/*

  * Copyright (c) 2004 Roman Shaposhnik

  * Copyright (c) 2008 Alexander Strange (astrange@ithinksw.com)

  *

  * Many thanks to Steven M. Schultz for providing clever ideas and
  * to Michael Niedermayer <michaelni@gmx.at> for writing initial
  * implementation.

  *

  * 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

  */

 
 /**
  * @file
  * Multithreading support functions
  * @see doc/multithreading.txt
  */
 

 #include <pthread.h>
 
 #include "avcodec.h"

 #include "thread.h"

 typedef int (action_func)(AVCodecContext *c, void *arg);

 typedef int (action_func2)(AVCodecContext *c, void *arg, int jobnr, int threadnr);

 typedef struct ThreadContext {
     pthread_t *workers;

     action_func *func;

     action_func2 *func2;

     void *args;

     int *rets;
     int rets_count;

     int job_count;

     int job_size;

     pthread_cond_t last_job_cond;
     pthread_cond_t current_job_cond;
     pthread_mutex_t current_job_lock;
     int current_job;
     int done;
 } ThreadContext;
 

 /// Max number of frame buffers that can be allocated when using frame threads.

 #define MAX_BUFFERS (32+1)

 
 /**
  * Context used by codec threads and stored in their AVCodecContext thread_opaque.
  */
 typedef struct PerThreadContext {
     struct FrameThreadContext *parent;
 
     pthread_t      thread;
     pthread_cond_t input_cond;      ///< Used to wait for a new packet from the main thread.
     pthread_cond_t progress_cond;   ///< Used by child threads to wait for progress to change.
     pthread_cond_t output_cond;     ///< Used by the main thread to wait for frames to finish.
 
     pthread_mutex_t mutex;          ///< Mutex used to protect the contents of the PerThreadContext.
     pthread_mutex_t progress_mutex; ///< Mutex used to protect frame progress values and progress_cond.
 
     AVCodecContext *avctx;          ///< Context used to decode packets passed to this thread.
 
     AVPacket       avpkt;           ///< Input packet (for decoding) or output (for encoding).
     int            allocated_buf_size; ///< Size allocated for avpkt.data
 
     AVFrame frame;                  ///< Output frame (for decoding) or input (for encoding).
     int     got_frame;              ///< The output of got_picture_ptr from the last avcodec_decode_video() call.
     int     result;                 ///< The result of the last codec decode/encode() call.
 
     enum {
         STATE_INPUT_READY,          ///< Set when the thread is awaiting a packet.
         STATE_SETTING_UP,           ///< Set before the codec has called ff_thread_finish_setup().
         STATE_GET_BUFFER,           /**<
                                      * Set when the codec calls get_buffer().
                                      * State is returned to STATE_SETTING_UP afterwards.
                                      */
         STATE_SETUP_FINISHED        ///< Set after the codec has called ff_thread_finish_setup().
     } state;
 
     /**
      * Array of frames passed to ff_thread_release_buffer().
      * Frames are released after all threads referencing them are finished.
      */
     AVFrame released_buffers[MAX_BUFFERS];
     int     num_released_buffers;
 
     /**
      * Array of progress values used by ff_thread_get_buffer().
      */
     int     progress[MAX_BUFFERS][2];
     uint8_t progress_used[MAX_BUFFERS];
 
     AVFrame *requested_frame;       ///< AVFrame the codec passed to get_buffer()
 } PerThreadContext;
 
 /**
  * Context stored in the client AVCodecContext thread_opaque.
  */
 typedef struct FrameThreadContext {
     PerThreadContext *threads;     ///< The contexts for each thread.
     PerThreadContext *prev_thread; ///< The last thread submit_packet() was called on.
 
     pthread_mutex_t buffer_mutex;  ///< Mutex used to protect get/release_buffer().
 
     int next_decoding;             ///< The next context to submit a packet to.
     int next_finished;             ///< The next context to return output from.
 
