FFmpeg: libavcodec/ac3enc_float.c Source File

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libavcodec

ac3enc_float.c

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1 /*

2 * The simplest AC-3 encoder

6 *

7 * This file is part of FFmpeg.

8 *

9 * FFmpeg is free software; you can redistribute it and/or

10 * modify it under the terms of the GNU Lesser General Public

11 * License as published by the Free Software Foundation; either

12 * version 2.1 of the License, or (at your option) any later version.

13 *

14 * FFmpeg is distributed in the hope that it will be useful,

15 * but WITHOUT ANY WARRANTY; without even the implied warranty of

16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU

17 * Lesser General Public License for more details.

18 *

19 * You should have received a copy of the GNU Lesser General Public

20 * License along with FFmpeg; if not, write to the Free Software

21 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

22 */

24 /**

25 * @file

26 * floating-point AC-3 encoder.

27 */

29 #define CONFIG_AC3ENC_FLOAT 1

30 #include "internal.h"

31 #include "ac3enc.h"

32 #include "eac3enc.h"

33 #include "kbdwin.h"

36 #if CONFIG_AC3_ENCODER

37 #define AC3ENC_TYPE AC3ENC_TYPE_AC3

38 #include "ac3enc_opts_template.c"

39 static const AVClass ac3enc_class = {

40 .class_name = "AC-3 Encoder",

41 .item_name = av_default_item_name,

42 .option = ac3_options,

43 .version = LIBAVUTIL_VERSION_INT,

44 };

45 #endif

47 #include "ac3enc_template.c"

50 /**

51 * Finalize MDCT and free allocated memory.

52 *

53 * @param s AC-3 encoder private context

54 */

55 av_cold void ff_ac3_float_mdct_end(AC3EncodeContext *s)

56 {

57 ff_mdct_end(&s->mdct);

58 av_freep(&s->mdct_window);

59 }

62 /**

63 * Initialize MDCT tables.

64 *

65 * @param s AC-3 encoder private context

66 * @return 0 on success, negative error code on failure

67 */

68 av_cold int ff_ac3_float_mdct_init(AC3EncodeContext *s)

69 {

70 float *window;

71 int i, n, n2;

73 n = 1 << 9;

74 n2 = n >> 1;

76 window = av_malloc(n * sizeof(*window));

77 if (!window) {

78 av_log(s->avctx, AV_LOG_ERROR, "Cannot allocate memory.\n");

79 return AVERROR(ENOMEM);

80 }

81 ff_kbd_window_init(window, 5.0, n2);

82 for (i = 0; i < n2; i++)

83 window[n-1-i] = window[i];

84 s->mdct_window = window;

86 return ff_mdct_init(&s->mdct, 9, 0, -2.0 / n);

87 }

90 /*

91 * Apply KBD window to input samples prior to MDCT.

92 */

93 static void apply_window(void *dsp, float *output,

94 const float *input, const float *window,

95 unsigned int len)

96 {

97 AVFloatDSPContext *fdsp = dsp;

98 fdsp->vector_fmul(output, input, window, len);

99 }

100

101

102 /*

103 * Normalize the input samples.

104 * Not needed for the floating-point encoder.

105 */

106 static int normalize_samples(AC3EncodeContext *s)

107 {

108 return 0;

109 }

110

111

112 /*

113 * Scale MDCT coefficients from float to 24-bit fixed-point.

114 */

115 static void scale_coefficients(AC3EncodeContext *s)

116 {

117 int chan_size = AC3_MAX_COEFS * s->num_blocks;

118 int cpl = s->cpl_on;

119 s->ac3dsp.float_to_fixed24(s->fixed_coef_buffer + (chan_size * !cpl),

120 s->mdct_coef_buffer + (chan_size * !cpl),

121 chan_size * (s->channels + cpl));

122 }

123

124 static void sum_square_butterfly(AC3EncodeContext *s, float sum[4],

125 const float *coef0, const float *coef1,

126 int len)

127 {

128 s->ac3dsp.sum_square_butterfly_float(sum, coef0, coef1, len);

129 }

130

131 /*

132 * Clip MDCT coefficients to allowable range.

133 */

134 static void clip_coefficients(DSPContext *dsp, float *coef, unsigned int len)

135 {

136 dsp->vector_clipf(coef, coef, COEF_MIN, COEF_MAX, len);

137 }

138

139

140 /*

141 * Calculate a single coupling coordinate.

142 */

143 static CoefType calc_cpl_coord(CoefSumType energy_ch, CoefSumType energy_cpl)

144 {

145 float coord = 0.125;

146 if (energy_cpl > 0)

147 coord *= sqrtf(energy_ch / energy_cpl);

148 return FFMIN(coord, COEF_MAX);

149 }

150

151

152 #if CONFIG_AC3_ENCODER

153 AVCodec ff_ac3_encoder = {

154 .name = "ac3",

155 .long_name = NULL_IF_CONFIG_SMALL("ATSC A/52A (AC-3)"),

156 .type = AVMEDIA_TYPE_AUDIO,

157 .id = AV_CODEC_ID_AC3,

158 .priv_data_size = sizeof(AC3EncodeContext),

159 .init = ff_ac3_encode_init,

160 .encode2 = ff_ac3_float_encode_frame,

161 .close = ff_ac3_encode_close,

162 .sample_fmts = (const enum AVSampleFormat[]){ AV_SAMPLE_FMT_FLTP,

163 AV_SAMPLE_FMT_NONE },

164 .priv_class = &ac3enc_class,

165 .channel_layouts = ff_ac3_channel_layouts,

166 .defaults = ac3_defaults,

167 };

168 #endif

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