avcodec.h

#ifndef AVCODEC_H
#define AVCODEC_H

/**
 * @file avcodec.h
 * external api header.
 */


#ifdef __cplusplus
extern "C" {
#endif

#include "common.h"

#define LIBAVCODEC_VERSION_INT 0x000406
#define LIBAVCODEC_VERSION     "0.4.6"
#define LIBAVCODEC_BUILD       4660
#define LIBAVCODEC_BUILD_STR   "4660"

enum CodecID {
    CODEC_ID_NONE, 
    CODEC_ID_MPEG1VIDEO,
    CODEC_ID_H263,
    CODEC_ID_RV10,
    CODEC_ID_MP2,
    CODEC_ID_MP3LAME,
    CODEC_ID_VORBIS,
    CODEC_ID_AC3,
    CODEC_ID_MJPEG,
    CODEC_ID_MJPEGB,
    CODEC_ID_MPEG4,
    CODEC_ID_RAWVIDEO,
    CODEC_ID_MSMPEG4V1,
    CODEC_ID_MSMPEG4V2,
    CODEC_ID_MSMPEG4V3,
    CODEC_ID_WMV1,
    CODEC_ID_WMV2,
    CODEC_ID_H263P,
    CODEC_ID_H263I,
    CODEC_ID_SVQ1,
    CODEC_ID_DVVIDEO,
    CODEC_ID_DVAUDIO,
    CODEC_ID_WMAV1,
    CODEC_ID_WMAV2,
    CODEC_ID_MACE3,
    CODEC_ID_MACE6,
    CODEC_ID_HUFFYUV,
    CODEC_ID_CYUV,

    /* various pcm "codecs" */
    CODEC_ID_PCM_S16LE,
    CODEC_ID_PCM_S16BE,
    CODEC_ID_PCM_U16LE,
    CODEC_ID_PCM_U16BE,
    CODEC_ID_PCM_S8,
    CODEC_ID_PCM_U8,
    CODEC_ID_PCM_MULAW,
    CODEC_ID_PCM_ALAW,

    /* various adpcm codecs */
    CODEC_ID_ADPCM_IMA_QT,
    CODEC_ID_ADPCM_IMA_WAV,
    CODEC_ID_ADPCM_MS,
};

enum CodecType {
    CODEC_TYPE_UNKNOWN = -1,
    CODEC_TYPE_VIDEO,
    CODEC_TYPE_AUDIO,
};

/**
 * Pixel format.
 */
enum PixelFormat {
    PIX_FMT_YUV420P,
    PIX_FMT_YUV422,
    PIX_FMT_RGB24,     ///< 3 bytes, R is first 
    PIX_FMT_BGR24,     ///< 3 bytes, B is first 
    PIX_FMT_YUV422P,
    PIX_FMT_YUV444P,
    PIX_FMT_RGBA32,    ///< always stored in cpu endianness 
    PIX_FMT_YUV410P,
    PIX_FMT_YUV411P,
    PIX_FMT_RGB565,    ///< always stored in cpu endianness 
    PIX_FMT_RGB555,    ///< always stored in cpu endianness, most significant bit to 1 
    PIX_FMT_GRAY8,
    PIX_FMT_MONOWHITE, ///< 0 is white 
    PIX_FMT_MONOBLACK, ///< 0 is black 
    PIX_FMT_PAL8,      ///< 8 bit with RGBA palette 
    PIX_FMT_NB,
};

/* currently unused, may be used if 24/32 bits samples ever supported */
enum SampleFormat {
    SAMPLE_FMT_S16 = 0,         ///< signed 16 bits 
};

/* in bytes */
#define AVCODEC_MAX_AUDIO_FRAME_SIZE 131072

/**
 * Required number of zero bytes at the end of the input bitstream for decoding.
 * to avoid overreading (and possibly segfaulting)
 */
#define FF_INPUT_BUFFER_PADDING_SIZE 8

