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/*
* Copyright (c) 2011 Stefano Sabatini
*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* FFmpeg is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
/**
* @file
* eval audio source
*/
#include "libavutil/audioconvert.h"
#include "libavutil/avassert.h"
#include "libavutil/avstring.h"
#include "libavutil/eval.h"
#include "libavutil/opt.h"
#include "avfilter.h"
#include "internal.h"
static const char * const var_names[] = {
"n", ///< number of frame
"t", ///< timestamp expressed in seconds
"s", ///< sample rate
NULL
};
enum var_name {
VAR_N,
VAR_T,
VAR_S,
VAR_VARS_NB
};
typedef struct {
const AVClass *class;
char *sample_rate_str;
int sample_rate;
int64_t chlayout;
int nb_channels;
int64_t pts;
AVExpr *expr[8];
char *expr_str[8];
int nb_samples; ///< number of samples per requested frame
uint64_t n;
double var_values[VAR_VARS_NB];
} EvalContext;
#define OFFSET(x) offsetof(EvalContext, x)
static const AVOption eval_options[]= {
{ "nb_samples", "set the number of samples per requested frame", OFFSET(nb_samples), AV_OPT_TYPE_INT, {.dbl = 1024}, 0, INT_MAX },
{ "n", "set the number of samples per requested frame", OFFSET(nb_samples), AV_OPT_TYPE_INT, {.dbl = 1024}, 0, INT_MAX },
{ "sample_rate", "set the sample rate", OFFSET(sample_rate_str), AV_OPT_TYPE_STRING, {.str = "44100"}, CHAR_MIN, CHAR_MAX },
{ "s", "set the sample rate", OFFSET(sample_rate_str), AV_OPT_TYPE_STRING, {.str = "44100"}, CHAR_MIN, CHAR_MAX },
{NULL},
};
static const char *eval_get_name(void *ctx)
{
return "aevalsrc";
}
static const AVClass eval_class = {
"AEvalSrcContext",
eval_get_name,
eval_options
};
static int init(AVFilterContext *ctx, const char *args, void *opaque)
{
EvalContext *eval = ctx->priv;
char *args1 = av_strdup(args);
char *expr, *buf, *bufptr;
int ret, i;
eval->class = &eval_class;
av_opt_set_defaults(eval);
/* parse expressions */
buf = args1;
i = 0;
while (expr = av_strtok(buf, ":", &bufptr)) {
if (i >= 8) {
av_log(ctx, AV_LOG_ERROR,
"More than 8 expressions provided, unsupported.\n");
ret = AVERROR(EINVAL);
return ret;
}
ret = av_expr_parse(&eval->expr[i], expr, var_names,
NULL, NULL, NULL, NULL, 0, ctx);
if (ret < 0)
goto end;
i++;
if (bufptr && *bufptr == ':') { /* found last expression */
bufptr++;
break;
}
buf = NULL;
}
/* guess channel layout from nb expressions/channels */
eval->nb_channels = i;
eval->chlayout = av_get_default_channel_layout(eval->nb_channels);
if (!eval->chlayout) {
av_log(ctx, AV_LOG_ERROR, "Invalid number of channels '%d' provided\n",
eval->nb_channels);
ret = AVERROR(EINVAL);
goto end;
}
if (bufptr && (ret = av_set_options_string(eval, bufptr, "=", ":")) < 0)
goto end;
if ((ret = ff_parse_sample_rate(&eval->sample_rate, eval->sample_rate_str, ctx)))
goto end;
eval->n = 0;
end:
av_free(args1);
return ret;
}
static void uninit(AVFilterContext *ctx)
{
EvalContext *eval = ctx->priv;
int i;
for (i = 0; i < 8; i++) {
av_expr_free(eval->expr[i]);
eval->expr[i] = NULL;
}
av_freep(&eval->sample_rate_str);
}
static int config_props(AVFilterLink *outlink)
{
EvalContext *eval = outlink->src->priv;
char buf[128];
outlink->time_base = (AVRational){1, eval->sample_rate};
outlink->sample_rate = eval->sample_rate;
eval->var_values[VAR_S] = eval->sample_rate;
av_get_channel_layout_string(buf, sizeof(buf), 0, eval->chlayout);
av_log(outlink->src, AV_LOG_INFO,
"sample_rate:%d chlayout:%s\n", eval->sample_rate, buf);
return 0;
}
static int query_formats(AVFilterContext *ctx)
{
EvalContext *eval = ctx->priv;
enum AVSampleFormat sample_fmts[] = { AV_SAMPLE_FMT_DBL, AV_SAMPLE_FMT_NONE };
int64_t chlayouts[] = { eval->chlayout, -1 };
int packing_fmts[] = { AVFILTER_PLANAR, -1 };
avfilter_set_common_sample_formats (ctx, avfilter_make_format_list(sample_fmts));
avfilter_set_common_channel_layouts(ctx, avfilter_make_format64_list(chlayouts));
avfilter_set_common_packing_formats(ctx, avfilter_make_format_list(packing_fmts));
return 0;
}
static int request_frame(AVFilterLink *outlink)
{
EvalContext *eval = outlink->src->priv;
AVFilterBufferRef *samplesref;
int i, j;
samplesref = avfilter_get_audio_buffer(outlink, AV_PERM_WRITE, eval->nb_samples);
/* evaluate expression for each single sample and for each channel */
for (i = 0; i < eval->nb_samples; i++, eval->n++) {
eval->var_values[VAR_N] = eval->n;
eval->var_values[VAR_T] = eval->var_values[VAR_N] * (double)1/eval->sample_rate;
for (j = 0; j < eval->nb_channels; j++) {
*((double *) samplesref->data[j] + i) =
av_expr_eval(eval->expr[j], eval->var_values, NULL);
}
}
samplesref->pts = eval->pts;
samplesref->pos = -1;
samplesref->audio->sample_rate = eval->sample_rate;
eval->pts += eval->nb_samples;
avfilter_filter_samples(outlink, samplesref);
return 0;
}
AVFilter avfilter_asrc_aevalsrc = {
.name = "aevalsrc",
.description = NULL_IF_CONFIG_SMALL("Generate an audio signal generated by an expression."),
.query_formats = query_formats,
.init = init,
.uninit = uninit,
.priv_size = sizeof(EvalContext),
.inputs = (AVFilterPad[]) {{ .name = NULL}},
.outputs = (AVFilterPad[]) {{ .name = "default",
.type = AVMEDIA_TYPE_AUDIO,
.config_props = config_props,
.request_frame = request_frame, },
{ .name = NULL}},
};
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