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

    for(i=0; i<count; i++){
        READ_2PIX(s->temp[0][2*i  ], s->temp[1][i], 1);
        READ_2PIX(s->temp[0][2*i+1], s->temp[2][i], 2);
    }
}

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

    count/=2;

    for(i=0; i<count; i++){
        READ_2PIX(s->temp[0][2*i  ], s->temp[0][2*i+1], 0);
    }
}

#ifdef CONFIG_ENCODERS
static int encode_422_bitstream(HYuvContext *s, int count){
    int i;

    if(s->pb.buf_end - s->pb.buf - (put_bits_count(&s->pb)>>3) < 2*4*count){
        av_log(s->avctx, AV_LOG_ERROR, "encoded frame too large\n");
        return -1;
    }

#define LOAD4\
            int y0 = s->temp[0][2*i];\
            int y1 = s->temp[0][2*i+1];\
            int u0 = s->temp[1][i];\
            int v0 = s->temp[2][i];

    count/=2;
    if(s->flags&CODEC_FLAG_PASS1){
        for(i=0; i<count; i++){
            LOAD4;
            s->stats[0][y0]++;
            s->stats[1][u0]++;
            s->stats[0][y1]++;
            s->stats[2][v0]++;
        }
    }
    if(s->avctx->flags2&CODEC_FLAG2_NO_OUTPUT)
        return 0;
    if(s->context){
        for(i=0; i<count; i++){
            LOAD4;
            s->stats[0][y0]++;
            put_bits(&s->pb, s->len[0][y0], s->bits[0][y0]);
            s->stats[1][u0]++;
            put_bits(&s->pb, s->len[1][u0], s->bits[1][u0]);
            s->stats[0][y1]++;
            put_bits(&s->pb, s->len[0][y1], s->bits[0][y1]);
            s->stats[2][v0]++;
            put_bits(&s->pb, s->len[2][v0], s->bits[2][v0]);
        }
    }else{
        for(i=0; i<count; i++){
            LOAD4;
            put_bits(&s->pb, s->len[0][y0], s->bits[0][y0]);
            put_bits(&s->pb, s->len[1][u0], s->bits[1][u0]);
            put_bits(&s->pb, s->len[0][y1], s->bits[0][y1]);
            put_bits(&s->pb, s->len[2][v0], s->bits[2][v0]);
        }
    }
    return 0;
}

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

    if(s->pb.buf_end - s->pb.buf - (put_bits_count(&s->pb)>>3) < 4*count){
        av_log(s->avctx, AV_LOG_ERROR, "encoded frame too large\n");
        return -1;
    }

#define LOAD2\
            int y0 = s->temp[0][2*i];\
            int y1 = s->temp[0][2*i+1];
#define STAT2\
            s->stats[0][y0]++;\
            s->stats[0][y1]++;
#define WRITE2\
            put_bits(&s->pb, s->len[0][y0], s->bits[0][y0]);\
            put_bits(&s->pb, s->len[0][y1], s->bits[0][y1]);

    count/=2;
    if(s->flags&CODEC_FLAG_PASS1){
        for(i=0; i<count; i++){
            LOAD2;
            STAT2;
        }
    }
    if(s->avctx->flags2&CODEC_FLAG2_NO_OUTPUT)
        return 0;

    if(s->context){
        for(i=0; i<count; i++){
            LOAD2;
            STAT2;
            WRITE2;
        }
    }else{
        for(i=0; i<count; i++){
            LOAD2;
            WRITE2;
        }
    }
    return 0;
}
#endif /* CONFIG_ENCODERS */

static av_always_inline void decode_bgr_1(HYuvContext *s, int count, int decorrelate, int alpha){
    int i;
    for(i=0; i<count; i++){
        int code = get_vlc2(&s->gb, s->vlc[3].table, VLC_BITS, 1);
        if(code != -1){
            *(uint32_t*)&s->temp[0][4*i] = s->pix_bgr_map[code];
        }else if(decorrelate){
            s->temp[0][4*i+G] = get_vlc2(&s->gb, s->vlc[1].table, VLC_BITS, 3);
            s->temp[0][4*i+B] = get_vlc2(&s->gb, s->vlc[0].table, VLC_BITS, 3) + s->temp[0][4*i+G];
            s->temp[0][4*i+R] = get_vlc2(&s->gb, s->vlc[2].table, VLC_BITS, 3) + s->temp[0][4*i+G];
        }else{
            s->temp[0][4*i+B] = get_vlc2(&s->gb, s->vlc[0].table, VLC_BITS, 3);
            s->temp[0][4*i+G] = get_vlc2(&s->gb, s->vlc[1].table, VLC_BITS, 3);
            s->temp[0][4*i+R] = get_vlc2(&s->gb, s->vlc[2].table, VLC_BITS, 3);
        }
        if(alpha)
            get_vlc2(&s->gb, s->vlc[2].table, VLC_BITS, 3); //?!
    }
}

static void decode_bgr_bitstream(HYuvContext *s, int count){
    if(s->decorrelate){
        if(s->bitstream_bpp==24)
            decode_bgr_1(s, count, 1, 0);
        else
            decode_bgr_1(s, count, 1, 1);
    }else{
        if(s->bitstream_bpp==24)
            decode_bgr_1(s, count, 0, 0);
        else
            decode_bgr_1(s, count, 0, 1);
    }
}

