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ffmpeg / libavcodec / h261.c @ d2d230a7

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1 c6148de2 Michael Niedermayer
/*
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 * H261 decoder
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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 library 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 of the License, or (at your option) any later version.
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 *
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 * This library 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 this library; if not, write to the Free Software
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 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19 c6148de2 Michael Niedermayer
 */
20
21
/**
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 * @file h261.c
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 * h261codec.
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 */
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#include "common.h"
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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 "h261data.h"
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#define H261_MBA_VLC_BITS 9
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#define H261_MTYPE_VLC_BITS 6
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#define H261_MV_VLC_BITS 7
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#define H261_CBP_VLC_BITS 9
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#define TCOEFF_VLC_BITS 9
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#define MBA_STUFFING 33
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#define MBA_STARTCODE 34
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#define IS_FIL(a)    ((a)&MB_TYPE_H261_FIL)
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43
/**
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 * H261Context
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 */
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typedef struct H261Context{
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    MpegEncContext s;
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    int current_mba;
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    int previous_mba;
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    int mba_diff;
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    int mtype;
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    int current_mv_x;
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    int current_mv_y;
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    int gob_number;
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    int gob_start_code_skipped; // 1 if gob start code is already read before gob header is read
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}H261Context;
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void ff_h261_loop_filter(MpegEncContext *s){
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    H261Context * h= (H261Context*)s;
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    const int linesize  = s->linesize;
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    const int uvlinesize= s->uvlinesize;
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    uint8_t *dest_y = s->dest[0];
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    uint8_t *dest_cb= s->dest[1];
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    uint8_t *dest_cr= s->dest[2];
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    if(!(IS_FIL (h->mtype)))
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        return;
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    s->dsp.h261_loop_filter(dest_y                   , linesize);
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    s->dsp.h261_loop_filter(dest_y                + 8, linesize);
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    s->dsp.h261_loop_filter(dest_y + 8 * linesize    , linesize);
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    s->dsp.h261_loop_filter(dest_y + 8 * linesize + 8, linesize);
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    s->dsp.h261_loop_filter(dest_cb, uvlinesize);
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    s->dsp.h261_loop_filter(dest_cr, uvlinesize);
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}
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static 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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}
89
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static void h261_encode_block(H261Context * h, DCTELEM * block,
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                              int n);
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static int h261_decode_block(H261Context *h, DCTELEM *block,
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                             int n, int coded);
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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 = pbBufPtr(&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_bits(&s->pb, 5, temp_ref & 0x1f); /* 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;
127
}
128
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/**
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 * Encodes 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;
134
    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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    }
167
}
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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){
173
        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])
190
{
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    int i, cbp;
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    cbp= 0;
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    for (i = 0; i < 6; i++) {
194
        if (s->block_last_index[i] >= 0)
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            cbp |= 1 << (5 - i);
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    }
197
    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)
202
{
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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 */
228
    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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230 1c3990db Michael Niedermayer
    /* calculate MTYPE */
231
    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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246
    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);
261
        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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        put_bits(&s->pb,h261_cbp_tab[cbp-1][1],h261_cbp_tab[cbp-1][0]);
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    }
269
    for(i=0; i<6; i++) {
270
        /* encode each block */
271
        h261_encode_block(h, block[i], i);
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    }
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274
    if ( ( h->current_mba == 11 ) || ( h->current_mba == 22 ) || ( h->current_mba == 33 ) || ( !IS_16X16 ( h->mtype ) )){
275
        h->current_mv_x=0;
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        h->current_mv_y=0;
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    }
278
}
279
280
void ff_h261_encode_init(MpegEncContext *s){
281
    static int done = 0;
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283 1c3990db Michael Niedermayer
    if (!done) {
284
        done = 1;
285 073c2593 Burkhard Plaum
        init_rl(&h261_rl_tcoeff, 1);
286 1c3990db Michael Niedermayer
    }
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288
    s->min_qcoeff= -127;
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    s->max_qcoeff=  127;
290
    s->y_dc_scale_table=
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    s->c_dc_scale_table= ff_mpeg1_dc_scale_table;
292
}
293
294
295
/**
296
 * encodes a 8x8 block.
