2 * Copyright (c) 2012 Justin Ruggles
4 * This file is part of FFmpeg.
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.
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.
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
25 * Determines the duration for each packet.
31 #include "vorbis_parser.h"
33 static int parse_id_header(AVCodecContext
*avctx
, VorbisParseContext
*s
,
34 const uint8_t *buf
, int buf_size
)
36 /* Id header should be 30 bytes */
38 av_log(avctx
, AV_LOG_ERROR
, "Id header is too short\n");
39 return AVERROR_INVALIDDATA
;
42 /* make sure this is the Id header */
44 av_log(avctx
, AV_LOG_ERROR
, "Wrong packet type in Id header\n");
45 return AVERROR_INVALIDDATA
;
48 /* check for header signature */
49 if (memcmp(&buf
[1], "vorbis", 6)) {
50 av_log(avctx
, AV_LOG_ERROR
, "Invalid packet signature in Id header\n");
51 return AVERROR_INVALIDDATA
;
54 if (!(buf
[29] & 0x1)) {
55 av_log(avctx
, AV_LOG_ERROR
, "Invalid framing bit in Id header\n");
56 return AVERROR_INVALIDDATA
;
59 s
->blocksize
[0] = 1 << (buf
[28] & 0xF);
60 s
->blocksize
[1] = 1 << (buf
[28] >> 4);
65 static int parse_setup_header(AVCodecContext
*avctx
, VorbisParseContext
*s
,
66 const uint8_t *buf
, int buf_size
)
68 GetBitContext gb
, gb0
;
71 int got_framing_bit
, mode_count
, got_mode_header
, last_mode_count
= 0;
75 av_log(avctx
, AV_LOG_ERROR
, "Setup header is too short\n");
76 return AVERROR_INVALIDDATA
;
79 /* make sure this is the Setup header */
81 av_log(avctx
, AV_LOG_ERROR
, "Wrong packet type in Setup header\n");
82 return AVERROR_INVALIDDATA
;
85 /* check for header signature */
86 if (memcmp(&buf
[1], "vorbis", 6)) {
87 av_log(avctx
, AV_LOG_ERROR
, "Invalid packet signature in Setup header\n");
88 return AVERROR_INVALIDDATA
;
91 /* reverse bytes so we can easily read backwards with get_bits() */
92 if (!(rev_buf
= av_malloc(buf_size
))) {
93 av_log(avctx
, AV_LOG_ERROR
, "Out of memory\n");
94 return AVERROR(ENOMEM
);
96 for (i
= 0; i
< buf_size
; i
++)
97 rev_buf
[i
] = buf
[buf_size
- 1 - i
];
98 init_get_bits(&gb
, rev_buf
, buf_size
* 8);
101 while (get_bits_left(&gb
) > 97) {
102 if (get_bits1(&gb
)) {
103 got_framing_bit
= get_bits_count(&gb
);
107 if (!got_framing_bit
) {
108 av_log(avctx
, AV_LOG_ERROR
, "Invalid Setup header\n");
109 ret
= AVERROR_INVALIDDATA
;
113 /* Now we search backwards to find possible valid mode counts. This is not
114 * fool-proof because we could have false positive matches and read too
115 * far, but there isn't really any way to be sure without parsing through
116 * all the many variable-sized fields before the modes. This approach seems
117 * to work well in testing, and it is similar to how it is handled in
121 while (get_bits_left(&gb
) >= 97) {
122 if (get_bits(&gb
, 8) > 63 || get_bits(&gb
, 16) || get_bits(&gb
, 16))
129 if (get_bits(&gb0
, 6) + 1 == mode_count
) {
131 last_mode_count
= mode_count
;
134 if (!got_mode_header
) {
135 av_log(avctx
, AV_LOG_ERROR
, "Invalid Setup header\n");
136 ret
= AVERROR_INVALIDDATA
;
139 /* All samples I've seen use <= 2 modes, so ask for a sample if we find
140 * more than that, as it is most likely a false positive. If we get any
141 * we may need to approach this the long way and parse the whole Setup
142 * header, but I hope very much that it never comes to that. */
143 if (last_mode_count
> 2) {
144 avpriv_request_sample(avctx
,
145 "%d modes (either a false positive or a "
146 "sample from an unknown encoder)",
149 /* We're limiting the mode count to 63 so that we know that the previous
150 * block flag will be in the first packet byte. */
