text: /*
   * Audio and Video frame extraction
   * Copyright (c) 2003 Fabrice Bellard
   * Copyright (c) 2003 Michael Niedermayer
   *
   * 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 <stdint.h>
  #include <string.h>
  
  #include "libavutil/atomic.h"
  #include "libavutil/mem.h"
  
  #include "parser.h"
  
  static AVCodecParser *av_first_parser = NULL;
  
  AVCodecParser *av_parser_next(const AVCodecParser *p)
  {
      if (p)
          return p->next;
      else
          return av_first_parser;
  }
  
  void av_register_codec_parser(AVCodecParser *parser)
  {
      do {
          parser->next = av_first_parser;
      } while (parser->next != avpriv_atomic_ptr_cas((void * volatile *)&av_first_parser, parser->next, parser));
  }
  
  AVCodecParserContext *av_parser_init(int codec_id)
  {
      AVCodecParserContext *s = NULL;
      AVCodecParser *parser;
      int ret;
  
      if (codec_id == AV_CODEC_ID_NONE)
          return NULL;
  
      for (parser = av_first_parser; parser; parser = parser->next) {
          if (parser->codec_ids[0] == codec_id ||
              parser->codec_ids[1] == codec_id ||
              parser->codec_ids[2] == codec_id ||
              parser->codec_ids[3] == codec_id ||
              parser->codec_ids[4] == codec_id)
              goto found;
      }
      return NULL;
  
  found:
      s = av_mallocz(sizeof(AVCodecParserContext));
      if (!s)
          goto err_out;
      s->parser = parser;
      s->priv_data = av_mallocz(parser->priv_data_size);
      if (!s->priv_data)
          goto err_out;
      s->fetch_timestamp=1;
      s->pict_type = AV_PICTURE_TYPE_I;
      if (parser->parser_init) {
          ret = parser->parser_init(s);
          if (ret != 0)
              goto err_out;
      }
      s->key_frame            = -1;
      s->convergence_duration = 0;
      s->dts_sync_point       = INT_MIN;
      s->dts_ref_dts_delta    = INT_MIN;
      s->pts_dts_delta        = INT_MIN;
      return s;
  
  err_out:
      if (s)
          av_freep(&s->priv_data);
      av_free(s);
      return NULL;
  }
  
  void ff_fetch_timestamp(AVCodecParserContext *s, int off, int remove)
  {
      int i;
  
      s->dts    =
      s->pts    = AV_NOPTS_VALUE;
      s->pos    = -1;
      s->offset = 0;
      for (i = 0; i < AV_PARSER_PTS_NB; i++) {
          if (s->cur_offset + off >= s->cur_frame_offset[i] &&
              (s->frame_offset < s->cur_frame_offset[i] ||
               (!s->frame_offset && !s->next_frame_offset)) && // first field/frame
              // check disabled since MPEG-TS does not send complete PES packets
              /*s->next_frame_offset + off <*/  s->cur_frame_end[i]){
  
              s->dts    = s->cur_frame_dts[i];
              s->pts    = s->cur_frame_pts[i];
              s->pos    = s->cur_frame_pos[i];
              s->offset = s->next_frame_offset - s->cur_frame_offset[i];
              if (remove)
                  s->cur_frame_offset[i] = INT64_MAX;
              if (s->cur_offset + off < s->cur_frame_end[i])
                  break;
          }
      }
  }
  
  int av_parser_parse2(AVCodecParserContext *s, AVCodecContext *avctx,
                       uint8_t **poutbuf, int *poutbuf_size,
                       const uint8_t *buf, int buf_size,
                       int64_t pts, int64_t dts, int64_t pos)
  {
      int index, i;
      uint8_t dummy_buf[FF_INPUT_BUFFER_PADDING_SIZE];
  
      if (!(s->flags & PARSER_FLAG_FETCHED_OFFSET)) {
          s->next_frame_offset =
          s->cur_offset        = pos;
          s->flags            |= PARSER_FLAG_FETCHED_OFFSET;
      }
  
      if (buf_size == 0) {
          /* padding is always necessary even if EOF, so we add it here */
          memset(dummy_buf, 0, sizeof(dummy_buf));
          buf = dummy_buf;
      } else if (s->cur_offset + buf_size != s->cur_frame_end[s->cur_frame_start_index]) { /* skip remainder packets */
          /* add a new packet descriptor */
          i = (s->cur_frame_start_index + 1) & (AV_PARSER_PTS_NB - 1);
          s->cur_frame_start_index = i;
          s->cur_frame_offset[i]   = s->cur_offset;
          s->cur_frame_end[i]      = s->cur_offset + buf_size;
          s->cur_frame_pts[i]      = pts;
          s->cur_frame_dts[i]      = dts;
          s->cur_frame_pos[i]      = pos;
      }
  
      if (s->fetch_timestamp) {
          s->fetch_timestamp = 0;
          s->last_pts        = s->pts;
          s->last_dts        = s->dts;
          s->last_pos        = s->pos;
          ff_fetch_timestamp(s, 0, 0);
      }
      /* WARNING: the returned index can be negative */
      index = s->parser->parser_parse(s, avctx, (const uint8_t **) poutbuf,
                                      poutbuf_size, buf, buf_size);
      /* update the file pointer */
      if (*poutbuf_size) {
          /* fill the data for the current frame */
          s->frame_offset = s->next_frame_offset;
  
