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ffmpeg-4.2.2/libavcodec/gsm_parser.c 2.52 KB
aac5773f   hucm   功能基本完成,接口待打磨
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  /*
   * Copyright (c) 2012  Justin Ruggles
   *
   * 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
   * GSM audio parser
   *
   * Splits packets into individual blocks.
   */
  
  #include "libavutil/avassert.h"
  #include "parser.h"
  #include "gsm.h"
  
  typedef struct GSMParseContext {
      ParseContext pc;
      int block_size;
      int duration;
      int remaining;
  } GSMParseContext;
  
  static int gsm_parse(AVCodecParserContext *s1, AVCodecContext *avctx,
                       const uint8_t **poutbuf, int *poutbuf_size,
                       const uint8_t *buf, int buf_size)
  {
      GSMParseContext *s = s1->priv_data;
      ParseContext *pc = &s->pc;
      int next;
  
      if (!s->block_size) {
          switch (avctx->codec_id) {
          case AV_CODEC_ID_GSM:
              s->block_size = GSM_BLOCK_SIZE;
              s->duration   = GSM_FRAME_SIZE;
              break;
          case AV_CODEC_ID_GSM_MS:
              s->block_size = avctx->block_align ? avctx->block_align
                                                 : GSM_MS_BLOCK_SIZE;
              s->duration   = GSM_FRAME_SIZE * 2;
              break;
          default:
              av_assert0(0);
          }
      }
  
      if (!s->remaining)
          s->remaining = s->block_size;
      if (s->remaining <= buf_size) {
          next = s->remaining;
          s->remaining = 0;
      } else {
          next = END_NOT_FOUND;
          s->remaining -= buf_size;
      }
  
      if (ff_combine_frame(pc, next, &buf, &buf_size) < 0 || !buf_size) {
          *poutbuf      = NULL;
          *poutbuf_size = 0;
          return buf_size;
      }
  
      s1->duration = s->duration;
  
      *poutbuf      = buf;
      *poutbuf_size = buf_size;
      return next;
  }
  
  AVCodecParser ff_gsm_parser = {
      .codec_ids      = { AV_CODEC_ID_GSM, AV_CODEC_ID_GSM_MS },
      .priv_data_size = sizeof(GSMParseContext),
      .parser_parse   = gsm_parse,
      .parser_close   = ff_parse_close,
  };