msmpeg4.c

ffmpeg的完整源代码和作者自己写的文档。不但有在Linux的工程哦

/*
 * MSMPEG4 backend for ffmpeg encoder and decoder
 * Copyright (c) 2001 Fabrice Bellard.
 * Copyright (c) 2002-2004 Michael Niedermayer <[e-mail]>
 *
 * msmpeg4v1 & v2 stuff by Michael Niedermayer <[e-mail]>
 *
 * 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 msmpeg4.c
 * MSMPEG4 backend for ffmpeg encoder and decoder.
 */

#include "avcodec.h"
#include "dsputil.h"
#include "mpegvideo.h"

/*
 * You can also call this codec : MPEG4 with a twist !
 *
 * TODO:
 *        - (encoding) select best mv table (two choices)
 *        - (encoding) select best vlc/dc table
 */
//#define DEBUG

#define DC_VLC_BITS 9
#define CBPY_VLC_BITS 6
#define INTER_INTRA_VLC_BITS 3
#define V1_INTRA_CBPC_VLC_BITS 6
#define V1_INTER_CBPC_VLC_BITS 6
#define V2_INTRA_CBPC_VLC_BITS 3
#define V2_MB_TYPE_VLC_BITS 7
#define MV_VLC_BITS 9
#define V2_MV_VLC_BITS 9
#define TEX_VLC_BITS 9
#define MB_NON_INTRA_VLC_BITS 9
#define MB_INTRA_VLC_BITS 9

#define II_BITRATE 128*1024
#define MBAC_BITRATE 50*1024

#define DEFAULT_INTER_INDEX 3

static uint32_t v2_dc_lum_table[512][2];
static uint32_t v2_dc_chroma_table[512][2];

void ff_msmpeg4_encode_block(MpegEncContext * s, DCTELEM * block, int n);
static inline int msmpeg4_decode_block(MpegEncContext * s, DCTELEM * block,
                                       int n, int coded, const uint8_t *scantable);
static int msmpeg4_decode_dc(MpegEncContext * s, int n, int *dir_ptr);
static int msmpeg4_decode_motion(MpegEncContext * s,
                                 int *mx_ptr, int *my_ptr);
static void init_h263_dc_for_msmpeg4(void);
static inline void msmpeg4_memsetw(short *tab, int val, int n);
#ifdef CONFIG_ENCODERS
static void msmpeg4v2_encode_motion(MpegEncContext * s, int val);
static int get_size_of_code(MpegEncContext * s, RLTable *rl, int last, int run, int level, int intra);
#endif //CONFIG_ENCODERS
static int msmpeg4v12_decode_mb(MpegEncContext *s, DCTELEM block[6][64]);
static int msmpeg4v34_decode_mb(MpegEncContext *s, DCTELEM block[6][64]);
static int wmv2_decode_mb(MpegEncContext *s, DCTELEM block[6][64]);

/* vc1 externs */
extern uint8_t wmv3_dc_scale_table[32];

#ifdef DEBUG
int intra_count = 0;
int frame_count = 0;
#endif

#include "msmpeg4data.h"

#ifdef CONFIG_ENCODERS //strangely gcc includes this even if it is not references
static uint8_t rl_length[NB_RL_TABLES][MAX_LEVEL+1][MAX_RUN+1][2];
#endif //CONFIG_ENCODERS

static uint8_t static_rl_table_store[NB_RL_TABLES][2][2*MAX_RUN + MAX_LEVEL + 3];

static void common_init(MpegEncContext * s)
{
    static int inited=0;

    switch(s->msmpeg4_version){
    case 1:
    case 2:
        s->y_dc_scale_table=
        s->c_dc_scale_table= ff_mpeg1_dc_scale_table;
        break;
    case 3:
        if(s->workaround_bugs){
            s->y_dc_scale_table= old_ff_y_dc_scale_table;
            s->c_dc_scale_table= old_ff_c_dc_scale_table;
        } else{
            s->y_dc_scale_table= ff_mpeg4_y_dc_scale_table;
            s->c_dc_scale_table= ff_mpeg4_c_dc_scale_table;
        }
        break;
    case 4:
    case 5:
        s->y_dc_scale_table= wmv1_y_dc_scale_table;
        s->c_dc_scale_table= wmv1_c_dc_scale_table;
        break;
#if defined(CONFIG_WMV3_DECODER)||defined(CONFIG_VC1_DECODER)
    case 6:
        s->y_dc_scale_table= wmv3_dc_scale_table;
        s->c_dc_scale_table= wmv3_dc_scale_table;
        break;
#endif

