/*
 * Copyright (c) 2021, Alliance for Open Media. All rights reserved
 *
 * This source code is subject to the terms of the BSD 3-Clause Clear License
 * and the Alliance for Open Media Patent License 1.0. If the BSD 3-Clause Clear
 * License was not distributed with this source code in the LICENSE file, you
 * can obtain it at aomedia.org/license/software-license/bsd-3-c-c/.  If the
 * Alliance for Open Media Patent License 1.0 was not distributed with this
 * source code in the PATENTS file, you can obtain it at
 * aomedia.org/license/patent-license/.
 */
#ifndef AOM_AOM_AOM_ENCODER_H_
#define AOM_AOM_AOM_ENCODER_H_

/*!\defgroup encoder Encoder Algorithm Interface
 * \ingroup codec
 * This abstraction allows applications using this encoder to easily support
 * multiple video formats with minimal code duplication. This section describes
 * the interface common to all encoders.
 * @{
 */

/*!\file
 * \brief Describes the encoder algorithm interface to applications.
 *
 * This file describes the interface between an application and a
 * video encoder algorithm.
 *
 */
#ifdef __cplusplus
extern "C" {
#endif

#include "config/aom_config.h"
#include "aom/aom_codec.h"

/*!\brief Current ABI version number
 *
 * \internal
 * If this file is altered in any way that changes the ABI, this value
 * must be bumped.  Examples include, but are not limited to, changing
 * types, removing or reassigning enums, adding/removing/rearranging
 * fields to structures
 */
#define AOM_ENCODER_ABI_VERSION \
  (8 + AOM_CODEC_ABI_VERSION) /**<\hideinitializer*/

/*! \brief Encoder capabilities bitfield
 *
 *  Each encoder advertises the capabilities it supports as part of its
 *  ::aom_codec_iface_t interface structure. Capabilities are extra
 *  interfaces or functionality, and are not required to be supported
 *  by an encoder.
 *
 *  The available flags are specified by AOM_CODEC_CAP_* defines.
 */
#define AOM_CODEC_CAP_PSNR 0x10000 /**< Can issue PSNR packets */

/*! \brief Initialization-time Feature Enabling
 *
 *  Certain codec features must be known at initialization time, to allow
 *  for proper memory allocation.
 *
 *  The available flags are specified by AOM_CODEC_USE_* defines.
 */
#define AOM_CODEC_USE_PSNR 0x10000 /**< Calculate PSNR on each frame */
/*!\brief Use stream PSNR instead of input PSNR. */
#define AOM_CODEC_USE_STREAM_PSNR 0x20000
/*!\brief Print per frame stats. */
#define AOM_CODEC_USE_PER_FRAME_STATS 0x80000 /**< Enable printing of stats */

/*!\brief Generic fixed size buffer structure
 *
 * This structure is able to hold a reference to any fixed size buffer.
 */
typedef struct aom_fixed_buf {
  void *buf;       /**< Pointer to the data. Does NOT own the data! */
  size_t sz;       /**< Length of the buffer, in chars */
} aom_fixed_buf_t; /**< alias for struct aom_fixed_buf */

/*!\brief Error Resilient flags
 *
 * These flags define which error resilient features to enable in the
 * encoder. The flags are specified through the
 * aom_codec_enc_cfg::g_error_resilient variable.
 */
typedef uint32_t aom_codec_er_flags_t;
/*!\brief Improve resiliency against losses of whole frames */
#define AOM_ERROR_RESILIENT_DEFAULT 0x1

/*!\brief Encoder output packet variants
 *
 * This enumeration lists the different kinds of data packets that can be
 * returned by calls to aom_codec_get_cx_data(). Algorithms \ref MAY
 * extend this list to provide additional functionality.
 */
enum aom_codec_cx_pkt_kind {
  AOM_CODEC_CX_FRAME_PKT,      /**< Compressed video frame */
  AOM_CODEC_STATS_PKT,         /**< Two-pass statistics for this frame */
  AOM_CODEC_FPMB_STATS_PKT,    /**< first pass mb statistics for this frame */
  AOM_CODEC_PSNR_PKT,          /**< PSNR statistics for this frame */
  AOM_CODEC_CX_FRAME_NULL_PKT, /**< Null show-existing frame */
  AOM_CODEC_CUSTOM_PKT = 256   /**< Algorithm extensions  */
};

/*!\brief Encoder output packet
 *
 * This structure contains the different kinds of output data the encoder
 * may produce while compressing a frame.
 */
typedef struct aom_codec_cx_pkt {
  enum aom_codec_cx_pkt_kind kind; /**< packet variant */
  union {
    struct {
      void *buf; /**< compressed data buffer */
      size_t sz; /**< length of compressed data */
      /*!\brief time stamp to show frame (in timebase units) */
      aom_codec_pts_t pts;
      /*!\brief duration to show frame (in timebase units) */
      unsigned long duration;
      aom_codec_frame_flags_t flags; /**< flags for this frame */
      /*!\brief the partition id defines the decoding order of the partitions.
       * Only applicable when "output partition" mode is enabled. First
       * partition has id 0.*/
      int partition_id;
      /*!\brief size of the visible frame in this packet */
      size_t vis_frame_size;
    } frame;                            /**< data for compressed frame packet */
    aom_fixed_buf_t twopass_stats;      /**< data for two-pass packet */
    aom_fixed_buf_t firstpass_mb_stats; /**< first pass mb packet */
    struct aom_psnr_pkt {
      unsigned int samples[4]; /**< Number of samples, total/y/u/v */
      uint64_t sse[4];         /**< sum squared error, total/y/u/v */
      double psnr[4];          /**< PSNR, total/y/u/v */
      /*!\brief Number of samples, total/y/u/v when
       * input bit-depth < stream bit-depth.*/
      unsigned int samples_hbd[4];
      /*!\brief sum squared error, total/y/u/v when
       * input bit-depth < stream bit-depth.*/
      uint64_t sse_hbd[4];
      /*!\brief PSNR, total/y/u/v when
       * input bit-depth < stream bit-depth.*/
      double psnr_hbd[4];
    } psnr;              /**< data for PSNR packet */
    aom_fixed_buf_t raw; /**< data for arbitrary packets */

    /* This packet size is fixed to allow codecs to extend this
     * interface without having to manage storage for raw packets,
     * i.e., if it's smaller than 128 bytes, you can store in the
     * packet list directly.
     */
    char pad[128 - sizeof(enum aom_codec_cx_pkt_kind)]; /**< fixed sz */
  } data;                                               /**< packet data */
} aom_codec_cx_pkt_t; /**< alias for struct aom_codec_cx_pkt */