/* motion estimation type, EPZS by default */
enum Motion_Est_ID {
    ME_ZERO = 1,
    ME_FULL,
    ME_LOG,
    ME_PHODS,
    ME_EPZS,
    ME_X1
};

typedef struct RcOverride{
    int start_frame;
    int end_frame;
    int qscale; // if this is 0 then quality_factor will be used instead
    float quality_factor;
} RcOverride;

/* only for ME compatiblity with old apps */
extern int motion_estimation_method;

/* ME algos sorted by quality */
static const int Motion_Est_QTab[] = { ME_ZERO, ME_PHODS, ME_LOG, 
                                       ME_X1, ME_EPZS, ME_FULL };


#define FF_MAX_B_FRAMES 8

/* encoding support
   these flags can be passed in AVCodecContext.flags before initing 
   Note: note not everything is supported yet 
*/

#define CODEC_FLAG_HQ     0x0001  ///< brute force MB-type decission mode (slow) 
#define CODEC_FLAG_QSCALE 0x0002  ///< use fixed qscale 
#define CODEC_FLAG_4MV    0x0004  ///< 4 MV per MB allowed 
#define CODEC_FLAG_QPEL   0x0010  ///< use qpel MC 
#define CODEC_FLAG_GMC    0x0020  ///< use GMC 
#define CODEC_FLAG_PART   0x0080  ///< use data partitioning 
/* parent program gurantees that the input for b-frame containing streams is not written to 
   for at least s->max_b_frames+1 frames, if this is not set than the input will be copied */
#define CODEC_FLAG_INPUT_PRESERVED 0x0100
#define CODEC_FLAG_PASS1 0x0200   ///< use internal 2pass ratecontrol in first  pass mode 
#define CODEC_FLAG_PASS2 0x0400   ///< use internal 2pass ratecontrol in second pass mode 
#define CODEC_FLAG_EXTERN_HUFF 0x1000 ///< use external huffman table (for mjpeg) 
#define CODEC_FLAG_GRAY  0x2000   ///< only decode/encode grayscale 
#define CODEC_FLAG_EMU_EDGE 0x4000///< dont draw edges 
#define CODEC_FLAG_PSNR           0x8000 ///< error[?] variables will be set during encoding 
#define CODEC_FLAG_TRUNCATED  0x00010000 /** input bitstream might be truncated at a random location instead 
                                            of only at frame boundaries */
#define CODEC_FLAG_NORMALIZE_AQP  0x00020000 ///< normalize adaptive quantization 
#define CODEC_FLAG_INTERLACED_DCT 0x00040000 ///< use interlaced dct 
#define CODEC_FLAG_LOW_DELAY      0x00080000 ///< force low delay / will fail on b frames 
#define CODEC_FLAG_ALT_SCAN       0x00100000 ///< use alternate scan 
#define CODEC_FLAG_TRELLIS_QUANT  0x00200000 ///< use trellis quantization 
#define CODEC_FLAG_GLOBAL_HEADER  0x00400000 ///< place global headers in extradata instead of every keyframe 
#define CODEC_FLAG_BITEXACT       0x00800000 ///< use only bitexact stuff (except (i)dct) 
/* Fx : Flag for h263+ extra options */
#define CODEC_FLAG_H263P_AIC      0x01000000 ///< Advanced intra coding 
#define CODEC_FLAG_H263P_UMV      0x02000000 ///< Unlimited motion vector  
/* For advanced prediction mode, we reuse the 4MV flag */
/* Unsupported options :
 * 		Syntax Arithmetic coding (SAC)
 * 		Deblocking filter internal loop
 * 		Slice structured
 * 		Reference Picture Selection
 * 		Independant Segment Decoding
 * 		Alternative Inter * 		VLC
 * 		Modified Quantization */
/* /Fx */
/* codec capabilities */

