83 lines
2.6 KiB
C
83 lines
2.6 KiB
C
|
/*
|
||
|
|
* Copyright (c) 2011 Justin Ruggles
|
||
|
|
*
|
||
|
|
* 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
|
||
|
|
*/
|
||
|
|
|
||
|
|
#include "libavutil/common.h"
|
||
|
|
#include "libavutil/intreadwrite.h"
|
||
|
|
#include "libavutil/mathematics.h"
|
||
|
|
#include "adx.h"
|
||
|
|
|
||
|
|
void ff_adx_calculate_coeffs(int cutoff, int sample_rate, int bits, int *coeff)
|
||
|
|
{
|
||
|
|
double a, b, c;
|
||
|
|
|
||
|
|
a = M_SQRT2 - cos(2.0 * M_PI * cutoff / sample_rate);
|
||
|
|
b = M_SQRT2 - 1.0;
|
||
|
|
c = (a - sqrt((a + b) * (a - b))) / b;
|
||
|
|
|
||
|
|
coeff[0] = lrintf(c * 2.0 * (1 << bits));
|
||
|
|
coeff[1] = lrintf(-(c * c) * (1 << bits));
|
||
|
|
}
|
||
|
|
|
||
|
|
int ff_adx_decode_header(AVCodecContext *avctx, const uint8_t *buf,
|
||
|
|
int bufsize, int *header_size, int *coeff)
|
||
|
|
{
|
||
|
|
int offset, cutoff;
|
||
|
|
|
||
|
|
if (bufsize < 24)
|
||
|
|
return AVERROR_INVALIDDATA;
|
||
|
|
|
||
|
|
if (AV_RB16(buf) != 0x8000)
|
||
|
|
return AVERROR_INVALIDDATA;
|
||
|
|
offset = AV_RB16(buf + 2) + 4;
|
||
|
|
|
||
|
|
/* if copyright string is within the provided data, validate it */
|
||
|
|
if (bufsize >= offset && offset >= 6 && memcmp(buf + offset - 6, "(c)CRI", 6))
|
||
|
|
return AVERROR_INVALIDDATA;
|
||
|
|
|
||
|
|
/* check for encoding=3 block_size=18, sample_size=4 */
|
||
|
|
if (buf[4] != 3 || buf[5] != 18 || buf[6] != 4) {
|
||
|
|
avpriv_request_sample(avctx, "Support for this ADX format");
|
||
|
|
return AVERROR_PATCHWELCOME;
|
||
|
|
}
|
||
|
|
|
||
|
|
/* channels */
|
||
|
|
avctx->channels = buf[7];
|
||
|
|
if (avctx->channels <= 0 || avctx->channels > 2)
|
||
|
|
return AVERROR_INVALIDDATA;
|
||
|
|
|
||
|
|
/* sample rate */
|
||
|
|
avctx->sample_rate = AV_RB32(buf + 8);
|
||
|
|
if (avctx->sample_rate < 1 ||
|
||
|
|
avctx->sample_rate > INT_MAX / (avctx->channels * BLOCK_SIZE * 8))
|
||
|
|
return AVERROR_INVALIDDATA;
|
||
|
|
|
||
|
|
/* bit rate */
|
||
|
|
avctx->bit_rate = avctx->sample_rate * avctx->channels * BLOCK_SIZE * 8 / BLOCK_SAMPLES;
|
||
|
|
|
||
|
|
/* LPC coefficients */
|
||
|
|
if (coeff) {
|
||
|
|
cutoff = AV_RB16(buf + 16);
|
||
|
|
ff_adx_calculate_coeffs(cutoff, avctx->sample_rate, COEFF_BITS, coeff);
|
||
|
|
}
|
||
|
|
|
||
|
|
*header_size = offset;
|
||
|
|
return 0;
|
||
|
|
}
|