/*!\brief Rational Number
 *
 * This structure holds a fractional value.
 */
typedef struct aom_rational {
  int num;        /**< fraction numerator */
  int den;        /**< fraction denominator */
} aom_rational_t; /**< alias for struct aom_rational */

/*!\brief Multi-pass Encoding Pass */
enum aom_enc_pass {
  AOM_RC_ONE_PASS,   /**< Single pass mode */
  AOM_RC_FIRST_PASS, /**< First pass of multi-pass mode */
  AOM_RC_LAST_PASS   /**< Final pass of multi-pass mode */
};

/*!\brief Rate control mode */
enum aom_rc_mode {
  AOM_VBR, /**< Variable Bit Rate (VBR) mode */
  AOM_CBR, /**< Constant Bit Rate (CBR) mode */
  AOM_CQ,  /**< Constrained Quality (CQ)  mode */
  AOM_Q,   /**< Constant Quality (Q) mode */
};

/*!\brief Keyframe placement mode.
 *
 * This enumeration determines whether keyframes are placed automatically by
 * the encoder or whether this behavior is disabled. Older releases of this
 * SDK were implemented such that AOM_KF_FIXED meant keyframes were disabled.
 * This name is confusing for this behavior, so the new symbols to be used
 * are AOM_KF_AUTO and AOM_KF_DISABLED.
 */
enum aom_kf_mode {
  AOM_KF_FIXED,       /**< deprecated, implies AOM_KF_DISABLED */
  AOM_KF_AUTO,        /**< Encoder determines optimal placement automatically */
  AOM_KF_DISABLED = 0 /**< Encoder does not place keyframes. */
};

/*!\brief Frame super-resolution mode. */
typedef enum {
  /**< Frame super-resolution is disabled for all frames. */
  AOM_SUPERRES_NONE,
  /**< All frames are coded at the specified scale and super-resolved. */
  AOM_SUPERRES_FIXED,
  /**< All frames are coded at a random scale and super-resolved. */
  AOM_SUPERRES_RANDOM,
  /**< Super-resolution scale for each frame is determined based on the q index
     of that frame. */
  AOM_SUPERRES_QTHRESH,
  /**< Full-resolution or super-resolution and the scale (in case of
     super-resolution) are automatically selected for each frame. */
  AOM_SUPERRES_AUTO,
} aom_superres_mode;

/*!\brief Frame super-resolution mode. */
typedef enum {
  /**< MV refinement is disabled for all frames. */
  AOM_OPFL_REFINE_NONE,
  /**< MV refinement is switchable per block and signaled by the encoder for all
   * frames. */
  AOM_OPFL_REFINE_SWITCHABLE,
  /**< MV refinement is done for all compound average blocks for all frames. */
  AOM_OPFL_REFINE_ALL,
  /**< One among the three above types is automatically selected by the encoder
   * for each frame. */
  AOM_OPFL_REFINE_AUTO,
} aom_opfl_refine_type;

/*!\brief Decoded Frame Hash Metadata OBU writing mode.
 *
 * This enumeration determines whether one or more metadata OBUs of type
 * Decoded Frame Hash are written before each encoded frame.
 */
enum aom_frame_hash_mode {
  /**< Encoder does not write Decoded Frame Hash Metadata OBUs. */
  AOM_DFH_DISABLED,
  /**< Encoder writes Decoded Frame Hash Metadata OBUs for frames as
   *   they are in reference picture buffer. */
  AOM_DFH_RAW,
  /**< Encoder writes Decoded Frame Hash Metadata OBUs for frames as
   *   they are output, which may be as they are in reference picture buffer
   *   or after Film Grain has been applied if such parameters are present. */
  AOM_DFH_FG,
  /**< Encoder writes Decoded Frame Hash Metadata OBUs for frames both
   *   as they are in reference picture buffer and as they are output.
   *   The latter is only written if it differs from the former (e.g.,
   *   film grain has been applied if such parameters are present.) */
  AOM_DFH_BOTH,
};

/*!\brief Encoder Config Options
 *
 * This type allows to enumerate and control flags defined for encoder control
 * via config file at runtime.
 */
typedef struct cfg_options {
  /*!\brief Indicate init by cfg file
   * 0 or 1
   */
  unsigned int init_by_cfg_file;
#if CONFIG_EXT_RECUR_PARTITIONS
  /*!\brief Superblock size
   * 0, 64, 128 or 256
   */
  unsigned int superblock_size;
  /*!\brief max partition size
   * 8, 16, 32, 64, 128, 256
   */
  unsigned int max_partition_size;
  /*!\brief min partition size
   * 8, 16, 32, 64, 128, 256
   */
  unsigned int min_partition_size;
#else
  /*!\brief Superblock size
   * 0, 64 or 128
   */
  unsigned int superblock_size;
  /*!\brief max partition size
   * 8, 16, 32, 64, 128
   */
  unsigned int max_partition_size;
  /*!\brief min partition size
   * 8, 16, 32, 64, 128
   */
  unsigned int min_partition_size;
#endif  // CONFIG_EXT_RECUR_PARTITIONS
  /*!\brief enable AB Shape partition type
   *
   */
  unsigned int enable_ab_partitions;
  /*!\brief enable rectangular partition type
   *
   */
  unsigned int enable_rect_partitions;
#if CONFIG_EXT_RECUR_PARTITIONS
  /*!\brief enable uneven 4 way partition type
   *
   */
  unsigned int enable_uneven_4way_partitions;
#else
  /*!\brief enable 1:4/4:1 partition type
   *
   */
  unsigned int enable_1to4_partitions;
#endif  // CONFIG_EXT_RECUR_PARTITIONS
  /*!\brief disable ml-based speed-up for partition search
   *
   */
  unsigned int disable_ml_partition_speed_features;
#if CONFIG_EXT_RECUR_PARTITIONS
  /*!\brief prune partitions for ERP
   *
   */
  unsigned int erp_pruning_level;
  /*!\brief use ml model for erp pruning
   *
   */
  unsigned int use_ml_erp_pruning;
  /*!\brief enable extended partitions
   *
   */
  unsigned int enable_ext_partitions;
#endif  // CONFIG_EXT_RECUR_PARTITIONS
  /*!\brief disable ml-based speed-up for transform search
   *
   */
  unsigned int disable_ml_transform_speed_features;
  /*!\brief enable Semi-decoupled partitioning
   *
   */
  unsigned int enable_sdp;
  /*!\brief enable Multiple reference line selection
   *
   */
  unsigned int enable_mrls;
  /*!\brief enable temporal interpolated prediction
   *
   */
  unsigned int enable_tip;
#if CONFIG_BAWP
  /*!\brief enable block adaptive weighted prediction
   *
   */
  unsigned int enable_bawp;
#endif  // CONFIG_BAWP
  /*!\brief enable compound weighted prediction
   *
   */
  unsigned int enable_cwp;
#if CONFIG_D071_IMP_MSK_BLD
  /*!\brief enable implicit maksed blending
   *
   */
  unsigned int enable_imp_msk_bld;
#endif  // CONFIG_D071_IMP_MSK_BLD
  /*!\brief enable Forward skip coding
   *
   */
  unsigned int enable_fsc;
  /*!\brief enable Offset based refinement of Intra prediction
   *
   */
  unsigned int enable_orip;
#if CONFIG_IDIF
  /*!\brief enable Intra Directional Interpolation Filter
   *
   */
  unsigned int enable_idif;
#endif  // CONFIG_IDIF
  /*!\brief enable Intra secondary transform
   *
   */
  unsigned int enable_ist;
  /*!\brief enable Inter secondary transform
   *
   */
  unsigned int enable_inter_ist;
#if CONFIG_CHROMA_TX
  unsigned int enable_chroma_dctonly;
#endif  // CONFIG_CHROMA_TX
#if CONFIG_INTER_DDT
  /*!\brief enable Inter data-driven transform
   *
   */
  unsigned int enable_inter_ddt;
#endif  // CONFIG_INTER_DDT
  /*!\brief enable cross-chroma component transform
   *
   */
  unsigned int enable_cctx;
  /*!\brief enable Intra Bi-Prediction (IBP)
   *
   */
  unsigned int enable_ibp;
  /*!\brief enable Adaptive MVD resolution
   *
   */
  unsigned int enable_adaptive_mvd;
  /*!\brief enable Flexible MV resolution
   *
   */
  unsigned int enable_flex_mvres;