#define CODEC_CAP_DRAW_HORIZ_BAND 0x0001 ///< decoder can use draw_horiz_band callback 
#define CODEC_CAP_DR1             0x0002 ///< direct rendering method 1 
/* if 'parse_only' field is true, then avcodec_parse_frame() can be
   used */
#define CODEC_CAP_PARSE_ONLY      0x0004
#define CODEC_CAP_TRUNCATED       0x0008

#define FRAME_RATE_BASE 10010

#define FF_COMMON_FRAME \
    uint8_t *data[4];\
    int linesize[4];\
    /**\
     * pointer to the first allocated byte of the picture. can be used in get_buffer/release_buffer\
     * this isnt used by lavc unless the default get/release_buffer() is used\
     * - encoding: \
     * - decoding: \
     */\
    uint8_t *base[4];\
    /**\
     * 1 -> keyframe, 0-> not\
     * - encoding: set by lavc\
     * - decoding: set by lavc\
     */\
    int key_frame;\
\
    /**\
     * picture type of the frame, see ?_TYPE below\
     * - encoding: set by lavc for coded_picture (and set by user for input)\
     * - decoding: set by lavc\
     */\
    int pict_type;\
\
    /**\
     * presentation timestamp in micro seconds (time when frame should be shown to user)\
     * if 0 then the frame_rate will be used as reference\
     * - encoding: MUST be set by user\
     * - decoding: set by lavc\
     */\
    long long int pts;\
\
    /**\
     * picture number in bitstream order.\
     * - encoding: set by\
     * - decoding: set by lavc\
     */\
    int coded_picture_number;\
    /**\
     * picture number in display order.\
     * - encoding: set by\
     * - decoding: set by lavc\
     */\
    int display_picture_number;\
\
    /**\
     * quality (between 1 (good) and 31 (bad)) \
     * - encoding: set by lavc for coded_picture (and set by user for input)\
     * - decoding: set by lavc\
     */\
    float quality; \
\
    /**\
     * buffer age (1->was last buffer and dint change, 2->..., ...).\
     * set to something large if the buffer has not been used yet \
     * - encoding: unused\
     * - decoding: MUST be set by get_buffer()\
     */\
    int age;\
\
    /**\
     * is this picture used as reference\
     * - encoding: unused\
     * - decoding: set by lavc (before get_buffer() call))\
     */\
    int reference;\
\
    /**\
     * QP table\
     * - encoding: unused\
     * - decoding: set by lavc\
     */\
    int8_t *qscale_table;\
    /**\
     * QP store stride\
     * - encoding: unused\
     * - decoding: set by lavc\
     */\
    int qstride;\
\
    /**\
     * mbskip_table[mb]>=1 if MB didnt change\
     * stride= mb_width = (width+15)>>4\
     * - encoding: unused\
     * - decoding: set by lavc\
     */\
    uint8_t *mbskip_table;\
\
    /**\
     * for some private data of the user\
     * - encoding: unused\
     * - decoding: set by user\
     */\
    void *opaque;\
\
    /**\
     * error\
     * - encoding: set by lavc if flags&CODEC_FLAG_PSNR\
     * - decoding: unused\
     */\
    uint64_t error[4];\
\
    /**\
     * type of the buffer (to keep track of who has to dealloc data[*])\
     * - encoding: set by the one who allocs it\
     * - decoding: set by the one who allocs it\
     * Note: user allocated (direct rendering) & internal buffers can not coexist currently\ 
     */\
    int type;\
    \
    /**\
     * when decoding, this signal how much the picture must be delayed.\
     * extra_delay = repeat_pict / (2*fps)\
     * - encoding: unused\
     * - decoding: set by lavc\
     */\
    int repeat_pict;


#define FF_BUFFER_TYPE_INTERNAL 1
#define FF_BUFFER_TYPE_USER     2 // Direct rendering buffers
#define FF_BUFFER_TYPE_SHARED   4 // input frame for encoding(wont be dealloced)