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

    if(s->pb.buf_end - s->pb.buf - (put_bits_count(&s->pb)>>3) < 3*4*count){
        av_log(s->avctx, AV_LOG_ERROR, "encoded frame too large\n");
        return -1;
    }

#define LOAD3\
            int g= s->temp[0][4*i+G];\
            int b= (s->temp[0][4*i+B] - g) & 0xff;\
            int r= (s->temp[0][4*i+R] - g) & 0xff;
#define STAT3\
            s->stats[0][b]++;\
            s->stats[1][g]++;\
            s->stats[2][r]++;
#define WRITE3\
            put_bits(&s->pb, s->len[1][g], s->bits[1][g]);\
            put_bits(&s->pb, s->len[0][b], s->bits[0][b]);\
            put_bits(&s->pb, s->len[2][r], s->bits[2][r]);

    if((s->flags&CODEC_FLAG_PASS1) && (s->avctx->flags2&CODEC_FLAG2_NO_OUTPUT)){
        for(i=0; i<count; i++){
            LOAD3;
            STAT3;
        }
    }else if(s->context || (s->flags&CODEC_FLAG_PASS1)){
        for(i=0; i<count; i++){
            LOAD3;
            STAT3;
            WRITE3;
        }
    }else{
        for(i=0; i<count; i++){
            LOAD3;
            WRITE3;
        }
    }
    return 0;
}

#ifdef CONFIG_DECODERS
static void draw_slice(HYuvContext *s, int y){
    int h, cy;
    int offset[4];

    if(s->avctx->draw_horiz_band==NULL)
        return;

    h= y - s->last_slice_end;
    y -= h;

    if(s->bitstream_bpp==12){
        cy= y>>1;
    }else{
        cy= y;
    }

    offset[0] = s->picture.linesize[0]*y;
    offset[1] = s->picture.linesize[1]*cy;
    offset[2] = s->picture.linesize[2]*cy;
    offset[3] = 0;
    emms_c();

    s->avctx->draw_horiz_band(s->avctx, &s->picture, offset, y, 3, h);

    s->last_slice_end= y + h;
}

static int decode_frame(AVCodecContext *avctx, void *data, int *data_size, uint8_t *buf, int buf_size){
    HYuvContext *s = avctx->priv_data;
    const int width= s->width;
    const int width2= s->width>>1;
    const int height= s->height;
    int fake_ystride, fake_ustride, fake_vstride;
    AVFrame * const p= &s->picture;
    int table_size= 0;

    AVFrame *picture = data;

    s->bitstream_buffer= av_fast_realloc(s->bitstream_buffer, &s->bitstream_buffer_size, buf_size + FF_INPUT_BUFFER_PADDING_SIZE);

    s->dsp.bswap_buf((uint32_t*)s->bitstream_buffer, (uint32_t*)buf, buf_size/4);

    if(p->data[0])
        avctx->release_buffer(avctx, p);

    p->reference= 0;
    if(avctx->get_buffer(avctx, p) < 0){
        av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
        return -1;
    }

    if(s->context){
        table_size = read_huffman_tables(s, s->bitstream_buffer, buf_size);
        if(table_size < 0)
            return -1;
    }

    if((unsigned)(buf_size-table_size) >= INT_MAX/8)
        return -1;

    init_get_bits(&s->gb, s->bitstream_buffer+table_size, (buf_size-table_size)*8);

    fake_ystride= s->interlaced ? p->linesize[0]*2  : p->linesize[0];
    fake_ustride= s->interlaced ? p->linesize[1]*2  : p->linesize[1];
    fake_vstride= s->interlaced ? p->linesize[2]*2  : p->linesize[2];

    s->last_slice_end= 0;

    if(s->bitstream_bpp<24){
        int y, cy;
        int lefty, leftu, leftv;
        int lefttopy, lefttopu, lefttopv;

        if(s->yuy2){
            p->data[0][3]= get_bits(&s->gb, 8);
            p->data[0][2]= get_bits(&s->gb, 8);
            p->data[0][1]= get_bits(&s->gb, 8);
            p->data[0][0]= get_bits(&s->gb, 8);

            av_log(avctx, AV_LOG_ERROR, "YUY2 output is not implemented yet\n");
            return -1;
        }else{

