avcodec.h

     */
    int inter_threshold;

    /**
     * CODEC_FLAG2_*
     * - encoding: Set by user.
     * - decoding: Set by user.
     */
    int flags2;

    /**
     * Simulates errors in the bitstream to test error concealment.
     * - encoding: Set by user.
     * - decoding: unused
     */
    int error_rate;

    /**
     * MP3 antialias algorithm, see FF_AA_* below.
     * - encoding: unused
     * - decoding: Set by user.
     */
    int antialias_algo;
#define FF_AA_AUTO    0
#define FF_AA_FASTINT 1 //not implemented yet
#define FF_AA_INT     2
#define FF_AA_FLOAT   3
    /**
     * quantizer noise shaping
     * - encoding: Set by user.
     * - decoding: unused
     */
    int quantizer_noise_shaping;

    /**
     * thread count
     * is used to decide how many independent tasks should be passed to execute()
     * - encoding: Set by user.
     * - decoding: Set by user.
     */
    int thread_count;

    /**
     * The codec may call this to execute several independent things.
     * It will return only after finishing all tasks.
     * The user may replace this with some multithreaded implementation,
     * the default implementation will execute the parts serially.
     * @param count the number of things to execute
     * - encoding: Set by libavcodec, user can override.
     * - decoding: Set by libavcodec, user can override.
     */
    int (*execute)(struct AVCodecContext *c, int (*func)(struct AVCodecContext *c2, void *arg), void *arg2, int *ret, int count, int size);

    /**
     * thread opaque
     * Can be used by execute() to store some per AVCodecContext stuff.
     * - encoding: set by execute()
     * - decoding: set by execute()
     */
    void *thread_opaque;

    /**
     * Motion estimation threshold below which no motion estimation is
     * performed, but instead the user specified motion vectors are used.
     *
     * - encoding: Set by user.
     * - decoding: unused
     */
     int me_threshold;

    /**
     * Macroblock threshold below which the user specified macroblock types will be used.
     * - encoding: Set by user.
     * - decoding: unused
     */
     int mb_threshold;

    /**
     * precision of the intra DC coefficient - 8
     * - encoding: Set by user.
     * - decoding: unused
     */
     int intra_dc_precision;

    /**
     * noise vs. sse weight for the nsse comparsion function
     * - encoding: Set by user.
     * - decoding: unused
     */
     int nsse_weight;

    /**
     * Number of macroblock rows at the top which are skipped.
     * - encoding: unused
     * - decoding: Set by user.
     */
     int skip_top;

    /**
     * Number of macroblock rows at the bottom which are skipped.
     * - encoding: unused
     * - decoding: Set by user.
     */
     int skip_bottom;

    /**
     * profile
     * - encoding: Set by user.
     * - decoding: Set by libavcodec.
     */
     int profile;
#define FF_PROFILE_UNKNOWN -99
#define FF_PROFILE_AAC_MAIN 0
#define FF_PROFILE_AAC_LOW  1
#define FF_PROFILE_AAC_SSR  2
#define FF_PROFILE_AAC_LTP  3

    /**
     * level
     * - encoding: Set by user.
     * - decoding: Set by libavcodec.
     */
     int level;
#define FF_LEVEL_UNKNOWN -99

    /**
     * low resolution decoding, 1-> 1/2 size, 2->1/4 size
     * - encoding: unused
     * - decoding: Set by user.
     */
     int lowres;

    /**
     * Bitstream width / height, may be different from width/height if lowres
     * or other things are used.
     * - encoding: unused
     * - decoding: Set by user before init if known. Codec should override / dynamically change if needed.
     */
    int coded_width, coded_height;

    /**
     * frame skip threshold
     * - encoding: Set by user.
     * - decoding: unused
     */
    int frame_skip_threshold;

    /**
     * frame skip factor
     * - encoding: Set by user.
     * - decoding: unused
     */
    int frame_skip_factor;

    /**
     * frame skip exponent
     * - encoding: Set by user.
     * - decoding: unused
     */
    int frame_skip_exp;

    /**
     * frame skip comparison function
     * - encoding: Set by user.
     * - decoding: unused
     */
    int frame_skip_cmp;

    /**
     * Border processing masking, raises the quantizer for mbs on the borders
     * of the picture.
     * - encoding: Set by user.
     * - decoding: unused
     */
    float border_masking;

