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ffmpeg-4.2.2/libavcodec/pthread.c 3.1 KB
aac5773f   hucm   功能基本完成,接口待打磨
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  /*
   * 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 "avcodec.h"
  #include "internal.h"
  #include "pthread_internal.h"
  #include "thread.h"
  
  /**
   * 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 & AV_CODEC_CAP_FRAME_THREADS)
                                  && !(avctx->flags  & AV_CODEC_FLAG_TRUNCATED)
                                  && !(avctx->flags  & AV_CODEC_FLAG_LOW_DELAY)
                                  && !(avctx->flags2 & AV_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 & AV_CODEC_CAP_SLICE_THREADS &&
                 avctx->thread_type & FF_THREAD_SLICE) {
          avctx->active_thread_type = FF_THREAD_SLICE;
      } else if (!(avctx->codec->capabilities & AV_CODEC_CAP_AUTO_THREADS)) {
          avctx->thread_count       = 1;
          avctx->active_thread_type = 0;
      }
  
      if (avctx->thread_count > MAX_AUTO_THREADS)
          av_log(avctx, AV_LOG_WARNING,
                 "Application has requested %d threads. Using a thread count greater than %d is not recommended.\n",
                 avctx->thread_count, MAX_AUTO_THREADS);
  }
  
  int ff_thread_init(AVCodecContext *avctx)
  {
      validate_thread_parameters(avctx);
  
      if (avctx->active_thread_type&FF_THREAD_SLICE)
          return ff_slice_thread_init(avctx);
      else if (avctx->active_thread_type&FF_THREAD_FRAME)
          return ff_frame_thread_init(avctx);
  
      return 0;
  }
  
  void ff_thread_free(AVCodecContext *avctx)
  {
      if (avctx->active_thread_type&FF_THREAD_FRAME)
          ff_frame_thread_free(avctx, avctx->thread_count);
      else
          ff_slice_thread_free(avctx);
  }