     int delaying;                  /**<
                                     * Set for the first N packets, where N is the number of threads.
                                     * While it is set, ff_thread_en/decode_frame won't return any results.
                                     */
 
     int die;                       ///< Set when threads should exit.
 } FrameThreadContext;
 

 static void* attribute_align_arg worker(void *v)

 {
     AVCodecContext *avctx = v;
     ThreadContext *c = avctx->thread_opaque;
     int our_job = c->job_count;
     int thread_count = avctx->thread_count;
     int self_id;
 
     pthread_mutex_lock(&c->current_job_lock);
     self_id = c->current_job++;

     for (;;){

         while (our_job >= c->job_count) {
             if (c->current_job == thread_count + c->job_count)
                 pthread_cond_signal(&c->last_job_cond);

             pthread_cond_wait(&c->current_job_cond, &c->current_job_lock);

             our_job = self_id;

             if (c->done) {
                 pthread_mutex_unlock(&c->current_job_lock);
                 return NULL;
             }
         }
         pthread_mutex_unlock(&c->current_job_lock);

         c->rets[our_job%c->rets_count] = c->func ? c->func(avctx, (char*)c->args + our_job*c->job_size):
                                                    c->func2(avctx, c->args, our_job, self_id);

         pthread_mutex_lock(&c->current_job_lock);
         our_job = c->current_job++;

     }
 }
 

 static av_always_inline void avcodec_thread_park_workers(ThreadContext *c, int thread_count)

 {
     pthread_cond_wait(&c->last_job_cond, &c->current_job_lock);
     pthread_mutex_unlock(&c->current_job_lock);

 }
 

 static void thread_free(AVCodecContext *avctx)

 {
     ThreadContext *c = avctx->thread_opaque;
     int i;

     pthread_mutex_lock(&c->current_job_lock);
     c->done = 1;

     pthread_cond_broadcast(&c->current_job_cond);

     pthread_mutex_unlock(&c->current_job_lock);
 
     for (i=0; i<avctx->thread_count; i++)
          pthread_join(c->workers[i], NULL);
 
     pthread_mutex_destroy(&c->current_job_lock);
     pthread_cond_destroy(&c->current_job_cond);
     pthread_cond_destroy(&c->last_job_cond);
     av_free(c->workers);

     av_freep(&avctx->thread_opaque);

 }

 static int avcodec_thread_execute(AVCodecContext *avctx, action_func* func, void *arg, int *ret, int job_count, int job_size)

 {
     ThreadContext *c= avctx->thread_opaque;
     int dummy_ret;

     if (!(avctx->active_thread_type&FF_THREAD_SLICE) || avctx->thread_count <= 1)
         return avcodec_default_execute(avctx, func, arg, ret, job_count, job_size);
 

     if (job_count <= 0)
         return 0;

     pthread_mutex_lock(&c->current_job_lock);
 
     c->current_job = avctx->thread_count;
     c->job_count = job_count;

     c->job_size = job_size;

     c->args = arg;
     c->func = func;
     if (ret) {
         c->rets = ret;

         c->rets_count = job_count;

     } else {

         c->rets = &dummy_ret;

         c->rets_count = 1;

     }

     pthread_cond_broadcast(&c->current_job_cond);

     avcodec_thread_park_workers(c, avctx->thread_count);

     return 0;
 }
 

 static int avcodec_thread_execute2(AVCodecContext *avctx, action_func2* func2, void *arg, int *ret, int job_count)

 {
     ThreadContext *c= avctx->thread_opaque;
     c->func2 = func2;
     return avcodec_thread_execute(avctx, NULL, arg, ret, job_count, 0);
 }
 

 static int thread_init(AVCodecContext *avctx)

