PeerStreamer

/*

 * H.26L/H.264/AVC/JVT/14496-10/... encoder/decoder

 * Copyright (c) 2003 Michael Niedermayer <michaelni@gmx.at>

 *

 * This file is part of FFmpeg.

 *

 * FFmpeg is free software; you can redistribute it and/or

 * modify it under the terms of the GNU Lesser General Public

 * License as published by the Free Software Foundation; either

 * version 2.1 of the License, or (at your option) any later version.

 *

 * FFmpeg is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

 * Lesser General Public License for more details.

 *

 * You should have received a copy of the GNU Lesser General Public

 * License along with FFmpeg; if not, write to the Free Software

 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

 */

/**

 * @file libavcodec/h264.h

 * H.264 / AVC / MPEG4 part10 codec.

 * @author Michael Niedermayer <michaelni@gmx.at>

 */

#ifndef AVCODEC_H264_H

#define AVCODEC_H264_H

#include "libavutil/intreadwrite.h"

#include "dsputil.h"

#include "cabac.h"

#include "mpegvideo.h"

#include "h264pred.h"

#include "rectangle.h"

#define interlaced_dct interlaced_dct_is_a_bad_name

#define mb_intra mb_intra_is_not_initialized_see_mb_type

#define LUMA_DC_BLOCK_INDEX   25

#define CHROMA_DC_BLOCK_INDEX 26

#define CHROMA_DC_COEFF_TOKEN_VLC_BITS 8

#define COEFF_TOKEN_VLC_BITS           8

#define TOTAL_ZEROS_VLC_BITS           9

#define CHROMA_DC_TOTAL_ZEROS_VLC_BITS 3

#define RUN_VLC_BITS                   3

#define RUN7_VLC_BITS                  6

#define MAX_SPS_COUNT 32

#define MAX_PPS_COUNT 256

#define MAX_MMCO_COUNT 66

#define MAX_DELAYED_PIC_COUNT 16

/* Compiling in interlaced support reduces the speed

 * of progressive decoding by about 2%. */

#define ALLOW_INTERLACE

#define ALLOW_NOCHROMA

#define FMO 0

/**

 * The maximum number of slices supported by the decoder.

 * must be a power of 2

 */

#define MAX_SLICES 16

#ifdef ALLOW_INTERLACE

#define MB_MBAFF h->mb_mbaff

#define MB_FIELD h->mb_field_decoding_flag

#define FRAME_MBAFF h->mb_aff_frame

#define FIELD_PICTURE (s->picture_structure != PICT_FRAME)

#else

#define MB_MBAFF 0

#define MB_FIELD 0

#define FRAME_MBAFF 0

#define FIELD_PICTURE 0

#undef  IS_INTERLACED

#define IS_INTERLACED(mb_type) 0

#endif

#define FIELD_OR_MBAFF_PICTURE (FRAME_MBAFF || FIELD_PICTURE)

#ifdef ALLOW_NOCHROMA

#define CHROMA h->sps.chroma_format_idc

#else

#define CHROMA 1

#endif

#ifndef CABAC

#define CABAC h->pps.cabac

#endif

#define EXTENDED_SAR          255

#define MB_TYPE_REF0       MB_TYPE_ACPRED //dirty but it fits in 16 bit

#define MB_TYPE_8x8DCT     0x01000000

#define IS_REF0(a)         ((a) & MB_TYPE_REF0)

#define IS_8x8DCT(a)       ((a) & MB_TYPE_8x8DCT)

/**

 * Value of Picture.reference when Picture is not a reference picture, but

 * is held for delayed output.

 */

#define DELAYED_PIC_REF 4

/* NAL unit types */

enum {

    NAL_SLICE=1,

    NAL_DPA,

    NAL_DPB,

    NAL_DPC,

    NAL_IDR_SLICE,

    NAL_SEI,

    NAL_SPS,

    NAL_PPS,

    NAL_AUD,

    NAL_END_SEQUENCE,

    NAL_END_STREAM,

    NAL_FILLER_DATA,

    NAL_SPS_EXT,

    NAL_AUXILIARY_SLICE=19

};

/**

 * SEI message types

 */

typedef enum {

    SEI_BUFFERING_PERIOD             =  0, ///< buffering period (H.264, D.1.1)

    SEI_TYPE_PIC_TIMING              =  1, ///< picture timing

    SEI_TYPE_USER_DATA_UNREGISTERED  =  5, ///< unregistered user data

    SEI_TYPE_RECOVERY_POINT          =  6  ///< recovery point (frame # to decoder sync)

} SEI_Type;

/**

 * pic_struct in picture timing SEI message

 */

typedef enum {

    SEI_PIC_STRUCT_FRAME             = 0, ///<  0: %frame

    SEI_PIC_STRUCT_TOP_FIELD         = 1, ///<  1: top field

    SEI_PIC_STRUCT_BOTTOM_FIELD      = 2, ///<  2: bottom field

    SEI_PIC_STRUCT_TOP_BOTTOM        = 3, ///<  3: top field, bottom field, in that order

    SEI_PIC_STRUCT_BOTTOM_TOP        = 4, ///<  4: bottom field, top field, in that order

    SEI_PIC_STRUCT_TOP_BOTTOM_TOP    = 5, ///<  5: top field, bottom field, top field repeated, in that order

    SEI_PIC_STRUCT_BOTTOM_TOP_BOTTOM = 6, ///<  6: bottom field, top field, bottom field repeated, in that order

    SEI_PIC_STRUCT_FRAME_DOUBLING    = 7, ///<  7: %frame doubling

    SEI_PIC_STRUCT_FRAME_TRIPLING    = 8  ///<  8: %frame tripling

} SEI_PicStructType;

/**

 * Sequence parameter set

 */

typedef struct SPS{

    int profile_idc;

    int level_idc;

    int chroma_format_idc;

    int transform_bypass;              ///< qpprime_y_zero_transform_bypass_flag

    int log2_max_frame_num;            ///< log2_max_frame_num_minus4 + 4

    int poc_type;                      ///< pic_order_cnt_type

    int log2_max_poc_lsb;              ///< log2_max_pic_order_cnt_lsb_minus4

    int delta_pic_order_always_zero_flag;

    int offset_for_non_ref_pic;

    int offset_for_top_to_bottom_field;

    int poc_cycle_length;              ///< num_ref_frames_in_pic_order_cnt_cycle

    int ref_frame_count;               ///< num_ref_frames

    int gaps_in_frame_num_allowed_flag;

    int mb_width;                      ///< pic_width_in_mbs_minus1 + 1

    int mb_height;                     ///< pic_height_in_map_units_minus1 + 1

    int frame_mbs_only_flag;

    int mb_aff;                        ///<mb_adaptive_frame_field_flag

    int direct_8x8_inference_flag;

    int crop;                   ///< frame_cropping_flag

    unsigned int crop_left;            ///< frame_cropping_rect_left_offset

    unsigned int crop_right;           ///< frame_cropping_rect_right_offset

    unsigned int crop_top;             ///< frame_cropping_rect_top_offset

    unsigned int crop_bottom;          ///< frame_cropping_rect_bottom_offset

    int vui_parameters_present_flag;

