FFmpeg: libavfilter/asrc_aevalsrc.c Source File

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libavfilter

asrc_aevalsrc.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 * eval audio source

24 */

26 #include "libavutil/avassert.h"

27 #include "libavutil/avstring.h"

28 #include "libavutil/channel_layout.h"

29 #include "libavutil/eval.h"

30 #include "libavutil/opt.h"

31 #include "libavutil/parseutils.h"

32 #include "avfilter.h"

33 #include "audio.h"

34 #include "internal.h"

36 static const char * const var_names[] = {

37 "n", ///< number of frame

38 "t", ///< timestamp expressed in seconds

39 "s", ///< sample rate

40 NULL

41 };

43 enum var_name {

44 VAR_N,

45 VAR_T,

46 VAR_S,

47 VAR_VARS_NB

48 };

50 typedef struct {

51 const AVClass *class;

52 char *sample_rate_str;

53 int sample_rate;

54 int64_t chlayout;

55 char *chlayout_str;

56 int nb_channels;

57 int64_t pts;

58 AVExpr *expr[8];

59 char *expr_str[8];

60 int nb_samples; ///< number of samples per requested frame

61 char *duration_str; ///< total duration of the generated audio

62 double duration;

63 uint64_t n;

64 double var_values[VAR_VARS_NB];

65 } EvalContext;

67 #define OFFSET(x) offsetof(EvalContext, x)

68 #define FLAGS AV_OPT_FLAG_AUDIO_PARAM|AV_OPT_FLAG_FILTERING_PARAM

70 static const AVOption aevalsrc_options[]= {

71 { "nb_samples", "set the number of samples per requested frame", OFFSET(nb_samples), AV_OPT_TYPE_INT, {.i64 = 1024}, 0, INT_MAX, FLAGS },

72 { "n", "set the number of samples per requested frame", OFFSET(nb_samples), AV_OPT_TYPE_INT, {.i64 = 1024}, 0, INT_MAX, FLAGS },

73 { "sample_rate", "set the sample rate", OFFSET(sample_rate_str), AV_OPT_TYPE_STRING, {.str = "44100"}, CHAR_MIN, CHAR_MAX, FLAGS },

74 { "s", "set the sample rate", OFFSET(sample_rate_str), AV_OPT_TYPE_STRING, {.str = "44100"}, CHAR_MIN, CHAR_MAX, FLAGS },

75 { "duration", "set audio duration", OFFSET(duration_str), AV_OPT_TYPE_STRING, {.str = NULL}, 0, 0, FLAGS },

76 { "d", "set audio duration", OFFSET(duration_str), AV_OPT_TYPE_STRING, {.str = NULL}, 0, 0, FLAGS },

77 { "channel_layout", "set channel layout", OFFSET(chlayout_str), AV_OPT_TYPE_STRING, {.str = NULL}, 0, 0, FLAGS },

78 { "c", "set channel layout", OFFSET(chlayout_str), AV_OPT_TYPE_STRING, {.str = NULL}, 0, 0, FLAGS },

79 {NULL},

80 };

82 AVFILTER_DEFINE_CLASS(aevalsrc);

84 static int init(AVFilterContext *ctx, const char *args)

85 {

86 EvalContext *eval = ctx->priv;

87 char *args1 = av_strdup(args);

88 char *expr, *buf, *bufptr;

89 int ret, i;

91 eval->class = &aevalsrc_class;

92 av_opt_set_defaults(eval);

94 if (!args1) {

95 av_log(ctx, AV_LOG_ERROR, "Argument is empty\n");

96 ret = args ? AVERROR(ENOMEM) : AVERROR(EINVAL);

97 goto end;

98 }

100 /* parse expressions */

101 buf = args1;

102 i = 0;

103 while (expr = av_strtok(buf, ":", &bufptr)) {

104 ret = av_expr_parse(&eval->expr[i], expr, var_names,

105 NULL, NULL, NULL, NULL, 0, ctx);

106 if (ret < 0)

107 goto end;

108 i++;

109 if (bufptr && *bufptr == ':') { /* found last expression */

110 bufptr++;

111 break;

112 }

113 buf = NULL;

114 }

115 eval->nb_channels = i;

116

117 if (bufptr && (ret = av_set_options_string(eval, bufptr, "=", ":")) < 0)

118 goto end;

119

120 if (eval->chlayout_str) {

121 int n;

122 ret = ff_parse_channel_layout(&eval->chlayout, eval->chlayout_str, ctx);

123 if (ret < 0)

124 goto end;

125

126 n = av_get_channel_layout_nb_channels(eval->chlayout);

127 if (n != eval->nb_channels) {

128 av_log(ctx, AV_LOG_ERROR,

129 "Mismatch between the specified number of channels '%d' "

130 "and the number of channels '%d' in the specified channel layout '%s'\n",

131 eval->nb_channels, n, eval->chlayout_str);

132 ret = AVERROR(EINVAL);

