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 "audiodsp.h"

32 #include "ac3enc.h"

33 #include "eac3enc.h"

34 #include "kbdwin.h"

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 };

46 #include "ac3enc_template.c"

49 /**

50 * Finalize MDCT and free allocated memory.

51 *

52 * @param s AC-3 encoder private context

53 */

54 av_cold void ff_ac3_float_mdct_end(AC3EncodeContext *s)

55 {

56 ff_mdct_end(&s->mdct);

57 av_freep(&s->mdct_window);

58 }

61 /**

62 * Initialize MDCT tables.

63 *

64 * @param s AC-3 encoder private context

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

66 */

67 av_cold int ff_ac3_float_mdct_init(AC3EncodeContext *s)

68 {

69 float *window;

70 int i, n, n2;

72 n = 1 << 9;

73 n2 = n >> 1;

75 window = av_malloc_array(n, sizeof(*window));

76 if (!window) {

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

78 return AVERROR(ENOMEM);

79 }

80 ff_kbd_window_init(window, 5.0, n2);

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

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

83 s->mdct_window = window;

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

86 }

89 /*

90 * Normalize the input samples.

91 * Not needed for the floating-point encoder.

92 */

93 static int normalize_samples(AC3EncodeContext *s)

94 {

95 return 0;

96 }

99 /*

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

101 */

102 static void scale_coefficients(AC3EncodeContext *s)

103 {

104 int chan_size = AC3_MAX_COEFS * s->num_blocks;

105 int cpl = s->cpl_on;

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

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

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

109 }

110

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

112 const float *coef0, const float *coef1,

113 int len)

114 {

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

116 }

117

118 /*

119 * Clip MDCT coefficients to allowable range.

120 */

121 static void clip_coefficients(AudioDSPContext *adsp, float *coef,

122 unsigned int len)

123 {

124 adsp->vector_clipf(coef, coef, COEF_MIN, COEF_MAX, len);

125 }

126

127

128 /*

129 * Calculate a single coupling coordinate.

130 */

131 static CoefType calc_cpl_coord(CoefSumType energy_ch, CoefSumType energy_cpl)

132 {

133 float coord = 0.125;

134 if (energy_cpl > 0)

135 coord *= sqrtf(energy_ch / energy_cpl);

136 return FFMIN(coord, COEF_MAX);

137 }

138

139 av_cold int ff_ac3_float_encode_init(AVCodecContext *avctx)

140 {

141 AC3EncodeContext *s = avctx->priv_data;

142 s->fdsp = avpriv_float_dsp_alloc(avctx->flags & CODEC_FLAG_BITEXACT);

143 if (!s->fdsp)

144 return AVERROR(ENOMEM);

145 return ff_ac3_encode_init(avctx);

146 }

147

148 AVCodec ff_ac3_encoder = {

149 .name = "ac3",

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

151 .type = AVMEDIA_TYPE_AUDIO,

152 .id = AV_CODEC_ID_AC3,

153 .priv_data_size = sizeof(AC3EncodeContext),

154 .init = ff_ac3_float_encode_init,

155 .encode2 = ff_ac3_float_encode_frame,

156 .close = ff_ac3_encode_close,

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

158 AV_SAMPLE_FMT_NONE },

159 .priv_class = &ac3enc_class,

160 .channel_layouts = ff_ac3_channel_layouts,

161 .defaults = ac3_defaults,

162 };

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