Imported Debian version 2.5.3~trusty1
[deb_ffmpeg.git] / ffmpeg / libavcodec / latm_parser.c
CommitLineData
2ba45a60
DM
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
33typedef 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 */
42static int latm_find_frame_end(AVCodecParserContext *s1, const uint8_t *buf,
43 int buf_size)
44{
45 LATMParseContext *s = s1->priv_data;
46 ParseContext *pc = &s->pc;
47 int pic_found, i;
48 uint32_t state;
49
50 pic_found = pc->frame_start_found;
51 state = pc->state;
52
53 if (!pic_found) {
54 for (i = 0; i < buf_size; i++) {
55 state = (state<<8) | buf[i];
56 if ((state & LATM_MASK) == LATM_HEADER) {
57 i++;
58 s->count = -i;
59 pic_found = 1;
60 break;
61 }
62 }
63 }
64
65 if (pic_found) {
66 /* EOF considered as end of frame */
67 if (buf_size == 0)
68 return 0;
69 if ((state & LATM_SIZE_MASK) - s->count <= buf_size) {
70 pc->frame_start_found = 0;
71 pc->state = -1;
72 return (state & LATM_SIZE_MASK) - s->count;
73 }
74 }
75
76 s->count += buf_size;
77 pc->frame_start_found = pic_found;
78 pc->state = state;
79
80 return END_NOT_FOUND;
81}
82
83static 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 LATMParseContext *s = s1->priv_data;
88 ParseContext *pc = &s->pc;
89 int next;
90
91 if (s1->flags & PARSER_FLAG_COMPLETE_FRAMES) {
92 next = buf_size;
93 } else {
94 next = latm_find_frame_end(s1, buf, buf_size);
95
96 if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) {
97 *poutbuf = NULL;
98 *poutbuf_size = 0;
99 return buf_size;
100 }
101 }
102 *poutbuf = buf;
103 *poutbuf_size = buf_size;
104 return next;
105}
106
107AVCodecParser 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};