 {

     int i;
     ThreadContext *c;

     int thread_count = avctx->thread_count;

 
     if (thread_count <= 1)
         return 0;
 

     c = av_mallocz(sizeof(ThreadContext));
     if (!c)
         return -1;

     c->workers = av_mallocz(sizeof(pthread_t)*thread_count);
     if (!c->workers) {
         av_free(c);
         return -1;
     }

     avctx->thread_opaque = c;
     c->current_job = 0;
     c->job_count = 0;

     c->job_size = 0;

     c->done = 0;

     pthread_cond_init(&c->current_job_cond, NULL);

     pthread_cond_init(&c->last_job_cond, NULL);
     pthread_mutex_init(&c->current_job_lock, NULL);
     pthread_mutex_lock(&c->current_job_lock);

     for (i=0; i<thread_count; i++) {

         if(pthread_create(&c->workers[i], NULL, worker, avctx)) {

            avctx->thread_count = i;
            pthread_mutex_unlock(&c->current_job_lock);

            ff_thread_free(avctx);

            return -1;
         }

     }

     avcodec_thread_park_workers(c, thread_count);

     avctx->execute = avcodec_thread_execute;

     avctx->execute2 = avcodec_thread_execute2;

     return 0;
 }

 
 /**
  * Codec worker thread.
  *
  * Automatically calls ff_thread_finish_setup() if the codec does
  * not provide an update_thread_context method, or if the codec returns
  * before calling it.
  */
 static attribute_align_arg void *frame_worker_thread(void *arg)
 {
     PerThreadContext *p = arg;
     FrameThreadContext *fctx = p->parent;
     AVCodecContext *avctx = p->avctx;
     AVCodec *codec = avctx->codec;
 
     while (1) {
         if (p->state == STATE_INPUT_READY && !fctx->die) {
             pthread_mutex_lock(&p->mutex);
             while (p->state == STATE_INPUT_READY && !fctx->die)
                 pthread_cond_wait(&p->input_cond, &p->mutex);
             pthread_mutex_unlock(&p->mutex);
         }
 
         if (fctx->die) break;
 

         if (!codec->update_thread_context && avctx->thread_safe_callbacks)
             ff_thread_finish_setup(avctx);

 
         pthread_mutex_lock(&p->mutex);
         avcodec_get_frame_defaults(&p->frame);
         p->got_frame = 0;
         p->result = codec->decode(avctx, &p->frame, &p->got_frame, &p->avpkt);
 
         if (p->state == STATE_SETTING_UP) ff_thread_finish_setup(avctx);
 
         p->state = STATE_INPUT_READY;
 
         pthread_mutex_lock(&p->progress_mutex);
         pthread_cond_signal(&p->output_cond);
         pthread_mutex_unlock(&p->progress_mutex);
 
         pthread_mutex_unlock(&p->mutex);
     }
 
     return NULL;
 }
 
 /**
  * Updates the next thread's AVCodecContext with values from the reference thread's context.
  *
  * @param dst The destination context.
  * @param src The source context.
  * @param for_user 0 if the destination is a codec thread, 1 if the destination is the user's thread
  */
 static int update_context_from_thread(AVCodecContext *dst, AVCodecContext *src, int for_user)
 {
     int err = 0;
 
     if (dst != src) {
         dst->sub_id    = src->sub_id;
         dst->time_base = src->time_base;
         dst->width     = src->width;
         dst->height    = src->height;
         dst->pix_fmt   = src->pix_fmt;
 

         dst->coded_width  = src->coded_width;
         dst->coded_height = src->coded_height;
 

         dst->has_b_frames = src->has_b_frames;
         dst->idct_algo    = src->idct_algo;
         dst->slice_count  = src->slice_count;
 
         dst->bits_per_coded_sample = src->bits_per_coded_sample;
         dst->sample_aspect_ratio   = src->sample_aspect_ratio;
         dst->dtg_active_format     = src->dtg_active_format;
 
         dst->profile = src->profile;
         dst->level   = src->level;
 
         dst->bits_per_raw_sample = src->bits_per_raw_sample;
         dst->ticks_per_frame     = src->ticks_per_frame;
         dst->color_primaries     = src->color_primaries;
 