    AVRational sar;

    int video_signal_type_present_flag;

    int full_range;

    int colour_description_present_flag;

    enum AVColorPrimaries color_primaries;

    enum AVColorTransferCharacteristic color_trc;

    enum AVColorSpace colorspace;

    int timing_info_present_flag;

    uint32_t num_units_in_tick;

    uint32_t time_scale;

    int fixed_frame_rate_flag;

    short offset_for_ref_frame[256]; //FIXME dyn aloc?

    int bitstream_restriction_flag;

    int num_reorder_frames;

    int scaling_matrix_present;

    uint8_t scaling_matrix4[6][16];

    uint8_t scaling_matrix8[2][64];

    int nal_hrd_parameters_present_flag;

    int vcl_hrd_parameters_present_flag;

    int pic_struct_present_flag;

    int time_offset_length;

    int cpb_cnt;                       ///< See H.264 E.1.2

    int initial_cpb_removal_delay_length; ///< initial_cpb_removal_delay_length_minus1 +1

    int cpb_removal_delay_length;      ///< cpb_removal_delay_length_minus1 + 1

    int dpb_output_delay_length;       ///< dpb_output_delay_length_minus1 + 1

    int bit_depth_luma;                ///< bit_depth_luma_minus8 + 8

    int bit_depth_chroma;              ///< bit_depth_chroma_minus8 + 8

    int residual_color_transform_flag; ///< residual_colour_transform_flag

}SPS;

/**

 * Picture parameter set

 */

typedef struct PPS{

    unsigned int sps_id;

    int cabac;                  ///< entropy_coding_mode_flag

    int pic_order_present;      ///< pic_order_present_flag

    int slice_group_count;      ///< num_slice_groups_minus1 + 1

    int mb_slice_group_map_type;

    unsigned int ref_count[2];  ///< num_ref_idx_l0/1_active_minus1 + 1

    int weighted_pred;          ///< weighted_pred_flag

    int weighted_bipred_idc;

    int init_qp;                ///< pic_init_qp_minus26 + 26

    int init_qs;                ///< pic_init_qs_minus26 + 26

    int chroma_qp_index_offset[2];

    int deblocking_filter_parameters_present; ///< deblocking_filter_parameters_present_flag

    int constrained_intra_pred; ///< constrained_intra_pred_flag

    int redundant_pic_cnt_present; ///< redundant_pic_cnt_present_flag

    int transform_8x8_mode;     ///< transform_8x8_mode_flag

    uint8_t scaling_matrix4[6][16];

    uint8_t scaling_matrix8[2][64];

    uint8_t chroma_qp_table[2][64];  ///< pre-scaled (with chroma_qp_index_offset) version of qp_table

    int chroma_qp_diff;

}PPS;

/**

 * Memory management control operation opcode.

 */

typedef enum MMCOOpcode{

    MMCO_END=0,

    MMCO_SHORT2UNUSED,

    MMCO_LONG2UNUSED,

    MMCO_SHORT2LONG,

    MMCO_SET_MAX_LONG,

    MMCO_RESET,

    MMCO_LONG,

} MMCOOpcode;

/**

 * Memory management control operation.

 */

typedef struct MMCO{

    MMCOOpcode opcode;

    int short_pic_num;  ///< pic_num without wrapping (pic_num & max_pic_num)

    int long_arg;       ///< index, pic_num, or num long refs depending on opcode

} MMCO;

/**

 * H264Context

 */

typedef struct H264Context{

    MpegEncContext s;

    int chroma_qp[2]; //QPc

    int qp_thresh;      ///< QP threshold to skip loopfilter

    int prev_mb_skipped;

    int next_mb_skipped;

    //prediction stuff

    int chroma_pred_mode;

    int intra16x16_pred_mode;

    int topleft_mb_xy;

    int top_mb_xy;

    int topright_mb_xy;

    int left_mb_xy[2];

    int topleft_type;

    int top_type;

    int topright_type;

    int left_type[2];

    const uint8_t * left_block;

    int topleft_partition;

    int8_t intra4x4_pred_mode_cache[5*8];

    int8_t (*intra4x4_pred_mode);

    H264PredContext hpc;

    unsigned int topleft_samples_available;

    unsigned int top_samples_available;

    unsigned int topright_samples_available;

    unsigned int left_samples_available;

    uint8_t (*top_borders[2])[16+2*8];

    /**

     * non zero coeff count cache.

     * is 64 if not available.

     */

    DECLARE_ALIGNED(8, uint8_t, non_zero_count_cache)[6*8];

    /*

    .UU.YYYY

    .UU.YYYY

    .vv.YYYY

    .VV.YYYY

    */

    uint8_t (*non_zero_count)[32];

    /**

     * Motion vector cache.

     */

    DECLARE_ALIGNED(16, int16_t, mv_cache)[2][5*8][2];

    DECLARE_ALIGNED(8, int8_t, ref_cache)[2][5*8];

#define LIST_NOT_USED -1 //FIXME rename?

#define PART_NOT_AVAILABLE -2

    /**

     * is 1 if the specific list MV&references are set to 0,0,-2.

