/*
  * copyright (c) 2008 Paul Kendall <paul@kcbbs.gen.nz>
  *
  * 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
  * AAC LATM parser
  */
 

 #include <stdint.h>

 #include "parser.h"
 
 #define LATM_HEADER     0x56e000        // 0x2b7 (11 bits)
 #define LATM_MASK       0xFFE000        // top 11 bits
 #define LATM_SIZE_MASK  0x001FFF        // bottom 13 bits
 
 typedef struct LATMParseContext{
     ParseContext pc;
     int count;
 } LATMParseContext;
 
 /**

  * Find the end of the current frame in the bitstream.

  * @return the position of the first byte of the next frame, or -1
  */
 static int latm_find_frame_end(AVCodecParserContext *s1, const uint8_t *buf,
                                int buf_size)
 {
     LATMParseContext *s = s1->priv_data;
     ParseContext *pc    = &s->pc;
     int pic_found, i;
     uint32_t state;
 
     pic_found = pc->frame_start_found;
     state     = pc->state;
 
     if (!pic_found) {
         for (i = 0; i < buf_size; i++) {
             state = (state<<8) | buf[i];
             if ((state & LATM_MASK) == LATM_HEADER) {
                 i++;
                 s->count  = -i;
                 pic_found = 1;
                 break;
             }
         }
     }
 
     if (pic_found) {
         /* EOF considered as end of frame */
         if (buf_size == 0)
             return 0;
         if ((state & LATM_SIZE_MASK) - s->count <= buf_size) {
             pc->frame_start_found = 0;
             pc->state             = -1;
             return (state & LATM_SIZE_MASK) - s->count;
         }
     }
 
     s->count             += buf_size;
     pc->frame_start_found = pic_found;
     pc->state             = state;
 
     return END_NOT_FOUND;
 }
 
 static int latm_parse(AVCodecParserContext *s1, AVCodecContext *avctx,
                       const uint8_t **poutbuf, int *poutbuf_size,
                       const uint8_t *buf, int buf_size)
 {
     LATMParseContext *s = s1->priv_data;
     ParseContext *pc    = &s->pc;
     int next;
 
     if (s1->flags & PARSER_FLAG_COMPLETE_FRAMES) {
         next = buf_size;
     } else {
         next = latm_find_frame_end(s1, buf, buf_size);
 
         if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) {
             *poutbuf      = NULL;
             *poutbuf_size = 0;
             return buf_size;
         }
     }
     *poutbuf      = buf;
     *poutbuf_size = buf_size;
     return next;
 }
 

 AVCodecParser ff_aac_latm_parser = {

     .codec_ids      = { AV_CODEC_ID_AAC_LATM },

     .priv_data_size = sizeof(LATMParseContext),
     .parser_parse   = latm_parse,
     .parser_close   = ff_parse_close

 };