avcodec.h

#ifndef AVCODEC_H
#define AVCODEC_H

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


#ifdef __cplusplus
extern "C" {
#endif

#include "common.h"
#include "rational.h"
#include <sys/types.h> /* size_t */

#define FFMPEG_VERSION_INT     0x000408
#define FFMPEG_VERSION         "0.4.8"
#define LIBAVCODEC_BUILD       4701

#define LIBAVCODEC_VERSION_INT FFMPEG_VERSION_INT
#define LIBAVCODEC_VERSION     FFMPEG_VERSION

#define AV_STRINGIFY(s)	AV_TOSTRING(s)
#define AV_TOSTRING(s) #s
#define LIBAVCODEC_IDENT	"FFmpeg" LIBAVCODEC_VERSION "b" AV_STRINGIFY(LIBAVCODEC_BUILD)

enum CodecID {
    CODEC_ID_NONE, 
    CODEC_ID_MPEG1VIDEO,
    CODEC_ID_MPEG2VIDEO, /* prefered ID for MPEG Video 1 or 2 decoding */
    CODEC_ID_MPEG2VIDEO_XVMC,
    CODEC_ID_H263,
    CODEC_ID_RV10,
    CODEC_ID_RV20,
    CODEC_ID_MP2,
    CODEC_ID_MP3, /* prefered ID for MPEG Audio layer 1, 2 or3 decoding */
    CODEC_ID_VORBIS,
    CODEC_ID_AC3,
    CODEC_ID_MJPEG,
    CODEC_ID_MJPEGB,
    CODEC_ID_LJPEG,
    CODEC_ID_SP5X,
    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_FLV1,
    CODEC_ID_SVQ1,
    CODEC_ID_SVQ3,
    CODEC_ID_DVVIDEO,
    CODEC_ID_DVAUDIO,
    CODEC_ID_WMAV1,
    CODEC_ID_WMAV2,
    CODEC_ID_MACE3,
    CODEC_ID_MACE6,
    CODEC_ID_HUFFYUV,
    CODEC_ID_CYUV,
    CODEC_ID_H264,
    CODEC_ID_INDEO3,
    CODEC_ID_VP3,
    CODEC_ID_THEORA,
    CODEC_ID_AAC,
    CODEC_ID_MPEG4AAC,
    CODEC_ID_ASV1,
    CODEC_ID_ASV2,
    CODEC_ID_FFV1,
    CODEC_ID_4XM,
    CODEC_ID_VCR1,
    CODEC_ID_CLJR,
    CODEC_ID_MDEC,
    CODEC_ID_ROQ,
    CODEC_ID_INTERPLAY_VIDEO,
    CODEC_ID_XAN_WC3,
    CODEC_ID_XAN_WC4,
    CODEC_ID_RPZA,
    CODEC_ID_CINEPAK,
    CODEC_ID_WS_VQA,
    CODEC_ID_MSRLE,
    CODEC_ID_MSVIDEO1,
    CODEC_ID_IDCIN,
    CODEC_ID_8BPS,
    CODEC_ID_SMC,
    CODEC_ID_FLIC,
    CODEC_ID_TRUEMOTION1,
    CODEC_ID_VMDVIDEO,
    CODEC_ID_VMDAUDIO,
    CODEC_ID_MSZH,
    CODEC_ID_ZLIB,

    /* 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_IMA_DK3,
    CODEC_ID_ADPCM_IMA_DK4,
    CODEC_ID_ADPCM_IMA_WS,
    CODEC_ID_ADPCM_IMA_SMJPEG,
    CODEC_ID_ADPCM_MS,
    CODEC_ID_ADPCM_4XM,
    CODEC_ID_ADPCM_XA,
    CODEC_ID_ADPCM_ADX,
    CODEC_ID_ADPCM_EA,

	/* AMR */
    CODEC_ID_AMR_NB,
    CODEC_ID_AMR_WB,

    /* RealAudio codecs*/
    CODEC_ID_RA_144,
    CODEC_ID_RA_288,

    /* various DPCM codecs */
    CODEC_ID_ROQ_DPCM,
    CODEC_ID_INTERPLAY_DPCM,
    CODEC_ID_XAN_DPCM,
    
