snow.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

  0,  4, 12, 24, 32, 44, 52, 56, 56, 52, 44, 32, 24, 12,  4,  0,
  0,  0,  4,  8, 12, 16, 20, 20, 20, 20, 16, 12,  8,  4,  0,  0,
  0,  0,  0,  0,  0,  4,  4,  4,  4,  4,  4,  0,  0,  0,  0,  0,
//error:0.000022
};
#endif

//linear *64
static const uint8_t obmc8[64]={
  4, 12, 20, 28, 28, 20, 12,  4,
 12, 36, 60, 84, 84, 60, 36, 12,
 20, 60,100,140,140,100, 60, 20,
 28, 84,140,196,196,140, 84, 28,
 28, 84,140,196,196,140, 84, 28,
 20, 60,100,140,140,100, 60, 20,
 12, 36, 60, 84, 84, 60, 36, 12,
  4, 12, 20, 28, 28, 20, 12,  4,
//error:0.000000
};

//linear *64
static const uint8_t obmc4[16]={
 16, 48, 48, 16,
 48,144,144, 48,
 48,144,144, 48,
 16, 48, 48, 16,
//error:0.000000
};

static const uint8_t *obmc_tab[4]={
    obmc32, obmc16, obmc8, obmc4
};

static int scale_mv_ref[MAX_REF_FRAMES][MAX_REF_FRAMES];

typedef struct BlockNode{
    int16_t mx;
    int16_t my;
    uint8_t ref;
    uint8_t color[3];
    uint8_t type;
//#define TYPE_SPLIT    1
#define BLOCK_INTRA   1
#define BLOCK_OPT     2
//#define TYPE_NOCOLOR  4
    uint8_t level; //FIXME merge into type?
}BlockNode;

static const BlockNode null_block= { //FIXME add border maybe
    .color= {128,128,128},
    .mx= 0,
    .my= 0,
    .ref= 0,
    .type= 0,
    .level= 0,
};

#define LOG2_MB_SIZE 4
#define MB_SIZE (1<<LOG2_MB_SIZE)
#define ENCODER_EXTRA_BITS 4
#define HTAPS_MAX 8

typedef struct x_and_coeff{
    int16_t x;
    uint16_t coeff;
} x_and_coeff;

typedef struct SubBand{
    int level;
    int stride;
    int width;
    int height;
    int qlog;                                   ///< log(qscale)/log[2^(1/6)]
    DWTELEM *buf;
    IDWTELEM *ibuf;
    int buf_x_offset;
    int buf_y_offset;
    int stride_line; ///< Stride measured in lines, not pixels.
    x_and_coeff * x_coeff;
    struct SubBand *parent;
    uint8_t state[/*7*2*/ 7 + 512][32];
}SubBand;

typedef struct Plane{
    int width;
    int height;
    SubBand band[MAX_DECOMPOSITIONS][4];

    int htaps;
    int8_t hcoeff[HTAPS_MAX/2];
    int diag_mc;
    int fast_mc;

    int last_htaps;
    int8_t last_hcoeff[HTAPS_MAX/2];
    int last_diag_mc;
}Plane;

typedef struct SnowContext{
//    MpegEncContext m; // needed for motion estimation, should not be used for anything else, the idea is to make the motion estimation eventually independent of MpegEncContext, so this will be removed then (FIXME/XXX)

    AVCodecContext *avctx;
    RangeCoder c;
    DSPContext dsp;
    AVFrame new_picture;
    AVFrame input_picture;              ///< new_picture with the internal linesizes
    AVFrame current_picture;
    AVFrame last_picture[MAX_REF_FRAMES];
    uint8_t *halfpel_plane[MAX_REF_FRAMES][4][4];
    AVFrame mconly_picture;
//     uint8_t q_context[16];
    uint8_t header_state[32];
    uint8_t block_state[128 + 32*128];
    int keyframe;
    int always_reset;
    int version;
    int spatial_decomposition_type;
    int last_spatial_decomposition_type;
    int temporal_decomposition_type;
    int spatial_decomposition_count;
    int last_spatial_decomposition_count;
    int temporal_decomposition_count;
    int max_ref_frames;
    int ref_frames;
    int16_t (*ref_mvs[MAX_REF_FRAMES])[2];
    uint32_t *ref_scores[MAX_REF_FRAMES];
    DWTELEM *spatial_dwt_buffer;
    IDWTELEM *spatial_idwt_buffer;
    int colorspace_type;
    int chroma_h_shift;
    int chroma_v_shift;
    int spatial_scalability;
    int qlog;
    int last_qlog;
    int lambda;
    int lambda2;
    int pass1_rc;
    int mv_scale;
    int last_mv_scale;
    int qbias;
    int last_qbias;
#define QBIAS_SHIFT 3
    int b_width;
    int b_height;
    int block_max_depth;
    int last_block_max_depth;
    Plane plane[MAX_PLANES];
    BlockNode *block;
#define ME_CACHE_SIZE 1024
    int me_cache[ME_CACHE_SIZE];
    int me_cache_generation;
    slice_buffer sb;

    MpegEncContext m; // needed for motion estimation, should not be used for anything else, the idea is to make the motion estimation eventually independent of MpegEncContext, so this will be removed then (FIXME/XXX)
}SnowContext;

typedef struct {
    IDWTELEM *b0;
    IDWTELEM *b1;
    IDWTELEM *b2;
    IDWTELEM *b3;
    int y;
} dwt_compose_t;

