huffyuv.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

                        map[i][G] = g;
                        map[i][B] = g+b;
                        map[i][R] = g+r;
                    }else{
                        map[i][B] = g;
                        map[i][G] = b;
                        map[i][R] = r;
                    }
                    i++;
                }
            }
        }
        free_vlc(&s->vlc[3]);
        init_vlc(&s->vlc[3], VLC_BITS, i, len, 1, 1, bits, 2, 2, 0);
    }
}

static int read_huffman_tables(HYuvContext *s, uint8_t *src, int length){
    GetBitContext gb;
    int i;

    init_get_bits(&gb, src, length*8);

    for(i=0; i<3; i++){
        read_len_table(s->len[i], &gb);

        if(generate_bits_table(s->bits[i], s->len[i])<0){
            return -1;
        }
#if 0
for(j=0; j<256; j++){
printf("%6X, %2d,  %3d\n", s->bits[i][j], s->len[i][j], j);
}
#endif
        free_vlc(&s->vlc[i]);
        init_vlc(&s->vlc[i], VLC_BITS, 256, s->len[i], 1, 1, s->bits[i], 4, 4, 0);
    }

    generate_joint_tables(s);

    return (get_bits_count(&gb)+7)/8;
}

static int read_old_huffman_tables(HYuvContext *s){
#if 1
    GetBitContext gb;
    int i;

    init_get_bits(&gb, classic_shift_luma, sizeof(classic_shift_luma)*8);
    read_len_table(s->len[0], &gb);
    init_get_bits(&gb, classic_shift_chroma, sizeof(classic_shift_chroma)*8);
    read_len_table(s->len[1], &gb);

    for(i=0; i<256; i++) s->bits[0][i] = classic_add_luma  [i];
    for(i=0; i<256; i++) s->bits[1][i] = classic_add_chroma[i];

    if(s->bitstream_bpp >= 24){
        memcpy(s->bits[1], s->bits[0], 256*sizeof(uint32_t));
        memcpy(s->len[1] , s->len [0], 256*sizeof(uint8_t));
    }
    memcpy(s->bits[2], s->bits[1], 256*sizeof(uint32_t));
    memcpy(s->len[2] , s->len [1], 256*sizeof(uint8_t));

    for(i=0; i<3; i++){
        free_vlc(&s->vlc[i]);
        init_vlc(&s->vlc[i], VLC_BITS, 256, s->len[i], 1, 1, s->bits[i], 4, 4, 0);
    }

    generate_joint_tables(s);

    return 0;
#else
    av_log(s->avctx, AV_LOG_DEBUG, "v1 huffyuv is not supported \n");
    return -1;
#endif
}

static void alloc_temp(HYuvContext *s){
    int i;

    if(s->bitstream_bpp<24){
        for(i=0; i<3; i++){
            s->temp[i]= av_malloc(s->width + 16);
        }
    }else{
        for(i=0; i<2; i++){
            s->temp[i]= av_malloc(4*s->width + 16);
        }
    }
}

static int common_init(AVCodecContext *avctx){
    HYuvContext *s = avctx->priv_data;

    s->avctx= avctx;
    s->flags= avctx->flags;

    dsputil_init(&s->dsp, avctx);

    s->width= avctx->width;
    s->height= avctx->height;
    assert(s->width>0 && s->height>0);

    return 0;
}

#ifdef CONFIG_DECODERS
static int decode_init(AVCodecContext *avctx)
{
    HYuvContext *s = avctx->priv_data;

    common_init(avctx);
    memset(s->vlc, 0, 3*sizeof(VLC));

    avctx->coded_frame= &s->picture;
    s->interlaced= s->height > 288;

s->bgr32=1;
//if(avctx->extradata)
//  printf("extradata:%X, extradata_size:%d\n", *(uint32_t*)avctx->extradata, avctx->extradata_size);
    if(avctx->extradata_size){
        if((avctx->bits_per_sample&7) && avctx->bits_per_sample != 12)
            s->version=1; // do such files exist at all?
        else
            s->version=2;
    }else
        s->version=0;

    if(s->version==2){
        int method, interlace;

