1 |
|
|
/* |
2 |
|
|
* Copyright (c) 2011 Justin Ruggles |
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 |
|
|
#include "libavutil/common.h" |
22 |
|
|
#include "libavutil/intreadwrite.h" |
23 |
|
|
#include "libavutil/mathematics.h" |
24 |
|
|
#include "adx.h" |
25 |
|
|
|
26 |
|
6 |
void ff_adx_calculate_coeffs(int cutoff, int sample_rate, int bits, int *coeff) |
27 |
|
|
{ |
28 |
|
|
double a, b, c; |
29 |
|
|
|
30 |
|
6 |
a = M_SQRT2 - cos(2.0 * M_PI * cutoff / sample_rate); |
31 |
|
6 |
b = M_SQRT2 - 1.0; |
32 |
|
6 |
c = (a - sqrt((a + b) * (a - b))) / b; |
33 |
|
|
|
34 |
|
6 |
coeff[0] = lrintf(c * 2.0 * (1 << bits)); |
35 |
|
6 |
coeff[1] = lrintf(-(c * c) * (1 << bits)); |
36 |
|
6 |
} |
37 |
|
|
|
38 |
|
4 |
int ff_adx_decode_header(AVCodecContext *avctx, const uint8_t *buf, |
39 |
|
|
int bufsize, int *header_size, int *coeff) |
40 |
|
|
{ |
41 |
|
|
int offset, cutoff; |
42 |
|
|
|
43 |
✗✓ |
4 |
if (bufsize < 24) |
44 |
|
|
return AVERROR_INVALIDDATA; |
45 |
|
|
|
46 |
✗✓ |
4 |
if (AV_RB16(buf) != 0x8000) |
47 |
|
|
return AVERROR_INVALIDDATA; |
48 |
|
4 |
offset = AV_RB16(buf + 2) + 4; |
49 |
|
|
|
50 |
|
|
/* if copyright string is within the provided data, validate it */ |
51 |
✓✗✓✗
✗✓ |
4 |
if (bufsize >= offset && offset >= 6 && memcmp(buf + offset - 6, "(c)CRI", 6)) |
52 |
|
|
return AVERROR_INVALIDDATA; |
53 |
|
|
|
54 |
|
|
/* check for encoding=3 block_size=18, sample_size=4 */ |
55 |
✓✗✓✗
✗✓ |
4 |
if (buf[4] != 3 || buf[5] != 18 || buf[6] != 4) { |
56 |
|
|
avpriv_request_sample(avctx, "Support for this ADX format"); |
57 |
|
|
return AVERROR_PATCHWELCOME; |
58 |
|
|
} |
59 |
|
|
|
60 |
|
|
/* channels */ |
61 |
|
4 |
avctx->channels = buf[7]; |
62 |
✓✗✗✓
|
4 |
if (avctx->channels <= 0 || avctx->channels > 2) |
63 |
|
|
return AVERROR_INVALIDDATA; |
64 |
|
|
|
65 |
|
|
/* sample rate */ |
66 |
|
4 |
avctx->sample_rate = AV_RB32(buf + 8); |
67 |
✓✗ |
4 |
if (avctx->sample_rate < 1 || |
68 |
✗✓ |
4 |
avctx->sample_rate > INT_MAX / (avctx->channels * BLOCK_SIZE * 8)) |
69 |
|
|
return AVERROR_INVALIDDATA; |
70 |
|
|
|
71 |
|
|
/* bit rate */ |
72 |
|
4 |
avctx->bit_rate = avctx->sample_rate * avctx->channels * BLOCK_SIZE * 8 / BLOCK_SAMPLES; |
73 |
|
|
|
74 |
|
|
/* LPC coefficients */ |
75 |
✓✗ |
4 |
if (coeff) { |
76 |
|
4 |
cutoff = AV_RB16(buf + 16); |
77 |
|
4 |
ff_adx_calculate_coeffs(cutoff, avctx->sample_rate, COEFF_BITS, coeff); |
78 |
|
|
} |
79 |
|
|
|
80 |
|
4 |
*header_size = offset; |
81 |
|
4 |
return 0; |
82 |
|
|
} |