    CODEC_ID_MPEG2TS, /* _FAKE_ codec to indicate a raw MPEG2 transport
                         stream (only used by libavformat) */
};

/* CODEC_ID_MP3LAME is absolete */
#define CODEC_ID_MP3LAME CODEC_ID_MP3

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

/**
 * Pixel format. Notes: 
 *
 * PIX_FMT_RGBA32 is handled in an endian-specific manner. A RGBA
 * color is put together as:
 *  (A << 24) | (R << 16) | (G << 8) | B
 * This is stored as BGRA on little endian CPU architectures and ARGB on
 * big endian CPUs.
 *
 * When the pixel format is palettized RGB (PIX_FMT_PAL8), the palettized
 * image data is stored in AVFrame.data[0]. The palette is transported in
 * AVFrame.data[1] and, is 1024 bytes long (256 4-byte entries) and is
 * formatted the same as in PIX_FMT_RGBA32 described above (i.e., it is
 * also endian-specific). Note also that the individual RGB palette
 * components stored in AVFrame.data[1] should be in the range 0..255.
 * This is important as many custom PAL8 video codecs that were designed
 * to run on the IBM VGA graphics adapter use 6-bit palette components.
 */
enum PixelFormat {
    PIX_FMT_YUV420P,   ///< Planar YUV 4:2:0 (1 Cr & Cb sample per 2x2 Y samples)
    PIX_FMT_YUV422,    
    PIX_FMT_RGB24,     ///< Packed pixel, 3 bytes per pixel, RGBRGB...
    PIX_FMT_BGR24,     ///< Packed pixel, 3 bytes per pixel, BGRBGR...
    PIX_FMT_YUV422P,   ///< Planar YUV 4:2:2 (1 Cr & Cb sample per 2x1 Y samples)
    PIX_FMT_YUV444P,   ///< Planar YUV 4:4:4 (1 Cr & Cb sample per 1x1 Y samples)
    PIX_FMT_RGBA32,    ///< Packed pixel, 4 bytes per pixel, BGRABGRA..., stored in cpu endianness
    PIX_FMT_YUV410P,   ///< Planar YUV 4:1:0 (1 Cr & Cb sample per 4x4 Y samples)
    PIX_FMT_YUV411P,   ///< Planar YUV 4:1:1 (1 Cr & Cb sample per 4x1 Y samples)
    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_YUVJ420P,  ///< Planar YUV 4:2:0 full scale (jpeg)
    PIX_FMT_YUVJ422P,  ///< Planar YUV 4:2:2 full scale (jpeg)
    PIX_FMT_YUVJ444P,  ///< Planar YUV 4:4:4 full scale (jpeg)
    PIX_FMT_XVMC_MPEG2_MC,///< XVideo Motion Acceleration via common packet passing(xvmc_render.h)
    PIX_FMT_XVMC_MPEG2_IDCT,
    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 additionally allocated bytes at the end of the input bitstream for decoding.
 * this is mainly needed because some optimized bitstream readers read 
 * 32 or 64 bit at once and could read over the end<br>
 * Note, if the first 23 bits of the additional bytes are not 0 then damaged
 * MPEG bitstreams could cause overread and segfault
 */
#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;