#define FF_I_TYPE 1 // Intra
#define FF_P_TYPE 2 // Predicted
#define FF_B_TYPE 3 // Bi-dir predicted
#define FF_S_TYPE 4 // S(GMC)-VOP MPEG4

typedef struct AVFrame {
    FF_COMMON_FRAME
} AVFrame;


/**
 * main external api structure.
 */
typedef struct AVCodecContext {
    /**
     * the average bitrate.
     * - encoding: set by user. unused for constant quantizer encoding
     * - decoding: set by lavc. 0 or some bitrate if this info is available in the stream 
     */
    int bit_rate;

    /**
     * number of bits the bitstream is allowed to diverge from the reference.
     *           the reference can be CBR (for CBR pass1) or VBR (for pass2)
     * - encoding: set by user. unused for constant quantizer encoding
     * - decoding: unused
     */
    int bit_rate_tolerance; 

    /**
     * CODEC_FLAG_*.
     * - encoding: set by user.
     * - decoding: set by user.
     */
    int flags;

    /**
     * some codecs needs additionnal format info. It is stored here
     * - encoding: set by user. 
     * - decoding: set by lavc. (FIXME is this ok?)
     */
    int sub_id;

    /**
     * motion estimation algorithm used for video coding.
     * - encoding: MUST be set by user.
     * - decoding: unused
     */
    int me_method;

    /**
     * some codecs need / can use extra-data like huffman tables.
     * mjpeg: huffman tables
     * rv10: additional flags
     * mpeg4: global headers (they can be in the bitstream or here)
     * - encoding: set/allocated/freed by lavc.
     * - decoding: set/allocated/freed by user.
     */
    void *extradata;
    int extradata_size;
    
    /* video only */
    /**
     * frames per sec multiplied by FRAME_RATE_BASE.
     * for variable fps this is the precission, so if the timestamps 
     * can be specified in msec precssion then this is 1000*FRAME_RATE_BASE
     * - encoding: MUST be set by user
     * - decoding: set by lavc. 0 or the frame_rate if available
     */
    int frame_rate;

    /**
     * width / height.
     * - encoding: MUST be set by user. 
     * - decoding: set by user, some codecs might override / change it during playback
     */
    int width, height;
    
#define FF_ASPECT_SQUARE 1
#define FF_ASPECT_4_3_625 2
#define FF_ASPECT_4_3_525 3
#define FF_ASPECT_16_9_625 4
#define FF_ASPECT_16_9_525 5
#define FF_ASPECT_EXTENDED 15

    /**
     * the number of pictures in a group of pitures, or 0 for intra_only.
     * - encoding: set by user.
     * - decoding: unused
     */
    int gop_size;

    /**
     * pixel format, see PIX_FMT_xxx.
     * - encoding: unused
     * - decoding: set by lavc.
     */
    enum PixelFormat pix_fmt;
 
    /**
     * Frame rate emulation. If not zero lower layer (i.e. format handler) 
     * has to read frames at native frame rate.
     * - encoding: set by user.
     * - decoding: unused.
     */
    int rate_emu;
       
    /**
     * if non NULL, 'draw_horiz_band' is called by the libavcodec
     * decoder to draw an horizontal band. It improve cache usage. Not
     * all codecs can do that. You must check the codec capabilities
     * before
     * - encoding: unused
     * - decoding: set by user.
     */
    void (*draw_horiz_band)(struct AVCodecContext *s,
                            uint8_t **src_ptr, int linesize,
                            int y, int width, int height);

    /* audio only */
    int sample_rate; ///< samples per sec 
    int channels;
    int sample_fmt;  ///< sample format, currenly unused 

    /* the following data should not be initialized */
    int frame_size;     ///< in samples, initialized when calling 'init' 
    int frame_number;   ///< audio or video frame number 
    int real_pict_num;  ///< returns the real picture number of previous encoded frame 
    