     */

    int mv_cache_clean[2];

    /**

     * number of neighbors (top and/or left) that used 8x8 dct

     */

    int neighbor_transform_size;

    /**

     * block_offset[ 0..23] for frame macroblocks

     * block_offset[24..47] for field macroblocks

     */

    int block_offset[2*(16+8)];

    uint32_t *mb2b_xy; //FIXME are these 4 a good idea?

    uint32_t *mb2br_xy;

    int b_stride; //FIXME use s->b4_stride

    int mb_linesize;   ///< may be equal to s->linesize or s->linesize*2, for mbaff

    int mb_uvlinesize;

    int emu_edge_width;

    int emu_edge_height;

    SPS sps; ///< current sps

    /**

     * current pps

     */

    PPS pps; //FIXME move to Picture perhaps? (->no) do we need that?

    uint32_t dequant4_buffer[6][52][16]; //FIXME should these be moved down?

    uint32_t dequant8_buffer[2][52][64];

    uint32_t (*dequant4_coeff[6])[16];

    uint32_t (*dequant8_coeff[2])[64];

    int slice_num;

    uint16_t *slice_table;     ///< slice_table_base + 2*mb_stride + 1

    int slice_type;

    int slice_type_nos;        ///< S free slice type (SI/SP are remapped to I/P)

    int slice_type_fixed;

    //interlacing specific flags

    int mb_aff_frame;

    int mb_field_decoding_flag;

    int mb_mbaff;              ///< mb_aff_frame && mb_field_decoding_flag

    DECLARE_ALIGNED(8, uint16_t, sub_mb_type)[4];

    //Weighted pred stuff

    int use_weight;

    int use_weight_chroma;

    int luma_log2_weight_denom;

    int chroma_log2_weight_denom;

    //The following 2 can be changed to int8_t but that causes 10cpu cycles speedloss

    int luma_weight[48][2][2];

    int chroma_weight[48][2][2][2];

    int implicit_weight[48][48];

    int direct_spatial_mv_pred;

    int col_parity;

    int col_fieldoff;

    int dist_scale_factor[16];

    int dist_scale_factor_field[2][32];

    int map_col_to_list0[2][16+32];

    int map_col_to_list0_field[2][2][16+32];

    /**

     * num_ref_idx_l0/1_active_minus1 + 1

     */

    unsigned int ref_count[2];   ///< counts frames or fields, depending on current mb mode

    unsigned int list_count;

    uint8_t *list_counts;            ///< Array of list_count per MB specifying the slice type

    Picture ref_list[2][48];         /**< 0..15: frame refs, 16..47: mbaff field refs.

                                          Reordered version of default_ref_list

                                          according to picture reordering in slice header */

    int ref2frm[MAX_SLICES][2][64];  ///< reference to frame number lists, used in the loop filter, the first 2 are for -2,-1

    //data partitioning

    GetBitContext intra_gb;

    GetBitContext inter_gb;

    GetBitContext *intra_gb_ptr;

    GetBitContext *inter_gb_ptr;

    DECLARE_ALIGNED(16, DCTELEM, mb)[16*24];

    DCTELEM mb_padding[256];        ///< as mb is addressed by scantable[i] and scantable is uint8_t we can either check that i is not too large or ensure that there is some unused stuff after mb

    /**

     * Cabac

     */

    CABACContext cabac;

    uint8_t      cabac_state[460];

    /* 0x100 -> non null luma_dc, 0x80/0x40 -> non null chroma_dc (cb/cr), 0x?0 -> chroma_cbp(0,1,2), 0x0? luma_cbp */

    uint16_t     *cbp_table;

    int cbp;

    int top_cbp;

    int left_cbp;

    /* chroma_pred_mode for i4x4 or i16x16, else 0 */

    uint8_t     *chroma_pred_mode_table;

    int         last_qscale_diff;

    uint8_t     (*mvd_table[2])[2];

    DECLARE_ALIGNED(16, uint8_t, mvd_cache)[2][5*8][2];

    uint8_t     *direct_table;

    uint8_t     direct_cache[5*8];

    uint8_t zigzag_scan[16];

    uint8_t zigzag_scan8x8[64];

    uint8_t zigzag_scan8x8_cavlc[64];

    uint8_t field_scan[16];

    uint8_t field_scan8x8[64];

    uint8_t field_scan8x8_cavlc[64];

    const uint8_t *zigzag_scan_q0;

    const uint8_t *zigzag_scan8x8_q0;

    const uint8_t *zigzag_scan8x8_cavlc_q0;

    const uint8_t *field_scan_q0;

    const uint8_t *field_scan8x8_q0;

    const uint8_t *field_scan8x8_cavlc_q0;

    int x264_build;

    int mb_xy;

    int is_complex;

    //deblock

    int deblocking_filter;         ///< disable_deblocking_filter_idc with 1<->0

    int slice_alpha_c0_offset;

    int slice_beta_offset;

//=============================================================

    //Things below are not used in the MB or more inner code

    int nal_ref_idc;

    int nal_unit_type;

    uint8_t *rbsp_buffer[2];

    unsigned int rbsp_buffer_size[2];

    /**

     * Used to parse AVC variant of h264

     */

    int is_avc; ///< this flag is != 0 if codec is avc1

    int nal_length_size; ///< Number of bytes used for nal length (1, 2 or 4)

    SPS *sps_buffers[MAX_SPS_COUNT];

    PPS *pps_buffers[MAX_PPS_COUNT];

    int dequant_coeff_pps;     ///< reinit tables when pps changes

    uint16_t *slice_table_base;

    //POC stuff

    int poc_lsb;

    int poc_msb;

    int delta_poc_bottom;

    int delta_poc[2];

    int frame_num;

    int prev_poc_msb;             ///< poc_msb of the last reference pic for POC type 0

    int prev_poc_lsb;             ///< poc_lsb of the last reference pic for POC type 0

    int frame_num_offset;         ///< for POC type 2

    int prev_frame_num_offset;    ///< for POC type 2

    int prev_frame_num;           ///< frame_num of the last pic for POC type 1/2

    /**

     * frame_num for frames or 2*frame_num+1 for field pics.

     */

    int curr_pic_num;

    /**

     * max_frame_num or 2*max_frame_num for field pics.

     */

    int max_pic_num;

    int redundant_pic_count;

    Picture *short_ref[32];

    Picture *long_ref[32];

    Picture default_ref_list[2][32]; ///< base reference list for all slices of a coded picture

    Picture *delayed_pic[MAX_DELAYED_PIC_COUNT+2]; //FIXME size?

    int outputed_poc;

    /**

     * memory management control operations buffer.

     */

    MMCO mmco[MAX_MMCO_COUNT];

    int mmco_index;

    int long_ref_count;  ///< number of actual long term references

    int short_ref_count; ///< number of actual short term references

    int          cabac_init_idc;

    /**

     * @defgroup multithreading Members for slice based multithreading

     * @{

     */

    struct H264Context *thread_context[MAX_THREADS];

    /**

     * current slice number, used to initalize slice_num of each thread/context

     */

    int current_slice;

    /**

     * Max number of threads / contexts.

     * This is equal to AVCodecContext.thread_count unless

     * multithreaded decoding is impossible, in which case it is

     * reduced to 1.

     */

    int max_contexts;

    /**

     *  1 if the single thread fallback warning has already been

     *  displayed, 0 otherwise.

