode MBA */

    put_bits(&s->pb,

             ff_h261_mba_bits[(h->current_mba - h->previous_mba) - 1],

             ff_h261_mba_code[(h->current_mba - h->previous_mba) - 1]);

    /* calculate MTYPE */

    if (!s->mb_intra) {

        h->mtype++;

        if (mvd || s->loop_filter)

            h->mtype += 3;

        if (s->loop_filter)

            h->mtype += 3;

        if (cbp || s->dquant)

            h->mtype++;

        av_assert1(h->mtype > 1);

    }

    if (s->dquant)

        h->mtype++;

    put_bits(&s->pb,

             ff_h261_mtype_bits[h->mtype],

             ff_h261_mtype_code[h->mtype]);

    h->mtype = ff_h261_mtype_map[h->mtype];

    if (IS_QUANT(h->mtype)) {

        ff_set_qscale(s, s->qscale + s->dquant);

        put_bits(&s->pb, 5, s->qscale);

    }

    if (IS_16X16(h->mtype)) {

        mv_diff_x       = (motion_x >> 1) - h->current_mv_x;

        mv_diff_y       = (motion_y >> 1) - h->current_mv_y;

        h->current_mv_x = (motion_x >> 1);

        h->current_mv_y = (motion_y >> 1);

        h261_encode_motion(h, mv_diff_x);

        h261_encode_motion(h, mv_diff_y);

    }

    h->previous_mba = h->current_mba;

    if (HAS_CBP(h->mtype)) {

        av_assert1(cbp > 0);

        put_bits(&s->pb,

                 ff_h261_cbp_tab[cbp - 1][1],

                 ff_h261_cbp_tab[cbp - 1][0]);

    }

    for (i = 0; i < 6; i++)

        /* encode each block */

        h261_encode_block(h, block[i], i);

    if ((h->current_mba == 11) || (h->current_mba == 22) ||

        (h->current_mba == 33) || (!IS_16X16(h->mtype))) {

        h->current_mv_x = 0;

        h->current_mv_y = 0;

    }

}

av_cold void ff_h261_encode_init(MpegEncContext *s)

{

    ff_h261_common_init();

    s->min_qcoeff       = -127;

    s->max_qcoeff       = 127;

    s->y_dc_scale_table =

    s->c_dc_scale_table = ff_mpeg1_dc_scale_table;

}

FF_MPV_GENERIC_CLASS(h261)

AVCodec ff_h261_encoder = {

    .name           = "h261",

    .long_name      = NULL_IF_CONFIG_SMALL("H.261"),

    .type           = AVMEDIA_TYPE_VIDEO,

    .id             = AV_CODEC_ID_H261,

    .priv_data_size = sizeof(H261Context),

    .init           = ff_MPV_encode_init,

    .encode2        = ff_MPV_encode_picture,

    .close          = ff_MPV_encode_end,

    .pix_fmts       = (const enum AVPixelFormat[]) { AV_PIX_FMT_YUV420P,

                                                     AV_PIX_FMT_NONE },

    .priv_class     = &h261_class,

};