ffv1.c

现在关于h.264的源码很多

        put_symbol(c, state, f->chroma_h_shift, 0);
        put_symbol(c, state, f->chroma_v_shift, 0);
    put_rac(c, state, 0); //no transparency plane

    for(i=0; i<5; i++)
        write_quant_table(c, f->quant_table[i]);
}

static int common_init(AVCodecContext *avctx){
    FFV1Context *s = avctx->priv_data;
    int width, height;

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

    dsputil_init(&s->dsp, avctx);

    width= s->width= avctx->width;
    height= s->height= avctx->height;

    assert(width && height);

    return 0;
}

static int encode_init(AVCodecContext *avctx)
{
    FFV1Context *s = avctx->priv_data;
    int i;

    if(avctx->strict_std_compliance >FF_COMPLIANCE_EXPERIMENTAL){
        av_log(avctx, AV_LOG_ERROR, "this codec is under development, files encoded with it may not be decodeable with future versions!!!\n"
               "use vstrict=-2 / -strict -2 to use it anyway\n");
        return -1;
    }

    common_init(avctx);

    s->version=0;
    s->ac= avctx->coder_type;

    s->plane_count=2;
    for(i=0; i<256; i++){
        s->quant_table[0][i]=           quant11[i];
        s->quant_table[1][i]=        11*quant11[i];
        if(avctx->context_model==0){
            s->quant_table[2][i]=     11*11*quant11[i];
            s->quant_table[3][i]=
            s->quant_table[4][i]=0;
        }else{
            s->quant_table[2][i]=     11*11*quant5 [i];
            s->quant_table[3][i]=   5*11*11*quant5 [i];
            s->quant_table[4][i]= 5*5*11*11*quant5 [i];
        }
    }

    for(i=0; i<s->plane_count; i++){
        PlaneContext * const p= &s->plane[i];

        if(avctx->context_model==0){
            p->context_count= (11*11*11+1)/2;
        }else{
            p->context_count= (11*11*5*5*5+1)/2;
        }

        if(s->ac){
            if(!p->state) p->state= av_malloc(CONTEXT_SIZE*p->context_count*sizeof(uint8_t));
        }else{
            if(!p->vlc_state) p->vlc_state= av_malloc(p->context_count*sizeof(VlcState));
        }
    }

    avctx->coded_frame= &s->picture;
    switch(avctx->pix_fmt){
    case PIX_FMT_YUV444P:
    case PIX_FMT_YUV422P:
    case PIX_FMT_YUV420P:
    case PIX_FMT_YUV411P:
    case PIX_FMT_YUV410P:
        s->colorspace= 0;
        break;
    case PIX_FMT_RGBA32:
        s->colorspace= 1;
        break;
    default:
        av_log(avctx, AV_LOG_ERROR, "format not supported\n");
        return -1;
    }
    avcodec_get_chroma_sub_sample(avctx->pix_fmt, &s->chroma_h_shift, &s->chroma_v_shift);

    s->picture_number=0;

    return 0;
}


static void clear_state(FFV1Context *f){
    int i, j;

    for(i=0; i<f->plane_count; i++){
        PlaneContext *p= &f->plane[i];

        p->interlace_bit_state[0]= 128;
        p->interlace_bit_state[1]= 128;

        for(j=0; j<p->context_count; j++){
            if(f->ac){
                memset(p->state[j], 128, sizeof(uint8_t)*CONTEXT_SIZE);
            }else{
                p->vlc_state[j].drift= 0;
                p->vlc_state[j].error_sum= 4; //FFMAX((RANGE + 32)/64, 2);
                p->vlc_state[j].bias= 0;
                p->vlc_state[j].count= 1;
            }
        }
    }
}

static int encode_frame(AVCodecContext *avctx, unsigned char *buf, int buf_size, void *data){
    FFV1Context *f = avctx->priv_data;
    RangeCoder * const c= &f->c;
    AVFrame *pict = data;
    const int width= f->width;
    const int height= f->height;
    AVFrame * const p= &f->picture;
    int used_count= 0;
    uint8_t keystate=128;

    ff_init_range_encoder(c, buf, buf_size);
//    ff_init_cabac_states(c, ff_h264_lps_range, ff_h264_mps_state, ff_h264_lps_state, 64);
    ff_build_rac_states(c, 0.05*(1LL<<32), 256-8);

