LCOV - code coverage report
Current view: top level - libavcodec - latm_parser.c (source / functions) Hit Total Coverage
Test: coverage.info Lines: 36 37 97.3 %
Date: 2017-12-11 04:34:20 Functions: 2 2 100.0 %

          Line data    Source code
       1             : /*
       2             :  * copyright (c) 2008 Paul Kendall <paul@kcbbs.gen.nz>
       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             :  * AAC LATM parser
      24             :  */
      25             : 
      26             : #include <stdint.h>
      27             : #include "parser.h"
      28             : 
      29             : #define LATM_HEADER     0x56e000        // 0x2b7 (11 bits)
      30             : #define LATM_MASK       0xFFE000        // top 11 bits
      31             : #define LATM_SIZE_MASK  0x001FFF        // bottom 13 bits
      32             : 
      33             : typedef struct LATMParseContext{
      34             :     ParseContext pc;
      35             :     int count;
      36             : } LATMParseContext;
      37             : 
      38             : /**
      39             :  * Find the end of the current frame in the bitstream.
      40             :  * @return the position of the first byte of the next frame, or -1
      41             :  */
      42        1327 : static int latm_find_frame_end(AVCodecParserContext *s1, const uint8_t *buf,
      43             :                                int buf_size)
      44             : {
      45        1327 :     LATMParseContext *s = s1->priv_data;
      46        1327 :     ParseContext *pc    = &s->pc;
      47             :     int pic_found, i;
      48             :     uint32_t state;
      49             : 
      50        1327 :     pic_found = pc->frame_start_found;
      51        1327 :     state     = pc->state;
      52             : 
      53        1327 :     if (!pic_found) {
      54        3763 :         for (i = 0; i < buf_size; i++) {
      55        3762 :             state = (state<<8) | buf[i];
      56        3762 :             if ((state & LATM_MASK) == LATM_HEADER) {
      57        1254 :                 i++;
      58        1254 :                 s->count  = -i;
      59        1254 :                 pic_found = 1;
      60        1254 :                 break;
      61             :             }
      62             :         }
      63             :     }
      64             : 
      65        1327 :     if (pic_found) {
      66             :         /* EOF considered as end of frame */
      67        1326 :         if (buf_size == 0)
      68           6 :             return 0;
      69        1320 :         if ((state & LATM_SIZE_MASK) - s->count <= buf_size) {
      70        1251 :             pc->frame_start_found = 0;
      71        1251 :             pc->state             = -1;
      72        1251 :             return (state & LATM_SIZE_MASK) - s->count;
      73             :         }
      74             :     }
      75             : 
      76          70 :     s->count             += buf_size;
      77          70 :     pc->frame_start_found = pic_found;
      78          70 :     pc->state             = state;
      79             : 
      80          70 :     return END_NOT_FOUND;
      81             : }
      82             : 
      83        1327 : static int latm_parse(AVCodecParserContext *s1, AVCodecContext *avctx,
      84             :                       const uint8_t **poutbuf, int *poutbuf_size,
      85             :                       const uint8_t *buf, int buf_size)
      86             : {
      87        1327 :     LATMParseContext *s = s1->priv_data;
      88        1327 :     ParseContext *pc    = &s->pc;
      89             :     int next;
      90             : 
      91        1327 :     if (s1->flags & PARSER_FLAG_COMPLETE_FRAMES) {
      92           0 :         next = buf_size;
      93             :     } else {
      94        1327 :         next = latm_find_frame_end(s1, buf, buf_size);
      95             : 
      96        1327 :         if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) {
      97          69 :             *poutbuf      = NULL;
      98          69 :             *poutbuf_size = 0;
      99          69 :             return buf_size;
     100             :         }
     101             :     }
     102        1258 :     *poutbuf      = buf;
     103        1258 :     *poutbuf_size = buf_size;
     104        1258 :     return next;
     105             : }
     106             : 
     107             : AVCodecParser ff_aac_latm_parser = {
     108             :     .codec_ids      = { AV_CODEC_ID_AAC_LATM },
     109             :     .priv_data_size = sizeof(LATMParseContext),
     110             :     .parser_parse   = latm_parse,
     111             :     .parser_close   = ff_parse_close
     112             : };

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