         dst->color_trc   = src->color_trc;
         dst->colorspace  = src->colorspace;
         dst->color_range = src->color_range;
         dst->chroma_sample_location = src->chroma_sample_location;
     }
 
     if (for_user) {
         dst->coded_frame   = src->coded_frame;
         dst->has_b_frames += src->thread_count - 1;
     } else {
         if (dst->codec->update_thread_context)
             err = dst->codec->update_thread_context(dst, src);
     }
 
     return err;
 }
 
 /**
  * Update the next thread's AVCodecContext with values set by the user.
  *
  * @param dst The destination context.
  * @param src The source context.
  */
 static void update_context_from_user(AVCodecContext *dst, AVCodecContext *src)
 {
 #define copy_fields(s, e) memcpy(&dst->s, &src->s, (char*)&dst->e - (char*)&dst->s);
     dst->flags          = src->flags;
 
     dst->draw_horiz_band= src->draw_horiz_band;
     dst->get_buffer     = src->get_buffer;
     dst->release_buffer = src->release_buffer;
 
     dst->opaque   = src->opaque;
     dst->dsp_mask = src->dsp_mask;
     dst->debug    = src->debug;
     dst->debug_mv = src->debug_mv;
 
     dst->slice_flags = src->slice_flags;
     dst->flags2      = src->flags2;
 
     copy_fields(skip_loop_filter, bidir_refine);
 
     dst->frame_number     = src->frame_number;
     dst->reordered_opaque = src->reordered_opaque;
 #undef copy_fields
 }
 
 static void free_progress(AVFrame *f)
 {
     PerThreadContext *p = f->owner->thread_opaque;
     int *progress = f->thread_opaque;
 
     p->progress_used[(progress - p->progress[0]) / 2] = 0;
 }
 
 /// Releases the buffers that this decoding thread was the last user of.
 static void release_delayed_buffers(PerThreadContext *p)
 {
     FrameThreadContext *fctx = p->parent;
 
     while (p->num_released_buffers > 0) {

         AVFrame *f;

 
         pthread_mutex_lock(&fctx->buffer_mutex);

         f = &p->released_buffers[--p->num_released_buffers];

         free_progress(f);
         f->thread_opaque = NULL;
 
         f->owner->release_buffer(f->owner, f);
         pthread_mutex_unlock(&fctx->buffer_mutex);
     }
 }
 
 static int submit_packet(PerThreadContext *p, AVPacket *avpkt)
 {
     FrameThreadContext *fctx = p->parent;
     PerThreadContext *prev_thread = fctx->prev_thread;
     AVCodec *codec = p->avctx->codec;
     uint8_t *buf = p->avpkt.data;
 
     if (!avpkt->size && !(codec->capabilities & CODEC_CAP_DELAY)) return 0;
 
     pthread_mutex_lock(&p->mutex);
 
     release_delayed_buffers(p);
 
     if (prev_thread) {
         int err;
         if (prev_thread->state == STATE_SETTING_UP) {
             pthread_mutex_lock(&prev_thread->progress_mutex);
             while (prev_thread->state == STATE_SETTING_UP)
                 pthread_cond_wait(&prev_thread->progress_cond, &prev_thread->progress_mutex);
             pthread_mutex_unlock(&prev_thread->progress_mutex);
         }
 
         err = update_context_from_thread(p->avctx, prev_thread->avctx, 0);
         if (err) {
             pthread_mutex_unlock(&p->mutex);
             return err;
         }
     }
 
     av_fast_malloc(&buf, &p->allocated_buf_size, avpkt->size + FF_INPUT_BUFFER_PADDING_SIZE);
     p->avpkt = *avpkt;
     p->avpkt.data = buf;
     memcpy(buf, avpkt->data, avpkt->size);
     memset(buf + avpkt->size, 0, FF_INPUT_BUFFER_PADDING_SIZE);
 
     p->state = STATE_SETTING_UP;
     pthread_cond_signal(&p->input_cond);
     pthread_mutex_unlock(&p->mutex);
 
