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ffmpeg / libavcodec / h261enc.c @ 2912e87a

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/*
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 * H261 encoder
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 * Copyright (c) 2002-2004 Michael Niedermayer <michaelni@gmx.at>
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 * Copyright (c) 2004 Maarten Daniels
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 *
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 * This file is part of Libav.
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 *
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 * Libav is free software; you can redistribute it and/or
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 * modify it under the terms of the GNU Lesser General Public
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 * License as published by the Free Software Foundation; either
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 * version 2.1 of the License, or (at your option) any later version.
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 *
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 * Libav is distributed in the hope that it will be useful,
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 * but WITHOUT ANY WARRANTY; without even the implied warranty of
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 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
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 * Lesser General Public License for more details.
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 *
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 * You should have received a copy of the GNU Lesser General Public
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 * License along with Libav; if not, write to the Free Software
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 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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 */
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/**
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 * @file
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 * H.261 encoder.
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 */
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#include "dsputil.h"
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#include "avcodec.h"
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#include "mpegvideo.h"
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#include "h263.h"
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#include "h261.h"
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#include "h261data.h"
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extern uint8_t ff_h261_rl_table_store[2][2*MAX_RUN + MAX_LEVEL + 3];
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static void h261_encode_block(H261Context * h, DCTELEM * block,
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                              int n);
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int ff_h261_get_picture_format(int width, int height){
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    // QCIF
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    if (width == 176 && height == 144)
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        return 0;
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    // CIF
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    else if (width == 352 && height == 288)
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        return 1;
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    // ERROR
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    else
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        return -1;
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}
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void ff_h261_encode_picture_header(MpegEncContext * s, int picture_number){
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    H261Context * h = (H261Context *) s;
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    int format, temp_ref;
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    align_put_bits(&s->pb);
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    /* Update the pointer to last GOB */
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    s->ptr_lastgob = put_bits_ptr(&s->pb);
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    put_bits(&s->pb, 20, 0x10); /* PSC */
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    temp_ref= s->picture_number * (int64_t)30000 * s->avctx->time_base.num /
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                         (1001 * (int64_t)s->avctx->time_base.den); //FIXME maybe this should use a timestamp
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    put_sbits(&s->pb, 5, temp_ref); /* TemporalReference */
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    put_bits(&s->pb, 1, 0); /* split screen off */
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    put_bits(&s->pb, 1, 0); /* camera  off */
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    put_bits(&s->pb, 1, 0); /* freeze picture release off */
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    format = ff_h261_get_picture_format(s->width, s->height);
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    put_bits(&s->pb, 1, format); /* 0 == QCIF, 1 == CIF */
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    put_bits(&s->pb, 1, 0); /* still image mode */
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    put_bits(&s->pb, 1, 0); /* reserved */
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    put_bits(&s->pb, 1, 0); /* no PEI */
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    if(format == 0)
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        h->gob_number = -1;
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    else
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        h->gob_number = 0;
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    h->current_mba = 0;
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}
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/**
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 * Encode a group of blocks header.
