It accepts the syntax: @var{exprs}[::@var{options}].
@var{exprs} is a list of expressions separated by ":", one for each
-separate channel. The output channel layout depends on the number of
-provided expressions, up to 8 channels are supported.
+separate channel. In case the @var{channel_layout} is not
+specified, the selected channel layout depends on the number of
+provided expressions.
@var{options} is an optional sequence of @var{key}=@var{value} pairs,
separated by ":".
@table @option
+@item channel_layout, c
+Set the channel layout. The number of channels in the specified layout
+must be equal to the number of specified expressions.
+
@item duration, d
Set the minimum duration of the sourced audio. See the function
@code{av_parse_time()} for the accepted format.
@end example
@item
+Generate a two channels signal, specify the channel layout (Front
+Center + Back Center) explicitly:
+@example
+aevalsrc="sin(420*2*PI*t):cos(430*2*PI*t)::c=FC|BC"
+@end example
+
+@item
Generate white noise:
@example
aevalsrc="-2+random(0)"
char *sample_rate_str;
int sample_rate;
int64_t chlayout;
+ char *chlayout_str;
int nb_channels;
int64_t pts;
AVExpr *expr[8];
{ "s", "set the sample rate", OFFSET(sample_rate_str), AV_OPT_TYPE_STRING, {.str = "44100"}, CHAR_MIN, CHAR_MAX },
{ "duration", "set audio duration", OFFSET(duration_str), AV_OPT_TYPE_STRING, {.str = NULL}, 0, 0 },
{ "d", "set audio duration", OFFSET(duration_str), AV_OPT_TYPE_STRING, {.str = NULL}, 0, 0 },
+ { "channel_layout", "set channel layout", OFFSET(chlayout_str), AV_OPT_TYPE_STRING, {.str = NULL}, 0, 0 },
+ { "c", "set channel layout", OFFSET(chlayout_str), AV_OPT_TYPE_STRING, {.str = NULL}, 0, 0 },
{NULL},
};
}
buf = NULL;
}
+ eval->nb_channels = i;
+
+ if (bufptr && (ret = av_set_options_string(eval, bufptr, "=", ":")) < 0)
+ goto end;
+
+ if (eval->chlayout_str) {
+ int n;
+ ret = ff_parse_channel_layout(&eval->chlayout, eval->chlayout_str, ctx);
+ if (ret < 0)
+ goto end;
+ n = av_get_channel_layout_nb_channels(eval->chlayout);
+ if (n != eval->nb_channels) {
+ av_log(ctx, AV_LOG_ERROR,
+ "Mismatch between the specified number of channels '%d' "
+ "and the number of channels '%d' in the specified channel layout '%s'\n",
+ eval->nb_channels, n, eval->chlayout_str);
+ ret = AVERROR(EINVAL);
+ goto end;
+ }
+ } else {
/* 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",
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;
av_expr_free(eval->expr[i]);
eval->expr[i] = NULL;
}
+ av_freep(&eval->chlayout_str);
av_freep(&eval->duration_str);
av_freep(&eval->sample_rate_str);
}