  /*!\brief enable downsample filter options for CFL
   *
   */
  unsigned int select_cfl_ds_filter;

  /*!\brief enable joint MVD coding
   *
   */
  unsigned int enable_joint_mvd;
#if CONFIG_REFINEMV
  /*!\brief enable refine MV mode
   *
   */
  unsigned int enable_refinemv;
#endif  // CONFIG_REFINEMV

#if CONFIG_DERIVED_MVD_SIGN
  /*!\brief enable mvd_sign_derive
   *
   */
  unsigned int enable_mvd_sign_derive;
#endif  // CONFIG_DERIVED_MVD_SIGN

  /*!\brief enable flip and identity transform type
   *
   */
  unsigned int enable_flip_idtx;
  /*!\brief enable deblocking filter
   *
   */
  unsigned int enable_deblocking;
  /*!\brief enable CDEF filter
   *
   */
  unsigned int enable_cdef;
  /*!\brief enable Loop Restoration Filter
   *
   */
  unsigned int enable_restoration;
  /*!\brief enable Wiener Filter in Loop Restoration
   *
   */
  unsigned int enable_wiener;
  /*!\brief enable Self-Guided Filter in Loop Restoration
   *
   */
  unsigned int enable_sgrproj;
  /*!\brief enable Pixel-Classified Wiener Filter in Loop Restoration
   *
   */
  unsigned int enable_pc_wiener;
  /*!\brief enable Noseparable Wiener Filter in Loop Restoration
   *
   */
  unsigned int enable_wiener_nonsep;
  /*!\brief enable cross-component sample offset
   *
   */
  unsigned int enable_ccso;
#if CONFIG_LF_SUB_PU
  /*!\brief enable loop filter on sub-block
   *
   */
  unsigned int enable_lf_sub_pu;
#endif  // CONFIG_LF_SUB_PU
  /*!\brief enable OBMC
   *
   */
  unsigned int enable_obmc;
  /*!\brief enable local warped motion
   *
   */
  unsigned int enable_warped_motion;
  /*!\brief enable spatial warp prediction
   *
   */
  unsigned int enable_warped_causal;
  /*!\brief enable explicit warp models
   *
   */
  unsigned int enable_warp_delta;
#if CONFIG_SIX_PARAM_WARP_DELTA
  /*!\brief enable explicit warp models
   *
   */
  unsigned int enable_six_param_warp_delta;
#endif  // CONFIG_SIX_PARAM_WARP_DELTA
  /*!\brief enable warp extension
   *
   */
  unsigned int enable_warp_extend;

  /*!\brief enable global motion
   *
   */
  unsigned int enable_global_motion;
  /*!\brief enable diff weighted compound
   *
   */
  unsigned int enable_diff_wtd_comp;
  /*!\brief enable inter/intra compound
   *
   */
  unsigned int enable_interintra_comp;
  /*!\brief enable masked compound
   *
   */
  unsigned int enable_masked_comp;
  /*!\brief enable one sided compound
   *
   */
  unsigned int enable_onesided_comp;
  /*!\brief enable Palette
   *
   */
  unsigned int enable_palette;
  /*!\brief enable Intra Block Copy
   *
   */
  unsigned int enable_intrabc;
#if CONFIG_IBC_SR_EXT
  /*!\brief enable search range extension for Intra Block Copy
   *
   */
  unsigned int enable_intrabc_ext;
#endif  // CONFIG_IBC_SR_EXT
  /*!\brief enable chroma from luma
   *
   */
  unsigned int enable_cfl_intra;