     /*
      * If the client doesn't have a thread-safe get_buffer(),
      * then decoding threads call back to the main thread,
      * and it calls back to the client here.
      */
 
     if (!p->avctx->thread_safe_callbacks &&
          p->avctx->get_buffer != avcodec_default_get_buffer) {
         while (p->state != STATE_SETUP_FINISHED && p->state != STATE_INPUT_READY) {
             pthread_mutex_lock(&p->progress_mutex);
             while (p->state == STATE_SETTING_UP)
                 pthread_cond_wait(&p->progress_cond, &p->progress_mutex);
 
             if (p->state == STATE_GET_BUFFER) {
                 p->result = p->avctx->get_buffer(p->avctx, p->requested_frame);
                 p->state  = STATE_SETTING_UP;
                 pthread_cond_signal(&p->progress_cond);
             }
             pthread_mutex_unlock(&p->progress_mutex);
         }
     }
 
     fctx->prev_thread = p;
 
     return 0;
 }
 
 int ff_thread_decode_frame(AVCodecContext *avctx,
                            AVFrame *picture, int *got_picture_ptr,
                            AVPacket *avpkt)
 {
     FrameThreadContext *fctx = avctx->thread_opaque;
     int finished = fctx->next_finished;
     PerThreadContext *p;
     int err;
 
     /*
      * Submit a packet to the next decoding thread.
      */
 
     p = &fctx->threads[fctx->next_decoding];
     update_context_from_user(p->avctx, avctx);
     err = submit_packet(p, avpkt);
     if (err) return err;
 
     fctx->next_decoding++;
 
     /*
      * If we're still receiving the initial packets, don't return a frame.
      */
 
     if (fctx->delaying && avpkt->size) {
         if (fctx->next_decoding >= (avctx->thread_count-1)) fctx->delaying = 0;
 
         *got_picture_ptr=0;
         return 0;
     }
 
     /*
      * Return the next available frame from the oldest thread.
      * If we're at the end of the stream, then we have to skip threads that
      * didn't output a frame, because we don't want to accidentally signal
      * EOF (avpkt->size == 0 && *got_picture_ptr == 0).
      */
 
     do {
         p = &fctx->threads[finished++];
 
         if (p->state != STATE_INPUT_READY) {
             pthread_mutex_lock(&p->progress_mutex);
             while (p->state != STATE_INPUT_READY)
                 pthread_cond_wait(&p->output_cond, &p->progress_mutex);
             pthread_mutex_unlock(&p->progress_mutex);
         }
 
         *picture = p->frame;
         *got_picture_ptr = p->got_frame;
         picture->pkt_dts = p->avpkt.dts;
 
         /*
          * A later call with avkpt->size == 0 may loop over all threads,
          * including this one, searching for a frame to return before being
          * stopped by the "finished != fctx->next_finished" condition.
          * Make sure we don't mistakenly return the same frame again.
          */
         p->got_frame = 0;
 
         if (finished >= avctx->thread_count) finished = 0;
     } while (!avpkt->size && !*got_picture_ptr && finished != fctx->next_finished);
 
     update_context_from_thread(avctx, p->avctx, 1);
 
     if (fctx->next_decoding >= avctx->thread_count) fctx->next_decoding = 0;
 
     fctx->next_finished = finished;
 
     return p->result;
 }
 
 void ff_thread_report_progress(AVFrame *f, int n, int field)
 {
     PerThreadContext *p;
     int *progress = f->thread_opaque;
 
     if (!progress || progress[field] >= n) return;
 
     p = f->owner->thread_opaque;
 
     if (f->owner->debug&FF_DEBUG_THREADS)
         av_log(f->owner, AV_LOG_DEBUG, "%p finished %d field %d\n", progress, n, field);
 