297
 * @param block the 8x8 block
298
 * @param n block index (0-3 are luma, 4-5 are chroma)
299
 */
300
static void h261_encode_block(H261Context * h, DCTELEM * block, int n){
301
    MpegEncContext * const s = &h->s;
302
    int level, run, last, i, j, last_index, last_non_zero, sign, slevel, code;
303
    RLTable *rl;
304
305
    rl = &h261_rl_tcoeff;
306
    if (s->mb_intra) {
307
        /* DC coef */
308
        level = block[0];
309
        /* 255 cannot be represented, so we clamp */
310
        if (level > 254) {
311
            level = 254;
312
            block[0] = 254;
313
        }
314
        /* 0 cannot be represented also */
315
        else if (level < 1) {
316
            level = 1;
317
            block[0] = 1;
318
        }
319
        if (level == 128)
320
            put_bits(&s->pb, 8, 0xff);
321
        else
322
            put_bits(&s->pb, 8, level);
323
        i = 1;
324
    } else if((block[0]==1 || block[0] == -1) && (s->block_last_index[n] > -1)){
325
        //special case
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        put_bits(&s->pb,2,block[0]>0 ? 2 : 3 );
327 1c3990db Michael Niedermayer
        i = 1;
328
    } else {
329
        i = 0;
330
    }
331 115329f1 Diego Biurrun
332 1c3990db Michael Niedermayer
    /* AC coefs */
333
    last_index = s->block_last_index[n];
334
    last_non_zero = i - 1;
335
    for (; i <= last_index; i++) {
336
        j = s->intra_scantable.permutated[i];
337
        level = block[j];
338
        if (level) {
339
            run = i - last_non_zero - 1;
340
            last = (i == last_index);
341
            sign = 0;
342
            slevel = level;
343
            if (level < 0) {
344
                sign = 1;
345
                level = -level;
346
            }
347
            code = get_rl_index(rl, 0 /*no last in H.261, EOB is used*/, run, level);
348
            if(run==0 && level < 16)
349
            code+=1;
350
            put_bits(&s->pb, rl->table_vlc[code][1], rl->table_vlc[code][0]);
351
            if (code == rl->n) {
352
                put_bits(&s->pb, 6, run);
353
                assert(slevel != 0);
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                assert(level <= 127);
355 1c3990db Michael Niedermayer
                put_bits(&s->pb, 8, slevel & 0xff);
356
            } else {
357
                put_bits(&s->pb, 1, sign);
358
            }
359
            last_non_zero = i;
360
        }
361
    }
362
    if(last_index > -1){
363
        put_bits(&s->pb, rl->table_vlc[0][1], rl->table_vlc[0][0]);// END OF BLOCK
364
    }
365
}
366
367 c6148de2 Michael Niedermayer
/***********************************************/
368
/* decoding */
369
370
static VLC h261_mba_vlc;
371
static VLC h261_mtype_vlc;
372
static VLC h261_mv_vlc;
373
static VLC h261_cbp_vlc;
374
375 073c2593 Burkhard Plaum
void init_vlc_rl(RLTable *rl, int use_static);
376 c6148de2 Michael Niedermayer
377
static void h261_decode_init_vlc(H261Context *h){
378
    static int done = 0;
379
380
    if(!done){
381
        done = 1;
382 49e5dcbc Maarten Daniels
        init_vlc(&h261_mba_vlc, H261_MBA_VLC_BITS, 35,
383 c6148de2 Michael Niedermayer
                 h261_mba_bits, 1, 1,
384 073c2593 Burkhard Plaum
                 h261_mba_code, 1, 1, 1);
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        init_vlc(&h261_mtype_vlc, H261_MTYPE_VLC_BITS, 10,
386
                 h261_mtype_bits, 1, 1,
387 073c2593 Burkhard Plaum
                 h261_mtype_code, 1, 1, 1);
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        init_vlc(&h261_mv_vlc, H261_MV_VLC_BITS, 17,
389
                 &h261_mv_tab[0][1], 2, 1,
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                 &h261_mv_tab[0][0], 2, 1, 1);
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        init_vlc(&h261_cbp_vlc, H261_CBP_VLC_BITS, 63,
392
                 &h261_cbp_tab[0][1], 2, 1,
393 073c2593 Burkhard Plaum
                 &h261_cbp_tab[0][0], 2, 1, 1);
394
        init_rl(&h261_rl_tcoeff, 1);
395
        init_vlc_rl(&h261_rl_tcoeff, 1);
396 c6148de2 Michael Niedermayer
    }
397
}
398
399
static int h261_decode_init(AVCodecContext *avctx){
400
    H261Context *h= avctx->priv_data;
401
    MpegEncContext * const s = &h->s;
402
403
    // set defaults
404
    MPV_decode_defaults(s);
405
    s->avctx = avctx;
406
407 21adafec Michael Niedermayer
    s->width  = s->avctx->coded_width;
408
    s->height = s->avctx->coded_height;
409 c6148de2 Michael Niedermayer
    s->codec_id = s->avctx->codec->id;
410
411
    s->out_format = FMT_H261;
412
    s->low_delay= 1;
413
    avctx->pix_fmt= PIX_FMT_YUV420P;
414
415
    s->codec_id= avctx->codec->id;
416
417
    h261_decode_init_vlc(h);
418
419 49e5dcbc Maarten Daniels
    h->gob_start_code_skipped = 0;
420 115329f1 Diego Biurrun
421 c6148de2 Michael Niedermayer
    return 0;
422
}
423
424
/**
425
 * decodes the group of blocks header or slice header.
