1
2/* -----------------------------------------------------------------------------------------------------------
3Software License for The Fraunhofer FDK AAC Codec Library for Android
4
5� Copyright  1995 - 2013 Fraunhofer-Gesellschaft zur F�rderung der angewandten Forschung e.V.
6  All rights reserved.
7
8 1.    INTRODUCTION
9The Fraunhofer FDK AAC Codec Library for Android ("FDK AAC Codec") is software that implements
10the MPEG Advanced Audio Coding ("AAC") encoding and decoding scheme for digital audio.
11This FDK AAC Codec software is intended to be used on a wide variety of Android devices.
12
13AAC's HE-AAC and HE-AAC v2 versions are regarded as today's most efficient general perceptual
14audio codecs. AAC-ELD is considered the best-performing full-bandwidth communications codec by
15independent studies and is widely deployed. AAC has been standardized by ISO and IEC as part
16of the MPEG specifications.
17
18Patent licenses for necessary patent claims for the FDK AAC Codec (including those of Fraunhofer)
19may be obtained through Via Licensing (www.vialicensing.com) or through the respective patent owners
20individually for the purpose of encoding or decoding bit streams in products that are compliant with
21the ISO/IEC MPEG audio standards. Please note that most manufacturers of Android devices already license
22these patent claims through Via Licensing or directly from the patent owners, and therefore FDK AAC Codec
23software may already be covered under those patent licenses when it is used for those licensed purposes only.
24
25Commercially-licensed AAC software libraries, including floating-point versions with enhanced sound quality,
26are also available from Fraunhofer. Users are encouraged to check the Fraunhofer website for additional
27applications information and documentation.
28
292.    COPYRIGHT LICENSE
30
31Redistribution and use in source and binary forms, with or without modification, are permitted without
32payment of copyright license fees provided that you satisfy the following conditions:
33
34You must retain the complete text of this software license in redistributions of the FDK AAC Codec or
35your modifications thereto in source code form.
36
37You must retain the complete text of this software license in the documentation and/or other materials
38provided with redistributions of the FDK AAC Codec or your modifications thereto in binary form.
39You must make available free of charge copies of the complete source code of the FDK AAC Codec and your
40modifications thereto to recipients of copies in binary form.
41
42The name of Fraunhofer may not be used to endorse or promote products derived from this library without
43prior written permission.
44
45You may not charge copyright license fees for anyone to use, copy or distribute the FDK AAC Codec
46software or your modifications thereto.
47
48Your modified versions of the FDK AAC Codec must carry prominent notices stating that you changed the software
49and the date of any change. For modified versions of the FDK AAC Codec, the term
50"Fraunhofer FDK AAC Codec Library for Android" must be replaced by the term
51"Third-Party Modified Version of the Fraunhofer FDK AAC Codec Library for Android."
52
533.    NO PATENT LICENSE
54
55NO EXPRESS OR IMPLIED LICENSES TO ANY PATENT CLAIMS, including without limitation the patents of Fraunhofer,
56ARE GRANTED BY THIS SOFTWARE LICENSE. Fraunhofer provides no warranty of patent non-infringement with
57respect to this software.
58
59You may use this FDK AAC Codec software or modifications thereto only for purposes that are authorized
60by appropriate patent licenses.
61
624.    DISCLAIMER
63
64This FDK AAC Codec software is provided by Fraunhofer on behalf of the copyright holders and contributors
65"AS IS" and WITHOUT ANY EXPRESS OR IMPLIED WARRANTIES, including but not limited to the implied warranties
66of merchantability and fitness for a particular purpose. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR
67CONTRIBUTORS BE LIABLE for any direct, indirect, incidental, special, exemplary, or consequential damages,
68including but not limited to procurement of substitute goods or services; loss of use, data, or profits,
69or business interruption, however caused and on any theory of liability, whether in contract, strict
70liability, or tort (including negligence), arising in any way out of the use of this software, even if
71advised of the possibility of such damage.
