FFmpeg: libavfilter/af_apad.c Source File

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libavfilter

af_apad.c

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1 /*

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 */

21 /**

22 * @file

23 * audio pad filter.

24 *

25 * Based on af_aresample.c

26 */

28 #include "libavutil/avstring.h"

29 #include "libavutil/channel_layout.h"

30 #include "libavutil/opt.h"

31 #include "libavutil/samplefmt.h"

32 #include "libavutil/avassert.h"

33 #include "avfilter.h"

34 #include "audio.h"

35 #include "internal.h"

37 typedef struct {

38 const AVClass *class;

39 int64_t next_pts;

41 int packet_size;

42 int64_t pad_len;

43 int64_t whole_len;

44 } APadContext;

46 #define OFFSET(x) offsetof(APadContext, x)

47 #define A AV_OPT_FLAG_AUDIO_PARAM|AV_OPT_FLAG_FILTERING_PARAM

49 static const AVOption apad_options[] = {

50 { "packet_size", "set silence packet size", OFFSET(packet_size), AV_OPT_TYPE_INT, { .i64 = 4096 }, 0, INT_MAX, A },

51 { "pad_len", "number of samples of silence to add", OFFSET(pad_len), AV_OPT_TYPE_INT64, { .i64 = 0 }, 0, INT64_MAX, A },

52 { "whole_len", "target number of samples in the audio stream", OFFSET(whole_len), AV_OPT_TYPE_INT64, { .i64 = 0 }, 0, INT64_MAX, A },

53 { NULL }

54 };

56 AVFILTER_DEFINE_CLASS(apad);

58 static av_cold int init(AVFilterContext *ctx)

59 {

60 APadContext *apad = ctx->priv;

62 apad->next_pts = AV_NOPTS_VALUE;

63 if (apad->whole_len && apad->pad_len) {

64 av_log(ctx, AV_LOG_ERROR, "Both whole and pad length are set, this is not possible\n");

65 return AVERROR(EINVAL);

66 }

68 return 0;

69 }

71 static int filter_frame(AVFilterLink *inlink, AVFrame *frame)

72 {

73 AVFilterContext *ctx = inlink->dst;

74 APadContext *apad = ctx->priv;

76 if (apad->whole_len)

77 apad->whole_len -= frame->nb_samples;

79 apad->next_pts = frame->pts + av_rescale_q(frame->nb_samples, (AVRational){1, inlink->sample_rate}, inlink->time_base);

80 return ff_filter_frame(ctx->outputs[0], frame);

81 }

83 static int request_frame(AVFilterLink *outlink)

84 {

85 AVFilterContext *ctx = outlink->src;

86 APadContext *apad = ctx->priv;

87 int ret;

89 ret = ff_request_frame(ctx->inputs[0]);

91 if (ret == AVERROR_EOF && !ctx->is_disabled) {

92 int n_out = apad->packet_size;

93 AVFrame *outsamplesref;

95 if (apad->whole_len > 0) {

96 apad->pad_len = apad->whole_len;

97 apad->whole_len = 0;

98 }

99 if (apad->pad_len > 0) {

100 n_out = FFMIN(n_out, apad->pad_len);

101 apad->pad_len -= n_out;

102 }

103

104 if(!n_out)

105 return AVERROR_EOF;

106

107 outsamplesref = ff_get_audio_buffer(outlink, n_out);

108 if (!outsamplesref)

109 return AVERROR(ENOMEM);

110

111 av_assert0(outsamplesref->sample_rate == outlink->sample_rate);

112 av_assert0(outsamplesref->nb_samples == n_out);

113

114 av_samples_set_silence(outsamplesref->extended_data, 0,

115 n_out,

116 av_frame_get_channels(outsamplesref),

117 outsamplesref->format);

118

119 outsamplesref->pts = apad->next_pts;

120 if (apad->next_pts != AV_NOPTS_VALUE)

121 apad->next_pts += av_rescale_q(n_out, (AVRational){1, outlink->sample_rate}, outlink->time_base);

122

123 return ff_filter_frame(outlink, outsamplesref);

124 }

125 return ret;

126 }

127

128 static const AVFilterPad apad_inputs[] = {

129 {

130 .name = "default",

131 .type = AVMEDIA_TYPE_AUDIO,

132 .filter_frame = filter_frame,

133 },

134 { NULL }

135 };

136

137 static const AVFilterPad apad_outputs[] = {

138 {

139 .name = "default",

140 .request_frame = request_frame,

141 .type = AVMEDIA_TYPE_AUDIO,

142 },

143 { NULL }

144 };

145

146 AVFilter ff_af_apad = {

147 .name = "apad",

148 .description = NULL_IF_CONFIG_SMALL("Pad audio with silence."),

149 .init = init,

150 .priv_size = sizeof(APadContext),

151 .inputs = apad_inputs,

152 .outputs = apad_outputs,

153 .priv_class = &apad_class,

154 .flags = AVFILTER_FLAG_SUPPORT_TIMELINE_INTERNAL,

155 };

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