LCOV - code coverage report
Current view: top level - src/libavcodec - adx.c (source / functions) Hit Total Coverage
Test: coverage.info Lines: 24 31 77.4 %
Date: 2017-08-17 10:06:07 Functions: 2 2 100.0 %

          Line data    Source code
       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           0 :         return AVERROR_INVALIDDATA;
      45             : 
      46           4 :     if (AV_RB16(buf) != 0x8000)
      47           0 :         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           0 :         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           0 :         avpriv_request_sample(avctx, "Support for this ADX format");
      57           0 :         return AVERROR_PATCHWELCOME;
      58             :     }
      59             : 
      60             :     /* channels */
      61           4 :     avctx->channels = buf[7];
      62           4 :     if (avctx->channels <= 0 || avctx->channels > 2)
      63           0 :         return AVERROR_INVALIDDATA;
      64             : 
      65             :     /* sample rate */
      66           4 :     avctx->sample_rate = AV_RB32(buf + 8);
      67           8 :     if (avctx->sample_rate < 1 ||
      68           4 :         avctx->sample_rate > INT_MAX / (avctx->channels * BLOCK_SIZE * 8))
      69           0 :         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             : }

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