     */

    int single_decode_warning;

    int last_slice_type;

    /** @} */

    /**

     * pic_struct in picture timing SEI message

     */

    SEI_PicStructType sei_pic_struct;

    /**

     * Complement sei_pic_struct

     * SEI_PIC_STRUCT_TOP_BOTTOM and SEI_PIC_STRUCT_BOTTOM_TOP indicate interlaced frames.

     * However, soft telecined frames may have these values.

     * This is used in an attempt to flag soft telecine progressive.

     */

    int prev_interlaced_frame;

    /**

     * Bit set of clock types for fields/frames in picture timing SEI message.

     * For each found ct_type, appropriate bit is set (e.g., bit 1 for

     * interlaced).

     */

    int sei_ct_type;

    /**

     * dpb_output_delay in picture timing SEI message, see H.264 C.2.2

     */

    int sei_dpb_output_delay;

    /**

     * cpb_removal_delay in picture timing SEI message, see H.264 C.1.2

     */

    int sei_cpb_removal_delay;

    /**

     * recovery_frame_cnt from SEI message

     *

     * Set to -1 if no recovery point SEI message found or to number of frames

     * before playback synchronizes. Frames having recovery point are key

     * frames.

     */

    int sei_recovery_frame_cnt;

    int luma_weight_flag[2];   ///< 7.4.3.2 luma_weight_lX_flag

    int chroma_weight_flag[2]; ///< 7.4.3.2 chroma_weight_lX_flag

    // Timestamp stuff

    int sei_buffering_period_present;  ///< Buffering period SEI flag

    int initial_cpb_removal_delay[32]; ///< Initial timestamps for CPBs

    //SVQ3 specific fields

    int halfpel_flag;

    int thirdpel_flag;

    int unknown_svq3_flag;

    int next_slice_index;

    uint32_t svq3_watermark_key;

}H264Context;

extern const uint8_t ff_h264_chroma_qp[52];

void ff_svq3_luma_dc_dequant_idct_c(DCTELEM *block, int qp);

void ff_svq3_add_idct_c(uint8_t *dst, DCTELEM *block, int stride, int qp, int dc);

/**

 * Decode SEI

 */

int ff_h264_decode_sei(H264Context *h);

/**

 * Decode SPS

 */

int ff_h264_decode_seq_parameter_set(H264Context *h);

/**

 * Decode PPS

 */

int ff_h264_decode_picture_parameter_set(H264Context *h, int bit_length);

/**

 * Decodes a network abstraction layer unit.

 * @param consumed is the number of bytes used as input

 * @param length is the length of the array

 * @param dst_length is the number of decoded bytes FIXME here or a decode rbsp tailing?

 * @returns decoded bytes, might be src+1 if no escapes

 */

const uint8_t *ff_h264_decode_nal(H264Context *h, const uint8_t *src, int *dst_length, int *consumed, int length);

/**

 * identifies the exact end of the bitstream

 * @return the length of the trailing, or 0 if damaged

 */

int ff_h264_decode_rbsp_trailing(H264Context *h, const uint8_t *src);

/**

 * frees any data that may have been allocated in the H264 context like SPS, PPS etc.

 */

av_cold void ff_h264_free_context(H264Context *h);

/**

 * reconstructs bitstream slice_type.

 */

int ff_h264_get_slice_type(const H264Context *h);

/**

 * allocates tables.

 * needs width/height

 */

int ff_h264_alloc_tables(H264Context *h);

/**

 * fills the default_ref_list.

 */

int ff_h264_fill_default_ref_list(H264Context *h);

int ff_h264_decode_ref_pic_list_reordering(H264Context *h);

void ff_h264_fill_mbaff_ref_list(H264Context *h);

void ff_h264_remove_all_refs(H264Context *h);

/**

 * Executes the reference picture marking (memory management control operations).

 */

int ff_h264_execute_ref_pic_marking(H264Context *h, MMCO *mmco, int mmco_count);

int ff_h264_decode_ref_pic_marking(H264Context *h, GetBitContext *gb);

/**

 * checks if the top & left blocks are available if needed & changes the dc mode so it only uses the available blocks.

 */

int ff_h264_check_intra4x4_pred_mode(H264Context *h);

/**

 * checks if the top & left blocks are available if needed & changes the dc mode so it only uses the available blocks.

 */

int ff_h264_check_intra_pred_mode(H264Context *h, int mode);

void ff_h264_write_back_intra_pred_mode(H264Context *h);

void ff_h264_hl_decode_mb(H264Context *h);

int ff_h264_frame_start(H264Context *h);

av_cold int ff_h264_decode_init(AVCodecContext *avctx);

av_cold int ff_h264_decode_end(AVCodecContext *avctx);

av_cold void ff_h264_decode_init_vlc(void);

/**

 * decodes a macroblock

 * @returns 0 if OK, AC_ERROR / DC_ERROR / MV_ERROR if an error is noticed

 */

int ff_h264_decode_mb_cavlc(H264Context *h);

/**

 * decodes a CABAC coded macroblock

 * @returns 0 if OK, AC_ERROR / DC_ERROR / MV_ERROR if an error is noticed

 */

int ff_h264_decode_mb_cabac(H264Context *h);

void ff_h264_init_cabac_states(H264Context *h);

void ff_h264_direct_dist_scale_factor(H264Context * const h);

void ff_h264_direct_ref_list_init(H264Context * const h);

void ff_h264_pred_direct_motion(H264Context * const h, int *mb_type);

void ff_h264_filter_mb_fast( H264Context *h, int mb_x, int mb_y, uint8_t *img_y, uint8_t *img_cb, uint8_t *img_cr, unsigned int linesize, unsigned int uvlinesize);

void ff_h264_filter_mb( H264Context *h, int mb_x, int mb_y, uint8_t *img_y, uint8_t *img_cb, uint8_t *img_cr, unsigned int linesize, unsigned int uvlinesize);

/**

 * Reset SEI values at the beginning of the frame.

 *

 * @param h H.264 context.

 */

void ff_h264_reset_sei(H264Context *h);

/*

o-o o-o

 / / /

o-o o-o

 ,---'

o-o o-o

 / / /

o-o o-o

*/

//This table must be here because scan8[constant] must be known at compiletime

static const uint8_t scan8[16 + 2*4]={

 4+1*8, 5+1*8, 4+2*8, 5+2*8,

 6+1*8, 7+1*8, 6+2*8, 7+2*8,

 4+3*8, 5+3*8, 4+4*8, 5+4*8,

 6+3*8, 7+3*8, 6+4*8, 7+4*8,

 1+1*8, 2+1*8,

 1+2*8, 2+2*8,

 1+4*8, 2+4*8,

 1+5*8, 2+5*8,

};

static av_always_inline uint32_t pack16to32(int a, int b){

#if HAVE_BIGENDIAN

   return (b&0xFFFF) + (a<<16);

#else

   return (a&0xFFFF) + (b<<16);

#endif

}

static av_always_inline uint16_t pack8to16(int a, int b){

#if HAVE_BIGENDIAN

   return (b&0xFF) + (a<<8);

#else

   return (a&0xFF) + (b<<8);

#endif

}

/**

 * gets the chroma qp.