  /*!\brief enable intra smooth mode
   *
   */
  unsigned int enable_smooth_intra;
  /*!\brief enable filter intra
   *
   */
  unsigned int enable_filter_intra;
#if CONFIG_DIP
  /*!\brief enable intra_dip
   *
   */
  unsigned int enable_intra_dip;
#endif
  /*!\brief enable intra angle delta
   *
   */
  unsigned int enable_angle_delta;
  /*!\brief enable optical flow refinement
   *
   */
  aom_opfl_refine_type enable_opfl_refine;
#if CONFIG_AFFINE_REFINEMENT
  /*!\brief enable affine refinement
   *
   */
  unsigned int enable_affine_refine;
#endif  // CONFIG_AFFINE_REFINEMENT
  /*!\brief enable intra edge filter
   *
   */
  unsigned int enable_intra_edge_filter;
  /*!\brief enable 64x64 transform
   *
   */
  unsigned int enable_tx64;
  /*!\brief enable smooth inter/intra
   *
   */
  unsigned int enable_smooth_interintra;
  /*!\brief enable inter/inter wedge comp
   *
   */
  unsigned int enable_interinter_wedge;
  /*!\brief enable inter/intra wedge comp
   *
   */
  unsigned int enable_interintra_wedge;
  /*!\brief enable paeth intra
   *
   */
  unsigned int enable_paeth_intra;
  /*!\brief enable trellis quantization
   *
   */
  unsigned int enable_trellis_quant;
  /*!\brief enable ref frame MV
   *
   */
  unsigned int enable_ref_frame_mvs;
  /*!\brief use reduced reference frame set
   *
   */
  unsigned int enable_reduced_reference_set;
  /*!\brief explicitly signal reference frame mapping
   *
   */
  unsigned int explicit_ref_frame_map;
  /*!\brief enable frame output order derivation based on order hint
   *
   */
  unsigned int enable_frame_output_order;
  /*!\brief use reduced transform type set
   *
   */
  unsigned int reduced_tx_type_set;
  /*!\brief Max number of reference mvs in dynamic reference list
   *
   */
  unsigned int max_drl_refmvs;
#if CONFIG_IBC_BV_IMPROVEMENT && CONFIG_IBC_MAX_DRL
  /*!\brief Max number of reference bvs in IntraBC ref bv list
   *
   */
  unsigned int max_drl_refbvs;
#endif  // CONFIG_IBC_BV_IMPROVEMENT && CONFIG_IBC_MAX_DRL
  /*!\brief enable reference MV Bank
   *
   */
  unsigned int enable_refmvbank;
#if CONFIG_DRL_REORDER_CONTROL
  /*!\brief enable the reorder of DRL
   *
   */
  unsigned int enable_drl_reorder;
#endif  // CONFIG_DRL_REORDER_CONTROL
#if CONFIG_ENHANCED_FRAME_CONTEXT_INIT
  /*!\brief enable the average of frame or tile cdfs for initialization
   *
   */
  unsigned int enable_avg_cdf;
  /*!\brief type of cdf averaging for initialization
   * If 0, enables cross frame averaging and initialization of CDFs
   * If 1, enables cross tile averaging and initialization of CDFs
   */
  unsigned int avg_cdf_type;
#elif CONFIG_TILE_CDFS_AVG_TO_FRAME
  /*!\brief enable the average of tiles' cdfs
   *
   */
  unsigned int enable_tiles_cdfs_avg;
#endif  // CONFIG_ENHANCED_FRAME_CONTEXT_INIT
  /*!\brief enable parity hiding for coefficients coding
   *
   */
  unsigned int enable_parity_hiding;
#if CONFIG_MRSSE
  /*!\brief enable mrsse for mean removed SSE
   *
   */
  unsigned int enable_mrsse;
#endif  // CONFIG_MRSSE

#if CONFIG_REFRESH_FLAG
  /*!\brief enable signaling refresh frame flags with 3 bits.
   * If 0, signal refresh frame flags with 8 bits, which allows to refresh
   * any number of frame buffers (up to 8).
   * If 1, signal refresh frame flags with 3 bits, which allows to refresh
   * exactly 1 frame buffer.
   */
  unsigned int enable_short_refresh_frame_flags;
#endif  // CONFIG_REFRESH_FLAG
} cfg_options_t;

/*!\brief Encoded Frame Flags
 *
 * This type indicates a bitfield to be passed to aom_codec_encode(), defining
 * per-frame boolean values. By convention, bits common to all codecs will be
 * named AOM_EFLAG_*, and bits specific to an algorithm will be named
 * /algo/_eflag_*. The lower order 16 bits are reserved for common use.
 */
typedef long aom_enc_frame_flags_t;
/*!\brief Force this frame to be a keyframe */
#define AOM_EFLAG_FORCE_KF (1 << 0)

/*!\brief Encoder configuration structure
 *
 * This structure contains the encoder settings that have common representations
 * across all codecs. This doesn't imply that all codecs support all features,
 * however.
 */
typedef struct aom_codec_enc_cfg {
  /*
   * generic settings (g)
   */

  /*!\brief Algorithm specific "usage" value
   *
   * Algorithms may define multiple values for usage, which may convey the
   * intent of how the application intends to use the stream. If this value
   * is non-zero, consult the documentation for the codec to determine its
   * meaning.
   */
  unsigned int g_usage;

  /*!\brief Maximum number of threads to use
   *
   * For multi-threaded implementations, use no more than this number of
   * threads. The codec may use fewer threads than allowed. The value
   * 0 is equivalent to the value 1.
   */
  unsigned int g_threads;

  /*!\brief Bitstream profile to use
   *
   * Some codecs support a notion of multiple bitstream profiles. Typically
   * this maps to a set of features that are turned on or off. Often the
   * profile to use is determined by the features of the intended decoder.
   * Consult the documentation for the codec to determine the valid values
   * for this parameter, or set to zero for a sane default.
   */
  unsigned int g_profile; /**< profile of bitstream to use */

  /*!\brief Width of the frame
   *
   * This value identifies the presentation resolution of the frame,
   * in pixels. Note that the frames passed as input to the encoder must
   * have this resolution. Frames will be presented by the decoder in this
   * resolution, independent of any spatial resampling the encoder may do.
   */
  unsigned int g_w;

  /*!\brief Height of the frame
   *
   * This value identifies the presentation resolution of the frame,
   * in pixels. Note that the frames passed as input to the encoder must
   * have this resolution. Frames will be presented by the decoder in this
   * resolution, independent of any spatial resampling the encoder may do.
   */
  unsigned int g_h;

  /*!\brief Max number of frames to encode
   *
   */
  unsigned int g_limit;

  /*!\brief Forced maximum width of the frame
   *
   * If this value is non-zero then it is used to force the maximum frame
   * width written in write_sequence_header().
   */
  unsigned int g_forced_max_frame_width;

  /*!\brief Forced maximum height of the frame
   *
   * If this value is non-zero then it is used to force the maximum frame
   * height written in write_sequence_header().
   */
  unsigned int g_forced_max_frame_height;
#if CONFIG_MULTIVIEW_CORE
  /*!\brief Number of views
   *
   *
   */
  unsigned int g_num_views;
#endif
  /*!\brief Bit-depth of the codec
   *
   * This value identifies the bit_depth of the codec,
   * Only certain bit-depths are supported as identified in the
   * aom_bit_depth_t enum.
   */
  aom_bit_depth_t g_bit_depth;