     pthread_mutex_lock(&p->progress_mutex);
     progress[field] = n;
     pthread_cond_broadcast(&p->progress_cond);
     pthread_mutex_unlock(&p->progress_mutex);
 }
 
 void ff_thread_await_progress(AVFrame *f, int n, int field)
 {
     PerThreadContext *p;
     int *progress = f->thread_opaque;
 
     if (!progress || progress[field] >= n) return;
 
     p = f->owner->thread_opaque;
 
     if (f->owner->debug&FF_DEBUG_THREADS)
         av_log(f->owner, AV_LOG_DEBUG, "thread awaiting %d field %d from %p\n", n, field, progress);
 
     pthread_mutex_lock(&p->progress_mutex);
     while (progress[field] < n)
         pthread_cond_wait(&p->progress_cond, &p->progress_mutex);
     pthread_mutex_unlock(&p->progress_mutex);
 }
 
 void ff_thread_finish_setup(AVCodecContext *avctx) {
     PerThreadContext *p = avctx->thread_opaque;
 
     if (!(avctx->active_thread_type&FF_THREAD_FRAME)) return;
 
     pthread_mutex_lock(&p->progress_mutex);
     p->state = STATE_SETUP_FINISHED;
     pthread_cond_broadcast(&p->progress_cond);
     pthread_mutex_unlock(&p->progress_mutex);
 }
 
 /// Waits for all threads to finish.
 static void park_frame_worker_threads(FrameThreadContext *fctx, int thread_count)
 {
     int i;
 
     for (i = 0; i < thread_count; i++) {
         PerThreadContext *p = &fctx->threads[i];
 
         if (p->state != STATE_INPUT_READY) {
             pthread_mutex_lock(&p->progress_mutex);
             while (p->state != STATE_INPUT_READY)
                 pthread_cond_wait(&p->output_cond, &p->progress_mutex);
             pthread_mutex_unlock(&p->progress_mutex);
         }
     }
 }
 
 static void frame_thread_free(AVCodecContext *avctx, int thread_count)
 {
     FrameThreadContext *fctx = avctx->thread_opaque;
     AVCodec *codec = avctx->codec;
     int i;
 
     park_frame_worker_threads(fctx, thread_count);
 
     if (fctx->prev_thread)
         update_context_from_thread(fctx->threads->avctx, fctx->prev_thread->avctx, 0);
 
     fctx->die = 1;
 
     for (i = 0; i < thread_count; i++) {
         PerThreadContext *p = &fctx->threads[i];
 
         pthread_mutex_lock(&p->mutex);
         pthread_cond_signal(&p->input_cond);
         pthread_mutex_unlock(&p->mutex);
 
         pthread_join(p->thread, NULL);
 
         if (codec->close)
             codec->close(p->avctx);
 
         avctx->codec = NULL;
 
         release_delayed_buffers(p);
     }
 
     for (i = 0; i < thread_count; i++) {
         PerThreadContext *p = &fctx->threads[i];
 
         avcodec_default_free_buffers(p->avctx);
 
         pthread_mutex_destroy(&p->mutex);
         pthread_mutex_destroy(&p->progress_mutex);
         pthread_cond_destroy(&p->input_cond);
         pthread_cond_destroy(&p->progress_cond);
         pthread_cond_destroy(&p->output_cond);
         av_freep(&p->avpkt.data);
 
         if (i)
             av_freep(&p->avctx->priv_data);
 
         av_freep(&p->avctx);
     }
 
     av_freep(&fctx->threads);
     pthread_mutex_destroy(&fctx->buffer_mutex);
     av_freep(&avctx->thread_opaque);
 }
 
 static int frame_thread_init(AVCodecContext *avctx)
 {
     int thread_count = avctx->thread_count;
     AVCodec *codec = avctx->codec;
     AVCodecContext *src = avctx;
     FrameThreadContext *fctx;
     int i, err = 0;
 

     if (thread_count <= 1) {
         avctx->active_thread_type = 0;
         return 0;
     }
 