 */

static inline int get_chroma_qp(H264Context *h, int t, int qscale){

    return h->pps.chroma_qp_table[t][qscale];

}

static inline void pred_pskip_motion(H264Context * const h, int * const mx, int * const my);

static void fill_decode_neighbors(H264Context *h, int mb_type){

    MpegEncContext * const s = &h->s;

    const int mb_xy= h->mb_xy;

    int topleft_xy, top_xy, topright_xy, left_xy[2];

    static const uint8_t left_block_options[4][16]={

        {0,1,2,3,7,10,8,11,7+0*8, 7+1*8, 7+2*8, 7+3*8, 2+0*8, 2+3*8, 2+1*8, 2+2*8},

        {2,2,3,3,8,11,8,11,7+2*8, 7+2*8, 7+3*8, 7+3*8, 2+1*8, 2+2*8, 2+1*8, 2+2*8},

        {0,0,1,1,7,10,7,10,7+0*8, 7+0*8, 7+1*8, 7+1*8, 2+0*8, 2+3*8, 2+0*8, 2+3*8},

        {0,2,0,2,7,10,7,10,7+0*8, 7+2*8, 7+0*8, 7+2*8, 2+0*8, 2+3*8, 2+0*8, 2+3*8}

    };

    h->topleft_partition= -1;

    top_xy     = mb_xy  - (s->mb_stride << MB_FIELD);

    /* Wow, what a mess, why didn't they simplify the interlacing & intra

     * stuff, I can't imagine that these complex rules are worth it. */

    topleft_xy = top_xy - 1;

    topright_xy= top_xy + 1;

    left_xy[1] = left_xy[0] = mb_xy-1;

    h->left_block = left_block_options[0];

    if(FRAME_MBAFF){

        const int left_mb_field_flag     = IS_INTERLACED(s->current_picture.mb_type[mb_xy-1]);

        const int curr_mb_field_flag     = IS_INTERLACED(mb_type);

        if(s->mb_y&1){

            if (left_mb_field_flag != curr_mb_field_flag) {

                left_xy[1] = left_xy[0] = mb_xy - s->mb_stride - 1;

                if (curr_mb_field_flag) {

                    left_xy[1] += s->mb_stride;

                    h->left_block = left_block_options[3];

                } else {

                    topleft_xy += s->mb_stride;

                    // take top left mv from the middle of the mb, as opposed to all other modes which use the bottom right partition

                    h->topleft_partition = 0;

                    h->left_block = left_block_options[1];

                }

            }

        }else{

            if(curr_mb_field_flag){

                topleft_xy  += s->mb_stride & (((s->current_picture.mb_type[top_xy - 1]>>7)&1)-1);

                topright_xy += s->mb_stride & (((s->current_picture.mb_type[top_xy + 1]>>7)&1)-1);

                top_xy      += s->mb_stride & (((s->current_picture.mb_type[top_xy    ]>>7)&1)-1);

            }

            if (left_mb_field_flag != curr_mb_field_flag) {

                if (curr_mb_field_flag) {

                    left_xy[1] += s->mb_stride;

                    h->left_block = left_block_options[3];

                } else {

                    h->left_block = left_block_options[2];

                }

            }

        }

    }

    h->topleft_mb_xy = topleft_xy;

    h->top_mb_xy     = top_xy;

    h->topright_mb_xy= topright_xy;

    h->left_mb_xy[0] = left_xy[0];

    h->left_mb_xy[1] = left_xy[1];

    //FIXME do we need all in the context?

    h->topleft_type = s->current_picture.mb_type[topleft_xy] ;

    h->top_type     = s->current_picture.mb_type[top_xy]     ;

    h->topright_type= s->current_picture.mb_type[topright_xy];

    h->left_type[0] = s->current_picture.mb_type[left_xy[0]] ;

    h->left_type[1] = s->current_picture.mb_type[left_xy[1]] ;

    if(FMO){

    if(h->slice_table[topleft_xy ] != h->slice_num) h->topleft_type = 0;

    if(h->slice_table[top_xy     ] != h->slice_num) h->top_type     = 0;

    if(h->slice_table[left_xy[0] ] != h->slice_num) h->left_type[0] = h->left_type[1] = 0;

    }else{

        if(h->slice_table[topleft_xy ] != h->slice_num){

            h->topleft_type = 0;

            if(h->slice_table[top_xy     ] != h->slice_num) h->top_type     = 0;

            if(h->slice_table[left_xy[0] ] != h->slice_num) h->left_type[0] = h->left_type[1] = 0;

        }

    }

    if(h->slice_table[topright_xy] != h->slice_num) h->topright_type= 0;

}

static void fill_decode_caches(H264Context *h, int mb_type){

    MpegEncContext * const s = &h->s;

    int topleft_xy, top_xy, topright_xy, left_xy[2];

    int topleft_type, top_type, topright_type, left_type[2];

    const uint8_t * left_block= h->left_block;

    int i;

    topleft_xy   = h->topleft_mb_xy ;

    top_xy       = h->top_mb_xy     ;

    topright_xy  = h->topright_mb_xy;

    left_xy[0]   = h->left_mb_xy[0] ;

    left_xy[1]   = h->left_mb_xy[1] ;

    topleft_type = h->topleft_type  ;

    top_type     = h->top_type      ;

    topright_type= h->topright_type ;

    left_type[0] = h->left_type[0]  ;

    left_type[1] = h->left_type[1]  ;

    if(!IS_SKIP(mb_type)){

        if(IS_INTRA(mb_type)){

            int type_mask= h->pps.constrained_intra_pred ? IS_INTRA(-1) : -1;

            h->topleft_samples_available=

            h->top_samples_available=

            h->left_samples_available= 0xFFFF;

            h->topright_samples_available= 0xEEEA;

            if(!(top_type & type_mask)){

                h->topleft_samples_available= 0xB3FF;

                h->top_samples_available= 0x33FF;

                h->topright_samples_available= 0x26EA;

            }

            if(IS_INTERLACED(mb_type) != IS_INTERLACED(left_type[0])){

                if(IS_INTERLACED(mb_type)){

                    if(!(left_type[0] & type_mask)){

                        h->topleft_samples_available&= 0xDFFF;