  /*!\brief Bit-depth of the input frames
   *
   * This value identifies the bit_depth of the input frames in bits.
   * Note that the frames passed as input to the encoder must have
   * this bit-depth.
   */
  unsigned int g_input_bit_depth;

  /*!\brief Stream timebase units
   *
   * Indicates the smallest interval of time, in seconds, used by the stream.
   * For fixed frame rate material, or variable frame rate material where
   * frames are timed at a multiple of a given clock (ex: video capture),
   * the \ref RECOMMENDED method is to set the timebase to the reciprocal
   * of the frame rate (ex: 1001/30000 for 29.970 Hz NTSC). This allows the
   * pts to correspond to the frame number, which can be handy. For
   * re-encoding video from containers with absolute time timestamps, the
   * \ref RECOMMENDED method is to set the timebase to that of the parent
   * container or multimedia framework (ex: 1/1000 for ms, as in FLV).
   */
  struct aom_rational g_timebase;

  /*!\brief Enable error resilient modes.
   *
   * The error resilient bitfield indicates to the encoder which features
   * it should enable to take measures for streaming over lossy or noisy
   * links.
   */
  aom_codec_er_flags_t g_error_resilient;

  /*!\brief Multi-pass Encoding Mode
   *
   * This value should be set to the current phase for multi-pass encoding.
   * For single pass, set to #AOM_RC_ONE_PASS.
   */
  enum aom_enc_pass g_pass;

  /*!\brief Allow lagged encoding
   *
   * If set, this value allows the encoder to consume a number of input
   * frames before producing output frames. This allows the encoder to
   * base decisions for the current frame on future frames. This does
   * increase the latency of the encoding pipeline, so it is not appropriate
   * in all situations (ex: realtime encoding).
   *
   * Note that this is a maximum value -- the encoder may produce frames
   * sooner than the given limit. Set this value to 0 to disable this
   * feature.
   */
  unsigned int g_lag_in_frames;

  /*
   * rate control settings (rc)
   */

  /*!\brief Temporal resampling configuration, if supported by the codec.
   *
   * Temporal resampling allows the codec to "drop" frames as a strategy to
   * meet its target data rate. This can cause temporal discontinuities in
   * the encoded video, which may appear as stuttering during playback. This
   * trade-off is often acceptable, but for many applications is not. It can
   * be disabled in these cases.
   *
   * Note that not all codecs support this feature. All aom AVx codecs do.
   * For other codecs, consult the documentation for that algorithm.
   *
   * This threshold is described as a percentage of the target data buffer.
   * When the data buffer falls below this percentage of fullness, a
   * dropped frame is indicated. Set the threshold to zero (0) to disable
   * this feature.
   */
  unsigned int rc_dropframe_thresh;

  /*!\brief Mode for spatial resampling, if supported by the codec.
   *
   * Spatial resampling allows the codec to compress a lower resolution
   * version of the frame, which is then upscaled by the decoder to the
   * correct presentation resolution. This increases visual quality at
   * low data rates, at the expense of CPU time on the encoder/decoder.
   */
  unsigned int rc_resize_mode;

  /*!\brief Frame resize denominator.
   *
   * The denominator for resize to use, assuming 8 as the numerator.
   *
   * Valid denominators are  8 - 16 for now.
   */
  unsigned int rc_resize_denominator;

  /*!\brief Keyframe resize denominator.
   *
   * The denominator for resize to use, assuming 8 as the numerator.
   *
   * Valid denominators are  8 - 16 for now.
   */
  unsigned int rc_resize_kf_denominator;

  /*!\brief Frame super-resolution scaling mode.
   *
   * Similar to spatial resampling, frame super-resolution integrates
   * upscaling after the encode/decode process. Taking control of upscaling and
   * using restoration filters should allow it to outperform normal resizing.
   */
  aom_superres_mode rc_superres_mode;

  /*!\brief Frame super-resolution denominator.
   *
   * The denominator for superres to use. If fixed it will only change if the
   * cumulative scale change over resizing and superres is greater than 1/2;
   * this forces superres to reduce scaling.
   *
   * Valid denominators are 8 to 16.
   *
   * Used only by AOM_SUPERRES_FIXED.
   */
  unsigned int rc_superres_denominator;

  /*!\brief Keyframe super-resolution denominator.
   *
   * The denominator for superres to use. If fixed it will only change if the
   * cumulative scale change over resizing and superres is greater than 1/2;
   * this forces superres to reduce scaling.
   *
   * Valid denominators are 8 - 16 for now.
   */
  unsigned int rc_superres_kf_denominator;

  /*!\brief Frame super-resolution q threshold.
   *
   * The q level threshold after which superres is used.
   * Valid values are 1 to 255.
   *
   * Used only by AOM_SUPERRES_QTHRESH
   */
  unsigned int rc_superres_qthresh;

  /*!\brief Keyframe super-resolution q threshold.
   *
   * The q level threshold after which superres is used for key frames.
   * Valid values are 1 to 255.
   *
   * Used only by AOM_SUPERRES_QTHRESH
   */
  unsigned int rc_superres_kf_qthresh;

  /*!\brief Rate control algorithm to use.
   *
   * Indicates whether the end usage of this stream is to be streamed over
   * a bandwidth constrained link, indicating that Constant Bit Rate (CBR)
   * mode should be used, or whether it will be played back on a high
   * bandwidth link, as from a local disk, where higher variations in
   * bitrate are acceptable.
   */
  enum aom_rc_mode rc_end_usage;

  /*!\brief first pass mb stats buffer.
   *
   * A buffer containing all of the first pass mb stats packets produced
   * in the first pass, concatenated.
   */
  aom_fixed_buf_t rc_firstpass_mb_stats_in;

  /*!\brief Target data rate
   *
   * Target bandwidth to use for this stream, in kilobits per second.
   */
  unsigned int rc_target_bitrate;

  /*
   * quantizer settings
   */

  /*!\brief Minimum (Best Quality) Quantizer
   *
   * The quantizer is the most direct control over the quality of the
   * encoded image. The range of valid values for the quantizer is codec
   * specific. Consult the documentation for the codec to determine the
   * values to use. To determine the range programmatically, call
   * aom_codec_enc_config_default() with a usage value of 0.
   */
  int rc_min_quantizer;

