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  1. /*
  2.  * common code shared by all WMA variants
  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/attributes.h"
  22. #include "wma_common.h"
  23.  
  24. /**
  25.  *@brief Get the samples per frame for this stream.
  26.  *@param sample_rate output sample_rate
  27.  *@param version wma version
  28.  *@param decode_flags codec compression features
  29.  *@return log2 of the number of output samples per frame
  30.  */
  31. av_cold int ff_wma_get_frame_len_bits(int sample_rate, int version,
  32.                                       unsigned int decode_flags)
  33. {
  34.  
  35.     int frame_len_bits;
  36.  
  37.     if (sample_rate <= 16000) {
  38.         frame_len_bits = 9;
  39.     } else if (sample_rate <= 22050 ||
  40.              (sample_rate <= 32000 && version == 1)) {
  41.         frame_len_bits = 10;
  42.     } else if (sample_rate <= 48000 || version < 3) {
  43.         frame_len_bits = 11;
  44.     } else if (sample_rate <= 96000) {
  45.         frame_len_bits = 12;
  46.     } else {
  47.         frame_len_bits = 13;
  48.     }
  49.  
  50.     if (version == 3) {
  51.         int tmp = decode_flags & 0x6;
  52.         if (tmp == 0x2) {
  53.             ++frame_len_bits;
  54.         } else if (tmp == 0x4) {
  55.             --frame_len_bits;
  56.         } else if (tmp == 0x6) {
  57.             frame_len_bits -= 2;
  58.         }
  59.     }
  60.  
  61.     return frame_len_bits;
  62. }
  63.