                        h->left_samples_available&= 0x5FFF;

                    }

                    if(!(left_type[1] & type_mask)){

                        h->topleft_samples_available&= 0xFF5F;

                        h->left_samples_available&= 0xFF5F;

                    }

                }else{

                    int left_typei = s->current_picture.mb_type[left_xy[0] + s->mb_stride];

                    assert(left_xy[0] == left_xy[1]);

                    if(!((left_typei & type_mask) && (left_type[0] & type_mask))){

                        h->topleft_samples_available&= 0xDF5F;

                        h->left_samples_available&= 0x5F5F;

                    }

                }

            }else{

                if(!(left_type[0] & type_mask)){

                    h->topleft_samples_available&= 0xDF5F;

                    h->left_samples_available&= 0x5F5F;

                }

            }

            if(!(topleft_type & type_mask))

                h->topleft_samples_available&= 0x7FFF;

            if(!(topright_type & type_mask))

                h->topright_samples_available&= 0xFBFF;

            if(IS_INTRA4x4(mb_type)){

                if(IS_INTRA4x4(top_type)){

                    AV_COPY32(h->intra4x4_pred_mode_cache+4+8*0, h->intra4x4_pred_mode + h->mb2br_xy[top_xy]);

                }else{

                    h->intra4x4_pred_mode_cache[4+8*0]=

                    h->intra4x4_pred_mode_cache[5+8*0]=

                    h->intra4x4_pred_mode_cache[6+8*0]=

                    h->intra4x4_pred_mode_cache[7+8*0]= 2 - 3*!(top_type & type_mask);

                }

                for(i=0; i<2; i++){

                    if(IS_INTRA4x4(left_type[i])){

                        int8_t *mode= h->intra4x4_pred_mode + h->mb2br_xy[left_xy[i]];

                        h->intra4x4_pred_mode_cache[3+8*1 + 2*8*i]= mode[6-left_block[0+2*i]];

                        h->intra4x4_pred_mode_cache[3+8*2 + 2*8*i]= mode[6-left_block[1+2*i]];

                    }else{

                        h->intra4x4_pred_mode_cache[3+8*1 + 2*8*i]=

                        h->intra4x4_pred_mode_cache[3+8*2 + 2*8*i]= 2 - 3*!(left_type[i] & type_mask);

                    }

                }

            }

        }

/*

0 . T T. T T T T

1 L . .L . . . .

2 L . .L . . . .

3 . T TL . . . .

4 L . .L . . . .

5 L . .. . . . .

*/

//FIXME constraint_intra_pred & partitioning & nnz (let us hope this is just a typo in the spec)

    if(top_type){

        AV_COPY32(&h->non_zero_count_cache[4+8*0], &h->non_zero_count[top_xy][4+3*8]);

            h->non_zero_count_cache[1+8*0]= h->non_zero_count[top_xy][1+1*8];

            h->non_zero_count_cache[2+8*0]= h->non_zero_count[top_xy][2+1*8];

            h->non_zero_count_cache[1+8*3]= h->non_zero_count[top_xy][1+2*8];

            h->non_zero_count_cache[2+8*3]= h->non_zero_count[top_xy][2+2*8];

    }else {

            h->non_zero_count_cache[1+8*0]=

            h->non_zero_count_cache[2+8*0]=

            h->non_zero_count_cache[1+8*3]=

            h->non_zero_count_cache[2+8*3]=

            AV_WN32A(&h->non_zero_count_cache[4+8*0], CABAC && !IS_INTRA(mb_type) ? 0 : 0x40404040);

    }

    for (i=0; i<2; i++) {

        if(left_type[i]){

            h->non_zero_count_cache[3+8*1 + 2*8*i]= h->non_zero_count[left_xy[i]][left_block[8+0+2*i]];

            h->non_zero_count_cache[3+8*2 + 2*8*i]= h->non_zero_count[left_xy[i]][left_block[8+1+2*i]];

                h->non_zero_count_cache[0+8*1 +   8*i]= h->non_zero_count[left_xy[i]][left_block[8+4+2*i]];

                h->non_zero_count_cache[0+8*4 +   8*i]= h->non_zero_count[left_xy[i]][left_block[8+5+2*i]];

        }else{

                h->non_zero_count_cache[3+8*1 + 2*8*i]=

                h->non_zero_count_cache[3+8*2 + 2*8*i]=

                h->non_zero_count_cache[0+8*1 +   8*i]=

                h->non_zero_count_cache[0+8*4 +   8*i]= CABAC && !IS_INTRA(mb_type) ? 0 : 64;

        }

    }

    if( CABAC ) {

        // top_cbp

        if(top_type) {

            h->top_cbp = h->cbp_table[top_xy];

        } else {

            h->top_cbp = IS_INTRA(mb_type) ? 0x1CF : 0x00F;

        }

        // left_cbp

        if (left_type[0]) {

            h->left_cbp = (h->cbp_table[left_xy[0]] & 0x1f0)

                        |  ((h->cbp_table[left_xy[0]]>>(left_block[0]&(~1)))&2)

                        | (((h->cbp_table[left_xy[1]]>>(left_block[2]&(~1)))&2) << 2);

        } else {

            h->left_cbp = IS_INTRA(mb_type) ? 0x1CF : 0x00F;

        }

    }

    }

#if 1

    if(IS_INTER(mb_type) || (IS_DIRECT(mb_type) && h->direct_spatial_mv_pred)){

        int list;

        for(list=0; list<h->list_count; list++){

            if(!USES_LIST(mb_type, list)){

                /*if(!h->mv_cache_clean[list]){

                    memset(h->mv_cache [list],  0, 8*5*2*sizeof(int16_t)); //FIXME clean only input? clean at all?

                    memset(h->ref_cache[list], PART_NOT_AVAILABLE, 8*5*sizeof(int8_t));

                    h->mv_cache_clean[list]= 1;

                }*/

                continue;

            }

            assert(!(IS_DIRECT(mb_type) && !h->direct_spatial_mv_pred));

            h->mv_cache_clean[list]= 0;

            if(USES_LIST(top_type, list)){

                const int b_xy= h->mb2b_xy[top_xy] + 3*h->b_stride;

                AV_COPY128(h->mv_cache[list][scan8[0] + 0 - 1*8], s->current_picture.motion_val[list][b_xy + 0]);

                    h->ref_cache[list][scan8[0] + 0 - 1*8]=

                    h->ref_cache[list][scan8[0] + 1 - 1*8]= s->current_picture.ref_index[list][4*top_xy + 2];

                    h->ref_cache[list][scan8[0] + 2 - 1*8]=

                    h->ref_cache[list][scan8[0] + 3 - 1*8]= s->current_picture.ref_index[list][4*top_xy + 3];