72
735.    CONTACT INFORMATION
74
75Fraunhofer Institute for Integrated Circuits IIS
76Attention: Audio and Multimedia Departments - FDK AAC LL
77Am Wolfsmantel 33
7891058 Erlangen, Germany
79
80www.iis.fraunhofer.de/amm
81amm-info@iis.fraunhofer.de
82----------------------------------------------------------------------------------------------------------- */
83
84/***************************************************************************\
85*
86 *   filename: ldfiltbank.c
87 *   project : MPEG-4 Audio Decoder
88 *   contents/description: low delay filterbank
89 *
90\***************************************************************************/
91
92#include "ldfiltbank.h"
93
94
95#include "aac_rom.h"
96#include "dct.h"
97#include "FDK_tools_rom.h"
98#include "mdct.h"
99
100#define LDFB_HEADROOM 2
101
102static void multE2_DinvF_fdk(INT_PCM *output, FIXP_DBL* x, const FIXP_WTB* fb, FIXP_DBL* z, const int N, const int  stride)
103{
104  int i, scale;
105
106  /*  scale for FIXP_DBL -> INT_PCM conversion. */
107  scale = (DFRACT_BITS - SAMPLE_BITS) - LDFB_HEADROOM;
108
109  for(i=0;i<N/4;i++)
110  {
111    FIXP_DBL z0, z2, tmp;
112
113    z2 = x[N/2+i];
114    z0 = z2 + ( fMultDiv2(z[N/2+i], fb[2*N + i]) >> (-WTS2-1) );
115
116    z[N/2+i] = x[N/2-1-i] + ( fMultDiv2(z[N + i], fb[2*N + N/2 + i]) >> (-WTS2-1) );
117
118    tmp = ( fMultDiv2(z[N/2+i], fb[N+N/2-1-i]) + fMultDiv2(z[i], fb[N+N/2+i]) ) ;
119
120#if (SAMPLE_BITS <= 16)
121    FDK_ASSERT( (-WTS1-1 + scale) >= 0);
122    output[(N*3/4-1-i)*stride] = (INT_PCM)SATURATE_RIGHT_SHIFT(tmp, -WTS1-1 + scale, SAMPLE_BITS);
123#else
124    FDK_ASSERT( (WTS1+1 - scale) >= 0);
125    output[(N*3/4-1-i)*stride] = (INT_PCM)SATURATE_LEFT_SHIFT(tmp, WTS1+1 - scale, SAMPLE_BITS);
126#endif
127
128    z[i] = z0;
129    z[N + i] = z2;
130  }
131
132  for(i=N/4;i<N/2;i++)
133  {
134    FIXP_DBL z0, z2, tmp0, tmp1;
135
136    z2 = x[N/2+i];
137    z0 = z2 + ( fMultDiv2(z[N/2+i], fb[2*N + i]) >> (-WTS2-1) );
138
139    z[N/2+i] = x[N/2-1-i] + ( fMultDiv2(z[N + i], fb[2*N + N/2 + i]) >> (-WTS2-1) );
140
141    tmp0 = ( fMultDiv2(z[N/2+i], fb[N/2-1-i])   + fMultDiv2(z[i], fb[N/2+i])   ) ;
142    tmp1 = ( fMultDiv2(z[N/2+i], fb[N+N/2-1-i]) + fMultDiv2(z[i], fb[N+N/2+i]) ) ;
143
144#if (SAMPLE_BITS <= 16)
145    FDK_ASSERT( (-WTS0-1 + scale) >= 0);
146    output[(i-N/4)*stride]     = (INT_PCM)SATURATE_RIGHT_SHIFT(tmp0, -WTS0-1 + scale, SAMPLE_BITS);
147    output[(N*3/4-1-i)*stride] = (INT_PCM)SATURATE_RIGHT_SHIFT(tmp1, -WTS1-1 + scale, SAMPLE_BITS);
148#else
149    FDK_ASSERT( (WTS0+1 - scale) >= 0);
150    output[(i-N/4)*stride]     = (INT_PCM)SATURATE_LEFT_SHIFT(tmp0, WTS0+1 - scale, SAMPLE_BITS);
151    output[(N*3/4-1-i)*stride] = (INT_PCM)SATURATE_LEFT_SHIFT(tmp1, WTS1+1 - scale, SAMPLE_BITS);
152#endif
153    z[i] = z0;
154    z[N + i] = z2;
155  }
156
157  /* Exchange quarter parts of x to bring them in the "right" order */
158  for(i=0;i<N/4;i++)
159  {
160    FIXP_DBL tmp0 = fMultDiv2(z[i], fb[N/2+i]);
161
162#if (SAMPLE_BITS <= 16)
163    FDK_ASSERT( (-WTS0-1 + scale) >= 0);
164    output[(N*3/4 + i)*stride] = (INT_PCM)SATURATE_RIGHT_SHIFT(tmp0, -WTS0-1 + scale, SAMPLE_BITS);
165#else
166    FDK_ASSERT( (WTS0+1 - scale) >= 0);
167    output[(N*3/4 + i)*stride] = (INT_PCM)SATURATE_LEFT_SHIFT(tmp0, WTS0+1 - scale, SAMPLE_BITS);
168#endif
169  }
170}
171
172int InvMdctTransformLowDelay_fdk (FIXP_DBL *mdctData, const int mdctData_e, INT_PCM *output, FIXP_DBL *fs_buffer, const int stride, const int N) {
173
174  const FIXP_WTB *coef;
175  FIXP_DBL gain = (FIXP_DBL)0;
176  int scale = mdctData_e + MDCT_OUT_HEADROOM - LDFB_HEADROOM; /* The LDFB_HEADROOM is compensated inside multE2_DinvF_fdk() below */
177
178  /* Select LD window slope */
179  if (N == 512)
180    coef = (FIXP_WTB*)LowDelaySynthesis512;
181  else
182    coef = (FIXP_WTB*)LowDelaySynthesis480;
183
184  /*
185     Apply exponent and 1/N factor.
186     Note: "scale" is off by one because for LD_MDCT the window length is twice
187     the window length of a regular MDCT. This is corrected inside multE2_DinvF_fdk().
188     Refer to ISO/IEC 14496-3:2009 page 277, chapter 4.6.20.2 "Low Delay Window".
189   */
190  imdct_gain(&gain, &scale, N);
191
192  dct_IV(mdctData, N, &scale);
193
194  if (gain != (FIXP_DBL)0) {
195    scaleValuesWithFactor(mdctData, gain, N, scale);
196  } else {
197    scaleValues(mdctData, N, scale);
198  }
199
200  /* Since all exponent and factors have been applied, current exponent is zero. */
201  multE2_DinvF_fdk(output, mdctData, coef, fs_buffer, N, stride);
202
203  return (1);
204}
205
206
207
208
209