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ffmpeg-4.2.2/libavcodec/sbc_parser.c 3.74 KB
aac5773f   hucm   功能基本完成,接口待打磨
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  /*
   * SBC parser
   *
   * Copyright (C) 2017  Aurelien Jacobs <aurel@gnuage.org>
   *
   * 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 "sbc.h"
  #include "parser.h"
  
  typedef struct SBCParseContext {
      ParseContext pc;
      uint8_t header[3];
      int header_size;
      int buffered_size;
  } SBCParseContext;
  
  static int sbc_parse_header(AVCodecParserContext *s, AVCodecContext *avctx,
                              const uint8_t *data, size_t len)
  {
      static const int sample_rates[4] = { 16000, 32000, 44100, 48000 };
      int sr, blocks, mode, subbands, bitpool, channels, joint;
      int length;
  
      if (len < 3)
          return -1;
  
      if (data[0] == MSBC_SYNCWORD && data[1] == 0 && data[2] == 0) {
          avctx->channels = 1;
          avctx->sample_fmt = AV_SAMPLE_FMT_S16;
          avctx->sample_rate = 16000;
          avctx->frame_size = 120;
          s->duration = avctx->frame_size;
          return 57;
      }
  
      if (data[0] != SBC_SYNCWORD)
          return -2;
  
      sr       =   (data[1] >> 6) & 0x03;
      blocks   = (((data[1] >> 4) & 0x03) + 1) << 2;
      mode     =   (data[1] >> 2) & 0x03;
      subbands = (((data[1] >> 0) & 0x01) + 1) << 2;
      bitpool  = data[2];
  
      channels = mode == SBC_MODE_MONO ? 1 : 2;
      joint    = mode == SBC_MODE_JOINT_STEREO;
  
      length = 4 + (subbands * channels) / 2
               + ((((mode == SBC_MODE_DUAL_CHANNEL) + 1) * blocks * bitpool
                   + (joint * subbands)) + 7) / 8;
  
      avctx->channels = channels;
      avctx->sample_fmt = AV_SAMPLE_FMT_S16;
      avctx->sample_rate = sample_rates[sr];
      avctx->frame_size = subbands * blocks;
      s->duration = avctx->frame_size;
      return length;
  }
  
  static int sbc_parse(AVCodecParserContext *s, AVCodecContext *avctx,
                       const uint8_t **poutbuf, int *poutbuf_size,
                       const uint8_t *buf, int buf_size)
  {
      SBCParseContext *pc = s->priv_data;
      int next;
  
      if (s->flags & PARSER_FLAG_COMPLETE_FRAMES) {
          next = buf_size;
      } else {
          if (pc->header_size) {
              memcpy(pc->header + pc->header_size, buf,
                     sizeof(pc->header) - pc->header_size);
              next = sbc_parse_header(s, avctx, pc->header, sizeof(pc->header))
                   - pc->buffered_size;
              pc->header_size = 0;
          } else {
              next = sbc_parse_header(s, avctx, buf, buf_size);
              if (next >= buf_size)
                  next = -1;
          }
  
          if (next < 0) {
              pc->header_size = FFMIN(sizeof(pc->header), buf_size);
              memcpy(pc->header, buf, pc->header_size);
              pc->buffered_size = buf_size;
              next = END_NOT_FOUND;
          }
  
          if (ff_combine_frame(&pc->pc, next, &buf, &buf_size) < 0) {
              *poutbuf      = NULL;
              *poutbuf_size = 0;
              return buf_size;
          }
      }
  
      *poutbuf      = buf;
      *poutbuf_size = buf_size;
      return next;
  }
  
  AVCodecParser ff_sbc_parser = {
      .codec_ids      = { AV_CODEC_ID_SBC },
      .priv_data_size = sizeof(SBCParseContext),
      .parser_parse   = sbc_parse,
      .parser_close   = ff_parse_close,
  };