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wma_common.c
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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  */
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 }