426
 * @return <0 if an error occured
427
 */
428
static int h261_decode_gob_header(H261Context *h){
429
    unsigned int val;
430
    MpegEncContext * const s = &h->s;
431 115329f1 Diego Biurrun
432 49e5dcbc Maarten Daniels
    if ( !h->gob_start_code_skipped ){
433
        /* Check for GOB Start Code */
434
        val = show_bits(&s->gb, 15);
435
        if(val)
436
            return -1;
437
438
        /* We have a GBSC */
439
        skip_bits(&s->gb, 16);
440
    }
441 c6148de2 Michael Niedermayer
442 49e5dcbc Maarten Daniels
    h->gob_start_code_skipped = 0;
443 c6148de2 Michael Niedermayer
444
    h->gob_number = get_bits(&s->gb, 4); /* GN */
445
    s->qscale = get_bits(&s->gb, 5); /* GQUANT */
446
447 49e5dcbc Maarten Daniels
    /* Check if gob_number is valid */
448
    if (s->mb_height==18){ //cif
449
        if ((h->gob_number<=0) || (h->gob_number>12))
450
            return -1;
451
    }
452
    else{ //qcif
453
        if ((h->gob_number!=1) && (h->gob_number!=3) && (h->gob_number!=5))
454
            return -1;
455
    }
456
457 c6148de2 Michael Niedermayer
    /* GEI */
458
    while (get_bits1(&s->gb) != 0) {
459
        skip_bits(&s->gb, 8);
460
    }
461
462
    if(s->qscale==0)
463
        return -1;
464
465
    // For the first transmitted macroblock in a GOB, MBA is the absolute address. For
466
    // subsequent macroblocks, MBA is the difference between the absolute addresses of
467
    // the macroblock and the last transmitted macroblock.
468
    h->current_mba = 0;
469
    h->mba_diff = 0;
470
471
    return 0;
472
}
473
474
/**
475
 * decodes the group of blocks / video packet header.
476
 * @return <0 if no resync found
477
 */
478
static int ff_h261_resync(H261Context *h){
479
    MpegEncContext * const s = &h->s;
480
    int left, ret;
481
482 49e5dcbc Maarten Daniels
    if ( h->gob_start_code_skipped ){
483 c6148de2 Michael Niedermayer
        ret= h261_decode_gob_header(h);
484
        if(ret>=0)
485
            return 0;
486
    }
487 49e5dcbc Maarten Daniels
    else{
488 c6148de2 Michael Niedermayer
        if(show_bits(&s->gb, 15)==0){
489
            ret= h261_decode_gob_header(h);
490
            if(ret>=0)
491
                return 0;
492 49e5dcbc Maarten Daniels
        }
493
        //ok, its not where its supposed to be ...
494
        s->gb= s->last_resync_gb;
495
        align_get_bits(&s->gb);
496
        left= s->gb.size_in_bits - get_bits_count(&s->gb);
497
498
        for(;left>15+1+4+5; left-=8){
499
            if(show_bits(&s->gb, 15)==0){
500
                GetBitContext bak= s->gb;
501 c6148de2 Michael Niedermayer
502 49e5dcbc Maarten Daniels
                ret= h261_decode_gob_header(h);
503
                if(ret>=0)
504
                    return 0;
505
506
                s->gb= bak;
507
            }
508
            skip_bits(&s->gb, 8);
509 c6148de2 Michael Niedermayer
        }
510
    }
511
512
    return -1;
513
}
514
515
/**
516 7344c87a Chris Flerackers
 * decodes skipped macroblocks
517 c6148de2 Michael Niedermayer
 * @return 0
518
 */
519 7344c87a Chris Flerackers
static int h261_decode_mb_skipped(H261Context *h, int mba1, int mba2 )
520 c6148de2 Michael Niedermayer
{
521
    MpegEncContext * const s = &h->s;
522
    int i;
523 115329f1 Diego Biurrun
524 c6148de2 Michael Niedermayer
    s->mb_intra = 0;
525 7344c87a Chris Flerackers
526
    for(i=mba1; i<mba2; i++){
527
        int j, xy;
528
529
        s->mb_x= ((h->gob_number-1) % 2) * 11 + i % 11;
530
        s->mb_y= ((h->gob_number-1) / 2) * 3 + i / 11;
531
        xy = s->mb_x + s->mb_y * s->mb_stride;
532
        ff_init_block_index(s);
533
        ff_update_block_index(s);
534
535
        for(j=0;j<6;j++)
536
            s->block_last_index[j] = -1;
537
538
