Libav
tak_parser.c
Go to the documentation of this file.
1 /*
2  * TAK parser
3  * Copyright (c) 2012 Michael Niedermayer
4  *
5  * This file is part of Libav.
6  *
7  * Libav is free software; you can redistribute it and/or
8  * modify it under the terms of the GNU Lesser General Public
9  * License as published by the Free Software Foundation; either
10  * version 2.1 of the License, or (at your option) any later version.
11  *
12  * Libav is distributed in the hope that it will be useful,
13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15  * Lesser General Public License for more details.
16  *
17  * You should have received a copy of the GNU Lesser General Public
18  * License along with Libav; if not, write to the Free Software
19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20  */
21 
27 #include "tak.h"
28 #include "parser.h"
29 
30 typedef struct TAKParseContext {
33  int index;
35 
37 {
39  return 0;
40 }
41 
43  const uint8_t **poutbuf, int *poutbuf_size,
44  const uint8_t *buf, int buf_size)
45 {
46  TAKParseContext *t = s->priv_data;
47  ParseContext *pc = &t->pc;
48  int next = END_NOT_FOUND;
49  GetBitContext gb;
50  int consumed = 0;
51  int needed = buf_size ? TAK_MAX_FRAME_HEADER_BYTES : 8;
52 
54  TAKStreamInfo ti;
55  init_get_bits(&gb, buf, buf_size);
56  if (!ff_tak_decode_frame_header(avctx, &gb, &ti, 127))
58  : t->ti.frame_samples;
59  *poutbuf = buf;
60  *poutbuf_size = buf_size;
61  return buf_size;
62  }
63 
64  while (buf_size || t->index + needed <= pc->index) {
65  if (buf_size && t->index + TAK_MAX_FRAME_HEADER_BYTES > pc->index) {
66  int tmp_buf_size = FFMIN(2 * TAK_MAX_FRAME_HEADER_BYTES,
67  buf_size);
68  const uint8_t *tmp_buf = buf;
69 
70  ff_combine_frame(pc, END_NOT_FOUND, &tmp_buf, &tmp_buf_size);
71  consumed += tmp_buf_size;
72  buf += tmp_buf_size;
73  buf_size -= tmp_buf_size;
74  }
75 
76  for (; t->index + needed <= pc->index; t->index++)
77  if (pc->buffer[t->index] == 0xFF &&
78  pc->buffer[t->index + 1] == 0xA0) {
79  TAKStreamInfo ti;
80 
81  init_get_bits(&gb, pc->buffer + t->index,
82  8 * (pc->index - t->index));
83  if (!ff_tak_decode_frame_header(avctx, &gb,
84  pc->frame_start_found ? &ti
85  : &t->ti,
86  127) &&
87  !ff_tak_check_crc(pc->buffer + t->index,
88  get_bits_count(&gb) / 8)) {
89  if (!pc->frame_start_found) {
90  pc->frame_start_found = 1;
93  t->ti.frame_samples;
94  } else {
95  pc->frame_start_found = 0;
96  next = t->index - pc->index;
97  t->index = 0;
98  goto found;
99  }
100  }
101  }
102  }
103 
104 found:
105  if (consumed && !buf_size && next == END_NOT_FOUND ||
106  ff_combine_frame(pc, next, &buf, &buf_size) < 0) {
107  *poutbuf = NULL;
108  *poutbuf_size = 0;
109  return buf_size + consumed;
110  }
111 
112  if (next != END_NOT_FOUND) {
113  next += consumed;
114  pc->overread = FFMAX(0, -next);
115  }
116 
117  *poutbuf = buf;
118  *poutbuf_size = buf_size;
119  return next;
120 }
121 
123  .codec_ids = { AV_CODEC_ID_TAK },
124  .priv_data_size = sizeof(TAKParseContext),
125  .parser_init = tak_init,
126  .parser_parse = tak_parse,
127  .parser_close = ff_parse_close,
128 };
int ff_tak_decode_frame_header(AVCodecContext *avctx, GetBitContext *gb, TAKStreamInfo *ti, int log_level_offset)
Validate and decode a frame header.
Definition: tak.c:121
int codec_ids[5]
Definition: avcodec.h:3822
AVCodecParser ff_tak_parser
Definition: tak_parser.c:122
int duration
Duration of the current frame.
Definition: avcodec.h:3798
int frame_start_found
Definition: parser.h:34
TAKStreamInfo ti
Definition: tak_parser.c:32
uint8_t
#define av_cold
Definition: attributes.h:66
static int tak_parse(AVCodecParserContext *s, AVCodecContext *avctx, const uint8_t **poutbuf, int *poutbuf_size, const uint8_t *buf, int buf_size)
Definition: tak_parser.c:42
int ff_tak_check_crc(const uint8_t *buf, unsigned int buf_size)
Definition: tak.c:70
static int get_bits_count(const GetBitContext *s)
Definition: get_bits.h:194
int ff_combine_frame(ParseContext *pc, int next, const uint8_t **buf, int *buf_size)
Combine the (truncated) bitstream to a complete frame.
Definition: parser.c:217
av_cold void ff_tak_init_crc(void)
Definition: tak.c:62
int last_frame_samples
Definition: tak.h:138
#define FFMAX(a, b)
Definition: common.h:55
void ff_parse_close(AVCodecParserContext *s)
Definition: parser.c:287
int overread
the number of bytes which where irreversibly read from the next frame
Definition: parser.h:35
#define FFMIN(a, b)
Definition: common.h:57
static av_cold int tak_init(AVCodecParserContext *s)
Definition: tak_parser.c:36
NULL
Definition: eval.c:55
uint8_t * buffer
Definition: parser.h:29
ParseContext pc
Definition: tak_parser.c:31
main external API structure.
Definition: avcodec.h:1050
int index
Definition: gxfenc.c:72
int frame_samples
Definition: tak.h:137
TAK (Tom's lossless Audio Kompressor) decoder/demuxer common functions.
static int init_get_bits(GetBitContext *s, const uint8_t *buffer, int bit_size)
Initialize GetBitContext.
Definition: get_bits.h:375
#define END_NOT_FOUND
Definition: parser.h:40
int index
Definition: parser.h:30
#define PARSER_FLAG_COMPLETE_FRAMES
Definition: avcodec.h:3700
#define TAK_MAX_FRAME_HEADER_BYTES
Definition: tak.h:97