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avfilter/af_amix: add sum option

This commit is contained in:
Paul B Mahol 2021-02-03 20:39:35 +01:00
parent e955f5ac01
commit 5765149392
2 changed files with 16 additions and 3 deletions
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6
doc/filters.texi
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@ -1879,6 +1879,11 @@ stream ends. The default value is 2 seconds.
@item weights
Specify weight of each input audio stream as sequence.
Each weight is separated by space. By default all inputs have same weight.
@item sum
Do not scale inputs but instead do only summation of samples.
Beware of heavy clipping if inputs are not normalized prior of filtering
or output from @var{amix} normalized after filtering. By default is disabled.
@end table
@subsection Commands
@ -1886,6 +1891,7 @@ Each weight is separated by space. By default all inputs have same weight.
This filter supports the following commands:
@table @option
@item weights
@item sum
Syntax is same as option with same name.
@end table

13
libavfilter/af_amix.c
View File

@ -164,6 +164,7 @@ typedef struct MixContext {
int duration_mode; /**< mode for determining duration */
float dropout_transition; /**< transition time when an input drops out */
char *weights_str; /**< string for custom weights for every input */
int sum; /**< inputs are not scaled, only added */
int nb_channels; /**< number of channels */
int sample_rate; /**< sample rate */
@ -195,6 +196,8 @@ static const AVOption amix_options[] = {
OFFSET(dropout_transition), AV_OPT_TYPE_FLOAT, { .dbl = 2.0 }, 0, INT_MAX, A|F },
{ "weights", "Set weight for each input.",
OFFSET(weights_str), AV_OPT_TYPE_STRING, {.str="1 1"}, 0, 0, A|F|T },
{ "sum", "Do not scale inputs instead do only sum",
OFFSET(sum), AV_OPT_TYPE_BOOL, {.i64=0}, 0, 1, A|F|T },
{ NULL }
};
@ -227,10 +230,14 @@ static void calculate_scales(MixContext *s, int nb_samples)
}
for (i = 0; i < s->nb_inputs; i++) {
if (s->input_state[i] & INPUT_ON)
s->input_scale[i] = 1.0f / s->scale_norm[i] * FFSIGN(s->weights[i]);
else
if (s->input_state[i] & INPUT_ON) {
if (s->sum)
s->input_scale[i] = 1.0f;
else
s->input_scale[i] = 1.0f / s->scale_norm[i] * FFSIGN(s->weights[i]);
} else {
s->input_scale[i] = 0.0f;
}
}
}