    /**
     * minimum MB lagrange multipler
     * - encoding: Set by user.
     * - decoding: unused
     */
    int mb_lmin;

    /**
     * maximum MB lagrange multipler
     * - encoding: Set by user.
     * - decoding: unused
     */
    int mb_lmax;

    /**
     *
     * - encoding: Set by user.
     * - decoding: unused
     */
    int me_penalty_compensation;

    /**
     *
     * - encoding: unused
     * - decoding: Set by user.
     */
    enum AVDiscard skip_loop_filter;

    /**
     *
     * - encoding: unused
     * - decoding: Set by user.
     */
    enum AVDiscard skip_idct;

    /**
     *
     * - encoding: unused
     * - decoding: Set by user.
     */
    enum AVDiscard skip_frame;

    /**
     *
     * - encoding: Set by user.
     * - decoding: unused
     */
    int bidir_refine;

    /**
     *
     * - encoding: Set by user.
     * - decoding: unused
     */
    int brd_scale;

    /**
     * constant rate factor - quality-based VBR - values ~correspond to qps
     * - encoding: Set by user.
     * - decoding: unused
     */
    float crf;

    /**
     * constant quantization parameter rate control method
     * - encoding: Set by user.
     * - decoding: unused
     */
    int cqp;

    /**
     * minimum GOP size
     * - encoding: Set by user.
     * - decoding: unused
     */
    int keyint_min;

    /**
     * number of reference frames
     * - encoding: Set by user.
     * - decoding: Set by lavc.
     */
    int refs;

    /**
     * chroma qp offset from luma
     * - encoding: Set by user.
     * - decoding: unused
     */
    int chromaoffset;

    /**
     * Influences how often B-frames are used.
     * - encoding: Set by user.
     * - decoding: unused
     */
    int bframebias;

    /**
     * trellis RD quantization
     * - encoding: Set by user.
     * - decoding: unused
     */
    int trellis;

    /**
     * Reduce fluctuations in qp (before curve compression).
     * - encoding: Set by user.
     * - decoding: unused
     */
    float complexityblur;

    /**
     * in-loop deblocking filter alphac0 parameter
     * alpha is in the range -6...6
     * - encoding: Set by user.
     * - decoding: unused
     */
    int deblockalpha;

    /**
     * in-loop deblocking filter beta parameter
     * beta is in the range -6...6
     * - encoding: Set by user.
     * - decoding: unused
     */
    int deblockbeta;

    /**
     * macroblock subpartition sizes to consider - p8x8, p4x4, b8x8, i8x8, i4x4
     * - encoding: Set by user.
     * - decoding: unused
     */
    int partitions;
#define X264_PART_I4X4 0x001  /* Analyze i4x4 */
#define X264_PART_I8X8 0x002  /* Analyze i8x8 (requires 8x8 transform) */
#define X264_PART_P8X8 0x010  /* Analyze p16x8, p8x16 and p8x8 */
#define X264_PART_P4X4 0x020  /* Analyze p8x4, p4x8, p4x4 */
#define X264_PART_B8X8 0x100  /* Analyze b16x8, b8x16 and b8x8 */

    /**
     * direct MV prediction mode - 0 (none), 1 (spatial), 2 (temporal), 3 (auto)
     * - encoding: Set by user.
     * - decoding: unused
     */
    int directpred;

    /**
     * Audio cutoff bandwidth (0 means "automatic")
     * - encoding: Set by user.
     * - decoding: unused
     */
    int cutoff;

    /**
     * Multiplied by qscale for each frame and added to scene_change_score.
     * - encoding: Set by user.
     * - decoding: unused
     */
    int scenechange_factor;

    /**
     *
     * Note: Value depends upon the compare function used for fullpel ME.
     * - encoding: Set by user.
     * - decoding: unused
     */
    int mv0_threshold;

    /**
     * Adjusts sensitivity of b_frame_strategy 1.
     * - encoding: Set by user.
     * - decoding: unused
     */
    int b_sensitivity;

    /**
     * - encoding: Set by user.
     * - decoding: unused
     */
    int compression_level;
#define FF_COMPRESSION_DEFAULT -1

    /**
     * Sets whether to use LPC mode - used by FLAC encoder.
     * - encoding: Set by user.
     * - decoding: unused
     */
    int use_lpc;