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 */
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static void h261_encode_gob_header(MpegEncContext * s, int mb_line){
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    H261Context * h = (H261Context *)s;
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    if(ff_h261_get_picture_format(s->width, s->height) == 0){
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        h->gob_number+=2; // QCIF
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    }
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    else{
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        h->gob_number++; // CIF
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    }
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    put_bits(&s->pb, 16, 1); /* GBSC */
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    put_bits(&s->pb, 4, h->gob_number); /* GN */
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    put_bits(&s->pb, 5, s->qscale); /* GQUANT */
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    put_bits(&s->pb, 1, 0); /* no GEI */
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    h->current_mba = 0;
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    h->previous_mba = 0;
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    h->current_mv_x=0;
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    h->current_mv_y=0;
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}
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void ff_h261_reorder_mb_index(MpegEncContext* s){
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    int index= s->mb_x + s->mb_y*s->mb_width;
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    if(index % 33 == 0)
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        h261_encode_gob_header(s,0);
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    /* for CIF the GOB's are fragmented in the middle of a scanline
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       that's why we need to adjust the x and y index of the macroblocks */
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    if(ff_h261_get_picture_format(s->width,s->height) == 1){ // CIF
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        s->mb_x =     index % 11 ; index /= 11;
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        s->mb_y =     index %  3 ; index /=  3;
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        s->mb_x+= 11*(index %  2); index /=  2;
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        s->mb_y+=  3*index;
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        ff_init_block_index(s);
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        ff_update_block_index(s);
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    }
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}
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static void h261_encode_motion(H261Context * h, int val){
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    MpegEncContext * const s = &h->s;
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    int sign, code;
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    if(val==0){
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        code = 0;
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        put_bits(&s->pb,h261_mv_tab[code][1],h261_mv_tab[code][0]);
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    }
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    else{
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        if(val > 15)
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            val -=32;
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        if(val < -16)
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            val+=32;
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        sign = val < 0;
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        code = sign ? -val : val;
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        put_bits(&s->pb,h261_mv_tab[code][1],h261_mv_tab[code][0]);
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        put_bits(&s->pb,1,sign);
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    }
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}
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static inline int get_cbp(MpegEncContext * s,
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                      DCTELEM block[6][64])
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{
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    int i, cbp;
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    cbp= 0;
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    for (i = 0; i < 6; i++) {
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        if (s->block_last_index[i] >= 0)
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            cbp |= 1 << (5 - i);
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    }
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    return cbp;
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}
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void ff_h261_encode_mb(MpegEncContext * s,
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         DCTELEM block[6][64],
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         int motion_x, int motion_y)
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{
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    H261Context * h = (H261Context *)s;
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    int mvd, mv_diff_x, mv_diff_y, i, cbp;
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    cbp = 63; // avoid warning
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    mvd = 0;
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    h->current_mba++;
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    h->mtype = 0;
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    if (!s->mb_intra){
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        /* compute cbp */
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        cbp= get_cbp(s, block);
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        /* mvd indicates if this block is motion compensated */
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        mvd = motion_x | motion_y;
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        if((cbp | mvd | s->dquant ) == 0) {
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            /* skip macroblock */
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            s->skip_count++;
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            h->current_mv_x=0;
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            h->current_mv_y=0;
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            return;
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        }
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    }
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    /* MB is not skipped, encode MBA */
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    put_bits(&s->pb, h261_mba_bits[(h->current_mba-h->previous_mba)-1], h261_mba_code[(h->current_mba-h->previous_mba)-1]);
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    /* calculate MTYPE */
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    if(!s->mb_intra){
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        h->mtype++;
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        if(mvd || s->loop_filter)
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            h->mtype+=3;
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        if(s->loop_filter)
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            h->mtype+=3;
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        if(cbp || s->dquant)
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            h->mtype++;
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        assert(h->mtype > 1);
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    }
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    if(s->dquant)
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        h->mtype++;
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    put_bits(&s->pb, h261_mtype_bits[h->mtype], h261_mtype_code[h->mtype]);
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    h->mtype = h261_mtype_map[h->mtype];
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    if(IS_QUANT(h->mtype)){
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        ff_set_qscale(s,s->qscale+s->dquant);
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        put_bits(&s->pb, 5, s->qscale);
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    }
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    if(IS_16X16(h->mtype)){
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        mv_diff_x = (motion_x >> 1) - h->current_mv_x;
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        mv_diff_y = (motion_y >> 1) - h->current_mv_y;
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        h->current_mv_x = (motion_x >> 1);
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        h->current_mv_y = (motion_y >> 1);
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        h261_encode_motion(h,mv_diff_x);
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        h261_encode_motion(h,mv_diff_y);
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    }
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    h->previous_mba = h->current_mba;
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    if(HAS_CBP(h->mtype)){
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        assert(cbp>0);
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        put_bits(&s->pb,h261_cbp_tab[cbp-1][1],h261_cbp_tab[cbp-1][0]);
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    }
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    for(i=0; i<6; i++) {
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        /* encode each block */
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        h261_encode_block(h, block[i], i);
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    }
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    if ( ( h->current_mba == 11 ) || ( h->current_mba == 22 ) || ( h->current_mba == 33 ) || ( !IS_16X16 ( h->mtype ) )){
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        h->current_mv_x=0;
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        h->current_mv_y=0;
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    }
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}
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void ff_h261_encode_init(MpegEncContext *s){
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    static int done = 0;
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    if (!done) {
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        done = 1;
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        init_rl(&h261_rl_tcoeff, ff_h261_rl_table_store);
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    }
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    s->min_qcoeff= -127;
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    s->max_qcoeff=  127;
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    s->y_dc_scale_table=
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    s->c_dc_scale_table= ff_mpeg1_dc_scale_table;
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}
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/**
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 * encodes a 8x8 block.