        s->mv_dir = MV_DIR_FORWARD;
539
        s->mv_type = MV_TYPE_16X16;
540
        s->current_picture.mb_type[xy]= MB_TYPE_SKIP | MB_TYPE_16x16 | MB_TYPE_L0;
541
        s->mv[0][0][0] = 0;
542
        s->mv[0][0][1] = 0;
543 160d679c Mike Melanson
        s->mb_skipped = 1;
544 5f6c92d4 Michael Niedermayer
        h->mtype &= ~MB_TYPE_H261_FIL;
545 7344c87a Chris Flerackers
546
        MPV_decode_mb(s, s->block);
547
    }
548
549 c6148de2 Michael Niedermayer
    return 0;
550
}
551
552 b37e98c8 Michael Niedermayer
static int decode_mv_component(GetBitContext *gb, int v){
553
    int mv_diff = get_vlc2(gb, h261_mv_vlc.table, H261_MV_VLC_BITS, 2);
554 49e5dcbc Maarten Daniels
555
    /* check if mv_diff is valid */
556
    if ( mv_diff < 0 )
557
        return v;
558
559 b37e98c8 Michael Niedermayer
    mv_diff = mvmap[mv_diff];
560
561
    if(mv_diff && !get_bits1(gb))
562
        mv_diff= -mv_diff;
563 115329f1 Diego Biurrun
564 b37e98c8 Michael Niedermayer
    v += mv_diff;
565
    if     (v <=-16) v+= 32;
566
    else if(v >= 16) v-= 32;
567
568
    return v;
569
}
570
571 49e5dcbc Maarten Daniels
static int h261_decode_mb(H261Context *h){
572 c6148de2 Michael Niedermayer
    MpegEncContext * const s = &h->s;
573 1499a1f7 Michael Niedermayer
    int i, cbp, xy;
574 c6148de2 Michael Niedermayer
575
    cbp = 63;
576
    // Read mba
577
    do{
578 49e5dcbc Maarten Daniels
        h->mba_diff = get_vlc2(&s->gb, h261_mba_vlc.table, H261_MBA_VLC_BITS, 2);
579
580
        /* Check for slice end */
581
        /* NOTE: GOB can be empty (no MB data) or exist only of MBA_stuffing */
582
        if (h->mba_diff == MBA_STARTCODE){ // start code
583
            h->gob_start_code_skipped = 1;
584
            return SLICE_END;
585
        }
586 c6148de2 Michael Niedermayer
    }
587 49e5dcbc Maarten Daniels
    while( h->mba_diff == MBA_STUFFING ); // stuffing
588 c6148de2 Michael Niedermayer
589 49e5dcbc Maarten Daniels
    if ( h->mba_diff < 0 ){
590
        if ( get_bits_count(&s->gb) + 7 >= s->gb.size_in_bits )
591
            return SLICE_END;
592
593
        av_log(s->avctx, AV_LOG_ERROR, "illegal mba at %d %d\n", s->mb_x, s->mb_y);
594
        return SLICE_ERROR;
595
    }
596 c6148de2 Michael Niedermayer
597 49e5dcbc Maarten Daniels
    h->mba_diff += 1;
598 c6148de2 Michael Niedermayer
    h->current_mba += h->mba_diff;
599
600 49e5dcbc Maarten Daniels
    if ( h->current_mba > MBA_STUFFING )
601
        return SLICE_ERROR;
602 115329f1 Diego Biurrun
603 c6148de2 Michael Niedermayer
    s->mb_x= ((h->gob_number-1) % 2) * 11 + ((h->current_mba-1) % 11);
604
    s->mb_y= ((h->gob_number-1) / 2) * 3 + ((h->current_mba-1) / 11);
605
    xy = s->mb_x + s->mb_y * s->mb_stride;
606
    ff_init_block_index(s);
607
    ff_update_block_index(s);
608
609
    // Read mtype
610
    h->mtype = get_vlc2(&s->gb, h261_mtype_vlc.table, H261_MTYPE_VLC_BITS, 2);
611
    h->mtype = h261_mtype_map[h->mtype];
612
613
    // Read mquant
614
    if ( IS_QUANT ( h->mtype ) ){
615 7344c87a Chris Flerackers
        ff_set_qscale(s, get_bits(&s->gb, 5));
616 c6148de2 Michael Niedermayer
    }
617
618
    s->mb_intra = IS_INTRA4x4(h->mtype);
619
620
    // Read mv
621
    if ( IS_16X16 ( h->mtype ) ){
622
        // Motion vector data is included for all MC macroblocks. MVD is obtained from the macroblock vector by subtracting the
623
        // vector of the preceding macroblock. For this calculation the vector of the preceding macroblock is regarded as zero in the
624
        // following three situations:
625
        // 1) evaluating MVD for macroblocks 1, 12 and 23;
626
        // 2) evaluating MVD for macroblocks in which MBA does not represent a difference of 1;
627
        // 3) MTYPE of the previous macroblock was not MC.