    }


    if(s->msmpeg4_version>=4){
        ff_init_scantable(s->dsp.idct_permutation, &s->intra_scantable  , wmv1_scantable[1]);
        ff_init_scantable(s->dsp.idct_permutation, &s->intra_h_scantable, wmv1_scantable[2]);
        ff_init_scantable(s->dsp.idct_permutation, &s->intra_v_scantable, wmv1_scantable[3]);
        ff_init_scantable(s->dsp.idct_permutation, &s->inter_scantable  , wmv1_scantable[0]);
    }
    //Note the default tables are set in common_init in mpegvideo.c

    if(!inited){
        inited=1;

        init_h263_dc_for_msmpeg4();
    }
}

#ifdef CONFIG_ENCODERS

/* build the table which associate a (x,y) motion vector to a vlc */
static void init_mv_table(MVTable *tab)
{
    int i, x, y;

    tab->table_mv_index = av_malloc(sizeof(uint16_t) * 4096);
    /* mark all entries as not used */
    for(i=0;i<4096;i++)
        tab->table_mv_index[i] = tab->n;

    for(i=0;i<tab->n;i++) {
        x = tab->table_mvx[i];
        y = tab->table_mvy[i];
        tab->table_mv_index[(x << 6) | y] = i;
    }
}

void ff_code012(PutBitContext *pb, int n)
{
    if (n == 0) {
        put_bits(pb, 1, 0);
    } else {
        put_bits(pb, 1, 1);
        put_bits(pb, 1, (n >= 2));
    }
}

void ff_msmpeg4_encode_init(MpegEncContext *s)
{
    static int init_done=0;
    int i;

    common_init(s);
    if(s->msmpeg4_version>=4){
        s->min_qcoeff= -255;
        s->max_qcoeff=  255;
    }

    if (!init_done) {
        /* init various encoding tables */
        init_done = 1;
        init_mv_table(&mv_tables[0]);
        init_mv_table(&mv_tables[1]);
        for(i=0;i<NB_RL_TABLES;i++)
            init_rl(&rl_table[i], static_rl_table_store[i]);

        for(i=0; i<NB_RL_TABLES; i++){
            int level;
            for(level=0; level<=MAX_LEVEL; level++){
                int run;
                for(run=0; run<=MAX_RUN; run++){
                    int last;
                    for(last=0; last<2; last++){
                        rl_length[i][level][run][last]= get_size_of_code(s, &rl_table[  i], last, run, level, 0);
                    }
                }
            }
        }
    }
}

static int get_size_of_code(MpegEncContext * s, RLTable *rl, int last, int run, int level, int intra){
    int size=0;
    int code;
    int run_diff= intra ? 0 : 1;

    code = get_rl_index(rl, last, run, level);
    size+= rl->table_vlc[code][1];
    if (code == rl->n) {
        int level1, run1;

        level1 = level - rl->max_level[last][run];
        if (level1 < 1)
            goto esc2;
        code = get_rl_index(rl, last, run, level1);
        if (code == rl->n) {
            esc2:
            size++;
            if (level > MAX_LEVEL)
                goto esc3;
            run1 = run - rl->max_run[last][level] - run_diff;
            if (run1 < 0)
                goto esc3;
            code = get_rl_index(rl, last, run1, level);
            if (code == rl->n) {
            esc3:
                /* third escape */
                size+=1+1+6+8;
            } else {
                /* second escape */
                size+= 1+1+ rl->table_vlc[code][1];
            }
        } else {
            /* first escape */
            size+= 1+1+ rl->table_vlc[code][1];
        }
    } else {
        size++;
    }
    return size;
}

void ff_find_best_tables(MpegEncContext * s)
{
    int i;
    int best       =-1, best_size       =9999999;
    int chroma_best=-1, best_chroma_size=9999999;

    for(i=0; i<3; i++){
        int level;
        int chroma_size=0;
        int size=0;

        if(i>0){// ;)
            size++;
            chroma_size++;
        }
        for(level=0; level<=MAX_LEVEL; level++){
            int run;
            for(run=0; run<=MAX_RUN; run++){
                int last;
                const int last_size= size + chroma_size;
                for(last=0; last<2; last++){
                    int inter_count       = s->ac_stats[0][0][level][run][last] + s->ac_stats[0][1][level][run][last];
                    int intra_luma_count  = s->ac_stats[1][0][level][run][last];
                    int intra_chroma_count= s->ac_stats[1][1][level][run][last];

