text: /*
   *  Copyright (c) 2011 The WebM project authors. All Rights Reserved.
   *
   *  Use of this source code is governed by a BSD-style license
   *  that can be found in the LICENSE file in the root of the source
   *  tree. An additional intellectual property rights grant can be found
   *  in the file PATENTS.  All contributing project authors may
   *  be found in the AUTHORS file in the root of the source tree.
   */
  #ifndef VP8_ENCODER_LOOKAHEAD_H_
  #define VP8_ENCODER_LOOKAHEAD_H_
  #include "vpx_scale/yv12config.h"
  #include "vpx/vpx_integer.h"
  
  struct lookahead_entry
  {
      YV12_BUFFER_CONFIG  img;
      int64_t             ts_start;
      int64_t             ts_end;
      unsigned int        flags;
  };
  
  
  struct lookahead_ctx;
  
  /**\brief Initializes the lookahead stage
   *
   * The lookahead stage is a queue of frame buffers on which some analysis
   * may be done when buffers are enqueued.
   *
   *
   */
  struct lookahead_ctx* vp8_lookahead_init(unsigned int width,
                                           unsigned int height,
                                           unsigned int depth
                                           );
  
  
  /**\brief Destroys the lookahead stage
   *
   */
  void vp8_lookahead_destroy(struct lookahead_ctx *ctx);
  
  
  /**\brief Enqueue a source buffer
   *
   * This function will copy the source image into a new framebuffer with
   * the expected stride/border.
   *
   * If active_map is non-NULL and there is only one frame in the queue, then copy
   * only active macroblocks.
   *
   * \param[in] ctx         Pointer to the lookahead context
   * \param[in] src         Pointer to the image to enqueue
   * \param[in] ts_start    Timestamp for the start of this frame
   * \param[in] ts_end      Timestamp for the end of this frame
   * \param[in] flags       Flags set on this frame
   * \param[in] active_map  Map that specifies which macroblock is active
   */
  int
  vp8_lookahead_push(struct lookahead_ctx *ctx,
                     YV12_BUFFER_CONFIG   *src,
                     int64_t               ts_start,
                     int64_t               ts_end,
                     unsigned int          flags,
                     unsigned char        *active_map);
  
  
  /**\brief Get the next source buffer to encode
   *
   *
   * \param[in] ctx       Pointer to the lookahead context
   * \param[in] drain     Flag indicating the buffer should be drained
   *                      (return a buffer regardless of the current queue depth)
   *
   * \retval NULL, if drain set and queue is empty
   * \retval NULL, if drain not set and queue not of the configured depth
   *
   */
  struct lookahead_entry*
  vp8_lookahead_pop(struct lookahead_ctx *ctx,
                    int                   drain);
  
  
  #define PEEK_FORWARD   1
  #define PEEK_BACKWARD -1
  /**\brief Get a future source buffer to encode
   *
   * \param[in] ctx       Pointer to the lookahead context
   * \param[in] index     Index of the frame to be returned, 0 == next frame
   *
   * \retval NULL, if no buffer exists at the specified index
   *
   */
  struct lookahead_entry*
  vp8_lookahead_peek(struct lookahead_ctx *ctx,
                     unsigned int          index,
                     int                   direction);
  
  
  /**\brief Get the number of frames currently in the lookahead queue
   *
   * \param[in] ctx       Pointer to the lookahead context
   */
  unsigned int
  vp8_lookahead_depth(struct lookahead_ctx *ctx);
  
  
  #endif  // VP8_ENCODER_LOOKAHEAD_H_
  