            }else{

                AV_ZERO128(h->mv_cache[list][scan8[0] + 0 - 1*8]);

                AV_WN32A(&h->ref_cache[list][scan8[0] + 0 - 1*8], ((top_type ? LIST_NOT_USED : PART_NOT_AVAILABLE)&0xFF)*0x01010101);

            }

            if(mb_type & (MB_TYPE_16x8|MB_TYPE_8x8)){

            for(i=0; i<2; i++){

                int cache_idx = scan8[0] - 1 + i*2*8;

                if(USES_LIST(left_type[i], list)){

                    const int b_xy= h->mb2b_xy[left_xy[i]] + 3;

                    const int b8_xy= 4*left_xy[i] + 1;

                    AV_COPY32(h->mv_cache[list][cache_idx  ], s->current_picture.motion_val[list][b_xy + h->b_stride*left_block[0+i*2]]);

                    AV_COPY32(h->mv_cache[list][cache_idx+8], s->current_picture.motion_val[list][b_xy + h->b_stride*left_block[1+i*2]]);

                        h->ref_cache[list][cache_idx  ]= s->current_picture.ref_index[list][b8_xy + (left_block[0+i*2]&~1)];

                        h->ref_cache[list][cache_idx+8]= s->current_picture.ref_index[list][b8_xy + (left_block[1+i*2]&~1)];

                }else{

                    AV_ZERO32(h->mv_cache [list][cache_idx  ]);

                    AV_ZERO32(h->mv_cache [list][cache_idx+8]);

                    h->ref_cache[list][cache_idx  ]=

                    h->ref_cache[list][cache_idx+8]= (left_type[i]) ? LIST_NOT_USED : PART_NOT_AVAILABLE;

                }

            }

            }else{

                if(USES_LIST(left_type[0], list)){

                    const int b_xy= h->mb2b_xy[left_xy[0]] + 3;

                    const int b8_xy= 4*left_xy[0] + 1;

                    AV_COPY32(h->mv_cache[list][scan8[0] - 1], s->current_picture.motion_val[list][b_xy + h->b_stride*left_block[0]]);

                    h->ref_cache[list][scan8[0] - 1]= s->current_picture.ref_index[list][b8_xy + (left_block[0]&~1)];

                }else{

                    AV_ZERO32(h->mv_cache [list][scan8[0] - 1]);

                    h->ref_cache[list][scan8[0] - 1]= left_type[0] ? LIST_NOT_USED : PART_NOT_AVAILABLE;

                }

            }

            if(USES_LIST(topright_type, list)){

                const int b_xy= h->mb2b_xy[topright_xy] + 3*h->b_stride;

                AV_COPY32(h->mv_cache[list][scan8[0] + 4 - 1*8], s->current_picture.motion_val[list][b_xy]);

                h->ref_cache[list][scan8[0] + 4 - 1*8]= s->current_picture.ref_index[list][4*topright_xy + 2];

            }else{

                AV_ZERO32(h->mv_cache [list][scan8[0] + 4 - 1*8]);

                h->ref_cache[list][scan8[0] + 4 - 1*8]= topright_type ? LIST_NOT_USED : PART_NOT_AVAILABLE;

            }

            if(h->ref_cache[list][scan8[0] + 4 - 1*8] < 0){

                if(USES_LIST(topleft_type, list)){

                    const int b_xy = h->mb2b_xy [topleft_xy] + 3 + h->b_stride + (h->topleft_partition & 2*h->b_stride);

                    const int b8_xy= 4*topleft_xy + 1 + (h->topleft_partition & 2);

                    AV_COPY32(h->mv_cache[list][scan8[0] - 1 - 1*8], s->current_picture.motion_val[list][b_xy]);

                    h->ref_cache[list][scan8[0] - 1 - 1*8]= s->current_picture.ref_index[list][b8_xy];

                }else{

                    AV_ZERO32(h->mv_cache[list][scan8[0] - 1 - 1*8]);

                    h->ref_cache[list][scan8[0] - 1 - 1*8]= topleft_type ? LIST_NOT_USED : PART_NOT_AVAILABLE;

                }

            }

            if((mb_type&(MB_TYPE_SKIP|MB_TYPE_DIRECT2)) && !FRAME_MBAFF)

                continue;

            if(!(mb_type&(MB_TYPE_SKIP|MB_TYPE_DIRECT2))) {

            h->ref_cache[list][scan8[4 ]] =

            h->ref_cache[list][scan8[12]] = PART_NOT_AVAILABLE;

            AV_ZERO32(h->mv_cache [list][scan8[4 ]]);

            AV_ZERO32(h->mv_cache [list][scan8[12]]);

            if( CABAC ) {

                /* XXX beurk, Load mvd */

                if(USES_LIST(top_type, list)){

                    const int b_xy= h->mb2br_xy[top_xy];

                    AV_COPY64(h->mvd_cache[list][scan8[0] + 0 - 1*8], h->mvd_table[list][b_xy + 0]);

                }else{

                    AV_ZERO64(h->mvd_cache[list][scan8[0] + 0 - 1*8]);

                }

                if(USES_LIST(left_type[0], list)){

                    const int b_xy= h->mb2br_xy[left_xy[0]] + 6;

                    AV_COPY16(h->mvd_cache[list][scan8[0] - 1 + 0*8], h->mvd_table[list][b_xy - left_block[0]]);

                    AV_COPY16(h->mvd_cache[list][scan8[0] - 1 + 1*8], h->mvd_table[list][b_xy - left_block[1]]);

                }else{

                    AV_ZERO16(h->mvd_cache [list][scan8[0] - 1 + 0*8]);

                    AV_ZERO16(h->mvd_cache [list][scan8[0] - 1 + 1*8]);

                }

                if(USES_LIST(left_type[1], list)){

                    const int b_xy= h->mb2br_xy[left_xy[1]] + 6;

                    AV_COPY16(h->mvd_cache[list][scan8[0] - 1 + 2*8], h->mvd_table[list][b_xy - left_block[2]]);

                    AV_COPY16(h->mvd_cache[list][scan8[0] - 1 + 3*8], h->mvd_table[list][b_xy - left_block[3]]);

                }else{

                    AV_ZERO16(h->mvd_cache [list][scan8[0] - 1 + 2*8]);

                    AV_ZERO16(h->mvd_cache [list][scan8[0] - 1 + 3*8]);