628
        if ( ( h->current_mba == 1 ) || ( h->current_mba == 12 ) || ( h->current_mba == 23 ) ||
629 1499a1f7 Michael Niedermayer
             ( h->mba_diff != 1))
630 c6148de2 Michael Niedermayer
        {
631
            h->current_mv_x = 0;
632
            h->current_mv_y = 0;
633
        }
634
635 b37e98c8 Michael Niedermayer
        h->current_mv_x= decode_mv_component(&s->gb, h->current_mv_x);
636
        h->current_mv_y= decode_mv_component(&s->gb, h->current_mv_y);
637 1499a1f7 Michael Niedermayer
    }else{
638
        h->current_mv_x = 0;
639
        h->current_mv_y = 0;
640 c6148de2 Michael Niedermayer
    }
641
642
    // Read cbp
643
    if ( HAS_CBP( h->mtype ) ){
644
        cbp = get_vlc2(&s->gb, h261_cbp_vlc.table, H261_CBP_VLC_BITS, 2) + 1;
645
    }
646
647
    if(s->mb_intra){
648
        s->current_picture.mb_type[xy]= MB_TYPE_INTRA;
649
        goto intra;
650
    }
651
652
    //set motion vectors
653
    s->mv_dir = MV_DIR_FORWARD;
654
    s->mv_type = MV_TYPE_16X16;
655
    s->current_picture.mb_type[xy]= MB_TYPE_16x16 | MB_TYPE_L0;
656 1499a1f7 Michael Niedermayer
    s->mv[0][0][0] = h->current_mv_x * 2;//gets divided by 2 in motion compensation
657
    s->mv[0][0][1] = h->current_mv_y * 2;
658 c6148de2 Michael Niedermayer
659
intra:
660
    /* decode each block */
661
    if(s->mb_intra || HAS_CBP(h->mtype)){
662 dee6dde6 Michael Niedermayer
        s->dsp.clear_blocks(s->block[0]);
663 c6148de2 Michael Niedermayer
        for (i = 0; i < 6; i++) {
664 49e5dcbc Maarten Daniels
            if (h261_decode_block(h, s->block[i], i, cbp&32) < 0){
665
                return SLICE_ERROR;
666 c6148de2 Michael Niedermayer
            }
667
            cbp+=cbp;
668
        }
669 dee6dde6 Michael Niedermayer
    }else{
670
        for (i = 0; i < 6; i++)
671
            s->block_last_index[i]= -1;
672 c6148de2 Michael Niedermayer
    }
673
674 49e5dcbc Maarten Daniels
    MPV_decode_mb(s, s->block);
675 c6148de2 Michael Niedermayer
676
    return SLICE_OK;
677
}
678
679
/**
680
 * decodes a macroblock
681
 * @return <0 if an error occured
682
 */
683
static int h261_decode_block(H261Context * h, DCTELEM * block,
684
                             int n, int coded)
685
{
686
    MpegEncContext * const s = &h->s;
687
    int code, level, i, j, run;
688
    RLTable *rl = &h261_rl_tcoeff;
689
    const uint8_t *scan_table;
690 115329f1 Diego Biurrun
691 c6148de2 Michael Niedermayer
    // For the variable length encoding there are two code tables, one being used for
692
    // the first transmitted LEVEL in INTER, INTER+MC and INTER+MC+FIL blocks, the second
693
    // for all other LEVELs except the first one in INTRA blocks which is fixed length
694
    // coded with 8 bits.
695
    // NOTE: the two code tables only differ in one VLC so we handle that manually.
696
    scan_table = s->intra_scantable.permutated;
697
    if (s->mb_intra){
698
        /* DC coef */
699
        level = get_bits(&s->gb, 8);
700
        // 0 (00000000b) and -128 (10000000b) are FORBIDDEN
701
        if((level&0x7F) == 0){
702
            av_log(s->avctx, AV_LOG_ERROR, "illegal dc %d at %d %d\n", level, s->mb_x, s->mb_y);
703
            return -1;
704
        }
705
        // The code 1000 0000 is not used, the reconstruction level of 1024 being coded as 1111 1111.
706
        if (level == 255)
707
            level = 128;
708
        block[0] = level;
709
        i = 1;
710
    }else if(coded){
711
        // Run  Level   Code
712
        // EOB                  Not possible for first level when cbp is available (that's why the table is different)
713
        // 0    1               1s
714
        // *    *               0*
715
        int check = show_bits(&s->gb, 2);
716
        i = 0;
717
        if ( check & 0x2 ){
718
            skip_bits(&s->gb, 2);
719
            block[0] = ( check & 0x1 ) ? -1 : 1;
720
            i = 1;
721
        }
722
    }else{
723
        i = 0;
724
    }
725
    if(!coded){
726
        s->block_last_index[n] = i - 1;
727
        return 0;
728
    }
729
    for(;;){
730
        code = get_vlc2(&s->gb, rl->vlc.table, TCOEFF_VLC_BITS, 2);
731
        if (code < 0){
732
            av_log(s->avctx, AV_LOG_ERROR, "illegal ac vlc code at %dx%d\n", s->mb_x, s->mb_y);
733
            return -1;
734
        }
735
        if (code == rl->n) {
736
            /* escape */
737
            // The remaining combinations of (run, level) are encoded with a 20-bit word consisting of 6 bits escape, 6 bits run and 8 bits level.
