text: /*
   * Copyright (c) 2007 Bobby Bingham
   *
   * 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
   * FIFO buffering filter
   */
  
  #include "libavutil/avassert.h"
  #include "libavutil/channel_layout.h"
  #include "libavutil/common.h"
  #include "libavutil/mathematics.h"
  #include "libavutil/samplefmt.h"
  
  #include "audio.h"
  #include "avfilter.h"
  #include "internal.h"
  #include "video.h"
  
  typedef struct Buf {
      AVFrame *frame;
      struct Buf        *next;
  } Buf;
  
  typedef struct FifoContext {
      Buf  root;
      Buf *last;   ///< last buffered frame
  
      /**
       * When a specific number of output samples is requested, the partial
       * buffer is stored here
       */
      AVFrame *out;
      int allocated_samples;      ///< number of samples out was allocated for
  } FifoContext;
  
  static av_cold int init(AVFilterContext *ctx)
  {
      FifoContext *fifo = ctx->priv;
      fifo->last = &fifo->root;
  
      return 0;
  }
  
  static av_cold void uninit(AVFilterContext *ctx)
  {
      FifoContext *fifo = ctx->priv;
      Buf *buf, *tmp;
  
      for (buf = fifo->root.next; buf; buf = tmp) {
          tmp = buf->next;
          av_frame_free(&buf->frame);
          av_free(buf);
      }
  
      av_frame_free(&fifo->out);
  }
  
  static int add_to_queue(AVFilterLink *inlink, AVFrame *frame)
  {
      FifoContext *fifo = inlink->dst->priv;
  
      fifo->last->next = av_mallocz(sizeof(Buf));
      if (!fifo->last->next) {
          av_frame_free(&frame);
          return AVERROR(ENOMEM);
      }
  
      fifo->last = fifo->last->next;
      fifo->last->frame = frame;
  
      return 0;
  }
  
  static void queue_pop(FifoContext *s)
  {
      Buf *tmp = s->root.next->next;
      if (s->last == s->root.next)
          s->last = &s->root;
      av_freep(&s->root.next);
      s->root.next = tmp;
  }
  
  /**
   * Move data pointers and pts offset samples forward.
   */
  static void buffer_offset(AVFilterLink *link, AVFrame *frame,
                            int offset)
  {
      int nb_channels = link->channels;
      int planar = av_sample_fmt_is_planar(link->format);
      int planes = planar ? nb_channels : 1;
      int block_align = av_get_bytes_per_sample(link->format) * (planar ? 1 : nb_channels);
      int i;
  
      av_assert0(frame->nb_samples > offset);
  
      for (i = 0; i < planes; i++)
          frame->extended_data[i] += block_align * offset;
      if (frame->data != frame->extended_data)
          memcpy(frame->data, frame->extended_data,
                 FFMIN(planes, FF_ARRAY_ELEMS(frame->data)) * sizeof(*frame->data));
      frame->linesize[0] -= block_align*offset;
      frame->nb_samples -= offset;
  
      if (frame->pts != AV_NOPTS_VALUE) {
          frame->pts += av_rescale_q(offset, (AVRational){1, link->sample_rate},
                                     link->time_base);
      }
  }
  
  static int calc_ptr_alignment(AVFrame *frame)
  {
      int planes = av_sample_fmt_is_planar(frame->format) ?
                   av_frame_get_channels(frame) : 1;
      int min_align = 128;
      int p;
  
      for (p = 0; p < planes; p++) {
          int cur_align = 128;
          while ((intptr_t)frame->extended_data[p] % cur_align)
              cur_align >>= 1;
          if (cur_align < min_align)
              min_align = cur_align;
      }
      return min_align;
  }
  
  static int return_audio_frame(AVFilterContext *ctx)
  {
      AVFilterLink *link = ctx->outputs[0];
      FifoContext *s = ctx->priv;
      AVFrame *head = s->root.next ? s->root.next->frame : NULL;
      AVFrame *out;
      int ret;
  
