PeerStreamer

/*

 * H261 encoder

 * Copyright (c) 2002-2004 Michael Niedermayer <michaelni@gmx.at>

 * 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 "dsputil.h"

#include "avcodec.h"

#include "mpegvideo.h"

#include "h263.h"

#include "h261.h"

#include "h261data.h"

extern uint8_t ff_h261_rl_table_store[2][2*MAX_RUN + MAX_LEVEL + 3];

static void h261_encode_block(H261Context * h, DCTELEM * block,

                              int n);

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;

    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,h261_mv_tab[code][1],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,h261_mv_tab[code][1],h261_mv_tab[code][0]);

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

    }

}

static inline int get_cbp(MpegEncContext * s,

                      DCTELEM 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;

}

void ff_h261_encode_mb(MpegEncContext * s,

         DCTELEM 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, h261_mba_bits[(h->current_mba-h->previous_mba)-1], 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++;

        assert(h->mtype > 1);

    }

    if(s->dquant)

        h->mtype++;

    put_bits(&s->pb, h261_mtype_bits[h->mtype], h261_mtype_code[h->mtype]);

    h->mtype = 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)){

        assert(cbp>0);

        put_bits(&s->pb,h261_cbp_tab[cbp-1][1],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;

    }

}

void ff_h261_encode_init(MpegEncContext *s){

    static int done = 0;

    if (!done) {

        done = 1;

        init_rl(&h261_rl_tcoeff, ff_h261_rl_table_store);

    }

    s->min_qcoeff= -127;

    s->max_qcoeff=  127;

    s->y_dc_scale_table=

    s->c_dc_scale_table= ff_mpeg1_dc_scale_table;

}

/**

 * encodes a 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, DCTELEM * block, int n){

    MpegEncContext * const s = &h->s;

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

    RLTable *rl;

    rl = &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);

                assert(slevel != 0);

                assert(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]);// END OF BLOCK

    }

}

AVCodec ff_h261_encoder = {

    "h261",

    AVMEDIA_TYPE_VIDEO,

    CODEC_ID_H261,

    sizeof(H261Context),

    MPV_encode_init,

    MPV_encode_picture,

    MPV_encode_end,

    .pix_fmts= (const enum PixelFormat[]){PIX_FMT_YUV420P, PIX_FMT_NONE},

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

};