    /**
     * LPC coefficient precision - used by FLAC encoder
     * - encoding: Set by user.
     * - decoding: unused
     */
    int lpc_coeff_precision;

    /**
     * - encoding: Set by user.
     * - decoding: unused
     */
    int min_prediction_order;

    /**
     * - encoding: Set by user.
     * - decoding: unused
     */
    int max_prediction_order;

    /**
     * search method for selecting prediction order
     * - encoding: Set by user.
     * - decoding: unused
     */
    int prediction_order_method;

    /**
     * - encoding: Set by user.
     * - decoding: unused
     */
    int min_partition_order;

    /**
     * - encoding: Set by user.
     * - decoding: unused
     */
    int max_partition_order;

    /**
     * GOP timecode frame start number, in non drop frame format
     * - encoding: Set by user.
     * - decoding: unused
     */
    int64_t timecode_frame_start;

#if LIBAVCODEC_VERSION_MAJOR < 53
    /**
     * Decoder should decode to this many channels if it can (0 for default)
     * - encoding: unused
     * - decoding: Set by user.
     * @deprecated Deprecated in favor of request_channel_layout.
     */
    int request_channels;
#endif

    /**
     * Percentage of dynamic range compression to be applied by the decoder.
     * The default value is 1.0, corresponding to full compression.
     * - encoding: unused
     * - decoding: Set by user.
     */
    float drc_scale;

    /**
     * opaque 64bit number (generally a PTS) that will be reordered and
     * output in AVFrame.reordered_opaque
     * - encoding: unused
     * - decoding: Set by user.
     */
    int64_t reordered_opaque;

    /**
     * Bits per sample/pixel of internal libavcodec pixel/sample format.
     * This field is applicable only when sample_fmt is SAMPLE_FMT_S32.
     * - encoding: set by user.
     * - decoding: set by libavcodec.
     */
    int bits_per_raw_sample;

    /**
     * Audio channel layout.
     * - encoding: set by user.
     * - decoding: set by libavcodec.
     */
    int64_t channel_layout;

    /**
     * Request decoder to use this channel layout if it can (0 for default)
     * - encoding: unused
     * - decoding: Set by user.
     */
    int64_t request_channel_layout;

    /**
     * Ratecontrol attempt to use, at maximum, <value> of what can be used without an underflow.
     * - encoding: Set by user.
     * - decoding: unused.
     */
    float rc_max_available_vbv_use;

    /**
     * Ratecontrol attempt to use, at least, <value> times the amount needed to prevent a vbv overflow.
     * - encoding: Set by user.
     * - decoding: unused.
     */
    float rc_min_vbv_overflow_use;

    /**
     * Hardware accelerator in use
     * - encoding: unused.
     * - decoding: Set by libavcodec
     */
    struct AVHWAccel *hwaccel;

    /**
     * For some codecs, the time base is closer to the field rate than the frame rate.
     * Most notably, H.264 and MPEG-2 specify time_base as half of frame duration
     * if no telecine is used ...
     *
     * Set to time_base ticks per frame. Default 1, e.g., H.264/MPEG-2 set it to 2.
     */
    int ticks_per_frame;

    /**
     * Hardware accelerator context.
     * For some hardware accelerators, a global context needs to be
     * provided by the user. In that case, this holds display-dependent
     * data FFmpeg cannot instantiate itself. Please refer to the
     * FFmpeg HW accelerator documentation to know how to fill this
     * is. e.g. for VA API, this is a struct vaapi_context.
     * - encoding: unused
     * - decoding: Set by user
     */
    void *hwaccel_context;

    /**
     * Chromaticity coordinates of the source primaries.
     * - encoding: Set by user
     * - decoding: Set by libavcodec
     */
    enum AVColorPrimaries color_primaries;

    /**
     * Color Transfer Characteristic.
     * - encoding: Set by user
     * - decoding: Set by libavcodec
     */
    enum AVColorTransferCharacteristic color_trc;

    /**
     * YUV colorspace type.
     * - encoding: Set by user
     * - decoding: Set by libavcodec
     */
    enum AVColorSpace colorspace;

    /**
     * MPEG vs JPEG YUV range.
     * - encoding: Set by user
     * - decoding: Set by libavcodec
     */
    enum AVColorRange color_range;