        method= ((uint8_t*)avctx->extradata)[0];
        s->decorrelate= method&64 ? 1 : 0;
        s->predictor= method&63;
        s->bitstream_bpp= ((uint8_t*)avctx->extradata)[1];
        if(s->bitstream_bpp==0)
            s->bitstream_bpp= avctx->bits_per_sample&~7;
        interlace= (((uint8_t*)avctx->extradata)[2] & 0x30) >> 4;
        s->interlaced= (interlace==1) ? 1 : (interlace==2) ? 0 : s->interlaced;
        s->context= ((uint8_t*)avctx->extradata)[2] & 0x40 ? 1 : 0;

        if(read_huffman_tables(s, ((uint8_t*)avctx->extradata)+4, avctx->extradata_size) < 0)
            return -1;
    }else{
        switch(avctx->bits_per_sample&7){
        case 1:
            s->predictor= LEFT;
            s->decorrelate= 0;
            break;
        case 2:
            s->predictor= LEFT;
            s->decorrelate= 1;
            break;
        case 3:
            s->predictor= PLANE;
            s->decorrelate= avctx->bits_per_sample >= 24;
            break;
        case 4:
            s->predictor= MEDIAN;
            s->decorrelate= 0;
            break;
        default:
            s->predictor= LEFT; //OLD
            s->decorrelate= 0;
            break;
        }
        s->bitstream_bpp= avctx->bits_per_sample & ~7;
        s->context= 0;

        if(read_old_huffman_tables(s) < 0)
            return -1;
    }

    switch(s->bitstream_bpp){
    case 12:
        avctx->pix_fmt = PIX_FMT_YUV420P;
        break;
    case 16:
        if(s->yuy2){
            avctx->pix_fmt = PIX_FMT_YUYV422;
        }else{
            avctx->pix_fmt = PIX_FMT_YUV422P;
        }
        break;
    case 24:
    case 32:
        if(s->bgr32){
            avctx->pix_fmt = PIX_FMT_RGB32;
        }else{
            avctx->pix_fmt = PIX_FMT_BGR24;
        }
        break;
    default:
        assert(0);
    }

    alloc_temp(s);

//    av_log(NULL, AV_LOG_DEBUG, "pred:%d bpp:%d hbpp:%d il:%d\n", s->predictor, s->bitstream_bpp, avctx->bits_per_sample, s->interlaced);

    return 0;
}
#endif

#ifdef CONFIG_ENCODERS
static int store_table(HYuvContext *s, uint8_t *len, uint8_t *buf){
    int i;
    int index= 0;

    for(i=0; i<256;){
        int val= len[i];
        int repeat=0;

        for(; i<256 && len[i]==val && repeat<255; i++)
            repeat++;

        assert(val < 32 && val >0 && repeat<256 && repeat>0);
        if(repeat>7){
            buf[index++]= val;
            buf[index++]= repeat;
        }else{
            buf[index++]= val | (repeat<<5);
        }
    }

    return index;
}

static int encode_init(AVCodecContext *avctx)
{
    HYuvContext *s = avctx->priv_data;
    int i, j;

    common_init(avctx);

    avctx->extradata= av_mallocz(1024*30); // 256*3+4 == 772
    avctx->stats_out= av_mallocz(1024*30); // 21*256*3(%llu ) + 3(\n) + 1(0) = 16132
    s->version=2;

    avctx->coded_frame= &s->picture;

    switch(avctx->pix_fmt){
    case PIX_FMT_YUV420P:
        s->bitstream_bpp= 12;
        break;
    case PIX_FMT_YUV422P:
        s->bitstream_bpp= 16;
        break;
    case PIX_FMT_RGB32:
        s->bitstream_bpp= 24;
        break;
    default:
        av_log(avctx, AV_LOG_ERROR, "format not supported\n");
        return -1;
    }
    avctx->bits_per_sample= s->bitstream_bpp;
    s->decorrelate= s->bitstream_bpp >= 24;
    s->predictor= avctx->prediction_method;
    s->interlaced= avctx->flags&CODEC_FLAG_INTERLACED_ME ? 1 : 0;
    if(avctx->context_model==1){
        s->context= avctx->context_model;
        if(s->flags & (CODEC_FLAG_PASS1|CODEC_FLAG_PASS2)){
            av_log(avctx, AV_LOG_ERROR, "context=1 is not compatible with 2 pass huffyuv encoding\n");
            return -1;
        }
    }else s->context= 0;