     avctx->thread_opaque = fctx = av_mallocz(sizeof(FrameThreadContext));
 
     fctx->threads = av_mallocz(sizeof(PerThreadContext) * thread_count);
     pthread_mutex_init(&fctx->buffer_mutex, NULL);
     fctx->delaying = 1;
 
     for (i = 0; i < thread_count; i++) {
         AVCodecContext *copy = av_malloc(sizeof(AVCodecContext));
         PerThreadContext *p  = &fctx->threads[i];
 
         pthread_mutex_init(&p->mutex, NULL);
         pthread_mutex_init(&p->progress_mutex, NULL);
         pthread_cond_init(&p->input_cond, NULL);
         pthread_cond_init(&p->progress_cond, NULL);
         pthread_cond_init(&p->output_cond, NULL);
 
         p->parent = fctx;
         p->avctx  = copy;
 
         *copy = *src;
         copy->thread_opaque = p;
         copy->pkt = &p->avpkt;
 
         if (!i) {
             src = copy;
 
             if (codec->init)
                 err = codec->init(copy);
 
             update_context_from_thread(avctx, copy, 1);
         } else {
             copy->is_copy   = 1;
             copy->priv_data = av_malloc(codec->priv_data_size);
             memcpy(copy->priv_data, src->priv_data, codec->priv_data_size);
 
             if (codec->init_thread_copy)
                 err = codec->init_thread_copy(copy);
         }
 
         if (err) goto error;
 
         pthread_create(&p->thread, NULL, frame_worker_thread, p);
     }
 
     return 0;
 
 error:
     frame_thread_free(avctx, i+1);
 
     return err;
 }
 
 void ff_thread_flush(AVCodecContext *avctx)
 {
     FrameThreadContext *fctx = avctx->thread_opaque;
 
     if (!avctx->thread_opaque) return;
 
     park_frame_worker_threads(fctx, avctx->thread_count);

     if (fctx->prev_thread) {
         if (fctx->prev_thread != &fctx->threads[0])
             update_context_from_thread(fctx->threads[0].avctx, fctx->prev_thread->avctx, 0);
         if (avctx->codec->flush)
             avctx->codec->flush(fctx->threads[0].avctx);
     }

 
     fctx->next_decoding = fctx->next_finished = 0;
     fctx->delaying = 1;
     fctx->prev_thread = NULL;
 }
 
 static int *allocate_progress(PerThreadContext *p)
 {
     int i;
 
     for (i = 0; i < MAX_BUFFERS; i++)
         if (!p->progress_used[i]) break;
 
     if (i == MAX_BUFFERS) {
         av_log(p->avctx, AV_LOG_ERROR, "allocate_progress() overflow\n");
         return NULL;
     }
 
     p->progress_used[i] = 1;
 
     return p->progress[i];
 }
 
 int ff_thread_get_buffer(AVCodecContext *avctx, AVFrame *f)
 {
     PerThreadContext *p = avctx->thread_opaque;
     int *progress, err;
 
     f->owner = avctx;
 
     if (!(avctx->active_thread_type&FF_THREAD_FRAME)) {
         f->thread_opaque = NULL;
         return avctx->get_buffer(avctx, f);
     }
 

     if (p->state != STATE_SETTING_UP &&
         (avctx->codec->update_thread_context || !avctx->thread_safe_callbacks)) {

         av_log(avctx, AV_LOG_ERROR, "get_buffer() cannot be called after ff_thread_finish_setup()\n");
         return -1;
     }
 
     pthread_mutex_lock(&p->parent->buffer_mutex);
     f->thread_opaque = progress = allocate_progress(p);
 
     if (!progress) {
         pthread_mutex_unlock(&p->parent->buffer_mutex);
         return -1;
     }
 
     progress[0] =
     progress[1] = -1;
 
     if (avctx->thread_safe_callbacks ||
         avctx->get_buffer == avcodec_default_get_buffer) {
         err = avctx->get_buffer(avctx, f);
     } else {
         p->requested_frame = f;
         p->state = STATE_GET_BUFFER;
         pthread_mutex_lock(&p->progress_mutex);
         pthread_cond_signal(&p->progress_cond);
 
         while (p->state != STATE_SETTING_UP)
             pthread_cond_wait(&p->progress_cond, &p->progress_mutex);
 
         err = p->result;
 
         pthread_mutex_unlock(&p->progress_mutex);

 
         if (!avctx->codec->update_thread_context)
             ff_thread_finish_setup(avctx);

