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/*
* copyright (c) 2008 Paul Kendall <paul@kcbbs.gen.nz>
*
* This file is part of Libav.
*
* Libav 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.
*
* Libav 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 Libav; 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;
/**
* finds 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;
i = 0;
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_ID_AAC_LATM },
sizeof(LATMParseContext),
NULL,
latm_parse,
ff_parse_close
};
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