    /**
     * This defines the location of chroma samples.
     * - encoding: Set by user
     * - decoding: Set by libavcodec
     */
    enum AVChromaLocation chroma_sample_location;

    /**
     * The codec may call this to execute several independent things.
     * It will return only after finishing all tasks.
     * The user may replace this with some multithreaded implementation,
     * the default implementation will execute the parts serially.
     * Also see avcodec_thread_init and e.g. the --enable-pthread configure option.
     * @param c context passed also to func
     * @param count the number of things to execute
     * @param arg2 argument passed unchanged to func
     * @param ret return values of executed functions, must have space for "count" values. May be NULL.
     * @param func function that will be called count times, with jobnr from 0 to count-1.
     *             threadnr will be in the range 0 to c->thread_count-1 < MAX_THREADS and so that no
     *             two instances of func executing at the same time will have the same threadnr.
     * @return always 0 currently, but code should handle a future improvement where when any call to func
     *         returns < 0 no further calls to func may be done and < 0 is returned.
     * - encoding: Set by libavcodec, user can override.
     * - decoding: Set by libavcodec, user can override.
     */
    int (*execute2)(struct AVCodecContext *c, int (*func)(struct AVCodecContext *c2, void *arg, int jobnr, int threadnr), void *arg2, int *ret, int count);
} AVCodecContext;

/**
 * AVCodec.
 */
typedef struct AVCodec {
    /**
     * Name of the codec implementation.
     * The name is globally unique among encoders and among decoders (but an
     * encoder and a decoder can share the same name).
     * This is the primary way to find a codec from the user perspective.
     */
    const char *name;
    enum CodecType type;
    enum CodecID id;
    int priv_data_size;
    int (*init)(AVCodecContext *);
    int (*encode)(AVCodecContext *, uint8_t *buf, int buf_size, void *data);
    int (*close)(AVCodecContext *);
    int (*decode)(AVCodecContext *, void *outdata, int *outdata_size, AVPacket *avpkt);
    /**
     * Codec capabilities.
     * see CODEC_CAP_*
     */
    int capabilities;
    struct AVCodec *next;
    /**
     * Flush buffers.
     * Will be called when seeking
     */
    void (*flush)(AVCodecContext *);
    const AVRational *supported_framerates; ///< array of supported framerates, or NULL if any, array is terminated by {0,0}
    const enum PixelFormat *pix_fmts;       ///< array of supported pixel formats, or NULL if unknown, array is terminated by -1
    /**
     * Descriptive name for the codec, meant to be more human readable than name.
     * You should use the NULL_IF_CONFIG_SMALL() macro to define it.
     */
    const char *long_name;
    const int *supported_samplerates;       ///< array of supported audio samplerates, or NULL if unknown, array is terminated by 0
    const enum SampleFormat *sample_fmts;   ///< array of supported sample formats, or NULL if unknown, array is terminated by -1
    const int64_t *channel_layouts;         ///< array of support channel layouts, or NULL if unknown. array is terminated by 0
} AVCodec;

/**
 * AVHWAccel.
 */
typedef struct AVHWAccel {
    /**
     * Name of the hardware accelerated codec.
     * The name is globally unique among encoders and among decoders (but an
     * encoder and a decoder can share the same name).
     */
    const char *name;

    /**
     * Type of codec implemented by the hardware accelerator.
     *
     * See CODEC_TYPE_xxx
     */
    enum CodecType type;

    /**
     * Codec implemented by the hardware accelerator.
     *
     * See CODEC_ID_xxx
     */
    enum CodecID id;

    /**
     * Supported pixel format.
     *
     * Only hardware accelerated formats are supported here.
     */
    enum PixelFormat pix_fmt;

    /**
     * Hardware accelerated codec capabilities.
     * see FF_HWACCEL_CODEC_CAP_*
     */
    int capabilities;

    struct AVHWAccel *next;

    /**
     * Called at the beginning of each frame or field picture.
     *
     * Meaningful frame information (codec specific) is guaranteed to
     * be parsed at this point. This function is mandatory.
     *
     * Note that buf can be NULL along with buf_size set to 0.
     * Otherwise, this means the whole frame is available at this point.
     *
     * @param avctx the codec context
     * @param buf the frame data buffer base
     * @param buf_size the size of the frame in bytes
     * @return zero if successful, a negative value otherwise
     */
    int (*start_frame)(AVCodecContext *avctx, const uint8_t *buf, uint32_t buf_size);

