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ffmpeg-4.2.2/libavcodec/noise_bsf.c 2.57 KB
aac5773f   hucm   功能基本完成,接口待打磨
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  /*
   * copyright (c) 2006 Michael Niedermayer <michaelni@gmx.at>
   *
   * 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
   */
  
  #include <stdlib.h>
  #include <string.h>
  
  #include "avcodec.h"
  #include "bsf.h"
  
  #include "libavutil/log.h"
  #include "libavutil/mem.h"
  #include "libavutil/opt.h"
  
  typedef struct NoiseContext {
      const AVClass *class;
      int amount;
      int dropamount;
      unsigned int state;
  } NoiseContext;
  
  static int noise(AVBSFContext *ctx, AVPacket *pkt)
  {
      NoiseContext *s = ctx->priv_data;
      int amount = s->amount > 0 ? s->amount : (s->state % 10001 + 1);
      int i, ret = 0;
  
      if (amount <= 0)
          return AVERROR(EINVAL);
  
      ret = ff_bsf_get_packet_ref(ctx, pkt);
      if (ret < 0)
          return ret;
  
      if (s->dropamount > 0 && s->state % s->dropamount == 0) {
          s->state++;
          av_packet_unref(pkt);
          return AVERROR(EAGAIN);
      }
  
      ret = av_packet_make_writable(pkt);
      if (ret < 0)
          goto fail;
  
      for (i = 0; i < pkt->size; i++) {
          s->state += pkt->data[i] + 1;
          if (s->state % amount == 0)
              pkt->data[i] = s->state;
      }
  fail:
      if (ret < 0)
          av_packet_unref(pkt);
  
      return ret;
  }
  
  #define OFFSET(x) offsetof(NoiseContext, x)
  #define FLAGS (AV_OPT_FLAG_VIDEO_PARAM|AV_OPT_FLAG_AUDIO_PARAM|AV_OPT_FLAG_BSF_PARAM)
  static const AVOption options[] = {
      { "amount", NULL, OFFSET(amount), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, INT_MAX, FLAGS },
      { "dropamount", NULL, OFFSET(dropamount), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, INT_MAX, FLAGS },
      { NULL },
  };
  
  static const AVClass noise_class = {
      .class_name = "noise",
      .item_name  = av_default_item_name,
      .option     = options,
      .version    = LIBAVUTIL_VERSION_INT,
  };
  
  const AVBitStreamFilter ff_noise_bsf = {
      .name           = "noise",
      .priv_data_size = sizeof(NoiseContext),
      .priv_class     = &noise_class,
      .filter         = noise,
  };