                    if(s->pict_type==I_TYPE){
                        size       += intra_luma_count  *rl_length[i  ][level][run][last];
                        chroma_size+= intra_chroma_count*rl_length[i+3][level][run][last];
                    }else{
                        size+=        intra_luma_count  *rl_length[i  ][level][run][last]
                                     +intra_chroma_count*rl_length[i+3][level][run][last]
                                     +inter_count       *rl_length[i+3][level][run][last];
                    }
                }
                if(last_size == size+chroma_size) break;
            }
        }
        if(size<best_size){
            best_size= size;
            best= i;
        }
        if(chroma_size<best_chroma_size){
            best_chroma_size= chroma_size;
            chroma_best= i;
        }
    }

//    printf("type:%d, best:%d, qp:%d, var:%d, mcvar:%d, size:%d //\n",
//           s->pict_type, best, s->qscale, s->mb_var_sum, s->mc_mb_var_sum, best_size);

    if(s->pict_type==P_TYPE) chroma_best= best;

    memset(s->ac_stats, 0, sizeof(int)*(MAX_LEVEL+1)*(MAX_RUN+1)*2*2*2);

    s->rl_table_index       =        best;
    s->rl_chroma_table_index= chroma_best;

    if(s->pict_type != s->last_non_b_pict_type){
        s->rl_table_index= 2;
        if(s->pict_type==I_TYPE)
            s->rl_chroma_table_index= 1;
        else
            s->rl_chroma_table_index= 2;
    }

}

/* write MSMPEG4 compatible frame header */
void msmpeg4_encode_picture_header(MpegEncContext * s, int picture_number)
{
    ff_find_best_tables(s);

    align_put_bits(&s->pb);
    put_bits(&s->pb, 2, s->pict_type - 1);

    put_bits(&s->pb, 5, s->qscale);
    if(s->msmpeg4_version<=2){
        s->rl_table_index = 2;
        s->rl_chroma_table_index = 2;
    }

    s->dc_table_index = 1;
    s->mv_table_index = 1; /* only if P frame */
    s->use_skip_mb_code = 1; /* only if P frame */
    s->per_mb_rl_table = 0;
    if(s->msmpeg4_version==4)
        s->inter_intra_pred= (s->width*s->height < 320*240 && s->bit_rate<=II_BITRATE && s->pict_type==P_TYPE);
//printf("%d %d %d %d %d\n", s->pict_type, s->bit_rate, s->inter_intra_pred, s->width, s->height);

    if (s->pict_type == I_TYPE) {
        s->slice_height= s->mb_height/1;
        put_bits(&s->pb, 5, 0x16 + s->mb_height/s->slice_height);

        if(s->msmpeg4_version==4){
            msmpeg4_encode_ext_header(s);
            if(s->bit_rate>MBAC_BITRATE)
                put_bits(&s->pb, 1, s->per_mb_rl_table);
        }

        if(s->msmpeg4_version>2){
            if(!s->per_mb_rl_table){
                ff_code012(&s->pb, s->rl_chroma_table_index);
                ff_code012(&s->pb, s->rl_table_index);
            }

            put_bits(&s->pb, 1, s->dc_table_index);
        }
    } else {
        put_bits(&s->pb, 1, s->use_skip_mb_code);

        if(s->msmpeg4_version==4 && s->bit_rate>MBAC_BITRATE)
            put_bits(&s->pb, 1, s->per_mb_rl_table);

        if(s->msmpeg4_version>2){
            if(!s->per_mb_rl_table)
                ff_code012(&s->pb, s->rl_table_index);

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

            put_bits(&s->pb, 1, s->mv_table_index);
        }
    }

    s->esc3_level_length= 0;
    s->esc3_run_length= 0;

#ifdef DEBUG
    intra_count = 0;
    av_log(s->avctx, AV_LOG_DEBUG, "*****frame %d:\n", frame_count++);
#endif
}

void msmpeg4_encode_ext_header(MpegEncContext * s)
{
        put_bits(&s->pb, 5, s->avctx->time_base.den / s->avctx->time_base.num); //yes 29.97 -> 29

        put_bits(&s->pb, 11, FFMIN(s->bit_rate/1024, 2047));

        if(s->msmpeg4_version>=3)
            put_bits(&s->pb, 1, s->flipflop_rounding);
        else
            assert(s->flipflop_rounding==0);
}