    /**
     * Callback for each slice.
     *
     * Meaningful slice information (codec specific) is guaranteed to
     * be parsed at this point. This function is mandatory.
     *
     * @param avctx the codec context
     * @param buf the slice data buffer base
     * @param buf_size the size of the slice in bytes
     * @return zero if successful, a negative value otherwise
     */
    int (*decode_slice)(AVCodecContext *avctx, const uint8_t *buf, uint32_t buf_size);

    /**
     * Called at the end of each frame or field picture.
     *
     * The whole picture is parsed at this point and can now be sent
     * to the hardware accelerator. This function is mandatory.
     *
     * @param avctx the codec context
     * @return zero if successful, a negative value otherwise
     */
    int (*end_frame)(AVCodecContext *avctx);

    /**
     * Size of HW accelerator private data.
     *
     * Private data is allocated with av_mallocz() before
     * AVCodecContext.get_buffer() and deallocated after
     * AVCodecContext.release_buffer().
     */
    int priv_data_size;
} AVHWAccel;

/**
 * four components are given, that's all.
 * the last component is alpha
 */
typedef struct AVPicture {
    uint8_t *data[4];
    int linesize[4];       ///< number of bytes per line
} AVPicture;

#if LIBAVCODEC_VERSION_MAJOR < 53
/**
 * AVPaletteControl
 * This structure defines a method for communicating palette changes
 * between and demuxer and a decoder.
 *
 * @deprecated Use AVPacket to send palette changes instead.
 * This is totally broken.
 */
#define AVPALETTE_SIZE 1024
#define AVPALETTE_COUNT 256
typedef struct AVPaletteControl {

    /* Demuxer sets this to 1 to indicate the palette has changed;
     * decoder resets to 0. */
    int palette_changed;

    /* 4-byte ARGB palette entries, stored in native byte order; note that
     * the individual palette components should be on a 8-bit scale; if
     * the palette data comes from an IBM VGA native format, the component
     * data is probably 6 bits in size and needs to be scaled. */
    unsigned int palette[AVPALETTE_COUNT];

} AVPaletteControl attribute_deprecated;
#endif

enum AVSubtitleType {
    SUBTITLE_NONE,

    SUBTITLE_BITMAP,                ///< A bitmap, pict will be set

    /**
     * Plain text, the text field must be set by the decoder and is
     * authoritative. ass and pict fields may contain approximations.
     */
    SUBTITLE_TEXT,

    /**
     * Formatted text, the ass field must be set by the decoder and is
     * authoritative. pict and text fields may contain approximations.
     */
    SUBTITLE_ASS,
};

typedef struct AVSubtitleRect {
    int x;         ///< top left corner  of pict, undefined when pict is not set
    int y;         ///< top left corner  of pict, undefined when pict is not set
    int w;         ///< width            of pict, undefined when pict is not set
    int h;         ///< height           of pict, undefined when pict is not set
    int nb_colors; ///< number of colors in pict, undefined when pict is not set

    /**
     * data+linesize for the bitmap of this subtitle.
     * can be set for text/ass as well once they where rendered
     */
    AVPicture pict;
    enum AVSubtitleType type;

    char *text;                     ///< 0 terminated plain UTF-8 text

    /**
     * 0 terminated ASS/SSA compatible event line.
     * The pressentation of this is unaffected by the other values in this
     * struct.
     */
    char *ass;
} AVSubtitleRect;

typedef struct AVSubtitle {
    uint16_t format; /* 0 = graphics */
    uint32_t start_display_time; /* relative to packet pts, in ms */
    uint32_t end_display_time; /* relative to packet pts, in ms */
    unsigned num_rects;
    AVSubtitleRect **rects;
    int64_t pts;    ///< Same as packet pts, in AV_TIME_BASE
} AVSubtitle;

/* packet functions */

/**
 * @deprecated use NULL instead
 */
attribute_deprecated void av_destruct_packet_nofree(AVPacket *pkt);

/**
 * Default packet destructor.
 */
void av_destruct_packet(AVPacket *pkt);

/**
 * Initialize optional fields of a packet with default values.
 *
 * @param pkt packet
 */
void av_init_packet(AVPacket *pkt);