738
            run = get_bits(&s->gb, 6);
739 5bbad3eb Michael Niedermayer
            level = get_sbits(&s->gb, 8);
740 c6148de2 Michael Niedermayer
        }else if(code == 0){
741
            break;
742
        }else{
743
            run = rl->table_run[code];
744
            level = rl->table_level[code];
745
            if (get_bits1(&s->gb))
746
                level = -level;
747
        }
748
        i += run;
749
        if (i >= 64){
750
            av_log(s->avctx, AV_LOG_ERROR, "run overflow at %dx%d\n", s->mb_x, s->mb_y);
751
            return -1;
752
        }
753
        j = scan_table[i];
754
        block[j] = level;
755
        i++;
756
    }
757 7344c87a Chris Flerackers
    s->block_last_index[n] = i-1;
758 c6148de2 Michael Niedermayer
    return 0;
759
}
760
761
/**
762
 * decodes the H261 picture header.
763
 * @return <0 if no startcode found
764
 */
765 1b47fafd Dieter
static int h261_decode_picture_header(H261Context *h){
766 c6148de2 Michael Niedermayer
    MpegEncContext * const s = &h->s;
767
    int format, i;
768 8c7aaf5b Michael Niedermayer
    uint32_t startcode= 0;
769 c6148de2 Michael Niedermayer
770
    for(i= s->gb.size_in_bits - get_bits_count(&s->gb); i>24; i-=1){
771
        startcode = ((startcode << 1) | get_bits(&s->gb, 1)) & 0x000FFFFF;
772
773
        if(startcode == 0x10)
774
            break;
775
    }
776
777
    if (startcode != 0x10){
778
        av_log(s->avctx, AV_LOG_ERROR, "Bad picture start code\n");
779
        return -1;
780
    }
781
782
    /* temporal reference */
783
    s->picture_number = get_bits(&s->gb, 5); /* picture timestamp */
784
785
    /* PTYPE starts here */
786
    skip_bits1(&s->gb); /* split screen off */
787
    skip_bits1(&s->gb); /* camera  off */
788
    skip_bits1(&s->gb); /* freeze picture release off */
789
790
    format = get_bits1(&s->gb);
791
792
    //only 2 formats possible
793
    if (format == 0){//QCIF
794
        s->width = 176;
795
        s->height = 144;
796
        s->mb_width = 11;
797
        s->mb_height = 9;
798
    }else{//CIF
799
        s->width = 352;
800
        s->height = 288;
801
        s->mb_width = 22;
802
        s->mb_height = 18;
803
    }
804
805
    s->mb_num = s->mb_width * s->mb_height;
806
807
    skip_bits1(&s->gb); /* still image mode off */
808
    skip_bits1(&s->gb); /* Reserved */
809
810
    /* PEI */
811
    while (get_bits1(&s->gb) != 0){
812
        skip_bits(&s->gb, 8);
813
    }
814
815 115329f1 Diego Biurrun
    // h261 has no I-FRAMES, but if we pass I_TYPE for the first frame, the codec crashes if it does
816 49e5dcbc Maarten Daniels
    // not contain all I-blocks (e.g. when a packet is lost)
817
    s->pict_type = P_TYPE;
818 c6148de2 Michael Niedermayer
819
    h->gob_number = 0;
820
    return 0;
821
}
822
823
static int h261_decode_gob(H261Context *h){
824
    MpegEncContext * const s = &h->s;
825 115329f1 Diego Biurrun
826 c6148de2 Michael Niedermayer
    ff_set_qscale(s, s->qscale);
827 7344c87a Chris Flerackers
828
    /* decode mb's */
829 49e5dcbc Maarten Daniels
    while(h->current_mba <= MBA_STUFFING)
830 c6148de2 Michael Niedermayer
    {
831
        int ret;
832
        /* DCT & quantize */