  /*!\brief Maximum (Worst Quality) Quantizer
   *
   * The quantizer is the most direct control over the quality of the
   * encoded image. The range of valid values for the quantizer is codec
   * specific. Consult the documentation for the codec to determine the
   * values to use. To determine the range programmatically, call
   * aom_codec_enc_config_default() with a usage value of 0.
   */
  int rc_max_quantizer;

  /*
   * bitrate tolerance
   */

  /*!\brief Rate control adaptation undershoot control
   *
   * This value, controls the tolerance of the VBR algorithm to undershoot
   * and is used as a trigger threshold for more aggressive adaptation of Q.
   *
   * Valid values in the range 0-100.
   */
  unsigned int rc_undershoot_pct;

  /*!\brief Rate control adaptation overshoot control
   *
   * This value, controls the tolerance of the VBR algorithm to overshoot
   * and is used as a trigger threshold for more aggressive adaptation of Q.
   *
   * Valid values in the range 0-1000.
   */
  unsigned int rc_overshoot_pct;

  /*
   * decoder buffer model parameters
   */

  /*!\brief Decoder Buffer Size
   *
   * This value indicates the amount of data that may be buffered by the
   * decoding application. Note that this value is expressed in units of
   * time (milliseconds). For example, a value of 5000 indicates that the
   * client will buffer (at least) 5000ms worth of encoded data. Use the
   * target bitrate (#rc_target_bitrate) to convert to bits/bytes, if
   * necessary.
   */
  unsigned int rc_buf_sz;

  /*!\brief Decoder Buffer Initial Size
   *
   * This value indicates the amount of data that will be buffered by the
   * decoding application prior to beginning playback. This value is
   * expressed in units of time (milliseconds). Use the target bitrate
   * (#rc_target_bitrate) to convert to bits/bytes, if necessary.
   */
  unsigned int rc_buf_initial_sz;

  /*!\brief Decoder Buffer Optimal Size
   *
   * This value indicates the amount of data that the encoder should try
   * to maintain in the decoder's buffer. This value is expressed in units
   * of time (milliseconds). Use the target bitrate (#rc_target_bitrate)
   * to convert to bits/bytes, if necessary.
   */
  unsigned int rc_buf_optimal_sz;

  /*
   * 2 pass rate control parameters
   */

  /*!\brief Two-pass mode per-GOP minimum bitrate
   *
   * This value, expressed as a percentage of the target bitrate, indicates
   * the minimum bitrate to be used for a single GOP (aka "section")
   */
  unsigned int rc_2pass_vbr_minsection_pct;

  /*!\brief Two-pass mode per-GOP maximum bitrate
   *
   * This value, expressed as a percentage of the target bitrate, indicates
   * the maximum bitrate to be used for a single GOP (aka "section")
   */
  unsigned int rc_2pass_vbr_maxsection_pct;

  /*
   * keyframing settings (kf)
   */

  /*!\brief Option to enable forward reference key frame
   *
   */
  int fwd_kf_enabled;

  /*!\brief Keyframe placement mode
   *
   * This value indicates whether the encoder should place keyframes at a
   * fixed interval, or determine the optimal placement automatically
   * (as governed by the #kf_min_dist and #kf_max_dist parameters)
   */
  enum aom_kf_mode kf_mode;

  /*!\brief Keyframe minimum interval
   *
   * This value, expressed as a number of frames, prevents the encoder from
   * placing a keyframe nearer than kf_min_dist to the previous keyframe. At
   * least kf_min_dist frames non-keyframes will be coded before the next
   * keyframe. Set kf_min_dist equal to kf_max_dist for a fixed interval.
   */
  unsigned int kf_min_dist;

  /*!\brief Keyframe maximum interval
   *
   * This value, expressed as a number of frames, forces the encoder to code
   * a keyframe if one has not been coded in the last kf_max_dist frames.
   * A value of 0 implies all frames will be keyframes. Set kf_min_dist
   * equal to kf_max_dist for a fixed interval.
   */
  unsigned int kf_max_dist;

  /*!\brief sframe interval
   *
   * This value, expressed as a number of frames, forces the encoder to code
   * an S-Frame every sframe_dist frames.
   */
  unsigned int sframe_dist;

  /*!\brief sframe insertion mode
   *
   * This value must be set to 1 or 2, and tells the encoder how to insert
   * S-Frames. It will only have an effect if sframe_dist != 0.
   *
   * If altref is enabled:
   *   - if sframe_mode == 1, the considered frame will be made into an
   *     S-Frame only if it is an altref frame
   *   - if sframe_mode == 2, the next altref frame will be made into an
   *     S-Frame.
   *
   * Otherwise: the considered frame will be made into an S-Frame.
   */
  unsigned int sframe_mode;

  /*!\brief Tile coding mode
   *
   * This value indicates the tile coding mode.
   * A value of 0 implies a normal non-large-scale tile coding. A value of 1
   * implies a large-scale tile coding.
   */
  unsigned int large_scale_tile;

  /*!\brief Monochrome mode
   *
   * If this is nonzero, the encoder will generate a monochrome stream
   * with no chroma planes.
   */
  unsigned int monochrome;

  /*!\brief full_still_picture_hdr
   *
   * If this is nonzero, the encoder will generate a full header even for
   * still picture encoding. if zero, a reduced header is used for still
   * picture. This flag has no effect when a regular video with more than
   * a single frame is encoded.
   */
  unsigned int full_still_picture_hdr;

#if CONFIG_TCQ
  /*!\brief enable_tcq
   *
   * If this is nonzero, the encoder will use trellis quantization.
   * 0 = disable, use scalar quantization.
   * 1 = use 8-state trellis
   * 2 = use 8-state trellis (frame adaptive (key/altref))
   */
  unsigned int enable_tcq;
#endif  // CONFIG_TCQ

  /*!\brief Bitstream syntax mode
   *
   * This value indicates the bitstream syntax mode.
   * A value of 0 indicates bitstream is saved as Section 5 bitstream. A value
   * of 1 indicates the bitstream is saved in Annex-B format
   */
  unsigned int save_as_annexb;

  /*!\brief Number of explicit tile widths specified
   *
   * This value indicates the number of tile widths specified
   * A value of 0 implies no tile widths are specified.
   * Tile widths are given in the array tile_widths[]
   */
  int tile_width_count;

  /*!\brief Number of explicit tile heights specified
   *
   * This value indicates the number of tile heights specified
   * A value of 0 implies no tile heights are specified.
   * Tile heights are given in the array tile_heights[]
   */
  int tile_height_count;