      /* if head is NULL then we're flushing the remaining samples in out */
      if (!head && !s->out)
          return AVERROR_EOF;
  
      if (!s->out &&
          head->nb_samples >= link->request_samples &&
          calc_ptr_alignment(head) >= 32) {
          if (head->nb_samples == link->request_samples) {
              out = head;
              queue_pop(s);
          } else {
              out = av_frame_clone(head);
              if (!out)
                  return AVERROR(ENOMEM);
  
              out->nb_samples = link->request_samples;
              buffer_offset(link, head, link->request_samples);
          }
      } else {
          int nb_channels = link->channels;
  
          if (!s->out) {
              s->out = ff_get_audio_buffer(link, link->request_samples);
              if (!s->out)
                  return AVERROR(ENOMEM);
  
              s->out->nb_samples = 0;
              s->out->pts                   = head->pts;
              s->allocated_samples          = link->request_samples;
          } else if (link->request_samples != s->allocated_samples) {
              av_log(ctx, AV_LOG_ERROR, "request_samples changed before the "
                     "buffer was returned.\n");
              return AVERROR(EINVAL);
          }
  
          while (s->out->nb_samples < s->allocated_samples) {
              int len;
  
              if (!s->root.next) {
                  ret = ff_request_frame(ctx->inputs[0]);
                  if (ret == AVERROR_EOF) {
                      av_samples_set_silence(s->out->extended_data,
                                             s->out->nb_samples,
                                             s->allocated_samples -
                                             s->out->nb_samples,
                                             nb_channels, link->format);
                      s->out->nb_samples = s->allocated_samples;
                      break;
                  } else if (ret < 0)
                      return ret;
                  if (!s->root.next)
                      return 0;
              }
              head = s->root.next->frame;
  
              len = FFMIN(s->allocated_samples - s->out->nb_samples,
                          head->nb_samples);
  
              av_samples_copy(s->out->extended_data, head->extended_data,
                              s->out->nb_samples, 0, len, nb_channels,
                              link->format);
              s->out->nb_samples += len;
  
              if (len == head->nb_samples) {
                  av_frame_free(&head);
                  queue_pop(s);
              } else {
                  buffer_offset(link, head, len);
              }
          }
          out = s->out;
          s->out = NULL;
      }
      return ff_filter_frame(link, out);
  }
  
  static int request_frame(AVFilterLink *outlink)
  {
      FifoContext *fifo = outlink->src->priv;
      int ret = 0;
  
      if (!fifo->root.next) {
          if ((ret = ff_request_frame(outlink->src->inputs[0])) < 0) {
              if (ret == AVERROR_EOF && outlink->request_samples)
                  return return_audio_frame(outlink->src);
              return ret;
          }
          if (!fifo->root.next)
              return 0;
      }
  
      if (outlink->request_samples) {
          return return_audio_frame(outlink->src);
      } else {
          ret = ff_filter_frame(outlink, fifo->root.next->frame);
          queue_pop(fifo);
      }
  
      return ret;
  }
  
  static const AVFilterPad avfilter_vf_fifo_inputs[] = {
      {
          .name             = "default",
          .type             = AVMEDIA_TYPE_VIDEO,
          .filter_frame     = add_to_queue,
      },
      { NULL }
  };
  
  static const AVFilterPad avfilter_vf_fifo_outputs[] = {
      {
          .name          = "default",
          .type          = AVMEDIA_TYPE_VIDEO,
          .request_frame = request_frame,
      },
      { NULL }
  };
  
  AVFilter ff_vf_fifo = {
      .name      = "fifo",
      .description = NULL_IF_CONFIG_SMALL("Buffer input images and send them when they are requested."),
  
      .init      = init,
      .uninit    = uninit,
  
      .priv_size = sizeof(FifoContext),
  
      .inputs    = avfilter_vf_fifo_inputs,
      .outputs   = avfilter_vf_fifo_outputs,
  };
  
  static const AVFilterPad avfilter_af_afifo_inputs[] = {
      {
          .name             = "default",
          .type             = AVMEDIA_TYPE_AUDIO,
          .filter_frame     = add_to_queue,
      },
      { NULL }
  };
  
  static const AVFilterPad avfilter_af_afifo_outputs[] = {
      {
          .name          = "default",
          .type          = AVMEDIA_TYPE_AUDIO,
          .request_frame = request_frame,
      },
      { NULL }
  };
  
  AVFilter ff_af_afifo = {
      .name        = "afifo",
      .description = NULL_IF_CONFIG_SMALL("Buffer input frames and send them when they are requested."),
  
      .init      = init,
      .uninit    = uninit,
  
      .priv_size = sizeof(FifoContext),
  
      .inputs    = avfilter_af_afifo_inputs,
      .outputs   = avfilter_af_afifo_outputs,
  };
  