/*
  * Generic frame queue
  * Copyright (c) 2016 Nicolas George
  *
  * This file is part of FFmpeg.
  *
  * FFmpeg is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public License
  * as published by the Free Software Foundation; either
  * version 2.1 of the License, or (at your option) any later version.
  *
  * FFmpeg is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU Lesser General Public License for more details.
  *
  * You should have received a copy of the GNU Lesser General Public License
  * along with FFmpeg; if not, write to the Free Software Foundation, Inc.,
  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
 #ifndef AVFILTER_FRAMEQUEUE_H
 #define AVFILTER_FRAMEQUEUE_H
 
 /**
  * FFFrameQueue: simple AVFrame queue API
  *
  * Note: this API is not thread-safe. Concurrent access to the same queue
  * must be protected by a mutex or any synchronization mechanism.
  */
 
 #include "libavutil/frame.h"
 
 typedef struct FFFrameBucket {
     AVFrame *frame;
 } FFFrameBucket;
 
 /**
  * Structure to hold global options and statistics for frame queues.
  *
  * This structure is intended to allow implementing global control of the
  * frame queues, including memory consumption caps.
  *
  * It is currently empty.
  */
 typedef struct FFFrameQueueGlobal {

     char dummy; /* C does not allow empty structs */

 } FFFrameQueueGlobal;
 
 /**
  * Queue of AVFrame pointers.
  */
 typedef struct FFFrameQueue {
 
     /**
      * Array of allocated buckets, used as a circular buffer.
      */
     FFFrameBucket *queue;
 
     /**
      * Size of the array of buckets.
      */
     size_t allocated;
 
     /**
      * Tail of the queue.
      * It is the index in the array of the next frame to take.
      */
     size_t tail;
 
     /**
      * Number of currently queued frames.
      */
     size_t queued;
 
     /**
      * Pre-allocated bucket for queues of size 1.
      */
     FFFrameBucket first_bucket;
 
     /**
      * Total number of frames entered in the queue.
      */
     uint64_t total_frames_head;
 
     /**
      * Total number of frames dequeued from the queue.
      * queued = total_frames_head - total_frames_tail
      */
     uint64_t total_frames_tail;
 
     /**
      * Total number of samples entered in the queue.
      */
     uint64_t total_samples_head;
 
     /**
      * Total number of samples dequeued from the queue.
      * queued_samples = total_samples_head - total_samples_tail
      */
     uint64_t total_samples_tail;
 

     /**
      * Indicate that samples are skipped
      */
     int samples_skipped;
 

 } FFFrameQueue;
 
 /**
  * Init a global structure.
  */
 void ff_framequeue_global_init(FFFrameQueueGlobal *fqg);
 
 /**
  * Init a frame queue and attach it to a global structure.
  */
 void ff_framequeue_init(FFFrameQueue *fq, FFFrameQueueGlobal *fqg);
 
 /**
  * Free the queue and all queued frames.
  */
 void ff_framequeue_free(FFFrameQueue *fq);
 
 /**
  * Add a frame.
  * @return  >=0 or an AVERROR code.
  */
 int ff_framequeue_add(FFFrameQueue *fq, AVFrame *frame);
 
 /**
  * Take the first frame in the queue.
  * Must not be used with empty queues.
  */
 AVFrame *ff_framequeue_take(FFFrameQueue *fq);
 
 /**
  * Access a frame in the queue, without removing it.
  * The first frame is numbered 0; the designated frame must exist.
  */
 AVFrame *ff_framequeue_peek(FFFrameQueue *fq, size_t idx);
 
 /**
  * Get the number of queued frames.
  */
 static inline size_t ff_framequeue_queued_frames(const FFFrameQueue *fq)
 {
     return fq->queued;
 }
 
 /**
  * Get the number of queued samples.
  */
 static inline uint64_t ff_framequeue_queued_samples(const FFFrameQueue *fq)
 {
     return fq->total_samples_head - fq->total_samples_tail;
 }
 
 /**
  * Update the statistics after a frame accessed using ff_framequeue_peek()
  * was modified.
  * Currently used only as a marker.
  */
 static inline void ff_framequeue_update_peeked(FFFrameQueue *fq, size_t idx)
 {
 }
 
 /**

  * Skip samples from the first frame in the queue.

  *
  * This function must be used when the first frame was accessed using

  * ff_framequeue_peek() and samples were consumed from it.
  * It adapts the data pointers and timestamps of the head frame to account
  * for the skipped samples.

  */

 void ff_framequeue_skip_samples(FFFrameQueue *fq, size_t samples, AVRational time_base);

 
 #endif /* AVFILTER_FRAMEQUEUE_H */