/*!\brief Maximum number of tile widths in tile widths array
 *
 * This define gives the maximum number of elements in the tile_widths array.
 */
#define MAX_TILE_WIDTHS 64  // maximum tile width array length

  /*!\brief Array of specified tile widths
   *
   * This array specifies tile widths (and may be empty)
   * The number of widths specified is given by tile_width_count
   */
  int tile_widths[MAX_TILE_WIDTHS];

/*!\brief Maximum number of tile heights in tile heights array.
 *
 * This define gives the maximum number of elements in the tile_heights array.
 */
#define MAX_TILE_HEIGHTS 64  // maximum tile height array length

  /*!\brief Array of specified tile heights
   *
   * This array specifies tile heights (and may be empty)
   * The number of heights specified is given by tile_height_count
   */
  int tile_heights[MAX_TILE_HEIGHTS];

  /*!\brief Whether encoder should use fixed QP offsets.
   *
   * If a value of 1 is provided, encoder will use fixed QP offsets for frames
   * at different levels of the pyramid.
   * - If 'fixed_qp_offsets' is also provided, encoder will use the given
   * offsets
   * - If not, encoder will select the fixed offsets based on the --qp
   *   provided.
   * If a value of 0 is provided and fixed_qp_offset are not provided, encoder
   * will NOT use fixed QP offsets.
   * Note: This option is only relevant for --end-usage=q.
   */
  unsigned int use_fixed_qp_offsets;

/*!\brief Max number of fixed QP offsets
 *
 * This defines the number of elements in the fixed_qp_offsets array.
 */
#define FIXED_QP_OFFSET_COUNT 6

  /*!\brief Array of fixed QP offsets
   *
   * This array specifies fixed QP offsets (range: 0 to 255) for frames at
   * different levels of the pyramid. It is a comma-separated list of 5 values:
   * - QP offset for keyframe
   * - QP offset for ALTREF frame
   * - QP offset for 1st level internal ARF
   * - QP offset for 2nd level internal ARF
   * - QP offset for 3rd level internal ARF
   * Notes:
   * - QP offset for leaf level frames is not explicitly specified. These frames
   *   use the worst quality allowed (--qp).
   * - This option is only relevant for --end-usage=q.
   */
  int fixed_qp_offsets[FIXED_QP_OFFSET_COUNT];

  /*!\brief Codec control function to set what decoded frame hash metadata to
   * write
   */
  enum aom_frame_hash_mode frame_hash_metadata;

  /*!\brief Codec control function to set if the hash values are written for
   * each plane instead of the entire frame, unsigned int parameter
   *
   * \attention Only applicable if decoded frame hash metadata is not disabled.
   *
   * - 0 = per frame (default)
   * - 1 = per plane
   */
  unsigned int frame_hash_per_plane;

  /*!\brief Options defined per config file
   *
   */
  cfg_options_t encoder_cfg;
} aom_codec_enc_cfg_t; /**< alias for struct aom_codec_enc_cfg */

/*!\brief Initialize an encoder instance
 *
 * Initializes a encoder context using the given interface. Applications
 * should call the aom_codec_enc_init convenience macro instead of this
 * function directly, to ensure that the ABI version number parameter
 * is properly initialized.
 *
 * If the library was configured with --disable-multithread, this call
 * is not thread safe and should be guarded with a lock if being used
 * in a multithreaded context.
 *
 * \param[in]    ctx     Pointer to this instance's context.
 * \param[in]    iface   Pointer to the algorithm interface to use.
 * \param[in]    cfg     Configuration to use, if known.
 * \param[in]    flags   Bitfield of AOM_CODEC_USE_* flags
 * \param[in]    ver     ABI version number. Must be set to
 *                       AOM_ENCODER_ABI_VERSION
 * \retval #AOM_CODEC_OK
 *     The decoder algorithm initialized.
 * \retval #AOM_CODEC_MEM_ERROR
 *     Memory allocation failed.
 */
aom_codec_err_t aom_codec_enc_init_ver(aom_codec_ctx_t *ctx,
                                       aom_codec_iface_t *iface,
                                       const aom_codec_enc_cfg_t *cfg,
                                       aom_codec_flags_t flags, int ver);

/*!\brief Convenience macro for aom_codec_enc_init_ver()
 *
 * Ensures the ABI version parameter is properly set.
 */
#define aom_codec_enc_init(ctx, iface, cfg, flags) \
  aom_codec_enc_init_ver(ctx, iface, cfg, flags, AOM_ENCODER_ABI_VERSION)

/*!\brief Get the default configuration for a usage.
 *
 * Initializes an encoder configuration structure with default values. Supports
 * the notion of "usages" so that an algorithm may offer different default
 * settings depending on the user's intended goal. This function \ref SHOULD
 * be called by all applications to initialize the configuration structure
 * before specializing the configuration with application specific values.
 *
 * \param[in]    iface     Pointer to the algorithm interface to use.
 * \param[out]   cfg       Configuration buffer to populate.
 * \param[in]    usage     Algorithm specific usage value. For AV1, must be
 *                         set to AOM_USAGE_GOOD_QUALITY (0).
 *
 * \retval #AOM_CODEC_OK
 *     The configuration was populated.
 * \retval #AOM_CODEC_INCAPABLE
 *     Interface is not an encoder interface.
 * \retval #AOM_CODEC_INVALID_PARAM
 *     A parameter was NULL, or the usage value was not recognized.
 */
aom_codec_err_t aom_codec_enc_config_default(aom_codec_iface_t *iface,
                                             aom_codec_enc_cfg_t *cfg,
                                             unsigned int usage);

/*!\brief Set or change configuration
 *
 * Reconfigures an encoder instance according to the given configuration.
 *
 * \param[in]    ctx     Pointer to this instance's context
 * \param[in]    cfg     Configuration buffer to use
 *
 * \retval #AOM_CODEC_OK
 *     The configuration was populated.
 * \retval #AOM_CODEC_INCAPABLE
 *     Interface is not an encoder interface.
 * \retval #AOM_CODEC_INVALID_PARAM
 *     A parameter was NULL, or the usage value was not recognized.
 */
aom_codec_err_t aom_codec_enc_config_set(aom_codec_ctx_t *ctx,
                                         const aom_codec_enc_cfg_t *cfg);