/**
 * Allocate the payload of a packet and initialize its fields with
 * default values.
 *
 * @param pkt packet
 * @param size wanted payload size
 * @return 0 if OK, AVERROR_xxx otherwise
 */
int av_new_packet(AVPacket *pkt, int size);

/**
 * Reduce packet size, correctly zeroing padding
 *
 * @param pkt packet
 * @param size new size
 */
void av_shrink_packet(AVPacket *pkt, int size);

/**
 * @warning This is a hack - the packet memory allocation stuff is broken. The
 * packet is allocated if it was not really allocated.
 */
int av_dup_packet(AVPacket *pkt);

/**
 * Free a packet.
 *
 * @param pkt packet to free
 */
void av_free_packet(AVPacket *pkt);

/* resample.c */

struct ReSampleContext;
struct AVResampleContext;

typedef struct ReSampleContext ReSampleContext;

#if LIBAVCODEC_VERSION_MAJOR < 53
/**
 * @deprecated Use av_audio_resample_init() instead.
 */
attribute_deprecated ReSampleContext *audio_resample_init(int output_channels, int input_channels,
                                                          int output_rate, int input_rate);
#endif
/**
 *  Initializes audio resampling context
 *
 * @param output_channels  number of output channels
 * @param input_channels   number of input channels
 * @param output_rate      output sample rate
 * @param input_rate       input sample rate
 * @param sample_fmt_out   requested output sample format
 * @param sample_fmt_in    input sample format
 * @param filter_length    length of each FIR filter in the filterbank relative to the cutoff freq
 * @param log2_phase_count log2 of the number of entries in the polyphase filterbank
 * @param linear           If 1 then the used FIR filter will be linearly interpolated
                           between the 2 closest, if 0 the closest will be used
 * @param cutoff           cutoff frequency, 1.0 corresponds to half the output sampling rate
 * @return allocated ReSampleContext, NULL if error occured
 */
ReSampleContext *av_audio_resample_init(int output_channels, int input_channels,
                                        int output_rate, int input_rate,
                                        enum SampleFormat sample_fmt_out,
                                        enum SampleFormat sample_fmt_in,
                                        int filter_length, int log2_phase_count,
                                        int linear, double cutoff);

int audio_resample(ReSampleContext *s, short *output, short *input, int nb_samples);
void audio_resample_close(ReSampleContext *s);


/**
 * Initializes an audio resampler.
 * Note, if either rate is not an integer then simply scale both rates up so they are.
 * @param filter_length length of each FIR filter in the filterbank relative to the cutoff freq
 * @param log2_phase_count log2 of the number of entries in the polyphase filterbank
 * @param linear If 1 then the used FIR filter will be linearly interpolated
                 between the 2 closest, if 0 the closest will be used
 * @param cutoff cutoff frequency, 1.0 corresponds to half the output sampling rate
 */
struct AVResampleContext *av_resample_init(int out_rate, int in_rate, int filter_length, int log2_phase_count, int linear, double cutoff);

/**
 * resamples.
 * @param src an array of unconsumed samples
 * @param consumed the number of samples of src which have been consumed are returned here
 * @param src_size the number of unconsumed samples available
 * @param dst_size the amount of space in samples available in dst
 * @param update_ctx If this is 0 then the context will not be modified, that way several channels can be resampled with the same context.
 * @return the number of samples written in dst or -1 if an error occurred
 */
int av_resample(struct AVResampleContext *c, short *dst, short *src, int *consumed, int src_size, int dst_size, int update_ctx);


/**
 * Compensates samplerate/timestamp drift. The compensation is done by changing
 * the resampler parameters, so no audible clicks or similar distortions occur
 * @param compensation_distance distance in output samples over which the compensation should be performed
 * @param sample_delta number of output samples which should be output less
 *
 * example: av_resample_compensate(c, 10, 500)
 * here instead of 510 samples only 500 samples would be output
 *
 * note, due to rounding the actual compensation might be slightly different,
 * especially if the compensation_distance is large and the in_rate used during init is small
 */
void av_resample_compensate(struct AVResampleContext *c, int sample_delta, int compensation_distance);
void av_resample_close(struct AVResampleContext *c);