151 if (last_mode_count
> 63) {
152 av_log(avctx
, AV_LOG_ERROR
, "Unsupported mode count: %d\n",
154 ret
= AVERROR_INVALIDDATA
;
157 s
->mode_count
= mode_count
= last_mode_count
;
158 /* Determine the number of bits required to code the mode and turn that
159 * into a bitmask to directly access the mode from the first frame byte. */
160 s
->mode_mask
= ((1 << (av_log2(mode_count
- 1) + 1)) - 1) << 1;
161 /* The previous window flag is the next bit after the mode */
162 s
->prev_mask
= (s
->mode_mask
| 0x1) + 1;
164 init_get_bits(&gb
, rev_buf
, buf_size
* 8);
165 skip_bits_long(&gb
, got_framing_bit
);
166 for (i
= mode_count
- 1; i
>= 0; i
--) {
167 skip_bits_long(&gb
, 40);
168 s
->mode_blocksize
[i
] = get_bits1(&gb
);
176 int avpriv_vorbis_parse_extradata(AVCodecContext
*avctx
, VorbisParseContext
*s
)
178 uint8_t *header_start
[3];
183 s
->extradata_parsed
= 1;
185 if ((ret
= avpriv_split_xiph_headers(avctx
->extradata
,
186 avctx
->extradata_size
, 30,
187 header_start
, header_len
)) < 0) {
188 av_log(avctx
, AV_LOG_ERROR
, "Extradata corrupt.\n");
192 if ((ret
= parse_id_header(avctx
, s
, header_start
[0], header_len
[0])) < 0)
195 if ((ret
= parse_setup_header(avctx
, s
, header_start
[2], header_len
[2])) < 0)
198 s
->valid_extradata
= 1;
199 s
->previous_blocksize
= s
->blocksize
[s
->mode_blocksize
[0]];
204 int avpriv_vorbis_parse_frame_flags(VorbisParseContext
*s
, const uint8_t *buf
,
205 int buf_size
, int *flags
)
209 if (s
->valid_extradata
&& buf_size
> 0) {
210 int mode
, current_blocksize
;
211 int previous_blocksize
= s
->previous_blocksize
;
214 /* If the user doesn't care about special packets, it's a bad one. */
218 /* Set the flag for which kind of special packet it is. */
220 *flags
|= VORBIS_FLAG_HEADER
;
221 else if (buf
[0] == 3)
222 *flags
|= VORBIS_FLAG_COMMENT
;
226 /* Special packets have no duration. */
230 av_log(s
->avctx
, AV_LOG_ERROR
, "Invalid packet\n");
231 return AVERROR_INVALIDDATA
;
233 if (s
->mode_count
== 1)
236 mode
= (buf
[0] & s
->mode_mask
) >> 1;
237 if (mode
>= s
->mode_count
) {
238 av_log(s
->avctx
, AV_LOG_ERROR
, "Invalid mode in packet\n");
239 return AVERROR_INVALIDDATA
;
241 if(s
->mode_blocksize
[mode
]){
242 int flag
= !!(buf
[0] & s
->prev_mask
);
243 previous_blocksize
= s
->blocksize
[flag
];
245 current_blocksize
= s
->blocksize
[s
->mode_blocksize
[mode
]];
246 duration
= (previous_blocksize
+ current_blocksize
) >> 2;
247 s
->previous_blocksize
= current_blocksize
;
253 int avpriv_vorbis_parse_frame(VorbisParseContext
*s
, const uint8_t *buf
,
256 return avpriv_vorbis_parse_frame_flags(s
, buf
, buf_size
, NULL
);
259 void avpriv_vorbis_parse_reset(VorbisParseContext
*s
)
261 if (s
->valid_extradata
)
262 s
->previous_blocksize
= s
->blocksize
[0];
265 #if CONFIG_VORBIS_PARSER
266 static int vorbis_parse(AVCodecParserContext
*s1
, AVCodecContext
*avctx
,
267 const uint8_t **poutbuf
, int *poutbuf_size
,
268 const uint8_t *buf
, int buf_size
)
270 VorbisParseContext
*s
= s1
->priv_data
;
273 if (!s
->extradata_parsed
&& avctx
->extradata
&& avctx
->extradata_size
)
274 if (avpriv_vorbis_parse_extradata(avctx
, s
))
277 if ((duration
= avpriv_vorbis_parse_frame(s
, buf
, buf_size
)) >= 0)
278 s1
->duration
= duration
;
281 /* always return the full packet. this parser isn't doing any splitting or
282 combining, only packet analysis */
284 *poutbuf_size
= buf_size
;
288 AVCodecParser ff_vorbis_parser
= {
289 .codec_ids
= { AV_CODEC_ID_VORBIS
},
290 .priv_data_size
= sizeof(VorbisParseContext
),
291 .parser_parse
= vorbis_parse
,
293 #endif /* CONFIG_VORBIS_PARSER */