    /**
     * number of frames the decoded output will be delayed relative to 
     * the encoded input.
     * - encoding: set by lavc.
     * - decoding: unused
     */
    int delay;
    
    /* - encoding parameters */
    float qcompress;  ///< amount of qscale change between easy & hard scenes (0.0-1.0)
    float qblur;      ///< amount of qscale smoothing over time (0.0-1.0) 
    
    /**
     * minimum quantizer.
     * - encoding: set by user.
     * - decoding: unused
     */
    int qmin;

    /**
     * maximum quantizer.
     * - encoding: set by user.
     * - decoding: unused
     */
    int qmax;

    /**
     * maximum quantizer difference etween frames.
     * - encoding: set by user.
     * - decoding: unused
     */
    int max_qdiff;

    /**
     * maximum number of b frames between non b frames.
     * note: the output will be delayed by max_b_frames+1 relative to the input
     * - encoding: set by user.
     * - decoding: unused
     */
    int max_b_frames;

    /**
     * qscale factor between ip and b frames.
     * - encoding: set by user.
     * - decoding: unused
     */
    float b_quant_factor;
    
    /** obsolete FIXME remove */
    int rc_strategy;
    int b_frame_strategy;

    /**
     * hurry up amount.
     * - encoding: unused
     * - decoding: set by user. 1-> skip b frames, 2-> skip idct/dequant too, 5-> skip everything except header
     */
    int hurry_up;
    
    struct AVCodec *codec;
    
    void *priv_data;

    /* The following data is for RTP friendly coding */
    /* By now only H.263/H.263+/MPEG4 coder honours this   */
    int rtp_mode;   /* 1 for activate RTP friendly-mode           */
                    /* highers numbers represent more error-prone */
                    /* enviroments, by now just "1" exist         */
    
    int rtp_payload_size;   /* The size of the RTP payload, the coder will  */
                            /* do it's best to deliver a chunk with size    */
                            /* below rtp_payload_size, the chunk will start */
                            /* with a start code on some codecs like H.263  */
                            /* This doesn't take account of any particular  */
                            /* headers inside the transmited RTP payload    */

    
    /* The RTP callcack: This function is called  */
    /* every time the encoder as a packet to send */
    /* Depends on the encoder if the data starts  */
    /* with a Start Code (it should) H.263 does   */
    void (*rtp_callback)(void *data, int size, int packet_number); 

    /* statistics, used for 2-pass encoding */
    int mv_bits;
    int header_bits;
    int i_tex_bits;
    int p_tex_bits;
    int i_count;
    int p_count;
    int skip_count;
    int misc_bits;
    
    /**
     * number of bits used for the previously encoded frame.
     * - encoding: set by lavc
     * - decoding: - for audio - bits_per_sample
     */
    int frame_bits;
                 
    /**
     * private data of the user, can be used to carry app specific stuff.
     * - encoding: set by user
     * - decoding: set by user
     */
    void *opaque;

    char codec_name[32];
    enum CodecType codec_type; /* see CODEC_TYPE_xxx */
    enum CodecID codec_id; /* see CODEC_ID_xxx */
    unsigned int codec_tag;  ///< codec tag, only used if unknown codec
    
    /**
     * workaround bugs in encoders which sometimes cannot be detected automatically.
     * - encoding: unused
     * - decoding: set by user
     */
    int workaround_bugs;
#define FF_BUG_AUTODETECT       1  ///< autodetection
#define FF_BUG_OLD_MSMPEG4      2
#define FF_BUG_XVID_ILACE       4
#define FF_BUG_UMP4             8
#define FF_BUG_NO_PADDING       16
#define FF_BUG_AC_VLC           32
#define FF_BUG_QPEL_CHROMA      64
#define FF_BUG_STD_QPEL         128
#define FF_BUG_QPEL_CHROMA2     256
#define FF_BUG_DIRECT_BLOCKSIZE 512
//#define FF_BUG_FAKE_SCALABILITY 16 //autodetection should work 100%
        
