FFmpeg: libswresample/dither.c Source File

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libswresample

dither.c

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1 /*

3 *

4 * This file is part of libswresample

5 *

6 * libswresample 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 * libswresample 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 libswresample; if not, write to the Free Software

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

19 */

21 #include "libavutil/avassert.h"

22 #include "swresample_internal.h"

24 #include "noise_shaping_data.c"

26 void swri_get_dither(SwrContext *s, void *dst, int len, unsigned seed, enum AVSampleFormat noise_fmt) {

27 double scale = s->dither.noise_scale;

28 #define TMP_EXTRA 2

29 double *tmp = av_malloc((len + TMP_EXTRA) * sizeof(double));

30 int i;

32 for(i=0; i<len + TMP_EXTRA; i++){

33 double v;

34 seed = seed* 1664525 + 1013904223;

36 switch(s->dither.method){

37 case SWR_DITHER_RECTANGULAR: v= ((double)seed) / UINT_MAX - 0.5; break;

38 default:

39 av_assert0(s->dither.method < SWR_DITHER_NB);

40 v = ((double)seed) / UINT_MAX;

41 seed = seed*1664525 + 1013904223;

42 v-= ((double)seed) / UINT_MAX;

43 break;

44 }

45 tmp[i] = v;

46 }

48 for(i=0; i<len; i++){

49 double v;

51 switch(s->dither.method){

52 default:

53 av_assert0(s->dither.method < SWR_DITHER_NB);

54 v = tmp[i];

55 break;

56 case SWR_DITHER_TRIANGULAR_HIGHPASS :

57 v = (- tmp[i] + 2*tmp[i+1] - tmp[i+2]) / sqrt(6);

58 break;

59 }

61 v*= scale;

63 switch(noise_fmt){

64 case AV_SAMPLE_FMT_S16P: ((int16_t*)dst)[i] = v; break;

65 case AV_SAMPLE_FMT_S32P: ((int32_t*)dst)[i] = v; break;

66 case AV_SAMPLE_FMT_FLTP: ((float *)dst)[i] = v; break;

67 case AV_SAMPLE_FMT_DBLP: ((double *)dst)[i] = v; break;

68 default: av_assert0(0);

69 }

70 }

72 av_free(tmp);

73 }

75 int swri_dither_init(SwrContext *s, enum AVSampleFormat out_fmt, enum AVSampleFormat in_fmt)

76 {

77 int i;

78 double scale = 0;

80 if (s->dither.method > SWR_DITHER_TRIANGULAR_HIGHPASS && s->dither.method <= SWR_DITHER_NS)

81 return AVERROR(EINVAL);

83 out_fmt = av_get_packed_sample_fmt(out_fmt);

84 in_fmt = av_get_packed_sample_fmt( in_fmt);

86 if(in_fmt == AV_SAMPLE_FMT_FLT || in_fmt == AV_SAMPLE_FMT_DBL){

87 if(out_fmt == AV_SAMPLE_FMT_S32) scale = 1.0/(1L<<31);

88 if(out_fmt == AV_SAMPLE_FMT_S16) scale = 1.0/(1L<<15);

89 if(out_fmt == AV_SAMPLE_FMT_U8 ) scale = 1.0/(1L<< 7);

90 }

91 if(in_fmt == AV_SAMPLE_FMT_S32 && out_fmt == AV_SAMPLE_FMT_S32 && (s->dither.output_sample_bits&31)) scale = 1;

92 if(in_fmt == AV_SAMPLE_FMT_S32 && out_fmt == AV_SAMPLE_FMT_S16) scale = 1L<<16;

93 if(in_fmt == AV_SAMPLE_FMT_S32 && out_fmt == AV_SAMPLE_FMT_U8 ) scale = 1L<<24;

94 if(in_fmt == AV_SAMPLE_FMT_S16 && out_fmt == AV_SAMPLE_FMT_U8 ) scale = 1L<<8;

96 scale *= s->dither.scale;

98 if (out_fmt == AV_SAMPLE_FMT_S32 && s->dither.output_sample_bits)

99 scale *= 1<<(32-s->dither.output_sample_bits);

100

101 s->dither.ns_pos = 0;

102 s->dither.noise_scale= scale;

103 s->dither.ns_scale = scale;

104 s->dither.ns_scale_1 = scale ? 1/scale : 0;

105 memset(s->dither.ns_errors, 0, sizeof(s->dither.ns_errors));

106 for (i=0; filters[i].coefs; i++) {

107 const filter_t *f = &filters[i];

108 if (fabs(s->out_sample_rate - f->rate) / f->rate <= .05 && f->name == s->dither.method) {

109 int j;

110 s->dither.ns_taps = f->len;

111 for (j=0; j<f->len; j++)

112 s->dither.ns_coeffs[j] = f->coefs[j];

113 s->dither.ns_scale_1 *= 1 - exp(f->gain_cB * M_LN10 * 0.005) * 2 / (1<<(8*av_get_bytes_per_sample(out_fmt)));

114 break;

115 }

116 }

117 if (!filters[i].coefs && s->dither.method > SWR_DITHER_NS) {

118 av_log(s, AV_LOG_WARNING, "Requested noise shaping dither not available at this sampling rate, using triangular hp dither\n");

119 s->dither.method = SWR_DITHER_TRIANGULAR_HIGHPASS;

120 }

121

122 av_assert0(!s->preout.count);

123 s->dither.noise = s->preout;

124 s->dither.temp = s->preout;

125 if (s->dither.method > SWR_DITHER_NS) {

126 s->dither.noise.bps = 4;

127 s->dither.noise.fmt = AV_SAMPLE_FMT_FLTP;

128 s->dither.noise_scale = 1;

129 }

130

131 return 0;

132 }

133

134 #define TEMPLATE_DITHER_S16

135 #include "dither_template.c"

136 #undef TEMPLATE_DITHER_S16

137

138 #define TEMPLATE_DITHER_S32

139 #include "dither_template.c"

140 #undef TEMPLATE_DITHER_S32

141

142 #define TEMPLATE_DITHER_FLT

143 #include "dither_template.c"

144 #undef TEMPLATE_DITHER_FLT

145

146 #define TEMPLATE_DITHER_DBL

147 #include "dither_template.c"

148 #undef TEMPLATE_DITHER_DBL

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