833 49e5dcbc Maarten Daniels
        ret= h261_decode_mb(h);
834 c6148de2 Michael Niedermayer
        if(ret<0){
835
            if(ret==SLICE_END){
836 115329f1 Diego Biurrun
                h261_decode_mb_skipped(h, h->current_mba, 33);
837 c6148de2 Michael Niedermayer
                return 0;
838
            }
839 49e5dcbc Maarten Daniels
            av_log(s->avctx, AV_LOG_ERROR, "Error at MB: %d\n", s->mb_x + s->mb_y*s->mb_stride);
840 c6148de2 Michael Niedermayer
            return -1;
841
        }
842 115329f1 Diego Biurrun
843 7344c87a Chris Flerackers
        h261_decode_mb_skipped(h, h->current_mba-h->mba_diff, h->current_mba-1);
844 c6148de2 Michael Niedermayer
    }
845 115329f1 Diego Biurrun
846 c6148de2 Michael Niedermayer
    return -1;
847
}
848
849
static int h261_find_frame_end(ParseContext *pc, AVCodecContext* avctx, const uint8_t *buf, int buf_size){
850 ccff9da6 Maarten Daniels
    int vop_found, i, j;
851 c6148de2 Michael Niedermayer
    uint32_t state;
852
853
    vop_found= pc->frame_start_found;
854
    state= pc->state;
855 115329f1 Diego Biurrun
856 e7316976 Michael Niedermayer
    for(i=0; i<buf_size && !vop_found; i++){
857
        state= (state<<8) | buf[i];
858
        for(j=0; j<8; j++){
859
            if(((state>>j)&0xFFFFF) == 0x00010){
860
                i++;
861
                vop_found=1;
862
                break;
863 c6148de2 Michael Niedermayer
            }
864
        }
865
    }
866
    if(vop_found){
867
        for(; i<buf_size; i++){
868 e7316976 Michael Niedermayer
            state= (state<<8) | buf[i];
869 c6148de2 Michael Niedermayer
            for(j=0; j<8; j++){
870 e7316976 Michael Niedermayer
                if(((state>>j)&0xFFFFF) == 0x00010){
871 c6148de2 Michael Niedermayer
                    pc->frame_start_found=0;
872 e7316976 Michael Niedermayer
                    pc->state= state>>(2*8);
873
                    return i-1;
874 c6148de2 Michael Niedermayer
                }
875
            }
876
        }
877
    }
878
879
    pc->frame_start_found= vop_found;
880
    pc->state= state;
881
    return END_NOT_FOUND;
882
}
883
884
static int h261_parse(AVCodecParserContext *s,
885
                      AVCodecContext *avctx,
886 115329f1 Diego Biurrun
                      uint8_t **poutbuf, int *poutbuf_size,
887 c6148de2 Michael Niedermayer
                      const uint8_t *buf, int buf_size)
888
{
889
    ParseContext *pc = s->priv_data;
890
    int next;
891 115329f1 Diego Biurrun
892 c6148de2 Michael Niedermayer
    next= h261_find_frame_end(pc,avctx, buf, buf_size);
893
    if (ff_combine_frame(pc, next, (uint8_t **)&buf, &buf_size) < 0) {
894
        *poutbuf = NULL;
895
        *poutbuf_size = 0;
896
        return buf_size;
897
    }
898
    *poutbuf = (uint8_t *)buf;
899
    *poutbuf_size = buf_size;
900
    return next;
901
}
902
903
/**
904
 * returns the number of bytes consumed for building the current frame
905
 */
906
static int get_consumed_bytes(MpegEncContext *s, int buf_size){
907 e7316976 Michael Niedermayer
    int pos= get_bits_count(&s->gb)>>3;
908
    if(pos==0) pos=1; //avoid infinite loops (i doubt thats needed but ...)
