mpeg12.c

arm平台下的H264编码和解码源代码

                run = SHOW_UBITS(re, &s->gb, 6)+1; LAST_SKIP_BITS(re, &s->gb, 6);
                UPDATE_CACHE(re, &s->gb);
                level = SHOW_SBITS(re, &s->gb, 8); SKIP_BITS(re, &s->gb, 8);
                if (level == -128) {
                    level = SHOW_UBITS(re, &s->gb, 8) - 256; LAST_SKIP_BITS(re, &s->gb, 8);
                } else if (level == 0) {
                    level = SHOW_UBITS(re, &s->gb, 8)      ; LAST_SKIP_BITS(re, &s->gb, 8);
                }
                i += run;
                j = scantable[i];
                if(level<0){
                    level= -level;
                    level= (level*qscale*quant_matrix[j])>>4;
                    level= (level-1)|1;
                    level= -level;
                }else{
                    level= (level*qscale*quant_matrix[j])>>4;
                    level= (level-1)|1;
                }
            }
            if (i > 63){
                av_log(s->avctx, AV_LOG_ERROR, "ac-tex damaged at %d %d\n", s->mb_x, s->mb_y);
                return -1;
            }

            block[j] = level;
        }
        CLOSE_READER(re, &s->gb);
    }
    s->block_last_index[n] = i;
   return 0;
}

static inline int mpeg1_decode_block_inter(MpegEncContext *s, 
                               DCTELEM *block, 
                               int n)
{
    int level, i, j, run;
    RLTable *rl = &rl_mpeg1;
    uint8_t * const scantable= s->intra_scantable.permutated;
    const uint16_t *quant_matrix= s->inter_matrix;
    const int qscale= s->qscale;

    {
        int v;
        OPEN_READER(re, &s->gb);
        i = -1;
        /* special case for the first coef. no need to add a second vlc table */
        UPDATE_CACHE(re, &s->gb);
        v= SHOW_UBITS(re, &s->gb, 2);
        if (v & 2) {
            LAST_SKIP_BITS(re, &s->gb, 2);
            level= (3*qscale*quant_matrix[0])>>5;
            level= (level-1)|1;
            if(v&1)
                level= -level;
            block[0] = level;
            i++;
        }

        /* now quantify & encode AC coefs */
        for(;;) {
            UPDATE_CACHE(re, &s->gb);
            GET_RL_VLC(level, run, re, &s->gb, rl->rl_vlc[0], TEX_VLC_BITS, 2);
            
            if(level == 127){
                break;
            } else if(level != 0) {
                i += run;
                j = scantable[i];
                level= ((level*2+1)*qscale*quant_matrix[j])>>5;
                level= (level-1)|1;
                level = (level ^ SHOW_SBITS(re, &s->gb, 1)) - SHOW_SBITS(re, &s->gb, 1);
                LAST_SKIP_BITS(re, &s->gb, 1);
            } else {
                /* escape */
                run = SHOW_UBITS(re, &s->gb, 6)+1; LAST_SKIP_BITS(re, &s->gb, 6);
                UPDATE_CACHE(re, &s->gb);
                level = SHOW_SBITS(re, &s->gb, 8); SKIP_BITS(re, &s->gb, 8);
                if (level == -128) {
                    level = SHOW_UBITS(re, &s->gb, 8) - 256; LAST_SKIP_BITS(re, &s->gb, 8);
                } else if (level == 0) {
                    level = SHOW_UBITS(re, &s->gb, 8)      ; LAST_SKIP_BITS(re, &s->gb, 8);
                }
                i += run;
                j = scantable[i];
                if(level<0){
                    level= -level;
                    level= ((level*2+1)*qscale*quant_matrix[j])>>5;
                    level= (level-1)|1;
                    level= -level;
                }else{
                    level= ((level*2+1)*qscale*quant_matrix[j])>>5;
                    level= (level-1)|1;
                }
            }
            if (i > 63){
                av_log(s->avctx, AV_LOG_ERROR, "ac-tex damaged at %d %d\n", s->mb_x, s->mb_y);
                return -1;
            }

            block[j] = level;
        }
        CLOSE_READER(re, &s->gb);
    }
    s->block_last_index[n] = i;
    return 0;
}

/* Also does unquantization here, since I will never support mpeg2
   encoding */
static inline int mpeg2_decode_block_non_intra(MpegEncContext *s, 
                               DCTELEM *block, 
                               int n)
{
    int level, i, j, run;
    RLTable *rl = &rl_mpeg1;
    uint8_t * const scantable= s->intra_scantable.permutated;
    const uint16_t *quant_matrix;
    const int qscale= s->qscale;
    int mismatch;

    mismatch = 1;