                }

                AV_ZERO16(h->mvd_cache [list][scan8[4 ]]);

                AV_ZERO16(h->mvd_cache [list][scan8[12]]);

                if(h->slice_type_nos == FF_B_TYPE){

                    fill_rectangle(&h->direct_cache[scan8[0]], 4, 4, 8, MB_TYPE_16x16>>1, 1);

                    if(IS_DIRECT(top_type)){

                        AV_WN32A(&h->direct_cache[scan8[0] - 1*8], 0x01010101u*(MB_TYPE_DIRECT2>>1));

                    }else if(IS_8X8(top_type)){

                        int b8_xy = 4*top_xy;

                        h->direct_cache[scan8[0] + 0 - 1*8]= h->direct_table[b8_xy + 2];

                        h->direct_cache[scan8[0] + 2 - 1*8]= h->direct_table[b8_xy + 3];

                    }else{

                        AV_WN32A(&h->direct_cache[scan8[0] - 1*8], 0x01010101*(MB_TYPE_16x16>>1));

                    }

                    if(IS_DIRECT(left_type[0]))

                        h->direct_cache[scan8[0] - 1 + 0*8]= MB_TYPE_DIRECT2>>1;

                    else if(IS_8X8(left_type[0]))

                        h->direct_cache[scan8[0] - 1 + 0*8]= h->direct_table[4*left_xy[0] + 1 + (left_block[0]&~1)];

                    else

                        h->direct_cache[scan8[0] - 1 + 0*8]= MB_TYPE_16x16>>1;

                    if(IS_DIRECT(left_type[1]))

                        h->direct_cache[scan8[0] - 1 + 2*8]= MB_TYPE_DIRECT2>>1;

                    else if(IS_8X8(left_type[1]))

                        h->direct_cache[scan8[0] - 1 + 2*8]= h->direct_table[4*left_xy[1] + 1 + (left_block[2]&~1)];

                    else

                        h->direct_cache[scan8[0] - 1 + 2*8]= MB_TYPE_16x16>>1;

                }

            }

            }

            if(FRAME_MBAFF){

#define MAP_MVS\

                    MAP_F2F(scan8[0] - 1 - 1*8, topleft_type)\

                    MAP_F2F(scan8[0] + 0 - 1*8, top_type)\

                    MAP_F2F(scan8[0] + 1 - 1*8, top_type)\

                    MAP_F2F(scan8[0] + 2 - 1*8, top_type)\

                    MAP_F2F(scan8[0] + 3 - 1*8, top_type)\

                    MAP_F2F(scan8[0] + 4 - 1*8, topright_type)\

                    MAP_F2F(scan8[0] - 1 + 0*8, left_type[0])\

                    MAP_F2F(scan8[0] - 1 + 1*8, left_type[0])\

                    MAP_F2F(scan8[0] - 1 + 2*8, left_type[1])\

                    MAP_F2F(scan8[0] - 1 + 3*8, left_type[1])

                if(MB_FIELD){

#define MAP_F2F(idx, mb_type)\

                    if(!IS_INTERLACED(mb_type) && h->ref_cache[list][idx] >= 0){\

                        h->ref_cache[list][idx] <<= 1;\

                        h->mv_cache[list][idx][1] /= 2;\

                        h->mvd_cache[list][idx][1] >>=1;\

                    }

                    MAP_MVS

#undef MAP_F2F

                }else{

#define MAP_F2F(idx, mb_type)\

                    if(IS_INTERLACED(mb_type) && h->ref_cache[list][idx] >= 0){\

                        h->ref_cache[list][idx] >>= 1;\

                        h->mv_cache[list][idx][1] <<= 1;\

                        h->mvd_cache[list][idx][1] <<= 1;\

                    }

                    MAP_MVS

#undef MAP_F2F

                }

            }

        }

    }

#endif

        h->neighbor_transform_size= !!IS_8x8DCT(top_type) + !!IS_8x8DCT(left_type[0]);

}

/**

 *

 * @returns non zero if the loop filter can be skiped

 */

static int fill_filter_caches(H264Context *h, int mb_type){

    MpegEncContext * const s = &h->s;

    const int mb_xy= h->mb_xy;

    int top_xy, left_xy[2];

    int top_type, left_type[2];

    top_xy     = mb_xy  - (s->mb_stride << MB_FIELD);

    //FIXME deblocking could skip the intra and nnz parts.

    /* Wow, what a mess, why didn't they simplify the interlacing & intra

     * stuff, I can't imagine that these complex rules are worth it. */

    left_xy[1] = left_xy[0] = mb_xy-1;

    if(FRAME_MBAFF){

        const int left_mb_field_flag     = IS_INTERLACED(s->current_picture.mb_type[mb_xy-1]);

        const int curr_mb_field_flag     = IS_INTERLACED(mb_type);

        if(s->mb_y&1){

            if (left_mb_field_flag != curr_mb_field_flag) {

                left_xy[0] -= s->mb_stride;

            }

        }else{

            if(curr_mb_field_flag){

                top_xy      += s->mb_stride & (((s->current_picture.mb_type[top_xy    ]>>7)&1)-1);

            }

            if (left_mb_field_flag != curr_mb_field_flag) {

                left_xy[1] += s->mb_stride;

            }

        }

    }

    h->top_mb_xy = top_xy;

    h->left_mb_xy[0] = left_xy[0];

    h->left_mb_xy[1] = left_xy[1];

    {

        //for sufficiently low qp, filtering wouldn't do anything

        //this is a conservative estimate: could also check beta_offset and more accurate chroma_qp

        int qp_thresh = h->qp_thresh; //FIXME strictly we should store qp_thresh for each mb of a slice

        int qp = s->current_picture.qscale_table[mb_xy];

        if(qp <= qp_thresh

           && (left_xy[0]<0 || ((qp + s->current_picture.qscale_table[left_xy[0]] + 1)>>1) <= qp_thresh)

           && (top_xy   < 0 || ((qp + s->current_picture.qscale_table[top_xy    ] + 1)>>1) <= qp_thresh)){

            if(!FRAME_MBAFF)

                return 1;

            if(   (left_xy[0]< 0            || ((qp + s->current_picture.qscale_table[left_xy[1]             ] + 1)>>1) <= qp_thresh)

               && (top_xy    < s->mb_stride || ((qp + s->current_picture.qscale_table[top_xy    -s->mb_stride] + 1)>>1) <= qp_thresh))

                return 1;

        }

    }

    top_type     = s->current_picture.mb_type[top_xy]    ;

    left_type[0] = s->current_picture.mb_type[left_xy[0]];