909
    if(pos+10>buf_size) pos=buf_size; // oops ;)
910 c6148de2 Michael Niedermayer
911 e7316976 Michael Niedermayer
    return pos;
912 c6148de2 Michael Niedermayer
}
913
914
static int h261_decode_frame(AVCodecContext *avctx,
915
                             void *data, int *data_size,
916
                             uint8_t *buf, int buf_size)
917
{
918
    H261Context *h= avctx->priv_data;
919
    MpegEncContext *s = &h->s;
920
    int ret;
921
    AVFrame *pict = data;
922
923
#ifdef DEBUG
924
    printf("*****frame %d size=%d\n", avctx->frame_number, buf_size);
925
    printf("bytes=%x %x %x %x\n", buf[0], buf[1], buf[2], buf[3]);
926
#endif
927
    s->flags= avctx->flags;
928
    s->flags2= avctx->flags2;
929
930 e7316976 Michael Niedermayer
    h->gob_start_code_skipped=0;
931 c6148de2 Michael Niedermayer
932
retry:
933
934 b658ecfe Michael Niedermayer
    init_get_bits(&s->gb, buf, buf_size*8);
935 c6148de2 Michael Niedermayer
936
    if(!s->context_initialized){
937
        if (MPV_common_init(s) < 0) //we need the idct permutaton for reading a custom matrix
938
            return -1;
939
    }
940
941
    //we need to set current_picture_ptr before reading the header, otherwise we cant store anyting im there
942
    if(s->current_picture_ptr==NULL || s->current_picture_ptr->data[0]){
943
        int i= ff_find_unused_picture(s, 0);
944
        s->current_picture_ptr= &s->picture[i];
945
    }
946
947
    ret = h261_decode_picture_header(h);
948
949
    /* skip if the header was thrashed */
950
    if (ret < 0){
951
        av_log(s->avctx, AV_LOG_ERROR, "header damaged\n");
952
        return -1;
953
    }
954
955 21adafec Michael Niedermayer
    if (s->width != avctx->coded_width || s->height != avctx->coded_height){
956 c6148de2 Michael Niedermayer
        ParseContext pc= s->parse_context; //FIXME move these demuxng hack to avformat
957
        s->parse_context.buffer=0;
958
        MPV_common_end(s);
959
        s->parse_context= pc;
960
    }
961
    if (!s->context_initialized) {
962 21adafec Michael Niedermayer
        avcodec_set_dimensions(avctx, s->width, s->height);
963 c6148de2 Michael Niedermayer
964
        goto retry;
965
    }
966
967
    // for hurry_up==5
968
    s->current_picture.pict_type= s->pict_type;
969
    s->current_picture.key_frame= s->pict_type == I_TYPE;
970
971
    /* skip everything if we are in a hurry>=5 */
972
    if(avctx->hurry_up>=5) return get_consumed_bytes(s, buf_size);
973 8c3eba7c Michael Niedermayer
    if(  (avctx->skip_frame >= AVDISCARD_NONREF && s->pict_type==B_TYPE)
974
       ||(avctx->skip_frame >= AVDISCARD_NONKEY && s->pict_type!=I_TYPE)
975
       || avctx->skip_frame >= AVDISCARD_ALL)
976
        return get_consumed_bytes(s, buf_size);
977 c6148de2 Michael Niedermayer
978
    if(MPV_frame_start(s, avctx) < 0)
979
        return -1;
980
981
    ff_er_frame_start(s);
982
983
    /* decode each macroblock */
984
    s->mb_x=0;
985
    s->mb_y=0;
986
987
    while(h->gob_number < (s->mb_height==18 ? 12 : 5)){
988
        if(ff_h261_resync(h)<0)
989
            break;
990
        h261_decode_gob(h);
991
    }
992
    MPV_frame_end(s);
993
994
assert(s->current_picture.pict_type == s->current_picture_ptr->pict_type);
995
assert(s->current_picture.pict_type == s->pict_type);
996 e7316976 Michael Niedermayer
    *pict= *(AVFrame*)s->current_picture_ptr;
997 b658ecfe Michael Niedermayer
    ff_print_debug_info(s, pict);
998 c6148de2 Michael Niedermayer
999
    /* Return the Picture timestamp as the frame number */
1000
    /* we substract 1 because it is added on utils.c    */
1001
    avctx->frame_number = s->picture_number - 1;
1002
1003 b658ecfe Michael Niedermayer
    *data_size = sizeof(AVFrame);
1004 c6148de2 Michael Niedermayer
1005 b658ecfe Michael Niedermayer
    return get_consumed_bytes(s, buf_size);
1006 c6148de2 Michael Niedermayer
}
1007
1008
static int h261_decode_end(AVCodecContext *avctx)
1009
{
1010
    H261Context *h= avctx->priv_data;
1011
    MpegEncContext *s = &h->s;
1012
1013
    MPV_common_end(s);
1014
    return 0;
1015
}
1016
1017 8ff53f5b Gianluigi Tiesi
#ifdef CONFIG_ENCODERS
1018 1c3990db Michael Niedermayer
AVCodec h261_encoder = {
1019
    "h261",
1020
    CODEC_TYPE_VIDEO,
1021
    CODEC_ID_H261,
1022
    sizeof(H261Context),
1023
    MPV_encode_init,
1024
    MPV_encode_picture,
1025
    MPV_encode_end,
1026
};
1027 8ff53f5b Gianluigi Tiesi
#endif
1028 1c3990db Michael Niedermayer
1029 c6148de2 Michael Niedermayer
AVCodec h261_decoder = {
1030
    "h261",
1031
    CODEC_TYPE_VIDEO,
1032
    CODEC_ID_H261,
1033
    sizeof(H261Context),
1034
    h261_decode_init,
1035
    NULL,
1036
    h261_decode_end,
1037
    h261_decode_frame,
1038 e7316976 Michael Niedermayer
    CODEC_CAP_DR1,
1039 c6148de2 Michael Niedermayer
};
1040
1041
AVCodecParser h261_parser = {
1042
    { CODEC_ID_H261 },
1043
    sizeof(ParseContext),
1044
    NULL,
1045
    h261_parse,
1046
    ff_parse_close,
1047
};