    *p = *pict;
    p->pict_type= FF_I_TYPE;

    if(avctx->gop_size==0 || f->picture_number % avctx->gop_size == 0){
        put_rac(c, &keystate, 1);
        p->key_frame= 1;
        write_header(f);
        clear_state(f);
    }else{
        put_rac(c, &keystate, 0);
        p->key_frame= 0;
    }

    if(!f->ac){
        used_count += ff_rac_terminate(c);
//printf("pos=%d\n", used_count);
        init_put_bits(&f->pb, buf + used_count, buf_size - used_count);
    }

    if(f->colorspace==0){
        const int chroma_width = -((-width )>>f->chroma_h_shift);
        const int chroma_height= -((-height)>>f->chroma_v_shift);

        encode_plane(f, p->data[0], width, height, p->linesize[0], 0);

        encode_plane(f, p->data[1], chroma_width, chroma_height, p->linesize[1], 1);
        encode_plane(f, p->data[2], chroma_width, chroma_height, p->linesize[2], 1);
    }else{
        encode_rgb_frame(f, (uint32_t*)(p->data[0]), width, height, p->linesize[0]/4);
    }
    emms_c();

    f->picture_number++;

    if(f->ac){
        return ff_rac_terminate(c);
    }else{
        flush_put_bits(&f->pb); //nicer padding FIXME
        return used_count + (put_bits_count(&f->pb)+7)/8;
    }
}

static void common_end(FFV1Context *s){
    int i;

    for(i=0; i<s->plane_count; i++){
        PlaneContext *p= &s->plane[i];

        av_freep(&p->state);
    }
}

static int encode_end(AVCodecContext *avctx)
{
    FFV1Context *s = avctx->priv_data;

    common_end(s);

    return 0;
}

static inline void decode_line(FFV1Context *s, int w, int_fast16_t *sample[2], int plane_index, int bits){
    PlaneContext * const p= &s->plane[plane_index];
    RangeCoder * const c= &s->c;
    int x;
    int run_count=0;
    int run_mode=0;
    int run_index= s->run_index;

    for(x=0; x<w; x++){
        int diff, context, sign;

        context= get_context(s, sample[1] + x, sample[0] + x, sample[1] + x);
        if(context < 0){
            context= -context;
            sign=1;
        }else
            sign=0;


        if(s->ac){
            diff= get_symbol(c, p->state[context], 1);
        }else{
            if(context == 0 && run_mode==0) run_mode=1;

            if(run_mode){
                if(run_count==0 && run_mode==1){
                    if(get_bits1(&s->gb)){
                        run_count = 1<<log2_run[run_index];
                        if(x + run_count <= w) run_index++;
                    }else{
                        if(log2_run[run_index]) run_count = get_bits(&s->gb, log2_run[run_index]);
                        else run_count=0;
                        if(run_index) run_index--;
                        run_mode=2;
                    }
                }
                run_count--;
                if(run_count < 0){
                    run_mode=0;
                    run_count=0;
                    diff= get_vlc_symbol(&s->gb, &p->vlc_state[context], bits);
                    if(diff>=0) diff++;
                }else
                    diff=0;
            }else
                diff= get_vlc_symbol(&s->gb, &p->vlc_state[context], bits);

//            printf("count:%d index:%d, mode:%d, x:%d y:%d pos:%d\n", run_count, run_index, run_mode, x, y, get_bits_count(&s->gb));
        }

        if(sign) diff= -diff;

        sample[1][x]= (predict(sample[1] + x, sample[0] + x) + diff) & ((1<<bits)-1);
    }
    s->run_index= run_index;
}

static void decode_plane(FFV1Context *s, uint8_t *src, int w, int h, int stride, int plane_index){
    int x, y;
    int_fast16_t sample_buffer[2][w+6];
    int_fast16_t *sample[2]= {sample_buffer[0]+3, sample_buffer[1]+3};

    s->run_index=0;

    memset(sample_buffer, 0, sizeof(sample_buffer));

    for(y=0; y<h; y++){
        int_fast16_t *temp= sample[0]; //FIXME try a normal buffer

        sample[0]= sample[1];
        sample[1]= temp;

        sample[1][-1]= sample[0][0  ];
        sample[0][ w]= sample[0][w-1];