     }
 
     pthread_mutex_unlock(&p->parent->buffer_mutex);
 
     /*
      * Buffer age is difficult to keep track of between
      * multiple threads, and the optimizations it allows
      * are not worth the effort. It is disabled for now.
      */
     f->age = INT_MAX;
 
     return err;
 }
 
 void ff_thread_release_buffer(AVCodecContext *avctx, AVFrame *f)
 {
     PerThreadContext *p = avctx->thread_opaque;

     FrameThreadContext *fctx;

 
     if (!(avctx->active_thread_type&FF_THREAD_FRAME)) {
         avctx->release_buffer(avctx, f);
         return;
     }
 
     if (p->num_released_buffers >= MAX_BUFFERS) {
         av_log(p->avctx, AV_LOG_ERROR, "too many thread_release_buffer calls!\n");
         return;
     }
 
     if(avctx->debug & FF_DEBUG_BUFFERS)
         av_log(avctx, AV_LOG_DEBUG, "thread_release_buffer called on pic %p, %d buffers used\n",
                                     f, f->owner->internal_buffer_count);
 

     fctx = p->parent;
     pthread_mutex_lock(&fctx->buffer_mutex);

     p->released_buffers[p->num_released_buffers++] = *f;

     pthread_mutex_unlock(&fctx->buffer_mutex);

     memset(f->data, 0, sizeof(f->data));
 }
 
 /**
  * Set the threading algorithms used.
  *
  * Threading requires more than one thread.
  * Frame threading requires entire frames to be passed to the codec,
  * and introduces extra decoding delay, so is incompatible with low_delay.
  *
  * @param avctx The context.
  */
 static void validate_thread_parameters(AVCodecContext *avctx)
 {
     int frame_threading_supported = (avctx->codec->capabilities & CODEC_CAP_FRAME_THREADS)
                                 && !(avctx->flags & CODEC_FLAG_TRUNCATED)
                                 && !(avctx->flags & CODEC_FLAG_LOW_DELAY)
                                 && !(avctx->flags2 & CODEC_FLAG2_CHUNKS);
     if (avctx->thread_count == 1) {
         avctx->active_thread_type = 0;
     } else if (frame_threading_supported && (avctx->thread_type & FF_THREAD_FRAME)) {
         avctx->active_thread_type = FF_THREAD_FRAME;

     } else if (avctx->codec->capabilities & CODEC_CAP_SLICE_THREADS &&
                avctx->thread_type & FF_THREAD_SLICE) {

         avctx->active_thread_type = FF_THREAD_SLICE;
     }
 }
 

 int ff_thread_init(AVCodecContext *avctx)

 {
     if (avctx->thread_opaque) {
         av_log(avctx, AV_LOG_ERROR, "avcodec_thread_init is ignored after avcodec_open\n");
         return -1;
     }
 
     if (avctx->codec) {
         validate_thread_parameters(avctx);
 
         if (avctx->active_thread_type&FF_THREAD_SLICE)
             return thread_init(avctx);
         else if (avctx->active_thread_type&FF_THREAD_FRAME)
             return frame_thread_init(avctx);
     }
 
     return 0;
 }
 

 void ff_thread_free(AVCodecContext *avctx)

 {
     if (avctx->active_thread_type&FF_THREAD_FRAME)
         frame_thread_free(avctx, avctx->thread_count);
     else
         thread_free(avctx);
 }