libavcodec/gsm_parser.c

   1 /*
   2  * Copyright (c) 2012  Justin Ruggles
   3  *
   4  * This file is part of Libav.
   5  *
   6  * Libav 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  * Libav 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 Libav; 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 "parser.h"
  29 #include "gsm.h"
  30
  31 typedef struct GSMParseContext {
  32     ParseContext pc;
  33     int block_size;
  34     int duration;
  35     int remaining;
  36 } GSMParseContext;
  37
  38 static int gsm_parse(AVCodecParserContext *s1, AVCodecContext *avctx,
  39                      const uint8_t **poutbuf, int *poutbuf_size,
  40                      const uint8_t *buf, int buf_size)
  41 {
  42     GSMParseContext *s = s1->priv_data;
  43     ParseContext *pc = &s->pc;
  44     int next;
  45
  46     if (!s->block_size) {
  47         switch (avctx->codec_id) {
  48         case AV_CODEC_ID_GSM:
  49             s->block_size = GSM_BLOCK_SIZE;
  50             s->duration   = GSM_FRAME_SIZE;
  51             break;
  52         case AV_CODEC_ID_GSM_MS:
  53             s->block_size = GSM_MS_BLOCK_SIZE;
  54             s->duration   = GSM_FRAME_SIZE * 2;
  55             break;
  56         default:
  57             return AVERROR(EINVAL);
  58         }
  59     }
  60
  61     if (!s->remaining)
  62         s->remaining = s->block_size;
  63     if (s->remaining <= buf_size) {
  64         next = s->remaining;
  65         s->remaining = 0;
  66     } else {
  67         next = END_NOT_FOUND;
  68         s->remaining -= buf_size;
  69     }
  70
  71     if (ff_combine_frame(pc, next, &buf, &buf_size) < 0 || !buf_size) {
  72         *poutbuf      = NULL;
  73         *poutbuf_size = 0;
  74         return buf_size;
  75     }
  76
  77     s1->duration = s->duration;
  78
  79     *poutbuf      = buf;
  80     *poutbuf_size = buf_size;
  81     return next;
  82 }
  83
  84 AVCodecParser ff_gsm_parser = {
  85     .codec_ids      = { AV_CODEC_ID_GSM, AV_CODEC_ID_GSM_MS },
  86     .priv_data_size = sizeof(GSMParseContext),
  87     .parser_parse   = gsm_parse,
  88     .parser_close   = ff_parse_close,
  89 };