    {
        int v;
        OPEN_READER(re, &s->gb);
        i = -1;
        if (n < 4)
            quant_matrix = s->inter_matrix;
        else
            quant_matrix = s->chroma_inter_matrix;

        /* special case for the first coef. no need to add a second vlc table */
        UPDATE_CACHE(re, &s->gb);
        v= SHOW_UBITS(re, &s->gb, 2);
        if (v & 2) {
            LAST_SKIP_BITS(re, &s->gb, 2);
            level= (3*qscale*quant_matrix[0])>>5;
            if(v&1)
                level= -level;
            block[0] = level;
            mismatch ^= level;
            i++;
        }

        /* now quantify & encode AC coefs */
        for(;;) {
            UPDATE_CACHE(re, &s->gb);
            GET_RL_VLC(level, run, re, &s->gb, rl->rl_vlc[0], TEX_VLC_BITS, 2);
            
            if(level == 127){
                break;
            } else if(level != 0) {
                i += run;
                j = scantable[i];
                level= ((level*2+1)*qscale*quant_matrix[j])>>5;
                level = (level ^ SHOW_SBITS(re, &s->gb, 1)) - SHOW_SBITS(re, &s->gb, 1);
                LAST_SKIP_BITS(re, &s->gb, 1);
            } else {
                /* escape */
                run = SHOW_UBITS(re, &s->gb, 6)+1; LAST_SKIP_BITS(re, &s->gb, 6);
                UPDATE_CACHE(re, &s->gb);
                level = SHOW_SBITS(re, &s->gb, 12); SKIP_BITS(re, &s->gb, 12);

                i += run;
                j = scantable[i];
                if(level<0){
                    level= ((-level*2+1)*qscale*quant_matrix[j])>>5;
                    level= -level;
                }else{
                    level= ((level*2+1)*qscale*quant_matrix[j])>>5;
                }
            }
            if (i > 63){
                av_log(s->avctx, AV_LOG_ERROR, "ac-tex damaged at %d %d\n", s->mb_x, s->mb_y);
                return -1;
            }
            
            mismatch ^= level;
            block[j] = level;
        }
        CLOSE_READER(re, &s->gb);
    }
    block[63] ^= (mismatch & 1);
    
    s->block_last_index[n] = i;
    return 0;
}

static inline int mpeg2_decode_block_intra(MpegEncContext *s, 
                               DCTELEM *block, 
                               int n)
{
    int level, dc, diff, i, j, run;
    int component;
    RLTable *rl;
    uint8_t * const scantable= s->intra_scantable.permutated;
    const uint16_t *quant_matrix;
    const int qscale= s->qscale;
    int mismatch;

    /* DC coef */
    if (n < 4){
        quant_matrix = s->intra_matrix;
        component = 0; 
    }else{
        quant_matrix = s->chroma_intra_matrix;
        component = (n&1) + 1;
    }
    diff = decode_dc(&s->gb, component);
    if (diff >= 0xffff)
        return -1;
    dc = s->last_dc[component];
    dc += diff;
    s->last_dc[component] = dc;
    block[0] = dc << (3 - s->intra_dc_precision);
    dprintf("dc=%d\n", block[0]);
    mismatch = block[0] ^ 1;
    i = 0;
    if (s->intra_vlc_format)
        rl = &rl_mpeg2;
    else
        rl = &rl_mpeg1;

    {
        OPEN_READER(re, &s->gb);    
        /* now quantify & encode AC coefs */
        for(;;) {
            UPDATE_CACHE(re, &s->gb);
            GET_RL_VLC(level, run, re, &s->gb, rl->rl_vlc[0], TEX_VLC_BITS, 2);
            
            if(level == 127){
                break;
            } else if(level != 0) {
                i += run;
                j = scantable[i];
                level= (level*qscale*quant_matrix[j])>>4;
                level = (level ^ SHOW_SBITS(re, &s->gb, 1)) - SHOW_SBITS(re, &s->gb, 1);
                LAST_SKIP_BITS(re, &s->gb, 1);
            } else {
                /* escape */
                run = SHOW_UBITS(re, &s->gb, 6)+1; LAST_SKIP_BITS(re, &s->gb, 6);
                UPDATE_CACHE(re, &s->gb);
                level = SHOW_SBITS(re, &s->gb, 12); SKIP_BITS(re, &s->gb, 12);
                i += run;
                j = scantable[i];
                if(level<0){
                    level= (-level*qscale*quant_matrix[j])>>4;
                    level= -level;
                }else{
                    level= (level*qscale*quant_matrix[j])>>4;
                }
            }
            if (i > 63){
                av_log(s->avctx, AV_LOG_ERROR, "ac-tex damaged at %d %d\n", s->mb_x, s->mb_y);
                return -1;
            }
            