            leftv= p->data[2][0]= get_bits(&s->gb, 8);
            lefty= p->data[0][1]= get_bits(&s->gb, 8);
            leftu= p->data[1][0]= get_bits(&s->gb, 8);
                   p->data[0][0]= get_bits(&s->gb, 8);

            switch(s->predictor){
            case LEFT:
            case PLANE:
                decode_422_bitstream(s, width-2);
                lefty= add_left_prediction(p->data[0] + 2, s->temp[0], width-2, lefty);
                if(!(s->flags&CODEC_FLAG_GRAY)){
                    leftu= add_left_prediction(p->data[1] + 1, s->temp[1], width2-1, leftu);
                    leftv= add_left_prediction(p->data[2] + 1, s->temp[2], width2-1, leftv);
                }

                for(cy=y=1; y<s->height; y++,cy++){
                    uint8_t *ydst, *udst, *vdst;

                    if(s->bitstream_bpp==12){
                        decode_gray_bitstream(s, width);

                        ydst= p->data[0] + p->linesize[0]*y;

                        lefty= add_left_prediction(ydst, s->temp[0], width, lefty);
                        if(s->predictor == PLANE){
                            if(y>s->interlaced)
                                s->dsp.add_bytes(ydst, ydst - fake_ystride, width);
                        }
                        y++;
                        if(y>=s->height) break;
                    }

                    draw_slice(s, y);

                    ydst= p->data[0] + p->linesize[0]*y;
                    udst= p->data[1] + p->linesize[1]*cy;
                    vdst= p->data[2] + p->linesize[2]*cy;

                    decode_422_bitstream(s, width);
                    lefty= add_left_prediction(ydst, s->temp[0], width, lefty);
                    if(!(s->flags&CODEC_FLAG_GRAY)){
                        leftu= add_left_prediction(udst, s->temp[1], width2, leftu);
                        leftv= add_left_prediction(vdst, s->temp[2], width2, leftv);
                    }
                    if(s->predictor == PLANE){
                        if(cy>s->interlaced){
                            s->dsp.add_bytes(ydst, ydst - fake_ystride, width);
                            if(!(s->flags&CODEC_FLAG_GRAY)){
                                s->dsp.add_bytes(udst, udst - fake_ustride, width2);
                                s->dsp.add_bytes(vdst, vdst - fake_vstride, width2);
                            }
                        }
                    }
                }
                draw_slice(s, height);

                break;
            case MEDIAN:
                /* first line except first 2 pixels is left predicted */
                decode_422_bitstream(s, width-2);
                lefty= add_left_prediction(p->data[0] + 2, s->temp[0], width-2, lefty);
                if(!(s->flags&CODEC_FLAG_GRAY)){
                    leftu= add_left_prediction(p->data[1] + 1, s->temp[1], width2-1, leftu);
                    leftv= add_left_prediction(p->data[2] + 1, s->temp[2], width2-1, leftv);
                }

                cy=y=1;

                /* second line is left predicted for interlaced case */
                if(s->interlaced){
                    decode_422_bitstream(s, width);
                    lefty= add_left_prediction(p->data[0] + p->linesize[0], s->temp[0], width, lefty);
                    if(!(s->flags&CODEC_FLAG_GRAY)){
                        leftu= add_left_prediction(p->data[1] + p->linesize[2], s->temp[1], width2, leftu);
                        leftv= add_left_prediction(p->data[2] + p->linesize[1], s->temp[2], width2, leftv);
                    }
                    y++; cy++;
                }

                /* next 4 pixels are left predicted too */
                decode_422_bitstream(s, 4);
                lefty= add_left_prediction(p->data[0] + fake_ystride, s->temp[0], 4, lefty);
                if(!(s->flags&CODEC_FLAG_GRAY)){
                    leftu= add_left_prediction(p->data[1] + fake_ustride, s->temp[1], 2, leftu);
                    leftv= add_left_prediction(p->data[2] + fake_vstride, s->temp[2], 2, leftv);
                }

                /* next line except the first 4 pixels is median predicted */
                lefttopy= p->data[0][3];
                decode_422_bitstream(s, width-4);
                add_median_prediction(p->data[0] + fake_ystride+4, p->data[0]+4, s->temp[0], width-4, &lefty, &lefttopy);
                if(!(s->flags&CODEC_FLAG_GRAY)){
                    lefttopu= p->data[1][1];
                    lefttopv= p->data[2][1];
                    add_median_prediction(p->data[1] + fake_ustride+2, p->data[1]+2, s->temp[1], width2-2, &leftu, &lefttopu);
                    add_median_prediction(p->data[2] + fake_vstride+2, p->data[2]+2, s->temp[2], width2-2, &leftv, &lefttopv);
                }
                y++; cy++;

                for(; y<height; y++,cy++){
                    uint8_t *ydst, *udst, *vdst;