2 * Copyright (c) 2011 Stefano Sabatini
4 * This file is part of FFmpeg.
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.
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.
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
26 #include "libavutil/audioconvert.h"
27 #include "libavutil/avassert.h"
28 #include "libavutil/avstring.h"
29 #include "libavutil/eval.h"
30 #include "libavutil/opt.h"
34 static const char * const var_names[] = {
35 "n", ///< number of frame
36 "t", ///< timestamp expressed in seconds
50 char *sample_rate_str;
57 int nb_samples; ///< number of samples per requested frame
59 double var_values[VAR_VARS_NB];
62 #define OFFSET(x) offsetof(EvalContext, x)
64 static const AVOption eval_options[]= {
65 { "nb_samples", "set the number of samples per requested frame", OFFSET(nb_samples), AV_OPT_TYPE_INT, {.dbl = 1024}, 0, INT_MAX },
66 { "n", "set the number of samples per requested frame", OFFSET(nb_samples), AV_OPT_TYPE_INT, {.dbl = 1024}, 0, INT_MAX },
67 { "sample_rate", "set the sample rate", OFFSET(sample_rate_str), AV_OPT_TYPE_STRING, {.str = "44100"}, CHAR_MIN, CHAR_MAX },
68 { "s", "set the sample rate", OFFSET(sample_rate_str), AV_OPT_TYPE_STRING, {.str = "44100"}, CHAR_MIN, CHAR_MAX },
72 static const char *eval_get_name(void *ctx)
77 static const AVClass eval_class = {
83 static int init(AVFilterContext *ctx, const char *args, void *opaque)
85 EvalContext *eval = ctx->priv;
86 char *args1 = av_strdup(args);
87 char *expr, *buf, *bufptr;
90 eval->class = &eval_class;
91 av_opt_set_defaults(eval);
93 /* parse expressions */
96 while (expr = av_strtok(buf, ":", &bufptr)) {
98 av_log(ctx, AV_LOG_ERROR,
99 "More than 8 expressions provided, unsupported.\n");
100 ret = AVERROR(EINVAL);
103 ret = av_expr_parse(&eval->expr[i], expr, var_names,
104 NULL, NULL, NULL, NULL, 0, ctx);
108 if (bufptr && *bufptr == ':') { /* found last expression */
115 /* guess channel layout from nb expressions/channels */
116 eval->nb_channels = i;
117 eval->chlayout = av_get_default_channel_layout(eval->nb_channels);
118 if (!eval->chlayout) {
119 av_log(ctx, AV_LOG_ERROR, "Invalid number of channels '%d' provided\n",
121 ret = AVERROR(EINVAL);
125 if (bufptr && (ret = av_set_options_string(eval, bufptr, "=", ":")) < 0)
128 if ((ret = ff_parse_sample_rate(&eval->sample_rate, eval->sample_rate_str, ctx)))
137 static void uninit(AVFilterContext *ctx)
139 EvalContext *eval = ctx->priv;
142 for (i = 0; i < 8; i++) {
143 av_expr_free(eval->expr[i]);
144 eval->expr[i] = NULL;
146 av_freep(&eval->sample_rate_str);
149 static int config_props(AVFilterLink *outlink)
151 EvalContext *eval = outlink->src->priv;
154 outlink->time_base = (AVRational){1, eval->sample_rate};
155 outlink->sample_rate = eval->sample_rate;
157 eval->var_values[VAR_S] = eval->sample_rate;
159 av_get_channel_layout_string(buf, sizeof(buf), 0, eval->chlayout);
161 av_log(outlink->src, AV_LOG_INFO,
162 "sample_rate:%d chlayout:%s\n", eval->sample_rate, buf);
167 static int query_formats(AVFilterContext *ctx)
169 EvalContext *eval = ctx->priv;
170 enum AVSampleFormat sample_fmts[] = { AV_SAMPLE_FMT_DBL, AV_SAMPLE_FMT_NONE };
171 int64_t chlayouts[] = { eval->chlayout, -1 };
172 int packing_fmts[] = { AVFILTER_PLANAR, -1 };
174 avfilter_set_common_sample_formats (ctx, avfilter_make_format_list(sample_fmts));
175 avfilter_set_common_channel_layouts(ctx, avfilter_make_format64_list(chlayouts));
176 avfilter_set_common_packing_formats(ctx, avfilter_make_format_list(packing_fmts));
181 static int request_frame(AVFilterLink *outlink)
183 EvalContext *eval = outlink->src->priv;
184 AVFilterBufferRef *samplesref;
187 samplesref = avfilter_get_audio_buffer(outlink, AV_PERM_WRITE, eval->nb_samples);
189 /* evaluate expression for each single sample and for each channel */
190 for (i = 0; i < eval->nb_samples; i++, eval->n++) {
191 eval->var_values[VAR_N] = eval->n;
192 eval->var_values[VAR_T] = eval->var_values[VAR_N] * (double)1/eval->sample_rate;
194 for (j = 0; j < eval->nb_channels; j++) {
195 *((double *) samplesref->data[j] + i) =
196 av_expr_eval(eval->expr[j], eval->var_values, NULL);
200 samplesref->pts = eval->pts;
201 samplesref->pos = -1;
202 samplesref->audio->sample_rate = eval->sample_rate;
203 eval->pts += eval->nb_samples;
205 avfilter_filter_samples(outlink, samplesref);
210 AVFilter avfilter_asrc_aevalsrc = {
212 .description = NULL_IF_CONFIG_SMALL("Generate an audio signal generated by an expression."),
214 .query_formats = query_formats,
217 .priv_size = sizeof(EvalContext),
219 .inputs = (const AVFilterPad[]) {{ .name = NULL}},
221 .outputs = (const AVFilterPad[]) {{ .name = "default",
222 .type = AVMEDIA_TYPE_AUDIO,
223 .config_props = config_props,
224 .request_frame = request_frame, },