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  1. /*
  2.  * Copyright (c) 2012  Justin Ruggles
  3.  *
  4.  * This file is part of FFmpeg.
  5.  *
  6.  * FFmpeg is free software; you can redistribute it and/or
  7.  * modify it under the terms of the GNU Lesser General Public
  8.  * License as published by the Free Software Foundation; either
  9.  * version 2.1 of the License, or (at your option) any later version.
  10.  *
  11.  * FFmpeg is distributed in the hope that it will be useful,
  12.  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13.  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14.  * Lesser General Public License for more details.
  15.  *
  16.  * You should have received a copy of the GNU Lesser General Public
  17.  * License along with FFmpeg; if not, write to the Free Software
  18.  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  19.  */
  20.  
  21. /**
  22.  * @file
  23.  * GSM audio parser
  24.  *
  25.  * Splits packets into individual blocks.
  26.  */
  27.  
  28. #include "libavutil/avassert.h"
  29. #include "parser.h"
  30. #include "gsm.h"
  31.  
  32. typedef struct GSMParseContext {
  33.     ParseContext pc;
  34.     int block_size;
  35.     int duration;
  36.     int remaining;
  37. } GSMParseContext;
  38.  
  39. static int gsm_parse(AVCodecParserContext *s1, AVCodecContext *avctx,
  40.                      const uint8_t **poutbuf, int *poutbuf_size,
  41.                      const uint8_t *buf, int buf_size)
  42. {
  43.     GSMParseContext *s = s1->priv_data;
  44.     ParseContext *pc = &s->pc;
  45.     int next;
  46.  
  47.     if (!s->block_size) {
  48.         switch (avctx->codec_id) {
  49.         case AV_CODEC_ID_GSM:
  50.             s->block_size = GSM_BLOCK_SIZE;
  51.             s->duration   = GSM_FRAME_SIZE;
  52.             break;
  53.         case AV_CODEC_ID_GSM_MS:
  54.             s->block_size = avctx->block_align ? avctx->block_align
  55.                                                : GSM_MS_BLOCK_SIZE;
  56.             s->duration   = GSM_FRAME_SIZE * 2;
  57.             break;
  58.         default:
  59.             av_assert0(0);
  60.         }
  61.     }
  62.  
  63.     if (!s->remaining)
  64.         s->remaining = s->block_size;
  65.     if (s->remaining <= buf_size) {
  66.         next = s->remaining;
  67.         s->remaining = 0;
  68.     } else {
  69.         next = END_NOT_FOUND;
  70.         s->remaining -= buf_size;
  71.     }
  72.  
  73.     if (ff_combine_frame(pc, next, &buf, &buf_size) < 0 || !buf_size) {
  74.         *poutbuf      = NULL;
  75.         *poutbuf_size = 0;
  76.         return buf_size;
  77.     }
  78.  
  79.     s1->duration = s->duration;
  80.  
  81.     *poutbuf      = buf;
  82.     *poutbuf_size = buf_size;
  83.     return next;
  84. }
  85.  
  86. AVCodecParser ff_gsm_parser = {
  87.     .codec_ids      = { AV_CODEC_ID_GSM, AV_CODEC_ID_GSM_MS },
  88.     .priv_data_size = sizeof(GSMParseContext),
  89.     .parser_parse   = gsm_parse,
  90.     .parser_close   = ff_parse_close,
  91. };
  92.