/src/ffmpeg/libavcodec/latm_parser.c

Source
/*
 * 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"
#include "parser_internal.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;
}

const FFCodecParser ff_aac_latm_parser = {
    PARSER_CODEC_LIST(AV_CODEC_ID_AAC_LATM),
    .priv_data_size = sizeof(LATMParseContext),
    .parse          = latm_parse,
    .close          = ff_parse_close
};

Line	Count	Source
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		#include "parser_internal.h"
29
30	8.81M	#define LATM_HEADER 0x56e000 // 0x2b7 (11 bits)
31	8.81M	#define LATM_MASK 0xFFE000 // top 11 bits
32	497k	#define LATM_SIZE_MASK 0x001FFF // bottom 13 bits
33
34		typedef struct LATMParseContext{
35		ParseContext pc;
36		int count;
37		} LATMParseContext;
38
39		/**
40		* Find the end of the current frame in the bitstream.
41		* @return the position of the first byte of the next frame, or -1
42		*/
43		static int latm_find_frame_end(AVCodecParserContext s1, const uint8_t buf,
44		int buf_size)
45	320k	{
46	320k	LATMParseContext *s = s1->priv_data;
47	320k	ParseContext *pc = &s->pc;
48	320k	int pic_found, i;
49	320k	uint32_t state;
50
51	320k	pic_found = pc->frame_start_found;
52	320k	state = pc->state;
53
54	320k	if (!pic_found) {
55	8.87M	for (i = 0; i < buf_size; i++) {
56	8.81M	state = (state<<8) \| buf[i];
57	8.81M	if ((state & LATM_MASK) == LATM_HEADER) {
58	232k	i++;
59	232k	s->count = -i;
60	232k	pic_found = 1;
61	232k	break;
62	232k	}
63	8.81M	}
64	287k	}
65
66	320k	if (pic_found) {
67		/* EOF considered as end of frame */
68	265k	if (buf_size == 0)
69	82	return 0;
70	265k	if ((state & LATM_SIZE_MASK) - s->count <= buf_size) {
71	232k	pc->frame_start_found = 0;
72	232k	pc->state = -1;
73	232k	return (state & LATM_SIZE_MASK) - s->count;
74	232k	}
75	265k	}
76
77	88.0k	s->count += buf_size;
78	88.0k	pc->frame_start_found = pic_found;
79	88.0k	pc->state = state;
80
81	88.0k	return END_NOT_FOUND;
82	320k	}
83
84		static int latm_parse(AVCodecParserContext s1, AVCodecContext avctx,
85		const uint8_t *poutbuf, int poutbuf_size,
86		const uint8_t *buf, int buf_size)
87	320k	{
88	320k	LATMParseContext *s = s1->priv_data;
89	320k	ParseContext *pc = &s->pc;
90	320k	int next;
91
92	320k	if (s1->flags & PARSER_FLAG_COMPLETE_FRAMES) {
93	108	next = buf_size;
94	320k	} else {
95	320k	next = latm_find_frame_end(s1, buf, buf_size);
96
97	320k	if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) {
98	87.8k	*poutbuf = NULL;
99	87.8k	*poutbuf_size = 0;
100	87.8k	return buf_size;
101	87.8k	}
102	320k	}
103	232k	*poutbuf = buf;
104	232k	*poutbuf_size = buf_size;
105	232k	return next;
106	320k	}
107
108		const FFCodecParser ff_aac_latm_parser = {
109		PARSER_CODEC_LIST(AV_CODEC_ID_AAC_LATM),
110		.priv_data_size = sizeof(LATMParseContext),
111		.parse = latm_parse,
112		.close = ff_parse_close
113		};

Coverage Report

Created: 2026-04-01 07:42