          /* offset of the next frame */
          s->next_frame_offset = s->cur_offset + index;
          s->fetch_timestamp   = 1;
      }
      if (index < 0)
          index = 0;
      s->cur_offset += index;
      return index;
  }
  
  int av_parser_change(AVCodecParserContext *s, AVCodecContext *avctx,
                       uint8_t **poutbuf, int *poutbuf_size,
                       const uint8_t *buf, int buf_size, int keyframe)
  {
      if (s && s->parser->split) {
          if (avctx->flags  & CODEC_FLAG_GLOBAL_HEADER ||
              avctx->flags2 & CODEC_FLAG2_LOCAL_HEADER) {
              int i = s->parser->split(avctx, buf, buf_size);
              buf      += i;
              buf_size -= i;
          }
      }
  
      /* cast to avoid warning about discarding qualifiers */
      *poutbuf      = (uint8_t *) buf;
      *poutbuf_size = buf_size;
      if (avctx->extradata) {
          if (keyframe && (avctx->flags2 & CODEC_FLAG2_LOCAL_HEADER)) {
              int size = buf_size + avctx->extradata_size;
  
              *poutbuf_size = size;
              *poutbuf      = av_malloc(size + FF_INPUT_BUFFER_PADDING_SIZE);
  
              memcpy(*poutbuf, avctx->extradata, avctx->extradata_size);
              memcpy(*poutbuf + avctx->extradata_size, buf,
                     buf_size + FF_INPUT_BUFFER_PADDING_SIZE);
              return 1;
          }
      }
  
      return 0;
  }
  
  void av_parser_close(AVCodecParserContext *s)
  {
      if (s) {
          if (s->parser->parser_close)
              s->parser->parser_close(s);
          av_freep(&s->priv_data);
          av_free(s);
      }
  }
  
  int ff_combine_frame(ParseContext *pc, int next,
                       const uint8_t **buf, int *buf_size)
  {
      if (pc->overread) {
          av_dlog(NULL, "overread %d, state:%X next:%d index:%d o_index:%d\n",
                  pc->overread, pc->state, next, pc->index, pc->overread_index);
          av_dlog(NULL, "%X %X %X %X\n",
                  (*buf)[0], (*buf)[1], (*buf)[2], (*buf)[3]);
      }
  
      /* Copy overread bytes from last frame into buffer. */
      for (; pc->overread > 0; pc->overread--)
          pc->buffer[pc->index++] = pc->buffer[pc->overread_index++];
  
      /* flush remaining if EOF */
      if (!*buf_size && next == END_NOT_FOUND)
          next = 0;
  
      pc->last_index = pc->index;
  
      /* copy into buffer end return */
      if (next == END_NOT_FOUND) {
          void *new_buffer = av_fast_realloc(pc->buffer, &pc->buffer_size,
                                             *buf_size + pc->index +
                                             FF_INPUT_BUFFER_PADDING_SIZE);
  
          if (!new_buffer) {
              pc->index = 0;
              return AVERROR(ENOMEM);
          }
          pc->buffer = new_buffer;
          memcpy(&pc->buffer[pc->index], *buf, *buf_size);
          pc->index += *buf_size;
          return -1;
      }
  
      *buf_size          =
      pc->overread_index = pc->index + next;
  
      /* append to buffer */
      if (pc->index) {
          void *new_buffer = av_fast_realloc(pc->buffer, &pc->buffer_size,
                                             next + pc->index +
                                             FF_INPUT_BUFFER_PADDING_SIZE);
          if (!new_buffer) {
              pc->overread_index =
              pc->index = 0;
              return AVERROR(ENOMEM);
          }
          pc->buffer = new_buffer;
          if (next > -FF_INPUT_BUFFER_PADDING_SIZE)
              memcpy(&pc->buffer[pc->index], *buf,
                     next + FF_INPUT_BUFFER_PADDING_SIZE);
          pc->index = 0;
          *buf      = pc->buffer;
      }
  
      /* store overread bytes */
      for (; next < 0; next++) {
          pc->state   = pc->state   << 8 | pc->buffer[pc->last_index + next];
          pc->state64 = pc->state64 << 8 | pc->buffer[pc->last_index + next];
          pc->overread++;
      }
  
      if (pc->overread) {
          av_dlog(NULL, "overread %d, state:%X next:%d index:%d o_index:%d\n",
                  pc->overread, pc->state, next, pc->index, pc->overread_index);
          av_dlog(NULL, "%X %X %X %X\n",
                  (*buf)[0], (*buf)[1], (*buf)[2], (*buf)[3]);
      }
  
      return 0;
  }
  
  void ff_parse_close(AVCodecParserContext *s)
  {
      ParseContext *pc = s->priv_data;
  
      av_freep(&pc->buffer);
  }
  
  int ff_mpeg4video_split(AVCodecContext *avctx, const uint8_t *buf, int buf_size)
  {
      int i;
      uint32_t state = -1;
  
      for (i = 0; i < buf_size; i++) {
          state = state << 8 | buf[i];
          if (state == 0x1B3 || state == 0x1B6)
              return i - 3;
      }
      return 0;
  }
  