            mismatch^= level;
            block[j] = level;
        }
        CLOSE_READER(re, &s->gb);
    }
    block[63]^= mismatch&1;
    
    s->block_last_index[n] = i;
    return 0;
}

typedef struct Mpeg1Context {
    MpegEncContext mpeg_enc_ctx;
    int mpeg_enc_ctx_allocated; /* true if decoding context allocated */
    int repeat_field; /* true if we must repeat the field */
    AVPanScan pan_scan; /** some temporary storage for the panscan */
    int slice_count;
    int swap_uv;//indicate VCR2
    int save_aspect_info;

} Mpeg1Context;

static int mpeg_decode_init(AVCodecContext *avctx)
{
    Mpeg1Context *s = avctx->priv_data;
    MpegEncContext *s2 = &s->mpeg_enc_ctx;
    
    MPV_decode_defaults(s2);
    
    s->mpeg_enc_ctx.avctx= avctx;
    s->mpeg_enc_ctx.flags= avctx->flags;
    s->mpeg_enc_ctx.flags2= avctx->flags2;
    common_init(&s->mpeg_enc_ctx);
    init_vlcs();

    s->mpeg_enc_ctx_allocated = 0;
    s->mpeg_enc_ctx.picture_number = 0;
    s->repeat_field = 0;
    s->mpeg_enc_ctx.codec_id= avctx->codec->id;
    return 0;
}

static void quant_matrix_rebuild(uint16_t *matrix, const uint8_t *old_perm, 
                                     const uint8_t *new_perm){
uint16_t temp_matrix[64];
int i;

    memcpy(temp_matrix,matrix,64*sizeof(uint16_t));
    
    for(i=0;i<64;i++){
        matrix[new_perm[i]] = temp_matrix[old_perm[i]];
    }      
}

//Call this function when we know all parameters
//it may be called in different places for mpeg1 and mpeg2
static int mpeg_decode_postinit(AVCodecContext *avctx){
Mpeg1Context *s1 = avctx->priv_data;
MpegEncContext *s = &s1->mpeg_enc_ctx;
uint8_t old_permutation[64];


    if (
    	(s1->mpeg_enc_ctx_allocated == 0)|| 
        avctx->width  != s->width ||
        avctx->height != s->height||
//      s1->save_aspect_info != avctx->aspect_ratio_info||
        0)
    {
    
        if (s1->mpeg_enc_ctx_allocated) {
            MPV_common_end(s);
        }

	if( (s->width == 0 )||(s->height == 0))
	    return -2;

        avctx->width = s->width;
        avctx->height = s->height;
        avctx->bit_rate = s->bit_rate;
        s1->save_aspect_info = s->aspect_ratio_info;

     //low_delay may be forced, in this case we will have B frames
     //that behave like P frames
        avctx->has_b_frames = !(s->low_delay);

        if(avctx->sub_id==1){//s->codec_id==avctx->codec_id==CODEC_ID
            //mpeg1 fps
            avctx->frame_rate     = frame_rate_tab[s->frame_rate_index].num;
            avctx->frame_rate_base= frame_rate_tab[s->frame_rate_index].den;
            //mpeg1 aspect
            avctx->sample_aspect_ratio= av_d2q(
                    1.0/mpeg1_aspect[s->aspect_ratio_info], 255);

        }else{//mpeg2
        //mpeg2 fps
            av_reduce(
                &s->avctx->frame_rate, 
                &s->avctx->frame_rate_base, 
                frame_rate_tab[s->frame_rate_index].num * (s->frame_rate_ext_n+1),
                frame_rate_tab[s->frame_rate_index].den * (s->frame_rate_ext_d+1),
                1<<30);
        //mpeg2 aspect
            if(s->aspect_ratio_info > 1){
#ifdef WINCE
				AVRational rational;
                if( (s1->pan_scan.width == 0 )||(s1->pan_scan.height == 0) )
				{
					rational.num = s->width;
					rational.den = s->height;
                    s->avctx->sample_aspect_ratio= 
                        av_