    /**
     * luma single coeff elimination threshold.
     * - encoding: set by user
     * - decoding: unused
     */
    int luma_elim_threshold;
    
    /**
     * chroma single coeff elimination threshold.
     * - encoding: set by user
     * - decoding: unused
     */
    int chroma_elim_threshold;
    
    /**
     * strictly follow the std (MPEG4, ...).
     * - encoding: set by user
     * - decoding: unused
     */
    int strict_std_compliance;
    
    /**
     * qscale offset between ip and b frames.
     * if > 0 then the last p frame quantizer will be used (q= lastp_q*factor+offset)
     * if < 0 then normal ratecontrol will be done (q= -normal_q*factor+offset)
     * - encoding: set by user.
     * - decoding: unused
     */
    float b_quant_offset;
    
    /**
     * error resilience higher values will detect more errors but may missdetect
     * some more or less valid parts as errors.
     * - encoding: unused
     * - decoding: set by user
     */
    int error_resilience;
#define FF_ER_CAREFULL        1
#define FF_ER_COMPLIANT       2
#define FF_ER_AGGRESSIVE      3
#define FF_ER_VERY_AGGRESSIVE 4
    
    /**
     * called at the beginning of each frame to get a buffer for it.
     * if pic.reference is set then the frame will be read later by lavc
     * - encoding: unused
     * - decoding: set by lavc, user can override
     */
    int (*get_buffer)(struct AVCodecContext *c, AVFrame *pic);
    
    /**
     * called to release buffers which where allocated with get_buffer.
     * a released buffer can be reused in get_buffer()
     * pic.data[*] must be set to NULL
     * - encoding: unused
     * - decoding: set by lavc, user can override
     */
    void (*release_buffer)(struct AVCodecContext *c, AVFrame *pic);

    /**
     * is 1 if the decoded stream contains b frames, 0 otherwise.
     * - encoding: unused
     * - decoding: set by lavc
     */
    int has_b_frames;
    
    int block_align; ///< used by some WAV based audio codecs
    
    int parse_only; /* - decoding only: if true, only parsing is done
                       (function avcodec_parse_frame()). The frame
                       data is returned. Only MPEG codecs support this now. */
    
    /**
     * 0-> h263 quant 1-> mpeg quant.
     * - encoding: set by user.
     * - decoding: unused
     */
    int mpeg_quant;
    
    /**
     * pass1 encoding statistics output buffer.
     * - encoding: set by lavc
     * - decoding: unused
     */
    char *stats_out;
    
    /**
     * pass2 encoding statistics input buffer.
     * concatenated stuff from stats_out of pass1 should be placed here
     * - encoding: allocated/set/freed by user
     * - decoding: unused
     */
    char *stats_in;
    
    /**
     * ratecontrol qmin qmax limiting method.
     * 0-> clipping, 1-> use a nice continous function to limit qscale wthin qmin/qmax
     * - encoding: set by user.
     * - decoding: unused
     */
    float rc_qsquish;

    float rc_qmod_amp;
    int rc_qmod_freq;
    
    /**
     * ratecontrol override, see RcOverride.
     * - encoding: allocated/set/freed by user.
     * - decoding: unused
     */
    RcOverride *rc_override;
    int rc_override_count;
    
    /**
     * rate control equation.
     * - encoding: set by user
     * - decoding: unused
     */
    char *rc_eq;
    
    /**
     * maximum bitrate.
     * - encoding: set by user.
     * - decoding: unused
     */
    int rc_max_rate;
    
    /**
     * minimum bitrate.
     * - encoding: set by user.
     * - decoding: unused
     */
    int rc_min_rate;
    
    /**
     * decoder bitstream buffer size.
     * - encoding: set by user.
     * - decoding: unused
     */
    int rc_buffer_size;
    float rc_buffer_aggressivity;

