mirror of
https://github.com/FFmpeg/FFmpeg.git
synced 2024-12-12 19:18:44 +02:00
114 lines
3.2 KiB
C
114 lines
3.2 KiB
C
/*
|
|
* 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_ids = { CODEC_ID_AAC_LATM },
|
|
.priv_data_size = sizeof(LATMParseContext),
|
|
.parser_parse = latm_parse,
|
|
.parser_close = ff_parse_close
|
|
};
|