#define slice_buffer_get_line(slice_buf, line_num) ((slice_buf)->line[line_num] ? (slice_buf)->line[line_num] : slice_buffer_load_line((slice_buf), (line_num)))
//#define slice_buffer_get_line(slice_buf, line_num) (slice_buffer_load_line((slice_buf), (line_num)))

static void iterative_me(SnowContext *s);

static void slice_buffer_init(slice_buffer * buf, int line_count, int max_allocated_lines, int line_width, IDWTELEM * base_buffer)
{
    int i;

    buf->base_buffer = base_buffer;
    buf->line_count = line_count;
    buf->line_width = line_width;
    buf->data_count = max_allocated_lines;
    buf->line = av_mallocz (sizeof(IDWTELEM *) * line_count);
    buf->data_stack = av_malloc (sizeof(IDWTELEM *) * max_allocated_lines);

    for (i = 0; i < max_allocated_lines; i++)
    {
        buf->data_stack[i] = av_malloc (sizeof(IDWTELEM) * line_width);
    }

    buf->data_stack_top = max_allocated_lines - 1;
}

static IDWTELEM * slice_buffer_load_line(slice_buffer * buf, int line)
{
    int offset;
    IDWTELEM * buffer;

//  av_log(NULL, AV_LOG_DEBUG, "Cache hit: %d\n", line);

    assert(buf->data_stack_top >= 0);
//  assert(!buf->line[line]);
    if (buf->line[line])
        return buf->line[line];

    offset = buf->line_width * line;
    buffer = buf->data_stack[buf->data_stack_top];
    buf->data_stack_top--;
    buf->line[line] = buffer;

//  av_log(NULL, AV_LOG_DEBUG, "slice_buffer_load_line: line: %d remaining: %d\n", line, buf->data_stack_top + 1);

    return buffer;
}

static void slice_buffer_release(slice_buffer * buf, int line)
{
    int offset;
    IDWTELEM * buffer;

    assert(line >= 0 && line < buf->line_count);
    assert(buf->line[line]);

    offset = buf->line_width * line;
    buffer = buf->line[line];
    buf->data_stack_top++;
    buf->data_stack[buf->data_stack_top] = buffer;
    buf->line[line] = NULL;

//  av_log(NULL, AV_LOG_DEBUG, "slice_buffer_release: line: %d remaining: %d\n", line, buf->data_stack_top + 1);
}

static void slice_buffer_flush(slice_buffer * buf)
{
    int i;
    for (i = 0; i < buf->line_count; i++)
    {
        if (buf->line[i])
        {
//      av_log(NULL, AV_LOG_DEBUG, "slice_buffer_flush: line: %d \n", i);
            slice_buffer_release(buf, i);
        }
    }
}

static void slice_buffer_destroy(slice_buffer * buf)
{
    int i;
    slice_buffer_flush(buf);

    for (i = buf->data_count - 1; i >= 0; i--)
    {
        av_freep(&buf->data_stack[i]);
    }
    av_freep(&buf->data_stack);
    av_freep(&buf->line);
}

#ifdef __sgi
// Avoid a name clash on SGI IRIX
#undef qexp
#endif
#define QEXPSHIFT (7-FRAC_BITS+8) //FIXME try to change this to 0
static uint8_t qexp[QROOT];

static inline int mirror(int v, int m){
    while((unsigned)v > (unsigned)m){
        v=-v;
        if(v<0) v+= 2*m;
    }
    return v;
}

static inline void put_symbol(RangeCoder *c, uint8_t *state, int v, int is_signed){
    int i;

    if(v){
        const int a= FFABS(v);
        const int e= av_log2(a);
#if 1
        const int el= FFMIN(e, 10);
        put_rac(c, state+0, 0);

        for(i=0; i<el; i++){
            put_rac(c, state+1+i, 1);  //1..10
        }
        for(; i<e; i++){
            put_rac(c, state+1+9, 1);  //1..10
        }
        put_rac(c, state+1+FFMIN(i,9), 0);

        for(i=e-1; i>=el; i--){
            put_rac(c, state+22+9, (a>>i)&1); //22..31
        }
        for(; i>=0; i--){
            put_rac(c, state+22+i, (a>>i)&1); //22..31
        }

        if(is_signed)
            put_rac(c, state+11 + el, v < 0); //11..21
#else

        put_rac(c, state+0, 0);
        if(e<=9){
            for(i=0; i<e; i++){
                put_rac(c, state+1+i, 1);  //1..10
            }
            put_rac(c, state+1+i, 0);

            for(i=e-1; i>=0; i--){
                put_rac(c, state+22+i, (a>>i)&1); //22..31
            }

            if(is_signed)
                put_rac(c, state+11 + e, v < 0); //11..21
        }else{
            for(i=0; i<e; i++){
                put_rac(c, state+1+FFMIN(i,9), 1);  //1..10
            }
            put_rac(c, state+1+FFMIN(i,9), 0);

            for(i=e-1; i>=0; i--){
                put_rac(c, state+22+FFMIN(i,9), (a>>i)&1); //22..31
            }

            if(is_signed)
                put_rac(c, state+11 + FFMIN(e,10), v < 0); //11..21
        }
#endif
    }else{
        put_rac(c, state+0, 1);
    }
}

static inline int get_symbol(RangeCoder *c, uint8_t *state, int is_signed){
    if(get_rac(c, state+0))
        return 0;
    else{
        int i, e, a;
        e= 0;
        while(get_rac(c, state+1 + FFMIN(e,9))){ //1..10