    if(avctx->codec->id==CODEC_ID_HUFFYUV){
        if(avctx->pix_fmt==PIX_FMT_YUV420P){
            av_log(avctx, AV_LOG_ERROR, "Error: YV12 is not supported by huffyuv; use vcodec=ffvhuff or format=422p\n");
            return -1;
        }
        if(avctx->context_model){
            av_log(avctx, AV_LOG_ERROR, "Error: per-frame huffman tables are not supported by huffyuv; use vcodec=ffvhuff\n");
            return -1;
        }
        if(s->interlaced != ( s->height > 288 ))
            av_log(avctx, AV_LOG_INFO, "using huffyuv 2.2.0 or newer interlacing flag\n");
    }

    if(s->bitstream_bpp>=24 && s->predictor==MEDIAN){
        av_log(avctx, AV_LOG_ERROR, "Error: RGB is incompatible with median predictor\n");
        return -1;
    }

    ((uint8_t*)avctx->extradata)[0]= s->predictor | (s->decorrelate << 6);
    ((uint8_t*)avctx->extradata)[1]= s->bitstream_bpp;
    ((uint8_t*)avctx->extradata)[2]= s->interlaced ? 0x10 : 0x20;
    if(s->context)
        ((uint8_t*)avctx->extradata)[2]|= 0x40;
    ((uint8_t*)avctx->extradata)[3]= 0;
    s->avctx->extradata_size= 4;

    if(avctx->stats_in){
        char *p= avctx->stats_in;

        for(i=0; i<3; i++)
            for(j=0; j<256; j++)
                s->stats[i][j]= 1;

        for(;;){
            for(i=0; i<3; i++){
                char *next;

                for(j=0; j<256; j++){
                    s->stats[i][j]+= strtol(p, &next, 0);
                    if(next==p) return -1;
                    p=next;
                }
            }
            if(p[0]==0 || p[1]==0 || p[2]==0) break;
        }
    }else{
        for(i=0; i<3; i++)
            for(j=0; j<256; j++){
                int d= FFMIN(j, 256-j);

                s->stats[i][j]= 100000000/(d+1);
            }
    }

    for(i=0; i<3; i++){
        generate_len_table(s->len[i], s->stats[i], 256);

        if(generate_bits_table(s->bits[i], s->len[i])<0){
            return -1;
        }

        s->avctx->extradata_size+=
        store_table(s, s->len[i], &((uint8_t*)s->avctx->extradata)[s->avctx->extradata_size]);
    }

    if(s->context){
        for(i=0; i<3; i++){
            int pels = s->width*s->height / (i?40:10);
            for(j=0; j<256; j++){
                int d= FFMIN(j, 256-j);
                s->stats[i][j]= pels/(d+1);
            }
        }
    }else{
        for(i=0; i<3; i++)
            for(j=0; j<256; j++)
                s->stats[i][j]= 0;
    }

//    printf("pred:%d bpp:%d hbpp:%d il:%d\n", s->predictor, s->bitstream_bpp, avctx->bits_per_sample, s->interlaced);

    alloc_temp(s);

    s->picture_number=0;

    return 0;
}
#endif /* CONFIG_ENCODERS */

/* TODO instead of restarting the read when the code isn't in the first level
 * of the joint table, jump into the 2nd level of the individual table. */
#define READ_2PIX(dst0, dst1, plane1){\
    uint16_t code = get_vlc2(&s->gb, s->vlc[3+plane1].table, VLC_BITS, 1);\
    if(code != 0xffff){\
        dst0 = code>>8;\
        dst1 = code;\
    }else{\
        dst0 = get_vlc2(&s->gb, s->vlc[0].table, VLC_BITS, 3);\
        dst1 = get_vlc2(&s->gb, s->vlc[plane1].table, VLC_BITS, 3);\
    }\
}

static void decode_422_bitstream(HYuvContext *s, int count){
    int i;

    count/=2;