//{START_TIMER
        decode_line(s, w, sample, plane_index, 8);
        for(x=0; x<w; x++){
            src[x + stride*y]= sample[1][x];
        }
//STOP_TIMER("decode-line")}
    }
}

static void decode_rgb_frame(FFV1Context *s, uint32_t *src, int w, int h, int stride){
    int x, y, p;
    int_fast16_t sample_buffer[3][2][w+6];
    int_fast16_t *sample[3][2]= {
        {sample_buffer[0][0]+3, sample_buffer[0][1]+3},
        {sample_buffer[1][0]+3, sample_buffer[1][1]+3},
        {sample_buffer[2][0]+3, sample_buffer[2][1]+3}};

    s->run_index=0;

    memset(sample_buffer, 0, sizeof(sample_buffer));

    for(y=0; y<h; y++){
        for(p=0; p<3; p++){
            int_fast16_t *temp= sample[p][0]; //FIXME try a normal buffer

            sample[p][0]= sample[p][1];
            sample[p][1]= temp;

            sample[p][1][-1]= sample[p][0][0  ];
            sample[p][0][ w]= sample[p][0][w-1];
            decode_line(s, w, sample[p], FFMIN(p, 1), 9);
        }
        for(x=0; x<w; x++){
            int g= sample[0][1][x];
            int b= sample[1][1][x];
            int r= sample[2][1][x];

//            assert(g>=0 && b>=0 && r>=0);
//            assert(g<256 && b<512 && r<512);

            b -= 0x100;
            r -= 0x100;
            g -= (b + r)>>2;
            b += g;
            r += g;

            src[x + stride*y]= b + (g<<8) + (r<<16);
        }
    }
}

static int read_quant_table(RangeCoder *c, int16_t *quant_table, int scale){
    int v;
    int i=0;
    uint8_t state[CONTEXT_SIZE];

    memset(state, 128, sizeof(state));

    for(v=0; i<128 ; v++){
        int len= get_symbol(c, state, 0) + 1;

        if(len + i > 128) return -1;

        while(len--){
            quant_table[i] = scale*v;
            i++;
//printf("%2d ",v);
//if(i%16==0) printf("\n");
        }
    }

    for(i=1; i<128; i++){
        quant_table[256-i]= -quant_table[i];
    }
    quant_table[128]= -quant_table[127];

    return 2*v - 1;
}

static int read_header(FFV1Context *f){
    uint8_t state[CONTEXT_SIZE];
    int i, context_count;
    RangeCoder * const c= &f->c;

    memset(state, 128, sizeof(state));

    f->version= get_symbol(c, state, 0);
    f->ac= f->avctx->coder_type= get_symbol(c, state, 0);
    f->colorspace= get_symbol(c, state, 0); //YUV cs type
    get_rac(c, state); //no chroma = false
    f->chroma_h_shift= get_symbol(c, state, 0);
    f->chroma_v_shift= get_symbol(c, state, 0);
    get_rac(c, state); //transparency plane
    f->plane_count= 2;

    if(f->colorspace==0){
        switch(16*f->chroma_h_shift + f->chroma_v_shift){
        case 0x00: f->avctx->pix_fmt= PIX_FMT_YUV444P; break;
        case 0x10: f->avctx->pix_fmt= PIX_FMT_YUV422P; break;
        case 0x11: f->avctx->pix_fmt= PIX_FMT_YUV420P; break;
        case 0x20: f->avctx->pix_fmt= PIX_FMT_YUV411P; break;
        case 0x22: f->avctx->pix_fmt= PIX_FMT_YUV410P; break;
        default:
            av_log(f->avctx, AV_LOG_ERROR, "format not supported\n");
            return -1;
        }
    }else if(f->colorspace==1){
        if(f->chroma_h_shift || f->chroma_v_shift){
            av_log(f->avctx, AV_LOG_ERROR, "chroma subsampling not supported in this colorspace\n");
            return -1;
        }
        f->avctx->pix_fmt= PIX_FMT_RGBA32;
    }else{
        av_log(f->avctx, AV_LOG_ERROR, "colorspace not supported\n");
        return -1;
    }