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 * @param block the 8x8 block
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 * @param n block index (0-3 are luma, 4-5 are chroma)
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 */
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static void h261_encode_block(H261Context * h, DCTELEM * block, int n){
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    MpegEncContext * const s = &h->s;
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    int level, run, i, j, last_index, last_non_zero, sign, slevel, code;
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    RLTable *rl;
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    rl = &h261_rl_tcoeff;
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    if (s->mb_intra) {
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        /* DC coef */
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        level = block[0];
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        /* 255 cannot be represented, so we clamp */
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        if (level > 254) {
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            level = 254;
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            block[0] = 254;
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        }
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        /* 0 cannot be represented also */
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        else if (level < 1) {
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            level = 1;
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            block[0] = 1;
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        }
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        if (level == 128)
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            put_bits(&s->pb, 8, 0xff);
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        else
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            put_bits(&s->pb, 8, level);
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        i = 1;
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    } else if((block[0]==1 || block[0] == -1) && (s->block_last_index[n] > -1)){
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        //special case
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        put_bits(&s->pb,2,block[0]>0 ? 2 : 3 );
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        i = 1;
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    } else {
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        i = 0;
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    }
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    /* AC coefs */
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    last_index = s->block_last_index[n];
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    last_non_zero = i - 1;
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    for (; i <= last_index; i++) {
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        j = s->intra_scantable.permutated[i];
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        level = block[j];
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        if (level) {
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            run = i - last_non_zero - 1;
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            sign = 0;
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            slevel = level;
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            if (level < 0) {
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                sign = 1;
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                level = -level;
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            }
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            code = get_rl_index(rl, 0 /*no last in H.261, EOB is used*/, run, level);
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            if(run==0 && level < 16)
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            code+=1;
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            put_bits(&s->pb, rl->table_vlc[code][1], rl->table_vlc[code][0]);
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            if (code == rl->n) {
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                put_bits(&s->pb, 6, run);
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                assert(slevel != 0);
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                assert(level <= 127);
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                put_sbits(&s->pb, 8, slevel);
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            } else {
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                put_bits(&s->pb, 1, sign);
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            }
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            last_non_zero = i;
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        }
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    }
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    if(last_index > -1){
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        put_bits(&s->pb, rl->table_vlc[0][1], rl->table_vlc[0][0]);// END OF BLOCK
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    }
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}
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AVCodec ff_h261_encoder = {
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    "h261",
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    AVMEDIA_TYPE_VIDEO,
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    CODEC_ID_H261,
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    sizeof(H261Context),
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    MPV_encode_init,
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    MPV_encode_picture,
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    MPV_encode_end,
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    .pix_fmts= (const enum PixelFormat[]){PIX_FMT_YUV420P, PIX_FMT_NONE},
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    .long_name= NULL_IF_CONFIG_SMALL("H.261"),
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};
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