/**
 * Allocate memory for a picture.  Call avpicture_free to free it.
 *
 * @param picture the picture to be filled in
 * @param pix_fmt the format of the picture
 * @param width the width of the picture
 * @param height the height of the picture
 * @return zero if successful, a negative value if not
 */
int avpicture_alloc(AVPicture *picture, enum PixelFormat pix_fmt, int width, int height);

/**
 * Free a picture previously allocated by avpicture_alloc().
 *
 * @param picture the AVPicture to be freed
 */
void avpicture_free(AVPicture *picture);

/**
 * Fill in the AVPicture fields.
 * The fields of the given AVPicture are filled in by using the 'ptr' address
 * which points to the image data buffer. Depending on the specified picture
 * format, one or multiple image data pointers and line sizes will be set.
 * If a planar format is specified, several pointers will be set pointing to
 * the different picture planes and the line sizes of the different planes
 * will be stored in the lines_sizes array.
 * Call with ptr == NULL to get the required size for the ptr buffer.
 *
 * @param picture AVPicture whose fields are to be filled in
 * @param ptr Buffer which will contain or contains the actual image data
 * @param pix_fmt The format in which the picture data is stored.
 * @param width the width of the image in pixels
 * @param height the height of the image in pixels
 * @return size of the image data in bytes
 */
int avpicture_fill(AVPicture *picture, uint8_t *ptr,
                   enum PixelFormat pix_fmt, int width, int height);
int avpicture_layout(const AVPicture* src, enum PixelFormat pix_fmt, int width, int height,
                     unsigned char *dest, int dest_size);

/**
 * Calculate the size in bytes that a picture of the given width and height
 * would occupy if stored in the given picture format.
 * Note that this returns the size of a compact representation as generated
 * by avpicture_layout, which can be smaller than the size required for e.g.
 * avpicture_fill.
 *
 * @param pix_fmt the given picture format
 * @param width the width of the image
 * @param height the height of the image
 * @return Image data size in bytes or -1 on error (e.g. too large dimensions).
 */
int avpicture_get_size(enum PixelFormat pix_fmt, int width, int height);
void avcodec_get_chroma_sub_sample(enum PixelFormat pix_fmt, int *h_shift, int *v_shift);
const char *avcodec_get_pix_fmt_name(enum PixelFormat pix_fmt);
void avcodec_set_dimensions(AVCodecContext *s, int width, int height);

/**
 * Returns the pixel format corresponding to the name name.
 *
 * If there is no pixel format with name name, then looks for a
 * pixel format with the name corresponding to the native endian
 * format of name.
 * For example in a little-endian system, first looks for "gray16",
 * then for "gray16le".
 *
 * Finally if no pixel format has been found, returns PIX_FMT_NONE.
 */
enum PixelFormat avcodec_get_pix_fmt(const char* name);
unsigned int avcodec_pix_fmt_to_codec_tag(enum PixelFormat p);

#define FF_LOSS_RESOLUTION  0x0001 /**< loss due to resolution change */
#define FF_LOSS_DEPTH       0x0002 /**< loss due to color depth change */
#define FF_LOSS_COLORSPACE  0x0004 /**< loss due to color space conversion */
#define FF_LOSS_ALPHA       0x0008 /**< loss of alpha bits */
#define FF_LOSS_COLORQUANT  0x0010 /**< loss due to color quantization */
#define FF_LOSS_CHROMA      0x0020 /**< loss of chroma (e.g. RGB to gray conversion) */

/**
 * Computes what kind of losses will occur when converting from one specific
 * pixel format to another.
 * When converting from one pixel format to another, information loss may occur.
 * For example, when converting from RGB24 to GRAY, the color information will
 * be lost. Similarly, other losses occur when converting from some formats to
 * other formats. These losses can involve loss of chroma, but also loss of
 * resolution, loss of color depth, loss due to the color space conversion, loss
 * of the alpha bits or loss due to color quantization.
 * avcodec_get_fix_fmt_loss() informs you about the various types of losses
 * which will occur when converting from one pixel format to another.
 *
 * @param[in] dst_pix_fmt destination pixel format
 * @param[in] src_pix_fmt source pixel format
 * @param[in] has_alpha Whether the source pixel format alpha channel is used.
 * @return Combination of flags informing you what kind of losses will occur.
 */
int avcodec_get_pix_fmt_loss(enum PixelFormat dst_pix_fmt, enum PixelFormat src_pix_fmt,
                             int has_alpha);