133 goto end;

134 }

135 } else {

136 /* guess channel layout from nb expressions/channels */

137 eval->chlayout = av_get_default_channel_layout(eval->nb_channels);

138 if (!eval->chlayout) {

139 av_log(ctx, AV_LOG_ERROR, "Invalid number of channels '%d' provided\n",

140 eval->nb_channels);

141 ret = AVERROR(EINVAL);

142 goto end;

143 }

144 }

145

146 if ((ret = ff_parse_sample_rate(&eval->sample_rate, eval->sample_rate_str, ctx)))

147 goto end;

148

149 eval->duration = -1;

150 if (eval->duration_str) {

151 int64_t us = -1;

152 if ((ret = av_parse_time(&us, eval->duration_str, 1)) < 0) {

153 av_log(ctx, AV_LOG_ERROR, "Invalid duration: '%s'\n", eval->duration_str);

154 goto end;

155 }

156 eval->duration = (double)us / 1000000;

157 }

158 eval->n = 0;

159

160 end:

161 av_free(args1);

162 return ret;

163 }

164

165 static void uninit(AVFilterContext *ctx)

166 {

167 EvalContext *eval = ctx->priv;

168 int i;

169

170 for (i = 0; i < 8; i++) {

171 av_expr_free(eval->expr[i]);

172 eval->expr[i] = NULL;

173 }

174 av_freep(&eval->chlayout_str);

175 av_freep(&eval->duration_str);

176 av_freep(&eval->sample_rate_str);

177 }

178

179 static int config_props(AVFilterLink *outlink)

180 {

181 EvalContext *eval = outlink->src->priv;

182 char buf[128];

183

184 outlink->time_base = (AVRational){1, eval->sample_rate};

185 outlink->sample_rate = eval->sample_rate;

186

187 eval->var_values[VAR_S] = eval->sample_rate;

188

189 av_get_channel_layout_string(buf, sizeof(buf), 0, eval->chlayout);

190

191 av_log(outlink->src, AV_LOG_VERBOSE,

192 "sample_rate:%d chlayout:%s duration:%f\n",

193 eval->sample_rate, buf, eval->duration);

194

195 return 0;

196 }

197

198 static int query_formats(AVFilterContext *ctx)

199 {

200 EvalContext *eval = ctx->priv;

201 static const enum AVSampleFormat sample_fmts[] = { AV_SAMPLE_FMT_DBLP, AV_SAMPLE_FMT_NONE };

202 int64_t chlayouts[] = { eval->chlayout, -1 };

203 int sample_rates[] = { eval->sample_rate, -1 };

204

205 ff_set_common_formats (ctx, ff_make_format_list(sample_fmts));

206 ff_set_common_channel_layouts(ctx, avfilter_make_format64_list(chlayouts));

207 ff_set_common_samplerates(ctx, ff_make_format_list(sample_rates));

208

209 return 0;

210 }

211

212 static int request_frame(AVFilterLink *outlink)

213 {

214 EvalContext *eval = outlink->src->priv;

215 AVFilterBufferRef *samplesref;

216 int i, j;

217 double t = eval->var_values[VAR_N] * (double)1/eval->sample_rate;

218

219 if (eval->duration >= 0 && t > eval->duration)

220 return AVERROR_EOF;

221

222 samplesref = ff_get_audio_buffer(outlink, AV_PERM_WRITE, eval->nb_samples);

223

224 /* evaluate expression for each single sample and for each channel */

225 for (i = 0; i < eval->nb_samples; i++, eval->n++) {

226 eval->var_values[VAR_N] = eval->n;

227 eval->var_values[VAR_T] = eval->var_values[VAR_N] * (double)1/eval->sample_rate;

228

229 for (j = 0; j < eval->nb_channels; j++) {

230 *((double *) samplesref->extended_data[j] + i) =

231 av_expr_eval(eval->expr[j], eval->var_values, NULL);

232 }

233 }

234

235 samplesref->pts = eval->pts;

236 samplesref->pos = -1;

237 samplesref->audio->sample_rate = eval->sample_rate;

238 eval->pts += eval->nb_samples;

239

240 ff_filter_frame(outlink, samplesref);

241

242 return 0;

243 }

244

245 static const AVFilterPad aevalsrc_outputs[] = {

246 {

247 .name = "default",

248 .type = AVMEDIA_TYPE_AUDIO,

249 .config_props = config_props,

250 .request_frame = request_frame,

251 },

252 { NULL }

253 };

254

255 AVFilter avfilter_asrc_aevalsrc = {

256 .name = "aevalsrc",

257 .description = NULL_IF_CONFIG_SMALL("Generate an audio signal generated by an expression."),

258

259 .query_formats = query_formats,

260 .init = init,

261 .uninit = uninit,

262 .priv_size = sizeof(EvalContext),

263 .inputs = NULL,

264 .outputs = aevalsrc_outputs,

265 .priv_class = &aevalsrc_class,

266 };

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