#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_QSCALE 0x0002  ///< use fixed qscale 
#define CODEC_FLAG_4MV    0x0004  ///< 4 MV per MB allowed / Advanced prediction for H263
#define CODEC_FLAG_QPEL   0x0010  ///< use qpel MC 
#define CODEC_FLAG_GMC    0x0020  ///< use GMC 
#define CODEC_FLAG_MV0    0x0040  ///< always try a MB with MV=<0,0> 
#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
#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 ///< H263 Advanced intra coding / MPEG4 AC prediction (remove this)
#define CODEC_FLAG_AC_PRED        0x01000000 ///< H263 Advanced intra coding / MPEG4 AC prediction
#define CODEC_FLAG_H263P_UMV      0x02000000 ///< Unlimited motion vector  
#define CODEC_FLAG_CBP_RD         0x04000000 ///< use rate distortion optimization for cbp
#define CODEC_FLAG_QP_RD          0x08000000 ///< use rate distortion optimization for qp selectioon
#define CODEC_FLAG_H263P_AIV      0x00000008 ///< H263 Alternative inter vlc
#define CODEC_FLAG_OBMC           0x00000001 ///< OBMC
#define CODEC_FLAG_LOOP_FILTER    0x00000800 ///< loop filter
#define CODEC_FLAG_H263P_SLICE_STRUCT 0x10000000
#define CODEC_FLAG_INTERLACED_ME  0x20000000 ///< interlaced motion estimation
#define CODEC_FLAG_SVCD_SCAN_OFFSET 0x40000000 ///< will reserve space for SVCD scan offset user data
#define CODEC_FLAG_CLOSED_GOP     0x80000000
/* Unsupported options :
 * 		Syntax Arithmetic coding (SAC)
 * 		Reference Picture Selection
 * 		Independant Segment Decoding */
/* /Fx */
/* codec capabilities */

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

//the following defines might change, so dont expect compatibility if u use them
#define MB_TYPE_INTRA4x4   0x0001
#define MB_TYPE_INTRA16x16 0x0002 //FIXME h264 specific
#define MB_TYPE_INTRA_PCM  0x0004 //FIXME h264 specific
#define MB_TYPE_16x16      0x0008
#define MB_TYPE_16x8       0x0010
#define MB_TYPE_8x16       0x0020
#define MB_TYPE_8x8        0x0040
#define MB_TYPE_INTERLACED 0x0080
#define MB_TYPE_DIRECT2     0x0100 //FIXME
#define MB_TYPE_ACPRED     0x0200
#define MB_TYPE_GMC        0x0400
#define MB_TYPE_SKIP       0x0800
#define MB_TYPE_P0L0       0x1000
#define MB_TYPE_P1L0       0x2000
#define MB_TYPE_P0L1       0x4000
#define MB_TYPE_P1L1       0x8000
#define MB_TYPE_L0         (MB_TYPE_P0L0 | MB_TYPE_P1L0)
#define MB_TYPE_L1         (MB_TYPE_P0L1 | MB_TYPE_P1L1)
#define MB_TYPE_L0L1       (MB_TYPE_L0   | MB_TYPE_L1)
#define MB_TYPE_QUANT      0x00010000
#define MB_TYPE_CBP        0x00020000
//Note bits 24-31 are reserved for codec specific use (h264 ref0, mpeg1 0mv, ...)

/**
 * Pan Scan area.
 * this specifies the area which should be displayed. Note there may be multiple such areas for one frame
 */
typedef struct AVPanScan{
    /**
     * id.
     * - encoding: set by user.
     * - decoding: set by lavc
     */
    int id;

    /**
     * width and height in 1/16 pel
     * - encoding: set by user.
     * - decoding: set by lavc
     */
    int width;
    int height;

    /**
     * position of the top left corner in 1/16 pel for up to 3 fields/frames.
     * - encoding: set by user.
     * - decoding: set by lavc
     */
    int16_t position[3][2];
}AVPanScan;