    /**
     * qscale factor between p and i frames.
     * - encoding: set by user.
     * - decoding: unused
     */
    float i_quant_factor;
    
    /**
     * qscale offset between p and i frames.
     * if > 0 then the last p frame quantizer will be used (q= lastp_q*factor+offset)
     * if < 0 then normal ratecontrol will be done (q= -normal_q*factor+offset)
     * - encoding: set by user.
     * - decoding: unused
     */
    float i_quant_offset;
    
    /**
     * initial complexity for pass1 ratecontrol.
     * - encoding: set by user.
     * - decoding: unused
     */
    float rc_initial_cplx;

    /**
     * dct algorithm, see FF_DCT_* below.
     * - encoding: set by user
     * - decoding: unused
     */
    int dct_algo;
#define FF_DCT_AUTO    0
#define FF_DCT_FASTINT 1
#define FF_DCT_INT     2
#define FF_DCT_MMX     3
#define FF_DCT_MLIB    4
#define FF_DCT_ALTIVEC 5
    
    /**
     * luminance masking (0-> disabled).
     * - encoding: set by user
     * - decoding: unused
     */
    float lumi_masking;
    
    /**
     * temporary complexity masking (0-> disabled).
     * - encoding: set by user
     * - decoding: unused
     */
    float temporal_cplx_masking;
    
    /**
     * spatial complexity masking (0-> disabled).
     * - encoding: set by user
     * - decoding: unused
     */
    float spatial_cplx_masking;
    
    /**
     * p block masking (0-> disabled).
     * - encoding: set by user
     * - decoding: unused
     */
    float p_masking;

    /**
     * darkness masking (0-> disabled).
     * - encoding: set by user
     * - decoding: unused
     */
    float dark_masking;
    
    /**
     * fourcc (LSB first, so "ABCD" -> ('D'<<24) + ('C'<<16) + ('B'<<8) + 'A').
     * this is used to workaround some encoder bugs
     * - encoding: unused
     * - decoding: set by user, will be converted to upper case by lavc during init
     */
    int fourcc;

    /**
     * idct algorithm, see FF_IDCT_* below.
     * - encoding: set by user
     * - decoding: set by user
     */
    int idct_algo;
#define FF_IDCT_AUTO         0
#define FF_IDCT_INT          1
#define FF_IDCT_SIMPLE       2
#define FF_IDCT_SIMPLEMMX    3
#define FF_IDCT_LIBMPEG2MMX  4
#define FF_IDCT_PS2          5
#define FF_IDCT_MLIB         6
#define FF_IDCT_ARM          7
#define FF_IDCT_ALTIVEC      8

    /**
     * slice count.
     * - encoding: set by lavc
     * - decoding: set by user (or 0)
     */
    int slice_count;
    /**
     * slice offsets in the frame in bytes.
     * - encoding: set/allocated by lavc
     * - decoding: set/allocated by user (or NULL)
     */
    int *slice_offset;

    /**
     * error concealment flags.
     * - encoding: unused
     * - decoding: set by user
     */
    int error_concealment;
#define FF_EC_GUESS_MVS   1
#define FF_EC_DEBLOCK     2

    /**
     * dsp_mask could be used to disable unwanted
     * CPU features (i.e. MMX, SSE. ...)
     */
     unsigned dsp_mask;

    /**
     * bits per sample/pixel from the demuxer (needed for huffyuv).
     * - encoding: set by lavc
     * - decoding: set by user
     */
     int bits_per_sample;
    
    /**
     * prediction method (needed for huffyuv).
     * - encoding: set by user
     * - decoding: unused
     */
     int prediction_method;
#define FF_PRED_LEFT   0
#define FF_PRED_PLANE  1
#define FF_PRED_MEDIAN 2
    