//printf("%d %d %d\n", f->chroma_h_shift, f->chroma_v_shift,f->avctx->pix_fmt);

    context_count=1;
    for(i=0; i<5; i++){
        context_count*= read_quant_table(c, f->quant_table[i], context_count);
        if(context_count < 0 || context_count > 32768){
            av_log(f->avctx, AV_LOG_ERROR, "read_quant_table error\n");
            return -1;
        }
    }
    context_count= (context_count+1)/2;

    for(i=0; i<f->plane_count; i++){
        PlaneContext * const p= &f->plane[i];

        p->context_count= context_count;

        if(f->ac){
            if(!p->state) p->state= av_malloc(CONTEXT_SIZE*p->context_count*sizeof(uint8_t));
        }else{
            if(!p->vlc_state) p->vlc_state= av_malloc(p->context_count*sizeof(VlcState));
        }
    }

    return 0;
}

static int decode_init(AVCodecContext *avctx)
{
//    FFV1Context *s = avctx->priv_data;

    common_init(avctx);

    return 0;
}

static int decode_frame(AVCodecContext *avctx, void *data, int *data_size, uint8_t *buf, int buf_size){
    FFV1Context *f = avctx->priv_data;
    RangeCoder * const c= &f->c;
    const int width= f->width;
    const int height= f->height;
    AVFrame * const p= &f->picture;
    int bytes_read;
    uint8_t keystate= 128;

    AVFrame *picture = data;

    ff_init_range_decoder(c, buf, buf_size);
    ff_build_rac_states(c, 0.05*(1LL<<32), 256-8);


    p->pict_type= FF_I_TYPE; //FIXME I vs. P
    if(get_rac(c, &keystate)){
        p->key_frame= 1;
        if(read_header(f) < 0)
            return -1;
        clear_state(f);
    }else{
        p->key_frame= 0;
    }
    if(!f->plane[0].state && !f->plane[0].vlc_state)
        return -1;

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

    if(avctx->debug&FF_DEBUG_PICT_INFO)
        av_log(avctx, AV_LOG_ERROR, "keyframe:%d coder:%d\n", p->key_frame, f->ac);

    if(!f->ac){
        bytes_read = c->bytestream - c->bytestream_start - 1;
        if(bytes_read ==0) av_log(avctx, AV_LOG_ERROR, "error at end of AC stream\n"); //FIXME
//printf("pos=%d\n", bytes_read);
        init_get_bits(&f->gb, buf + bytes_read, buf_size - bytes_read);
    } else {
        bytes_read = 0; /* avoid warning */
    }

    if(f->colorspace==0){
        const int chroma_width = -((-width )>>f->chroma_h_shift);
        const int chroma_height= -((-height)>>f->chroma_v_shift);
        decode_plane(f, p->data[0], width, height, p->linesize[0], 0);

        decode_plane(f, p->data[1], chroma_width, chroma_height, p->linesize[1], 1);
        decode_plane(f, p->data[2], chroma_width, chroma_height, p->linesize[2], 1);
    }else{
        decode_rgb_frame(f, (uint32_t*)p->data[0], width, height, p->linesize[0]/4);
    }

    emms_c();

    f->picture_number++;

    *picture= *p;

    avctx->release_buffer(avctx, p); //FIXME

    *data_size = sizeof(AVFrame);

    if(f->ac){
        bytes_read= c->bytestream - c->bytestream_start - 1;
        if(bytes_read ==0) av_log(f->avctx, AV_LOG_ERROR, "error at end of frame\n");
    }else{
        bytes_read+= (get_bits_count(&f->gb)+7)/8;
    }

    return bytes_read;
}

AVCodec ffv1_decoder = {
    "ffv1",
    CODEC_TYPE_VIDEO,
    CODEC_ID_FFV1,
    sizeof(FFV1Context),
    decode_init,
    NULL,
    NULL,
    decode_frame,
    CODEC_CAP_DR1 /*| CODEC_CAP_DRAW_HORIZ_BAND*/,
    NULL
};

#ifdef CONFIG_ENCODERS
AVCodec ffv1_encoder = {
    "ffv1",
    CODEC_TYPE_VIDEO,
    CODEC_ID_FFV1,
    sizeof(FFV1Context),
    encode_init,
    encode_frame,
    encode_end,
};
#endif