/*!\brief Get global stream headers
 *
 * Retrieves a stream level global header packet, if supported by the codec.
 * Calls to this function should be deferred until all configuration information
 * has been passed to libaom. Otherwise the global header data may be
 * invalidated by additional configuration changes.
 *
 * The AV1 implementation of this function returns an OBU. The OBU returned is
 * in Low Overhead Bitstream Format. Specifically, the obu_has_size_field bit is
 * set, and the buffer contains the obu_size field for the returned OBU.
 *
 * \param[in]    ctx     Pointer to this instance's context
 *
 * \retval NULL
 *     Encoder does not support global header, or an error occurred while
 *     generating the global header.
 *
 * \retval Non-NULL
 *     Pointer to buffer containing global header packet. The caller owns the
 *     memory associated with this buffer, and must free the 'buf' member of the
 *     aom_fixed_buf_t as well as the aom_fixed_buf_t pointer. Memory returned
 *     must be freed via call to free().
 */
aom_fixed_buf_t *aom_codec_get_global_headers(aom_codec_ctx_t *ctx);

/*!\brief usage parameter analogous to AV1 GOOD QUALITY mode. */
#define AOM_USAGE_GOOD_QUALITY (0)

/*!\brief Encode a frame
 *
 * Encodes a video frame at the given "presentation time." The presentation
 * time stamp (PTS) \ref MUST be strictly increasing.
 *
 * When the last frame has been passed to the encoder, this function should
 * continue to be called in a loop, with the img parameter set to NULL. This
 * will signal the end-of-stream condition to the encoder and allow it to
 * encode any held buffers. Encoding is complete when aom_codec_encode() is
 * called with img set to NULL and aom_codec_get_cx_data() returns no data.
 *
 * \param[in]    ctx       Pointer to this instance's context
 * \param[in]    img       Image data to encode, NULL to flush.
 * \param[in]    pts       Presentation time stamp, in timebase units. If img
 *                         is NULL, pts is ignored.
 * \param[in]    duration  Duration to show frame, in timebase units. If img
 *                         is not NULL, duration must be nonzero. If img is
 *                         NULL, duration is ignored.
 * \param[in]    flags     Flags to use for encoding this frame.
 *
 * \retval #AOM_CODEC_OK
 *     The configuration was populated.
 * \retval #AOM_CODEC_INCAPABLE
 *     Interface is not an encoder interface.
 * \retval #AOM_CODEC_INVALID_PARAM
 *     A parameter was NULL, the image format is unsupported, etc.
 */
aom_codec_err_t aom_codec_encode(aom_codec_ctx_t *ctx, const aom_image_t *img,
                                 aom_codec_pts_t pts, unsigned long duration,
                                 aom_enc_frame_flags_t flags);

/*!\brief Set compressed data output buffer
 *
 * Sets the buffer that the codec should output the compressed data
 * into. This call effectively sets the buffer pointer returned in the
 * next AOM_CODEC_CX_FRAME_PKT packet. Subsequent packets will be
 * appended into this buffer. The buffer is preserved across frames,
 * so applications must periodically call this function after flushing
 * the accumulated compressed data to disk or to the network to reset
 * the pointer to the buffer's head.
 *
 * `pad_before` bytes will be skipped before writing the compressed
 * data, and `pad_after` bytes will be appended to the packet. The size
 * of the packet will be the sum of the size of the actual compressed
 * data, pad_before, and pad_after. The padding bytes will be preserved
 * (not overwritten).
 *
 * Note that calling this function does not guarantee that the returned
 * compressed data will be placed into the specified buffer. In the
 * event that the encoded data will not fit into the buffer provided,
 * the returned packet \ref MAY point to an internal buffer, as it would
 * if this call were never used. In this event, the output packet will
 * NOT have any padding, and the application must free space and copy it
 * to the proper place. This is of particular note in configurations
 * that may output multiple packets for a single encoded frame (e.g., lagged
 * encoding) or if the application does not reset the buffer periodically.
 *
 * Applications may restore the default behavior of the codec providing
 * the compressed data buffer by calling this function with a NULL
 * buffer.
 *
 * Applications \ref MUSTNOT call this function during iteration of
 * aom_codec_get_cx_data().
 *
 * \param[in]    ctx         Pointer to this instance's context
 * \param[in]    buf         Buffer to store compressed data into
 * \param[in]    pad_before  Bytes to skip before writing compressed data
 * \param[in]    pad_after   Bytes to skip after writing compressed data
 *
 * \retval #AOM_CODEC_OK
 *     The buffer was set successfully.
 * \retval #AOM_CODEC_INVALID_PARAM
 *     A parameter was NULL, the image format is unsupported, etc.
 */
aom_codec_err_t aom_codec_set_cx_data_buf(aom_codec_ctx_t *ctx,
                                          const aom_fixed_buf_t *buf,
                                          unsigned int pad_before,
                                          unsigned int pad_after);

/*!\brief Encoded data iterator
 *
 * Iterates over a list of data packets to be passed from the encoder to the
 * application. The different kinds of packets available are enumerated in
 * #aom_codec_cx_pkt_kind.
 *
 * #AOM_CODEC_CX_FRAME_PKT packets should be passed to the application's
 * muxer. Multiple compressed frames may be in the list.
 * #AOM_CODEC_STATS_PKT packets should be appended to a global buffer.
 *
 * The application \ref MUST silently ignore any packet kinds that it does
 * not recognize or support.
 *
 * The data buffers returned from this function are only guaranteed to be
 * valid until the application makes another call to any aom_codec_* function.
 *
 * \param[in]     ctx      Pointer to this instance's context
 * \param[in,out] iter     Iterator storage, initialized to NULL
 *
 * \return Returns a pointer to an output data packet (compressed frame data,
 *         two-pass statistics, etc.) or NULL to signal end-of-list.
 *
 */
const aom_codec_cx_pkt_t *aom_codec_get_cx_data(aom_codec_ctx_t *ctx,
                                                aom_codec_iter_t *iter);

/*!\brief Get Preview Frame
 *
 * Returns an image that can be used as a preview. Shows the image as it would
 * exist at the decompressor. The application \ref MUST NOT write into this
 * image buffer.
 *
 * \param[in]     ctx      Pointer to this instance's context
 *
 * \return Returns a pointer to a preview image, or NULL if no image is
 *         available.
 *
 */
const aom_image_t *aom_codec_get_preview_frame(aom_codec_ctx_t *ctx);

/*!@} - end defgroup encoder*/
#ifdef __cplusplus
}
#endif
#endif  // AOM_AOM_AOM_ENCODER_H_