    /**
     * aspect ratio (0 if unknown).
     * - encoding: set by user.
     * - decoding: set by lavc.
     */
    float aspect_ratio;

    /**
     * the picture in the bitstream.
     * - encoding: set by lavc
     * - decoding: set by lavc
     */
    AVFrame *coded_frame;

    /**
     * debug.
     * - encoding: set by user.
     * - decoding: set by user.
     */
    int debug;
#define FF_DEBUG_PICT_INFO 1
#define FF_DEBUG_RC        2
#define FF_DEBUG_BITSTREAM 4
#define FF_DEBUG_MB_TYPE   8
#define FF_DEBUG_QP        16
#define FF_DEBUG_MV        32
#define FF_DEBUG_VIS_MV    0x00000040
#define FF_DEBUG_SKIP      0x00000080
#define FF_DEBUG_STARTCODE 0x00000100
#define FF_DEBUG_PTS       0x00000200
    
    /**
     * error.
     * - encoding: set by lavc if flags&CODEC_FLAG_PSNR
     * - decoding: unused
     */
    uint64_t error[4];
    
    /**
     * minimum MB quantizer.
     * - encoding: set by user.
     * - decoding: unused
     */
    int mb_qmin;

    /**
     * maximum MB quantizer.
     * - encoding: set by user.
     * - decoding: unused
     */
    int mb_qmax;
    
    /**
     * motion estimation compare function.
     * - encoding: set by user.
     * - decoding: unused
     */
    int me_cmp;
    /**
     * subpixel motion estimation compare function.
     * - encoding: set by user.
     * - decoding: unused
     */
    int me_sub_cmp;
    /**
     * macroblock compare function (not supported yet).
     * - encoding: set by user.
     * - decoding: unused
     */
    int mb_cmp;
#define FF_CMP_SAD  0
#define FF_CMP_SSE  1
#define FF_CMP_SATD 2
#define FF_CMP_DCT  3
#define FF_CMP_PSNR 4
#define FF_CMP_BIT  5
#define FF_CMP_RD   6
#define FF_CMP_ZERO 7
#define FF_CMP_CHROMA 256
    
    /**
     * ME diamond size & shape.
     * - encoding: set by user.
     * - decoding: unused
     */
    int dia_size;

    /**
     * amount of previous MV predictors (2a+1 x 2a+1 square).
     * - encoding: set by user.
     * - decoding: unused
     */
    int last_predictor_count;

    /**
     * pre pass for motion estimation.
     * - encoding: set by user.
     * - decoding: unused
     */
    int pre_me;

    /**
     * motion estimation pre pass compare function.
     * - encoding: set by user.
     * - decoding: unused
     */
    int me_pre_cmp;

    /**
     * ME pre pass diamond size & shape.
     * - encoding: set by user.
     * - decoding: unused
     */
    int pre_dia_size;

    /**
     * subpel ME quality.
     * - encoding: set by user.
     * - decoding: unused
     */
    int me_subpel_quality;

    /**
     * callback to negotiate the pixelFormat.
     * @param fmt is the list of formats which are supported by the codec,
     * its terminated by -1 as 0 is a valid format, the formats are ordered by quality
     * the first is allways the native one
     * @return the choosen format
     * - encoding: unused
     * - decoding: set by user, if not set then the native format will always be choosen
     */
    enum PixelFormat (*get_format)(struct AVCodecContext *s, enum PixelFormat * fmt);

    /**
     * DTG active format information (additionnal aspect ratio
     * information only used in DVB MPEG2 transport streams). 0 if
     * not set.
     * 
     * - encoding: unused.
     * - decoding: set by decoder 
     */
    int dtg_active_format;
#define FF_DTG_AFD_SAME         8
#define FF_DTG_AFD_4_3          9
#define FF_DTG_AFD_16_9         10
#define FF_DTG_AFD_14_9         11
#define FF_DTG_AFD_4_3_SP_14_9  13