#define FF_COMMON_FRAME \
    /**\
     * pointer to the picture planes.\
     * this might be different from the first allocated byte\
     * - encoding: \
     * - decoding: \
     */\
    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\
     */\
    int64_t 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 FF_LAMBDA_MAX (bad)) \
     * - encoding: set by lavc for coded_picture (and set by user for input)\
     * - decoding: set by lavc\
     */\
    int quality; \
\
    /**\
     * buffer age (1->was last buffer and dint change, 2->..., ...).\
     * set to INT_MAX 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;\
\
    /**\
     * Motion vector table\
     * - encoding: unused\
     * - decoding: set by lavc\
     */\
    int16_t (*motion_val[2])[2];\
\
    /**\
     * Macroblock type table\
     * mb_type_base + mb_width + 2\
     * - encoding: unused\
     * - decoding: set by lavc\
     */\
    uint32_t *mb_type;\
\
    /**\
     * Macroblock size: (0->16x16, 1->8x8, 2-> 4x4, 3-> 2x2)\
     * - encoding: unused\
     * - decoding: set by lavc\
     */\
    uint8_t motion_subsample_log2;\
\
    /**\
     * 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;\
    \
    /**\
     * \
     */\
    int qscale_type;\
    \
    /**\
     * The content of the picture is interlaced.\
     * - encoding: set by user\
     * - decoding: set by lavc (default 0)\
     */\
    int interlaced_frame;\
    \
    /**\
     * if the content is interlaced, is top field displayed first.\
     * - encoding: set by user\
     * - decoding: set by lavc\
     */\
    int top_field_first;\
    \
    /**\
     * Pan scan.\
     * - encoding: set by user\
     * - decoding: set by lavc\
     */\
    AVPanScan *pan_scan;\
    \
    /**\
     * tell user application that palette has changed from previous frame.\
     * - encoding: ??? (no palette-enabled encoder yet)\
     * - decoding: set by lavc (default 0)\
     */\
    int palette_has_changed;\
    \
    /**\
     * Codec suggestion on buffer type if != 0\
     * - encoding: unused\
     * - decoding: set by lavc (before get_buffer() call))\
     */\
    int buffer_hints;\

#define FF_QSCALE_TYPE_MPEG1	0
#define FF_QSCALE_TYPE_MPEG2	1

#define FF_BUFFER_TYPE_INTERNAL 1
#define FF_BUFFER_TYPE_USER     2 ///< Direct rendering buffers (image is (de)allocated by user)
#define FF_BUFFER_TYPE_SHARED   4 ///< buffer from somewher else, dont dealloc image (data/base)
#define FF_BUFFER_TYPE_COPY     8 ///< just a (modified) copy of some other buffer, dont dealloc anything


#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
#define FF_SI_TYPE 5
#define FF_SP_TYPE 6

#define FF_BUFFER_HINTS_VALID    0x01 // Buffer hints value is meaningful (if 0 ignore)
#define FF_BUFFER_HINTS_READABLE 0x02 // Codec will read from buffer
#define FF_BUFFER_HINTS_PRESERVE 0x04 // User must not alter buffer content
#define FF_BUFFER_HINTS_REUSABLE 0x08 // Codec will reuse the buffer (update)

/**
 * Audio Video Frame.
 */
typedef struct AVFrame {
    FF_COMMON_FRAME
} AVFrame;

#define DEFAULT_FRAME_RATE_BASE 1001000

/**
 * 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 if known, codec should override / dynamically change if needed
     */
    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: FIXME: used by ffmpeg to decide whether an pix_fmt
     *                    conversion is in order. This only works for
     *                    codecs with one supported pix_fmt, we should
     *                    do something for a generic case as well.
     * - 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.
     * @param height the height of the slice
     * @param y the y position of the slice
     * @param type 1->top field, 2->bottom field, 3->frame
     * @param offset offset into the AVFrame.data from which the slice should be read
     */
    void (*draw_horiz_band)(struct AVCodecContext *s,
                            const AVFrame *src, int offset[4],
                            int y, int type, 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;

    /* unused, FIXME remove*/
    int rtp_mode;
    
    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: unused
     */
    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 */
    
    /**
     * fourcc (LSB first, so "ABCD" -> ('D'<<24) + ('C'<<16) + ('B'<<8) + 'A').
     * this is used to workaround some encoder bugs
     * - encoding: set by user, if not then the default based on codec_id will be used
     * - decoding: set by user, will be converted to upper case by lavc during init
     */
    unsigned int codec_tag;
    
    /**
     * 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           0  ///< will be removed, libavcodec can now handle these non compliant files by default
#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_EDGE             1024
//#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
     * width and height should be rounded up to the next multiple of 16
     * - 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.
     * 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_factor;
    
    /**
     * qscale offset between p and i frames.
     * - 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
#define FF_DCT_FAAN    6
    
    /**
     * luminance masking (0-> disabled).
     * - encoding: set by user
     * - decoding: unused